OUR Mars Colony

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I have allocated a percentage of my attention recently to the significant problem of colonising Mars. This thread is dedicated to addressing the problems, collating relevant data, and providing potential solutions within OUR means.

The recent discovery of ice cliffs on Mars and the theory that most of the liquid water on Mars is locked up as a solid just below the surface has given a significant boost to a potential Earth colony for Everyman on an extraterrestrial planet.

Mars ice cliffs could be key to supporting life on Red Planet

https://www.rt.com/news/415706-mars-ice-sheets-water/

Mars has ice sheets more than 100 meters deep hiding beneath its red dust, offering a potential water source for future explorers of the Red Planet, according to new research.

A team of scientists, led by Colin Dundas, a geologist at the US Geological Survey, analyzed data from the Mars Reconnaissance Orbiter (MRO), specifically looking at eight areas where erosion occurred.

The results revealed massive subsurface ice sheets on the planet extending from just below the surface to a depth of at least 100 meters (328ft).

    Mars might not be as dry as previously thought https://t.co/eO943EF8hj
    — RT (@RT_com) December 25, 2017

The remarkable ice cliffs appear to contain distinct layers, which could preserve a record of Mars' past climate, according to the report.

Scientists say an analysis of the deposits would unleash a treasure trove of information to geologists about the past Martian climate.

"That preserved record would be of extreme importance to go back to," G. Scott Hubbard, a space scientist at Stanford University in Palo Alto, California told Science.

The discovery is particularly exciting for future human exploration of the planet previously renowned for its dry arid landscape.

    Future Martian explorers may have a more accessible supply of water thanks to a new discovery from our Mars Orbiter: Eight sites of thick, relatively pure water ice deposits, likely accumulated as snow long ago, have been found on the Red Planet. Details: https://t.co/fE16INLoaepic.twitter.com/bITL6PdfjD
    — NASA (@NASA) January 11, 2018

Scientists point out that the hidden ice sheets could pave the way for supporting life on Mars. These sites are "very exciting" for potential human bases, Angel Abbud-Madrid, director of the Center for Space Resources at the Colorado School of Mines in Golden said.

The ice cliffs promise abundant, accessible ice, noted Abbud-Madrid, who led a recent NASA study exploring potential landing sites for astronauts.

This is not the first time ice has been found on Mars. Over the last decade the MRO has returned high resolution images and data detailing the landscape.

A radar instrument on the MRO previously detected signatures of thick, buried ice across the planet's belly, however, this latest study indicates a greater prevalence of Martian ice.

"This kind of ice is more widespread than previously thought," Dundas told Science.

READ MORE: Martian 'rocket test' proves worms can thrive in Red Planet soil

The cliffs were all found at latitudes about 55° north or south – discouraging latitudes for a solar-powered human base, according to the team.

Scientists now want to seek out similar cliffs closer to the equator, hoping that the next surprise awaiting them is the discovery of ice nearer to the tropics.

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colony

https://www.thefreedictionary.com/colony

col·o·ny  (kŏl′ə-nē)
n. pl. col·o·nies
1.
     a. A group of emigrants or their descendants who settle in a distant territory but remain subject to or closely associated with the parent country.
     b. A territory thus settled.
2. A region politically controlled by a distant country; a dependency.
3.
     a. A group of people with the same interests or ethnic origin concentrated in a particular area: the American colony in Paris.
     b. The area occupied by such a group.
4. Colonies The British colonies that became the original 13 states of the United States.
5. A group of people who have been institutionalized in a relatively remote area: an island penal colony.
6. A group of the same kind of animals, plants, or one-celled organisms living or growing together.
7. A visible growth of microorganisms, usually in a solid or semisolid nutrient medium.

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Mars Compared to Earth

https://www.universetoday.com/22603/mars-compared-to-earth/

Article written: 5 Dec , 2015
Updated: 10 Jan , 2018
by Matt Williams

At one time, astronomers believed the surface of Mars was crisscrossed by canal systems. This in turn gave rise to speculation that Mars was very much like Earth, capable of supporting life and home to a native civilization. But as human satellites and rovers began to conduct flybys and surveys of the planet, this vision of Mars quickly dissolved, replaced by one in which the Red Planet was a cold, desiccated and lifeless world.

However, over the past few decades, scientists have come to learn a great deal about the history of Mars that has altered this view as well. We now know that though Mars may currently be very cold, very dry, and very inhospitable, this wasn't always the case. What's more, we have come to see that even in its current form, Mars and Earth actually have a lot in common.

Between the two planets, there are similarities in size, inclination, structure, composition, and even the presence of water on their surfaces. That being said, they also have a lot of key differences that would make living on Mars, a growing preoccupation among many humans (looking at you, Elon Musk and Bas Lansdorp!), a significant challenge. Let's go over these similarities and the difference in an orderly fashion, shall we?

Sizes, Masses and Orbits:

In terms of their size and mass, Earth and Mars are quite different. With a mean radius of 6371 km and a mass of 5.97×1024 kg, Earth is the fifth largest and fifth most-massive planet in the Solar System, and the largest of the terrestrial planets. Mars, meanwhile, has a radius of approximately 3,396 km at its equator (3,376 km at its polar regions), which is the equivalent of roughly 0.53 Earths. However, it's mass is just 6.4185 x 10²³ kg, which is around 10.7% that of Earth's.

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Similarly, Earth's volume is a hefty 1.08321 x 1012 km3, which works out 1,083 billion cubic kilometers. By comparison, Mars has a volume of 1.6318 x 10¹¹ km³ (163 billion cubic kilometers) which is the equivalent of 0.151 Earths. Between this difference in size, mass, and volume, Mars's surface gravity is 3.711 m/s², which works out to 37.6% of Earths (0.376 g).

In terms of their orbits, Earth and Mars are also quite different. For instance, Earth orbits the Sun at an average distance (aka. semi-major axis) of 149,598,261 km – or one Astronomical Unit (AU). This orbit has a very minor eccentricity (approx. 0.0167), which means its orbit ranges from 147,095,000 km (0.983 AU) at perihelion to 151,930,000 km (1.015 AU) at aphelion.

At its greatest distance from the Sun (aphelion), Mars orbits at a distance of approximately 249,200,000 million km (1.666 AU). At perihelion, when it is closest to the Sun, it orbits at a distance of approximately 206,700,000 million km (1.3814 AU). At these distances, the Earth has an orbital period of 365.25 days (1.000017 Julian years) while Mars has an orbital period of 686.971 days (1.88 Earth years).

However, in terms of their sidereal rotation (time it takes for the planet to complete a single rotation on its axis) Earth and Mars are again in the same boat. While Earth takes precisely 23h 56m and 4 s to complete a single sidereal rotation (0.997 Earth days), Mars does the same in about 24 hours and 40 minutes. This means that one Martian day (aka. Sol) is very close to single day on Earth.

Mars's axial tilt is very similar to Earth's, being inclined 25.19° to its orbital plane (whereas Earth's axial tilt is just over 23°). This means that Mars also experiences seasons and temperature variations similar to that of Earth (see below).

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Structure and Composition:

Earth and Mars are similar when it comes to their basic makeups, given that they are both terrestrial planets. This means that both are differentiated between a dense metallic core and an overlying mantle and crust composed of less dense materials (like silicate rock). However, Earth's density is higher than that of Mars – 5.514 g/cm3 compared to 3.93 g/cm³ (or 0.71 Earths) – which indicates that Mars' core region contains more lighter elements than Earth's.

Earth's core region is made up of a solid inner core that has a radius of about 1,220 km and a liquid outer core that extends to a radius of about 3,400 km. Both the inner and outer cores are composed of iron and nickel, with trace amounts of lighter elements, and together, they add to a radius that is as large as Mars itself. Current models of Mars' interior suggest that its core region is roughly  1,794 ± 65 kilometers (1,115 ± 40 mi) in radius, and is composed primarily of iron and nickel with about 16-17% sulfur.

Both planets have a silicate mantle surrounding their cores and a surface crust of solid material. Earth's mantle – consisting of an upper mantle of slightly viscous material and a lower mantle that is more solid – is roughly 2,890 km (1,790 mi) thick and is composed of silicate rocks that are rich in iron and magnesium. The Earth's crust is on average 40 km (25 mi) thick, and is composed of rocks that are rich in iron and magnesium (i.e. igneous rocks) and granite (rich in sodium, potassium, and aluminum).

Comparatively, Mars' mantle is quite thin, measuring some 1,300 to 1,800 kilometers (800 – 1,100 mi) in thickness. Like Earth, this mantle is believed to be composed of silicate rock that are rich in minerals compared to the crust, and to be partially viscous (resulting in convection currents which shaped the surface). The crust, meanwhile, averages about 50 km (31 mi) in thickness, with a maximum of 125 km (78 mi). This makes it about three times as hick as Earth's crust, relative to the sizes of the two planets.

Ergo, the two planets are similar in composition, owing to their common status as terrestrial planets. And while they are both differentiated between a metallic core and layers of less dense material, there is some variance in terms of how proportionately thick their respective layers are.

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Surface Features:

When it comes to the surfaces of Earth and Mars, things once again become a case of contrasts. Naturally, it is the differences that are most apparent when comparing Blue Earth to the Red Planet – as the nicknames would suggest. Unlike other planet's in our Solar System, the vast majority of Earth is covered in liquid water, about 70% of the surface – or 361.132 million km² (139.43 million sq mi) to be exact.

The surface of Mars is dry, dusty, and covered in dirt that is rich iron oxide (aka. rust, leading to its reddish appearance). However, large concentrations of ice water are known to exist within the polar ice caps – Planum Boreum and Planum Australe. In addition, a permafrost mantle stretches from the pole to latitudes of about 60°, meaning that ice water exists beneath much of the Martian surface. Radar data and soil samples have confirmed the presence of shallow subsurface water at the middle latitudes as well.

As for the similarities, Earth and Mars' both have terrains that varies considerably from place to place. On Earth, both above and below sea level, there are mountainous features, volcanoes, scarps (trenches), canyons, plateaus, and abyssal plains. The remaining portions of the surface are covered by mountains, deserts, plains, plateaus, and other landforms.

Mars is quite similar, with a surface covered by mountain ranges, sandy plains, and even some of the largest sand dunes in the Solar System. It also has the largest mountain in the Solar System, the shield volcano Olympus Mons, and the longest, deepest chasm in the Solar System: Valles Marineris.

Earth and Mars have also experienced many impacts from asteroids and meteors over the years. However, Mars' own impact craters are far better preserved, with many dating back billions of years. The reason for this is the low air pressure and lack of precipitation on Mars, which results in a very slow rate of erosion. However, this was not always the case.

Mars has discernible gullies and channels on its surface, and many scientists believe that liquid water used to flow through them. By comparing them to similar features on Earth, it is believed that these were were at least partially formed by water erosion.  Some of these channels are quite large, reaching 2,000 kilometers in length and 100 kilometers in width.

So while they look quite different today, Earth and Mars were once quite similar. And similar geological processes occurred on both planets to give them the kind of varied terrain they both currently have.

https://www.youtube.com/watch?time_continue=5&v=7koIlNPay-s

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Atmosphere and Temperature:

Atmospheric pressure and temperatures are another way in which Earth and Mars are quite different. Earth has a dense atmosphere composed of five main layers – the Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, and the Exosphere. Mars' is very thin by comparison, with pressure ranging from 0.4 – 0.87 kPa – which is equivalent to about 1% of Earth's at sea level.

Earth's atmosphere is also primarily composed of nitrogen (78%) and oxygen (21%) with trace concentrations of water vapor, carbon dioxide, and other gaseous molecules. Mars' is composed of 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water. Recent surveys have also noted trace amounts of methane, with an estimated concentration of about 30 parts per billion (ppb).

Because of this, there is a considerable difference between the average surface temperature on Earth and Mars. On Earth, it is approximately 14°C, with plenty of variation due to geographical region, elevation, and time of year. The hottest temperature ever recorded on Earth was 70.7°C (159°F) in the Lut Desert of Iran, while the coldest temperature was -89.2°C (-129°F) at the Soviet Vostok Station on the Antarctic Plateau.

Because of its thin atmosphere and its greater distance from the Sun, the surface temperature of Mars is much colder, averaging at -46 °C (-51 °F). However, because of its tilted axis and orbital eccentricity, Mars also experiences considerable variations in temperature. These can be seen in the form of a low temperature of -143 °C (-225.4 °F) during the winter at the poles, and a high of 35 °C (95 °F) during summer and midday at the equator.

The atmosphere of Mars is also quite dusty, containing particulates that measure 1.5 micrometers in diameter, which is what gives the Martian sky a tawny color when seen from the surface. The planet also experiences dust storms, which can turn into what resembles small tornadoes. Larger dust storms occur when the dust is blown into the atmosphere and heats up from the Sun.

So basically, Earth has a dense atmosphere that is rich in oxygen and water vapor, and which is generally warm and conducive to life. Mars, meanwhile, is generally very cold, but can become quite warm at times. It's also quite dry and very dusty.

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Magnetic Fields:

When it comes to magnetic fields, Earth and Mars are in stark contrast to each other. On Earth, the dynamo effect created by the rotation of Earth's inner core, relative to the rotation of the planet, generates the currents which are presumed to be the source of its magnetic field. The presence of this field is of extreme importance to both Earth's atmosphere and to life on Earth as we know it.

Essentially, Earth's magnetosphere serves to deflect most of the solar wind's charged particles which would otherwise strip away the ozone layer and expose Earth to harmful radiation. The field ranges in strength between approximately 25,000 and 65,000 nanoteslas (nT), or 0.25–0.65 Gauss units (G).

Today, Mars has weak magnetic fields in various regions of the planet which appear to be the remnant of a magnetosphere. These fields were first measured by the Mars Global Surveyor, which indicated fields of inconsistent strengths measuring at most 1500 nT (~16-40 times less than Earth's). In the northern lowlands, deep impact basins, and the Tharsis volcanic province, the field strength is very low. But in the ancient southern crust, which is undisturbed by giant impacts and volcanism, the field strength is higher.

This would seem to indicate that Mars had a magnetosphere in the past, and explanations vary as to how it lost it. Some suggest that it was blown off, along with the majority of Mars' atmosphere, by a large impact during the Late Heavy Bombardment. This impact, it is reasoned, would have also upset the heat flow in Mars' iron core, arresting the dynamo effect that would have produced the magnetic field.

Another theory, based on NASA's MAVEN mission to study the Martian atmosphere, has it that Mars' lost its magnetosphere when the smaller planet cooled, causing its dynamo effect to cease some 4.2 billion years ago. During the next several hundred million years, the Sun's powerful solar wind stripped particles away from the unprotected Martian atmosphere at a rate 100 to 1,000 times greater than that of today. This in turn is what caused Mars to lose the liquid water that existed on its surface, as the environment to become increasing cold, desiccated, and inhospitable.

https://www.youtube.com/watch?time_continue=1&v=wDNDz_VP3PE

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Satellites:

Earth and Mars are also similar in that both have satellites that orbit them. In Earth's case, this is none other than The Moon, our only natural satellite and the source of the Earth's tides. It's existence has been known of since prehistoric times, and it has played a major role in the mythological and astronomical traditions of all human cultures. In addition, its size, mass and other characteristics are used as a reference point when assessing other satellites.

The Moon is one of the largest natural satellites in the Solar System and is the second-densest satellite of those whose moons who's densities are known (after Jupiter's satellite Io). Its diameter, at 3,474.8 km, is one-fourth the diameter of Earth; and at 7.3477 × 1022 kg, its mass is 1.2% of the Earth's mass. It's mean density is 3.3464 g/cm3 , which is equivalent to roughly 0.6 that of Earth. All of this results in our Moon possessing gravity that is about 16.54% the strength of Earth's (aka. 1.62 m/s2).

The Moon varies in orbit around Earth, going from 362,600 km at perigee to 405,400 km at apogee. And like most known satellites within our Solar System, the Moon's sidereal rotation period (27.32 days) is the same as its orbital period. This means that the Moon is tidally locked with Earth, with one side is constantly facing towards us while the other is facing away.

Thanks to examinations of Moon rocks that were brought back to Earth, the predominant theory states that the Moon was created roughly 4.5 billion years ago from a collision between Earth and a Mars-sized object (known as Theia). This collision created a massive cloud of debris that began circling our planet, which eventually coalesced to form the Moon we see today.

https://www.youtube.com/watch?v=yThdl3fVuaE

Mars has two small satellites, Phobos and Deimos. These moons were discovered in 1877 by the astronomer Asaph Hall and were named after mythological characters. In keeping with the tradition of deriving names from classical mythology, Phobos and Deimos are the sons of Ares – the Greek god of war that inspired the Roman god Mars. Phobos represents fear while Deimos stands for terror or dread.

Phobos measures about 22 km (14 mi) in diameter, and orbits Mars at a distance of 9,234.42 km when it is at periapsis (closest to Mars) and 9,517.58 km when it is at apoapsis (farthest). At this distance, Phobos is below synchronous altitude, which means that it takes only 7 hours to orbit Mars and is gradually getting closer to the planet. Scientists estimate that in 10 to 50 million years, Phobos could crash into Mars' surface or break up into a ring structure around the planet.

Meanwhile, Deimos measures about 12 km (7.5 mi) and orbits the planet at a distance of 23,455.5 km (periapsis) and 23,470.9 km (apoapsis). It has a longer orbital period, taking 1.26 days to complete a full rotation around the planet. Mars may have additional moons that are smaller than 50- 100 meters (160 to 330 ft) in diameter, and a dust ring is predicted between Phobos and Deimos.

https://www.youtube.com/watch?time_continue=1&v=BJHRyjkmxss

Scientists believe that these two satellites were once asteroids that were captured by the planet's gravity. The low albedo and the carboncaceous chondrite composition of both moons – which is similar to asteroids – supports this theory, and Phobos' unstable orbit would seem to suggest a recent capture. However, both moons have circular orbits near the equator, which is unusual for captured bodies.

So while Earth has a single satellite that is quite large and dense, Mars has two satellites that are small and orbit it at a comparatively close distance. And whereas the Moon was formed from Earth's own debris after a rather severe collision, Mars' satellites were likely captured asteroids.

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Conclusion:

Okay, let's review. Earth and Mars have their share of similarities, but also some rather stark differences.

Mean Radius:                6,371 km                      3,396 km

Mass:                                59.7×1023 kg              6.42 x 10²³ kg

Volume:                           10.8 x 1011 km3         1.63 x 10¹¹ km³

Semi-Major Axis:         0.983 – 1.015 AU      1.3814 – 1.666 AU

Air Pressure:                 101.325 kPa                0.4 – 0.87 kPa

Gravity:                            9.8 m/s²                     3.711 m/s²

Avg. Temperature:      14°C (57.2 °F)            -46 °C (-51 °F)

Temp. Variations:       ±160 °C (278°F)        ±178 °C (320°F)

Axial Tilt:                          23°                               25.19°

Length of Day:               24 hours                     24h 40m

Length of Year:             365.25 days                686.971 days

Water:                              Plentiful                      Intermittent (mostly frozen)

Polar Ice Caps:               Yep                              Yep

In short, compared to Earth, Mars is a pretty small, dry, cold, and dusty planet. It has comparatively low gravity, very little atmosphere and no breathable air. And the years are also mighty long, almost twice that of Earth, in fact. However, the planet does have its fair share of water (albeit mostly in ice form), has seasonal cycles similar to Earth, temperature variations that are similar, and a day that is almost as long.

All of these factors will have to be addressed if ever human beings want to live there. And whereas some can be worked with, others will have to be overcome or adapted to. And for that, we will have to lean pretty heavily on our technology (i.e. terraforming and geoengineering). Best of luck to those who would like to venture there someday, and who do not plan on coming home!

We have written many articles about Mars here on Universe Today. Here's an article about how difficult it will be to land large payloads onto the surface of Mars, and here's an article about the Mars methane mystery.

And here are some on the distance between Earth and Mars, Mars' gravity, and if humans can live on Mars.

If you'd like more info on Mars, check out Hubblesite's News Releases about Mars, and here's a link to the NASA Mars Exploration home page.

And be sure to check out NASA's Solar System Exploration: Earth and Mars Comparison Chart

We have recorded several podcasts just about Mars. Including Episode 52: Mars and Episode 92: Missions to Mars, Part 1.

Sources:

    NASA – All About Mars
    NASA: Solar System Overview – Earth
    University of Phoenix – Mars Mission
    Wikipedia – Mars

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NASA: New Mars Gravity Map Is the Best Ever

https://www.space.com/32362-mars-gravity-map-best-ever-video.html

By Elizabeth Howell, Space.com Contributor | March 24, 2016 07:22am ET

A new map of Mars' gravity, which NASA is touting as the best one ever made, will make it easier for future spacecraft to make their way to the Red Planet. The new Martian gravity map also reveals clues into how the planet's past was shaped, scientists say.

The new map of Mars' gravity was generated by scientists using data from three NASA spacecraft — the Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter —which mapped the Red Planet from orbit. The data allowed NASA to create a video look at Mars' gravity, as well.

"Gravity maps allow us to see inside a planet, just as a doctor uses an X-ray to see inside a patient," lead author Antonio Genova of the Massachusetts Institute of Technology (MIT) and the NASA Goddard Space Flight Center, said in a statement. [The 7 Biggest Mars Mysteries]

"The new gravity map will be helpful for future Mars exploration, because better knowledge of the planet's gravity anomalies helps mission controllers insert spacecraft more precisely into orbit about Mars. Furthermore, the improved resolution of our gravity map will help us understand the still-mysterious formation of specific regions of the planet."

The new map has also revealed additional insights about Mars. By observing tides in the Martian crust and mantle created from the gravitational pull of the sun and Mars' two moons, the team confirmed that the core of Mars has a liquid exterior of molten rock. They also looked at changes in Martian gravity — which is about one-third that of Earth's gravity — over 11 years (the same as the sun's cycle of activity). An examination of these changes gave them new insights into how much of the polar ice cap's carbon dioxide freezes out of the atmosphere during winter. The team also gained insights into features across the north-south boundary of Mars, and how carbon dioxide moves between the south pole and the north pole.

NASA created the map by tracking small fluctuations in the orbits of three spacecraft over 16 years using the Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter. The gravity in different regions of Mars changes according to what is below; mountains exert a slightly stronger tug and canyons a slightly weaker one, for example. The team also had to take into account orbital fluctuations from other sources, such as sunlight's force on the vehicle's solar panels and drag from Mars' atmosphere.

"With this new map, we've been able to see gravity anomalies as small as about 100 kilometers (about 62 miles) across, and we've determined the crustal thickness of Mars with a resolution of around 120 kilometers (almost 75 miles)," Genova said in the NASA statement. "The better resolution of the new map helps interpret how the crust of the planet changed over Mars' history in many regions."

Scientists also gained more information about why there is an area of lower gravity between Acidalia Planitia and Tempe Terra. An earlier explanation was that, billions of years ago, when the Red Planet was warmer and wetter, there were channels under the soil that moved water and regolith from Mars' south highlands to its north lowlands.

The new map, however, suggests that the lower gravity is not solely due to these buried channels, because it shows some features running against the downhill slope of water. The team suggests that this may instead be due to flexing of the lithosphere (the outermost layer of the planet) that occurred when the volcanic Tharsis region formed. The volcanoes in Tharsis are so large that their weight caused the lithosphere to cave in slightly.

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What is the Temperature of Mars?

https://www.space.com/16907-what-is-the-temperature-of-mars.html

By Tim Sharp, Reference Editor | November 29, 2017 07:29pm ET

Mars is a harsh, cold world. It is much colder than Earth; but then, it is also farther from the sun. The small, barren planet also has a thin atmosphere that is 95 percent carbon dioxide.

Extreme differences

Mars's atmosphere is about 100 times thinner than Earth's. Without a "thermal blanket," Mars can't retain any heat energy. On average, the temperature on Mars is about minus 80 degrees Fahrenheit (minus 60 degrees Celsius). In winter, near the poles temperatures can get down to minus 195 degrees F (minus 125 degrees C). A summer day on Mars may get up to 70 degrees F (20 degrees C) near the equator, but at night the temperature can plummet to about minus 100 degrees F (minus 73 C).

NASA's Mars Curiosity rover measured air temperatures as high as 43 degrees F (6 degrees C) in the afternoon, with temperatures climbing above freezing for a significant number of days.

"That we are seeing temperatures this warm already during the day is a surprise and very interesting," Felipe Gómez, of the Centro de Astrobiologia in Madrid, said in a statement.

Frost forms on the rocks at night, but as dawn approaches and the air gets warmer, the frost turns to vapor, and there is 100 percent humidity until it evaporates. The high humidity could help make Mars more habitable, if the water condenses to form short-term puddles in the early morning hours.

"The conditions on Mars, where the relative humidity is high and the available water vapor is approximately 100 precipitable microns, is the equivalent of the drier parts of the Atacama Desert in Chile," John Rummel, of East Carolina University, told Space.com by email.

According to Rummel, the humidity of Mars is tied to temperature fluctuations. At night, relative humidity levels can rise to 80 to 100 percent, with the air sometimes reaching atmospheric saturation. The daytime air is far drier, due to warmer temperatures.

On Earth, some forms of life are able to survive in parched regions by poaching water from the humid air. Among these, lichens dominate, surviving in arid climates without succumbing to the dry spells that frequently occur. Some lichens in super-dry areas have been found to photosynthesize at relative humidity levels as low as 70 percent. Other research has demonstrated that a form of Antarctic lichen can adapt to life under simulated Martian conditions.

"Such short-term wet periods might be long enough and warm enough to allow for Earth organisms to metabolize and even reproduce," Rummel said.

Seasons on Mars

Like Earth, Mars has four seasons because the planet tilts on its axis. The seasons vary in length because of Mars' eccentric orbit around the sun. In the northern hemisphere, spring is the longest season at seven months. Summer and fall are both about six months long. Winter is only four months long.

During a Martian summer, the polar ice cap, composed mainly of carbon dioxide ice, shrinks and may disappear altogether. When winter comes, the ice cap grows back. There may be some liquid water trapped beneath the carbon dioxide ice sheets, scientists say. 

An evolving world

In the past, Mars may have been warmer and wetter, with an average global temperature of 50 degrees F (10 degrees C).

"We've learned that Mars is a dynamic planet," Michael Meyer, lead scientist for NASA's Mars exploration program, told reporters in 2011. "We've learned that it has a history where it was warm and wet at the same time that life started here on Earth."

Other research suggests that the Red Planet may have once been white, an icy wasteland with an average temperature of minus 54 degrees F (minus 48 degrees C). According to Robin Wordsworth, a researcher at Harvard, a colder scenario is more straightforward to model because Mars only gets 43 percent of the solar energy of Earth, and early Mars was lit by a younger Sun believed to have been 25 percent dimmer than it is today.

"That makes it very likely early Mars was cold and icy," he said in a statement.

And the planet continues to change today. Recent research found that the planet is emerging from an ice age involving shrinking polar caps and growing glaciers at midlatitudes.

"All around the ice cap, there is evidence for a climate change from ice age to interglacial period," planetary scientist Isaac Smith told Space.com. Smith studied the shrinking ice caps while at the Southwest Research Institute in Colorado.

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Electric power transmission

https://en.wikipedia.org/wiki/Electric_power_transmission

Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines which facilitate this movement are known as a transmission network. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. The combined transmission and distribution network is known as the "power grid" in North America, or just "the grid". In the United Kingdom, India, Malaysia and New Zealand, the network is known as the "National Grid".

A wide area synchronous grid, also known as an "interconnection" in North America, directly connects a large number of generators delivering AC power with the same relative frequency to a large number of consumers. For example, there are four major interconnections in North America (the Western Interconnection, the Eastern Interconnection, the Quebec Interconnection and the Electric Reliability Council of Texas (ERCOT) grid). In Europe one large grid connects most of continental Europe.

Historically, transmission and distribution lines were owned by the same company, but starting in the 1990s, many countries have liberalized the regulation of the electricity market in ways that have led to the separation of the electricity transmission business from the distribution business.[1]

System

Most transmission lines are high-voltage three-phase alternating current (AC), although single phase AC is sometimes used in railway electrification systems. High-voltage direct-current (HVDC) technology is used for greater efficiency over very long distances (typically hundreds of miles). HVDC technology is also used in submarine power cables (typically longer than 30 miles (50 km)), and in the interchange of power between grids that are not mutually synchronized. HVDC links are used to stabilize large power distribution networks where sudden new loads, or blackouts, in one part of a network can result in synchronization problems and cascading failures.

Electricity is transmitted at high voltages (115 kV or above) to reduce the energy loss which occurs in long-distance transmission. Power is usually transmitted through overhead power lines. Underground power transmission has a significantly higher installation cost and greater operational limitations, but reduced maintenance costs. Underground transmission is sometimes used in urban areas or environmentally sensitive locations.

A lack of electrical energy storage facilities in transmission systems leads to a key limitation. Electrical energy must be generated at the same rate at which it is consumed. A sophisticated control system is required to ensure that the power generation very closely matches the demand. If the demand for power exceeds supply, the imbalance can cause generation plant(s) and transmission equipment to automatically disconnect or shut down to prevent damage. In the worst case, this may lead to a cascading series of shut downs and a major regional blackout. Examples include the US Northeast blackouts of 1965, 1977, 2003, and major blackouts in other US regions in 1996 and 2011. Electric transmission networks are interconnected into regional, national, and even continent wide networks to reduce the risk of such a failure by providing multiple redundant, alternative routes for power to flow should such shut downs occur. Transmission companies determine the maximum reliable capacity of each line (ordinarily less than its physical or thermal limit) to ensure that spare capacity is available in the event of a failure in another part of the network.

Overhead transmission

High-voltage overhead conductors are not covered by insulation. The conductor material is nearly always an aluminum alloy, made into several strands and possibly reinforced with steel strands. Copper was sometimes used for overhead transmission, but aluminum is lighter, yields only marginally reduced performance and costs much less. Overhead conductors are a commodity supplied by several companies worldwide. Improved conductor material and shapes are regularly used to allow increased capacity and modernize transmission circuits. Conductor sizes range from 12 mm2 (#6 American wire gauge) to 750 mm2 (1,590,000 circular mils area), with varying resistance and current-carrying capacity. Thicker wires would lead to a relatively small increase in capacity due to the skin effect (which causes most of the current to flow close to the surface of the wire). Because of this current limitation, multiple parallel cables (called bundle conductors) are used when higher capacity is needed. Bundle conductors are also used at high voltages to reduce energy loss caused by corona discharge.

Today, transmission-level voltages are usually considered to be 110 kV and above. Lower voltages, such as 66 kV and 33 kV, are usually considered subtransmission voltages, but are occasionally used on long lines with light loads. Voltages less than 33 kV are usually used for distribution. Voltages above 765 kV are considered extra high voltage and require different designs compared to equipment used at lower voltages.

Since overhead transmission wires depend on air for insulation, the design of these lines requires minimum clearances to be observed to maintain safety. Adverse weather conditions, such as high wind and low temperatures, can lead to power outages. Wind speeds as low as 23 knots (43 km/h) can permit conductors to encroach operating clearances, resulting in a flashover and loss of supply.[2] Oscillatory motion of the physical line can be termed gallop or flutter depending on the frequency and amplitude of oscillation.

Underground transmission

Electric power can also be transmitted by underground power cables instead of overhead power lines. Underground cables take up less right-of-way than overhead lines, have lower visibility, and are less affected by bad weather. However, costs of insulated cable and excavation are much higher than overhead construction. Faults in buried transmission lines take longer to locate and repair. Underground lines are strictly limited by their thermal capacity, which permits less overload or re-rating than overhead lines. Long underground AC cables have significant capacitance, which may reduce their ability to provide useful power to loads beyond 50 miles (80 kilometres). DC cables are not limited in length by their capacitance.

History

In the early days of commercial electric power, transmission of electric power at the same voltage as used by lighting and mechanical loads restricted the distance between generating plant and consumers. In 1882, generation was with direct current (DC), which could not easily be increased in voltage for long-distance transmission. Different classes of loads (for example, lighting, fixed motors, and traction/railway systems) required different voltages, and so used different generators and circuits.[3][4]

Due to this specialization of lines and because transmission was inefficient for low-voltage high-current circuits, generators needed to be near their loads. It seemed, at the time, that the industry would develop into what is now known as a distributed generation system with large numbers of small generators located near their loads.[5]

The transmission of electric power with alternating current (AC) became possible after Lucien Gaulard and John Dixon Gibbs built what they called the secondary generator, an early transformer provided with 1:1 turn ratio and open magnetic circuit, in 1881.

The first long distance AC line was 34 kilometres (21 miles) long, built for the 1884 International Exhibition of Turin, Italy. It was powered by a 2000 V, 130 Hz Siemens & Halske alternator and featured several Gaulard secondary generators with their primary windings connected in series, which fed incandescent lamps. The system proved the feasibility of AC electric power transmission on long distances.[4]

A very first operative AC line was put into service in 1885 in via dei Cerchi, Rome, Italy, for public lighting. It was powered by two Siemens & Halske alternators rated 30 hp (22 kW), 2000 V at 120 Hz and used 19 km of cables and 200 parallel-connected 2000 V to 20 V step-down transformers provided with a closed magnetic circuit, one for each lamp. Few months later it was followed by the first British AC system, which was put into service at the Grosvenor Gallery, London. It also featured Siemens alternators and 2400 V to 100 V step-down transformers – one per user – with shunt-connected primaries.[6]

Working from what he considered an impractical Gaulard-Gibbs design, electrical engineer William Stanley, Jr. developed what is considered the first practical series AC transformer in 1885.[7] Working with the support of George Westinghouse, in 1886 he installed demonstration transformer based alternating current lighting system in Great Barrington, Massachusetts. Powered by a steam engine driven 500 V Siemens generator, voltage was stepped down to 100 Volts using the new Stanley transformer to power incandescent lamps at 23 businesses along main street with very little power loss over 4000 feet.[8] This practical demonstration of a transformer and alternating current lighting system would lead Westinghouse to begin installing AC based systems later that year.[7]

1888 saw designs for a functional AC motor, something these systems had lacked up till then. These were induction motors running on polyphase current, independently invented by Galileo Ferraris and Nikola Tesla (with Tesla's design being licensed by Westinghouse in the US). This design was further developed into the modern practical three-phase form by Mikhail Dolivo-Dobrovolsky and Charles Eugene Lancelot Brown.[9] Practical use of these types of motors would be delayed many years by development problems and the scarcity of poly-phase power systems needed to power them.[10][11]

The late 1880s and early 1890s would see a financial merger of many smaller electric companies into a few larger corporations such as Ganz and AEG in Europe and General Electric and Westinghouse Electric in the US. These companies continued to develop AC systems but the technical difference between direct and alternating current systems would follow a much longer technical merger.[12] Due to innovation in the US and Europe, alternating current's economy of scale with very large generating plants linked to loads via long distance transmission was slowly being combined with the ability to link it up with all of the existing systems that needed to be supplied. These included single phase AC systems, poly-phase AC systems, low voltage incandescent lighting, high voltage arc lighting, and existing DC motors in factories and street cars. In what was becoming a universal system, these technological differences were temporarily being bridged via the development of rotary converters and motor-generators that would allow the large number of legacy systems to be connected to the AC grid.[12][13] These stopgaps would slowly be replaced as older systems were retired or upgraded.

The first transmission of single-phase alternating current using high voltage took place in Oregon in 1890 when power was delivered from a hydroelectric plant at Willamette Falls to the city of Portland 14 miles downriver.[14] The first three-phase alternating current using high voltage took place in 1891 during the international electricity exhibition in Frankfurt. A 15,000 V transmission line, approximately 175 km long, connected Lauffen on the Neckar and Frankfurt.[6][15]

Voltages used for electric power transmission increased throughout the 20th century. By 1914, fifty-five transmission systems each operating at more than 70,000 V were in service. The highest voltage then used was 150,000 V.[16] By allowing multiple generating plants to be interconnected over a wide area, electricity production cost was reduced. The most efficient available plants could be used to supply the varying loads during the day. Reliability was improved and capital investment cost was reduced, since stand-by generating capacity could be shared over many more customers and a wider geographic area. Remote and low-cost sources of energy, such as hydroelectric power or mine-mouth coal, could be exploited to lower energy production cost.[3][6]

The rapid industrialization in the 20th century made electrical transmission lines and grids a critical infrastructure item in most industrialized nations. The interconnection of local generation plants and small distribution networks was greatly spurred by the requirements of World War I, with large electrical generating plants built by governments to provide power to munitions factories. Later these generating plants were connected to supply civil loads through long-distance transmission.[17]

Bulk power transmission

Engineers design transmission networks to transport the energy as efficiently as feasible, while at the same time taking into account economic factors, network safety and redundancy. These networks use components such as power lines, cables, circuit breakers, switches and transformers. The transmission network is usually administered on a regional basis by an entity such as a regional transmission organization or transmission system operator.

Transmission efficiency is greatly improved by devices that increase the voltage (and thereby proportionately reduce the current), in the line conductors, thus allowing power to be transmitted with acceptable losses. The reduced current flowing through the line reduces the heating losses in the conductors. According to Joule's Law, energy losses are directly proportional to the square of the current. Thus, reducing the current by a factor of two will lower the energy lost to conductor resistance by a factor of four for any given size of conductor.

The optimum size of a conductor for a given voltage and current can be estimated by Kelvin's law for conductor size, which states that the size is at its optimum when the annual cost of energy wasted in the resistance is equal to the annual capital charges of providing the conductor. At times of lower interest rates, Kelvin's law indicates that thicker wires are optimal; while, when metals are expensive, thinner conductors are indicated: however, power lines are designed for long-term use, so Kelvin's law has to be used in conjunction with long-term estimates of the price of copper and aluminum as well as interest rates for capital.

The increase in voltage is achieved in AC circuits by using a step-up transformer. HVDC systems require relatively costly conversion equipment which may be economically justified for particular projects such as submarine cables and longer distance high capacity point-to-point transmission. HVDC is necessary for the import and export of energy between grid systems that are not synchronized with each other.

A transmission grid is a network of power stations, transmission lines, and substations. Energy is usually transmitted within a grid with three-phase AC. Single-phase AC is used only for distribution to end users since it is not usable for large polyphase induction motors. In the 19th century, two-phase transmission was used but required either four wires or three wires with unequal currents. Higher order phase systems require more than three wires, but deliver little or no benefit.

The price of electric power station capacity is high, and electric demand is variable, so it is often cheaper to import some portion of the needed power than to generate it locally. Because loads are often regionally correlated (hot weather in the Southwest portion of the US might cause many people to use air conditioners), electric power often comes from distant sources. Because of the economic benefits of load sharing between regions, wide area transmission grids now span countries and even continents. The web of interconnections between power producers and consumers should enable power to flow, even if some links are inoperative.

The unvarying (or slowly varying over many hours) portion of the electric demand is known as the base load and is generally served by large facilities (which are more efficient due to economies of scale) with fixed costs for fuel and operation. Such facilities are nuclear, coal-fired or hydroelectric, while other energy sources such as concentrated solar thermal and geothermal power have the potential to provide base load power. Renewable energy sources, such as solar photovoltaics, wind, wave, and tidal, are, due to their intermittency, not considered as supplying "base load" but will still add power to the grid. The remaining or 'peak' power demand, is supplied by peaking power plants, which are typically smaller, faster-responding, and higher cost sources, such as combined cycle or combustion turbine plants fueled by natural gas.

Long-distance transmission of electricity (hundreds of kilometers) is cheap and efficient, with costs of US$0.005–0.02 per kWh (compared to annual averaged large producer costs of US$0.01–0.025 per kWh, retail rates upwards of US$0.10 per kWh, and multiples of retail for instantaneous suppliers at unpredicted highest demand moments).[18] Thus distant suppliers can be cheaper than local sources (e.g., New York often buys over 1000 MW of electricity from Canada).[19] Multiple local sources (even if more expensive and infrequently used) can make the transmission grid more fault tolerant to weather and other disasters that can disconnect distant suppliers.

Long-distance transmission allows remote renewable energy resources to be used to displace fossil fuel consumption. Hydro and wind sources cannot be moved closer to populous cities, and solar costs are lowest in remote areas where local power needs are minimal. Connection costs alone can determine whether any particular renewable alternative is economically sensible. Costs can be prohibitive for transmission lines, but various proposals for massive infrastructure investment in high capacity, very long distance super grid transmission networks could be recovered with modest usage fees.

Grid input

At the power stations, the power is produced at a relatively low voltage between about 2.3 kV and 30 kV, depending on the size of the unit. The generator terminal voltage is then stepped up by the power station transformer to a higher voltage (115 kV to 765 kV AC, varying by the transmission system and by the country) for transmission over long distances.

In the United States, power transmission is, variously, 230 kV to 500 kV, with less than 230 kV or more than 500 kV being local exceptions. For example, the Western System has two primary interchange voltages: 500 kV AC at 60 Hz, and ±500 kV (1,000 kV net) DC from North to South (U.S.-Canada border to U.S.-Mexico border).

The 287.5 kV (Hoover to Los Angeles line, via Victorville) and 345 kV (APS line) being local standards, both of which were implemented before 500 kV became practical, and thereafter the Western System standard.

Losses

Transmitting electricity at high voltage reduces the fraction of energy lost to resistance, which varies depending on the specific conductors, the current flowing, and the length of the transmission line. For example, a 100 mi (160 km) span at 765 kV carrying 1000 MW of power can have losses of 1.1% to 0.5%. A 345 kV line carrying the same load across the same distance has losses of 4.2%.[20] For a given amount of power, a higher voltage reduces the current and thus the resistive losses in the conductor. For example, raising the voltage by a factor of 10 reduces the current by a corresponding factor of 10 and therefore the I 2 R {\displaystyle I^{2}R} {\displaystyle I^{2}R} losses by a factor of 100, provided the same sized conductors are used in both cases. Even if the conductor size (cross-sectional area) is reduced ten-fold to match the lower current, the I 2 R {\displaystyle I^{2}R} {\displaystyle I^{2}R} losses are still reduced ten-fold. Long-distance transmission is typically done with overhead lines at voltages of 115 to 1,200 kV. At extremely high voltages, more than 2,000 kV exists between conductor and ground, corona discharge losses are so large that they can offset the lower resistive losses in the line conductors. Measures to reduce corona losses include conductors having larger diameters; often hollow to save weight,[21] or bundles of two or more conductors.

Factors that affect the resistance, and thus loss, of conductors used in transmission and distribution lines include temperature, spiraling, and the skin effect. The resistance of a conductor increases with its temperature. Temperature changes in electric power lines can have a significant effect on power losses in the line. Spiraling, which refers to the way stranded conductors spiral about the center, also contributes to increases in conductor resistance. The skin effect causes the effective resistance of a conductor to increase at higher alternating current frequencies.

Transmission and distribution losses in the USA were estimated at 6.6% in 1997[22] and 6.5% in 2007.[22] In general, losses are estimated from the discrepancy between power produced (as reported by power plants) and power sold to the end customers; the difference between what is produced and what is consumed constitute transmission and distribution losses, assuming no utility theft occurs.

As of 1980, the longest cost-effective distance for direct-current transmission was determined to be 7,000 kilometres (4,300 miles). For alternating current it was 4,000 kilometres (2,500 miles), though all transmission lines in use today are substantially shorter than this.[18]

In any alternating current transmission line, the inductance and capacitance of the conductors can be significant. Currents that flow solely in 'reaction' to these properties of the circuit, (which together with the resistance define the impedance) constitute reactive power flow, which transmits no 'real' power to the load. These reactive currents, however, are very real and cause extra heating losses in the transmission circuit. The ratio of 'real' power (transmitted to the load) to 'apparent' power (the product of a circuit's voltage and current, without reference to phase angle) is the power factor. As reactive current increases, the reactive power increases and the power factor decreases. For transmission systems with low power factor, losses are higher than for systems with high power factor. Utilities add capacitor banks, reactors and other components (such as phase-shifting transformers; static VAR compensators; and flexible AC transmission systems, FACTS) throughout the system help to compensate for the reactive power flow, reduce the losses in power transmission and stabilize system voltages. These measures are collectively called 'reactive support'.

Transposition

Current flowing through transmission lines induces a magnetic field that surrounds the lines of each phase and affects the inductance of the surrounding conductors of other phases. The mutual inductance of the conductors is partially dependent on the physical orientation of the lines with respect to each other. Three-phase power transmission lines are conventionally strung with phases separated on different vertical levels. The mutual inductance seen by a conductor of the phase in the middle of the other two phases will be different than the inductance seen by the conductors on the top or bottom. An imbalanced inductance among the three conductors is problematic because it may result in the middle line carrying a disproportionate amount of the total power transmitted. Similarly, an imbalanced load may occur if one line is consistently closest to the ground and operating at a lower impedance. Because of this phenomenon, conductors must be periodically transposed along the length of the transmission line so that each phase sees equal time in each relative position to balance out the mutual inductance seen by all three phases. To accomplish this, line position is swapped at specially designed transposition towers at regular intervals along the length of the transmission line in various transposition schemes.

Subtransmission

Subtransmission is part of an electric power transmission system that runs at relatively lower voltages. It is uneconomical to connect all distribution substations to the high main transmission voltage, because the equipment is larger and more expensive. Typically, only larger substations connect with this high voltage. It is stepped down and sent to smaller substations in towns and neighborhoods. Subtransmission circuits are usually arranged in loops so that a single line failure does not cut off service to a large number of customers for more than a short time. Loops can be "normally closed", where loss of one circuit should result in no interruption, or "normally open" where substations can switch to a backup supply. While subtransmission circuits are usually carried on overhead lines, in urban areas buried cable may be used. The lower-voltage subtransmission lines use less right-of-way and simpler structures; it is much more feasible to put them underground where needed. Higher-voltage lines require more space and are usually above-ground since putting them underground is very expensive.

There is no fixed cutoff between subtransmission and transmission, or subtransmission and distribution. The voltage ranges overlap somewhat. Voltages of 69 kV, 115 kV, and 138 kV are often used for subtransmission in North America. As power systems evolved, voltages formerly used for transmission were used for subtransmission, and subtransmission voltages became distribution voltages. Like transmission, subtransmission moves relatively large amounts of power, and like distribution, subtransmission covers an area instead of just point-to-point.[23]

Transmission grid exit

At the substations, transformers reduce the voltage to a lower level for distribution to commercial and residential users. This distribution is accomplished with a combination of sub-transmission (33 to 132 kV) and distribution (3.3 to 25 kV). Finally, at the point of use, the energy is transformed to low voltage (varying by country and customer requirements – see Mains electricity by country).

High-voltage direct current

High-voltage direct current (HVDC) is used to transmit large amounts of power over long distances or for interconnections between asynchronous grids. When electrical energy is to be transmitted over very long distances, the power lost in AC transmission becomes appreciable and it is less expensive to use direct current instead of alternating current. For a very long transmission line, these lower losses (and reduced construction cost of a DC line) can offset the additional cost of the required converter stations at each end.

HVDC is also used for submarine cables because AC cannot be supplied over distances of more than about 300 kilometres (190 mi), due to the fact that the cables produce too much reactive power.[24] In these cases special high-voltage cables for DC are used. Submarine HVDC systems are often used to connect the electricity grids of islands, for example, between Great Britain and continental Europe, between Great Britain and Ireland, between Tasmania and the Australian mainland, and between the North and South Islands of New Zealand. Submarine connections up to 600 kilometres (370 mi) in length are presently in use.[25]

HVDC links can be used to control problems in the grid with AC electricity flow. The power transmitted by an AC line increases as the phase angle between source end voltage and destination ends increases, but too large a phase angle will allow the systems at either end of the line to fall out of step. Since the power flow in a DC link is controlled independently of the phases of the AC networks at either end of the link, this phase angle limit does not exist, and a DC link is always able to transfer its full rated power. A DC link therefore stabilizes the AC grid at either end, since power flow and phase angle can then be controlled independently.

As an example, to adjust the flow of AC power on a hypothetical line between Seattle and Boston would require adjustment of the relative phase of the two regional electrical grids. This is an everyday occurrence in AC systems, but one that can become disrupted when AC system components fail and place unexpected loads on the remaining working grid system. With an HVDC line instead, such an interconnection would:

    Convert AC in Seattle into HVDC;
    Use HVDC for the 3,000 miles of cross-country transmission; and
    Convert the HVDC to locally synchronized AC in Boston,

(and possibly in other cooperating cities along the transmission route). Such a system could be less prone to failure if parts of it were suddenly shut down. One example of a long DC transmission line is the Pacific DC Intertie located in the Western United States.

Capacity

The amount of power that can be sent over a transmission line is limited. The origins of the limits vary depending on the length of the line. For a short line, the heating of conductors due to line losses sets a thermal limit. If too much current is drawn, conductors may sag too close to the ground, or conductors and equipment may be damaged by overheating. For intermediate-length lines on the order of 100 kilometres (62 miles), the limit is set by the voltage drop in the line. For longer AC lines, system stability sets the limit to the power that can be transferred. Approximately, the power flowing over an AC line is proportional to the cosine of the phase angle of the voltage and current at the receiving and transmitting ends. This angle varies depending on system loading and generation. It is undesirable for the angle to approach 90 degrees, as the power flowing decreases but the resistive losses remain. Very approximately, the allowable product of line length and maximum load is proportional to the square of the system voltage. Series capacitors or phase-shifting transformers are used on long lines to improve stability. High-voltage direct current lines are restricted only by thermal and voltage drop limits, since the phase angle is not material to their operation.

Up to now, it has been almost impossible to foresee the temperature distribution along the cable route, so that the maximum applicable current load was usually set as a compromise between understanding of operation conditions and risk minimization. The availability of industrial distributed temperature sensing (DTS) systems that measure in real time temperatures all along the cable is a first step in monitoring the transmission system capacity. This monitoring solution is based on using passive optical fibers as temperature sensors, either integrated directly inside a high voltage cable or mounted externally on the cable insulation. A solution for overhead lines is also available. In this case the optical fiber is integrated into the core of a phase wire of overhead transmission lines (OPPC). The integrated Dynamic Cable Rating (DCR) or also called Real Time Thermal Rating (RTTR) solution enables not only to continuously monitor the temperature of a high voltage cable circuit in real time, but to safely utilize the existing network capacity to its maximum. Furthermore, it provides the ability to the operator to predict the behavior of the transmission system upon major changes made to its initial operating conditions.

Control

To ensure safe and predictable operation, the components of the transmission system are controlled with generators, switches, circuit breakers and loads. The voltage, power, frequency, load factor, and reliability capabilities of the transmission system are designed to provide cost effective performance for the customers.

Load balancing

The transmission system provides for base load and peak load capability, with safety and fault tolerance margins. The peak load times vary by region largely due to the industry mix. In very hot and very cold climates home air conditioning and heating loads have an effect on the overall load. They are typically highest in the late afternoon in the hottest part of the year and in mid-mornings and mid-evenings in the coldest part of the year. This makes the power requirements vary by the season and the time of day. Distribution system designs always take the base load and the peak load into consideration.

The transmission system usually does not have a large buffering capability to match the loads with the generation. Thus generation has to be kept matched to the load, to prevent overloading failures of the generation equipment.

Multiple sources and loads can be connected to the transmission system and they must be controlled to provide orderly transfer of power. In centralized power generation, only local control of generation is necessary, and it involves synchronization of the generation units, to prevent large transients and overload conditions.

In distributed power generation the generators are geographically distributed and the process to bring them online and offline must be carefully controlled. The load control signals can either be sent on separate lines or on the power lines themselves. Voltage and frequency can be used as signalling mechanisms to balance the loads.

In voltage signaling, the variation of voltage is used to increase generation. The power added by any system increases as the line voltage decreases. This arrangement is stable in principle. Voltage-based regulation is complex to use in mesh networks, since the individual components and setpoints would need to be reconfigured every time a new generator is added to the mesh.

In frequency signaling, the generating units match the frequency of the power transmission system. In droop speed control, if the frequency decreases, the power is increased. (The drop in line frequency is an indication that the increased load is causing the generators to slow down.)

Wind turbines, vehicle-to-grid and other locally distributed storage and generation systems can be connected to the power grid, and interact with it to improve system operation. Internationally, the trend has been a slow move from a heavily centralized power system to a decentralized power system. The main draw of locally distributed generation systems which involve a number of new and innovative solutions is that they reduce transmission losses by leading to consumption of electricity closer to where it was produced.[26]

Failure protection

Under excess load conditions, the system can be designed to fail gracefully rather than all at once. Brownouts occur when the supply power drops below the demand. Blackouts occur when the supply fails completely.

Rolling blackouts (also called load shedding) are intentionally engineered electrical power outages, used to distribute insufficient power when the demand for electricity exceeds the supply.

Communications

Operators of long transmission lines require reliable communications for control of the power grid and, often, associated generation and distribution facilities. Fault-sensing protective relays at each end of the line must communicate to monitor the flow of power into and out of the protected line section so that faulted conductors or equipment can be quickly de-energized and the balance of the system restored. Protection of the transmission line from short circuits and other faults is usually so critical that common carrier telecommunications are insufficiently reliable, and in remote areas a common carrier may not be available. Communication systems associated with a transmission project may use:

    Microwaves
    Power line communication
    Optical fibers

Rarely, and for short distances, a utility will use pilot-wires strung along the transmission line path. Leased circuits from common carriers are not preferred since availability is not under control of the electric power transmission organization.

Transmission lines can also be used to carry data: this is called power-line carrier, or PLC. PLC signals can be easily received with a radio for the long wave range.

Optical fibers can be included in the stranded conductors of a transmission line, in the overhead shield wires. These cables are known as optical ground wire (OPGW). Sometimes a standalone cable is used, all-dielectric self-supporting (ADSS) cable, attached to the transmission line cross arms.

Some jurisdictions, such as Minnesota, prohibit energy transmission companies from selling surplus communication bandwidth or acting as a telecommunications common carrier. Where the regulatory structure permits, the utility can sell capacity in extra dark fibers to a common carrier, providing another revenue stream.

Superconducting cables

High-temperature superconductors (HTS) promise to revolutionize power distribution by providing lossless transmission of electrical power. The development of superconductors with transition temperatures higher than the boiling point of liquid nitrogen has made the concept of superconducting power lines commercially feasible, at least for high-load applications.[43] It has been estimated that the waste would be halved using this method, since the necessary refrigeration equipment would consume about half the power saved by the elimination of the majority of resistive losses. Some companies such as Consolidated Edison and American Superconductor have already begun commercial production of such systems.[44] In one hypothetical future system called a SuperGrid, the cost of cooling would be eliminated by coupling the transmission line with a liquid hydrogen pipeline.

Superconducting cables are particularly suited to high load density areas such as the business district of large cities, where purchase of an easement for cables would be very costly.[45]

Single wire earth return

Single-wire earth return (SWER) or single wire ground return is a single-wire transmission line for supplying single-phase electrical power for an electrical grid to remote areas at low cost. It is principally used for rural electrification, but also finds use for larger isolated loads such as water pumps. Single wire earth return is also used for HVDC over submarine power cables.

Wireless power transmission

Both Nikola Tesla and Hidetsugu Yagi attempted to devise systems for large scale wireless power transmission in the late 1800s and early 1900s, with no commercial success.

In November 2009, LaserMotive won the NASA 2009 Power Beaming Challenge by powering a cable climber 1 km vertically using a ground-based laser transmitter. The system produced up to 1 kW of power at the receiver end. In August 2010, NASA contracted with private companies to pursue the design of laser power beaming systems to power low earth orbit satellites and to launch rockets using laser power beams.

Wireless power transmission has been studied for transmission of power from solar power satellites to the earth. A high power array of microwave or laser transmitters would beam power to a rectenna. Major engineering and economic challenges face any solar power satellite project.

[evolvingape]

'Space skunk': Tech for growing veg on Mars perfect for weed

https://www.rt.com/news/413675-grow-food-in-space-marijuana/

Perhaps taking their lead from the Matt Damon film 'The Martian,' a team of biologists are developing the technology to grow everyday vegetables in space. The technology also has a surprising use here on Earth.

Earlier this year NASA outlined plans to reach Mars between 2030 and 2040, however, humans face a range of obstacles before we can survive on the Red Planet. Chief among them is what we will eat when we get there. Constant access to fresh food will be essential to ensure that space explorers remain healthy and productive while working in the hostile terrain.

"We're not leaving this planet without green plants, at least we're not going very far and we're not staying very long," Mike Dixon of the University of Guelph's Controlled Environment Systems Research Facility (CESRF) explained.

https://www.youtube.com/watch?v=PQMuAAton3w

A team of researchers at the facility have been busily trying to solve this problem. The work includes understanding how plants can function under environmental conditions such as very low atmospheric pressures and a lack of oxygen.

"Oddly enough, space [for crop production] in space is limited," another CESRF scientist, Thomas Graham, noted in a statement. "Plants must be small without sacrificing production if they are to be viable candidates for life-support systems in space."

To overcome these restraints the team has developed a special chamber, affectionately referred to as 'The Fridge.' The system is a version of what will eventually accompany astronauts on the first mission to mars.

As the team waits for manned missions to Mars to finally take off, the technology isn't being let sit idle, instead it's being used to grow marijuana.

"All the technologies required to [grow fresh food in space] are being deployed in the service of growing really good marijuana," Dixon told Motherboard.

Because of the extraordinary cost of space travel, Dixon says it'll be a long time before astronauts will be growing marijuana, or any vegetable, that can't be eaten in space. However he does think it could happen one day.

"They're going to grow barley and make single malt whiskey at some point. Why not marijuana?"

[evolvingape]

The cliffs were all found at latitudes about 55° north or south – discouraging latitudes for a solar-powered human base, according to the team.

Scientists now want to seek out similar cliffs closer to the equator, hoping that the next surprise awaiting them is the discovery of ice nearer to the tropics.

So.. Just to annoy Susie Dent .. The power is generated most efficiently by solar panels at the equator and the water is way up north, or south..

High-voltage direct current (HVDC) is used to transmit large amounts of power over long distances or for interconnections between asynchronous grids. When electrical energy is to be transmitted over very long distances, the power lost in AC transmission becomes appreciable and it is less expensive to use direct current instead of alternating current. For a very long transmission line, these lower losses (and reduced construction cost of a DC line) can offset the additional cost of the required converter stations at each end.

So.. we have a DC supply from the solar panels and a DC powered hhop to pump it..

Measures to reduce corona losses include conductors having larger diameters; often hollow to save weight,[21] or bundles of two or more conductors.

Hollow cable.. hmm.. would it be possible to have a DC power cable (with high voltage step up) transmitting electrical power from the solar array to the hhop pump and pumping water back through a micro bore center..

The water is going to freeze at some point.. can we heat it with some of the electrical energy being transmitted to keep it liquid ?

If an ice deposit can be located in a suitable high solar energy area near the equator it might only be a relatively small distance to a suitable colony site with the other raw materials we would need to survive.

What does the community think the potential for this dual electricity / water cable is ?

[evolvingape]

Nukes on Mars? NASA tests reactor to sustain human life

https://www.rt.com/usa/416341-nasa-mars-nuclear-reactor-test/

NASA has carried out successful tests on a compact nuclear reactor which the space agency hopes will be able to sustain human settlements on the moon, Mars, and beyond.

The reactor could power equipment to turn the Red Planet's natural resources into water, oxygen and fuel. The agency, in conjunction with the US Department of Energy, announced the initial test results at a news conference in Las Vegas Thursday.

'Kilopower' is capable of generating up to 10 kw – more than enough to power an average US household. Such technology is key if humans want to maintain a longer stay on the moon than the Apollo astronauts, who visited the lunar surface a total of six times between 1969 and 1972.

    Russia to develop space nuclear power plant to charge satellites via laser beam – reports https://t.co/gLpcdMmDZI
    — RT (@RT_com) October 30, 2017

"Mars is a very difficult environment for power systems, with less sunlight than Earth or the moon, very cold nighttime temperatures, very interesting dust storms that can last weeks and months that engulf the entire planet," NASA spokesman Steve Jurczyk said, as cited by Reuters.

"So Kilopower's compact size and robustness allows us to deliver multiple units on a single lander to the surface that provides tens of kilowatts of power," he added.

https://www.youtube.com/watch?time_continue=3&v=DcdfMcjUy_U

Project lead Patrick McClure said the device creates new opportunities for astronauts working in extreme conditions. "A space nuclear reactor could provide a high energy density power source with the ability to operate independent of solar energy or orientation, and the ability to operate in extremely harsh environments, such as the Martian surface," he said in a news release.

A full power test of Kilopower, which uses a uranium reactor not much bigger than a paper towel roll, is scheduled for the end of March, before it is ready to venture out into the stars.

NASA sees a future with nuclear power

http://physicstoday.scitation.org/doi/10.1063/PT.3.3787

The space agency views reactors as options both for propulsion to Mars and as a power source for life on the red planet.

NASA engineers have estimated that 40 kW is needed for a crewed Mars surface base. One possible mission approach would be to send five of the 10 kW Kilopower reactors to Mars to provide a spare unit for increased reliability.

Even the smallest Kilopower reactor would produce considerably more electricity than the radioisotope thermoelectric generators (RTGs) that have powered more than two dozen NASA spacecraft since the 1960s. The largest RTGs, whose deployments have included Cassini, Galileo, and New Horizons, produced 300 watts, and the RTG on the Curiosity Mars rover makes 110 watts. The human health hazards, however small, that come with the potential launch failure of an RTG-fueled spacecraft aren't an issue with uranium fuels. Unlike the highly radioactive plutonium-238 that fuels RTGs, 235U emits only tiny amounts of radiation, and Kilopower reactors wouldn't begin generating fission products until they are turned on after landing.

The Kilopower design being tested in Nevada has eight Stirling engines to convert heat from the reactor to electricity. They produce mechanical energy by using the temperature difference between their hot and cold ends to alternately heat and expand, and then cool and compress, a gas. To save on costs, only two Stirlings, borrowed from another NASA development program, will be included in the Nevada tests. Other options being considered for converting reactor heat to electricity include thermoelectric devices and small turbines. But the Stirling route is attractive for its efficiency, which allows for a simple reactor design, says McClure.

Stirling Engine Efficiency

https://www.real-world-physics-problems.com/support-files/stirling_engine_efficiency.pdf

https://en.wikipedia.org/wiki/Stirling_engine

[evolvingape]

Pulsometer pump

https://en.wikipedia.org/wiki/Pulsometer_pump

The Pulsometer steam pump is a pistonless pump which was patented in 1872[1] by American Charles Henry Hall. In 1875 a British engineer bought the patent rights of the Pulsometer[2] and it was introduced to the market soon thereafter. The invention was inspired by the Savery steam pump invented by Thomas Savery. Around the turn of the century, it was a popular and effective pump for quarry pumping.

https://www.gracesguide.co.uk/Pulsometer_Engineering_Co

http://www.eng-tips.com/viewthread.cfm?qid=300669

moreshk (Civil/Environmental)
(OP)
13 Jun 11 10:02
Solar panels are too expensive, then you need a battery, MPPT chargers, invertors (if AC) else DC pumps. All of this shoots up the price, I have researched this for a while. In fact we even developed a Solar powered DC pump but the price does not make it viable.

I developed a DC powered pump too..

http://www.overunityresearch.com/index.php?topic=2288.msg35176#msg35176

The hhop AKA hho pulsometer is a direct current electrical input device. Electrolysis is the energy conversion method for creating gas pressure from electricity, creating variable pressure hho