Marspedia - User contributions [en]

Starlink

2020-01-05T04:00:56Z

CZMatt:

'''Starlink''' is a [[satellite constellation]] currently being constructed by [[SpaceX]] to provide fast internet access worldwide.

==History==
The first concept of Starlink was first announced in January 2015<ref>''[https://www.youtube.com/watch?v=kcJcQA0-qDU Elon Musk Announces Plan for Internet Satellite Network 2015]''. YouTube.</ref> by Elon Musk. The project was kept closely under wraps for the next four years until scheduling the launch of the first batch of experimental Starlink satellites in May 2019.<ref>"[https://www.elonx.net/starlink-compendium/ Starlink Compendium]". ElonX. December 21, 2019. </ref> These sixty satellites launched aboard a Falcon 9 on 24 May 2019 from SLC-40 at Cape Canaveral Air Force Station.

==References==
<references />

Starship

2020-01-05T03:59:24Z

CZMatt: /* 2019 Starship-Super Heavy */

[[File:Starship on booster.jpg|thumb|The 2018 Starship-Super Heavy launch stack]]'''Starship''' is the name of the 2019 version of the second stage of the [[SpaceX]] reusable super heavy lift vehicle, resting upon the [[Booster|Super Heavy]] booster. The term "Starship" may also be used to refer to the complete stack of both stages as well.

==Development history==

===2016 Interplanetary Transportation System===
The origins of Starship are rooted in the Interplanetary Transportation System. This architecture was revealed in a 2016 speech by [[Elon Musk]] at the [[International Astronomical Congress]].<ref>Musk, Elon. 2016. ''[https://www.youtube.com/watch?v=H7Uyfqi_TE8 Making Humans a Multiplanetary Species]''. Guadalajara, Mexico.</ref> The concept was conceived as a two-stage spacecraft able to be reused a thousand times and to hold crews of over a hundred people with its primary intent to send people to Mars. The concept would depend upon tanker ships and orbital refueling, and it would extensively utilize [[in-situ resource utilization]] to produce the methane fuel required for the return voyage to Earth.<ref name=":0">"[http://spaceflight101.com/spx/ Interplanetary Transport System]". n.d. Spaceflight101.com. Accessed January 4, 2020.</ref>

The design was immense, with a twelve meter diameter and depended upon forty-two methane [[Raptor engine|Raptor engines]] on the booster alone, allowing it to produce thrust of thirteen-thousand metric tons. The stacked system would stretch up one-hundred-twenty-two meters into the sky. Upon stage separation, the booster would return to the launch site, landing propulsively on the launch mounts so that it could quickly be refueled and again flown. The second stage, which in some launches would include a habitat, had nine additional Raptor engines to accelerate the ship to Low Earth Orbit. In order to continue a trip to Mars, the second stage would have to be refueled by one or more tankers.<ref name=":0" />

The proposal of the carbon fiber launch vehicle came with an estimated necessary cost of investment of ten billion dollars by Elon Musk, who suggested that a massive public-private partnership might be the best option for the vehicle. The original timeline of the proposal called for structures and propulsion development to be completed in 2019, when ship testing and orbital testing where to begin. Orbital testing was to be completed in late 2022, and shortly thereafter Mars flights were to begin.<ref name=":0" />

Musk acknowledged that this timeline was incredibly ambitious, but he believed that it was not ''too'' unreasonable. Musk took pride in announcing that two components of the system had already been built and were undergoing testing: the twelve-meter carbon fiber tank to store oxidizer in the second stage<ref>"[https://twitter.com/spacex/status/780859793443401728?lang=en First Development Tank for Mars Ship]". 2016. Twitter. September 27, 2016.</ref><ref>Mitchell, Jacob. 2016. "[https://twitter.com/JandCandO/status/780862729204723713 Here Is the inside of This Tank for You Guys!]" Twitter. September 27, 2016. </ref> and the first development versions of the Raptor methane full-flow staged combustion engine.<ref>Musk, Elon. 2016. "[https://twitter.com/elonmusk/status/780275236922994688 SpaceX Propulsion Just Achieved First Firing of the Raptor Interplanetary Transport Engine]". Twitter. September 26, 2016.</ref> Initial tests of the carbon fiber tank proved to be successful, with Musk noting that his company had not "seen any leaks or major issues" when testing the tanks with cryogenic propellent.<ref>Milberg, Evan. 2016. "[http://compositesmanufacturingmagazine.com/2016/11/spacex-successfully-tests-carbon-fiber-tank-mars-spaceship/ SpaceX Successfully Tests Carbon Fiber Tank for Mars Spaceship]". Composites Manufacturing. November 29, 2016.</ref> After heavy testing, the tank was destroyed in February 2017.<ref>"[https://www.reddit.com/r/spacex/comments/5ul1du/remains_of_the_its_composite_tank_in_anacortes_wa/ Remains of the ITS Composite Tank in Anacortes, WA]". 2017. r/SpaceXLounge on Reddit. February 17, 2017. </ref>

===2017 Big Falcon Rocket===
Over the course of a year, Musk and SpaceX recognized that a smaller, more feasible system was necessary to be pursued. Musk revealed the scaled-back design at the 2017 International Astronomical Congress<ref>Musk, Elon. 2017. ''[https://www.youtube.com/watch?v=tdUX3ypDVwI Making Life Multiplanetary]''. Adelaide, Australia.</ref> almost exactly a year after the original unveil of the system. Musk also announced that the working name for the spacecraft was BFR, officially the Big Falcon Rocket. The height of the two-stage craft was reduced to one-hundred-six meters, and the diameter was reduced to nine meters.<ref>Dodd, Tim. 2017. "[https://everydayastronaut.com/2017-bfr-vs-2016-its/ 2017 BFR vs 2016 ITS]". Everyday Astronaut. September 29, 2017.</ref>

===2018 Starship-Super Heavy===
This version was presented by Elon Musk during the announcement of Yusaku Maezawa's Dear Moon project, as an evolution of the BFR/BFS concept and Interplanetary Transportation System (ITS) concepts.

===2019 Starship-Super Heavy===
Originally planned to be constructed of carbon fiber composite, it was changed to a Stainless Steel design in January 2019 .<ref>Popular Mechanics article [https://www.popularmechanics.com/space/rockets/a25953663/elon-muhttps://www.popularmechanics.com/space/rockets/a25953663/elon-musk-spacex-bfr-stainless-steel/sk-spacex-bfr-stainless-steel/]</ref>
{| class="wikitable"
|+
Comparison of various iterations
!
!2016 ITS
!2017 BFR
!2018 Super Heavy-Starship
!2019 Super Heavy-Starship
|-
|Iteration announced
|27 Septemer 2016
|
|
|
|-
|Stack height
|122 m
|106 m
|118 m
|118 m
|-
|– First stage height
|
|58 m
|63 m
|68 m
|-
|– Second stage height
|
|48 m
|55 m
|50 m
|-
|Diameter †
|12 m
|9 m
|9 m
|9 m
|-
|Principle material
|Carbon fiber
|Carbon fiber
|Carbon fiber
|301 Stainless steel
|-
|First stage thrust
|128 MN
|48 MN
|
|72 MN
|-
|Mass to Low Earth Orbit
|300 t
|150 t
|100 t
|100 t
|-
|Engines
|51 Raptors
|47 Raptors
|
|43 Raptors
|-
|– First stage engines
|42 Raptors
|31 Raptors
|
|37 Raptors
|-
|– Second stage engines
|9 Raptors
|2 Sea-level Raptors
4 Vacuum Raptors
|7 Sea-level Raptors
|6 Raptors
|-
|Propellant capacity
|
|3625* t
|
|4500 t
|-
|– First stage capacity
|
|2525* t
|
|3300 t
|-
|– Second stage capacity
|
|1100 t
|
|1200 t
|-
|Pressurized volume
|
|825 m³
|1000 m³
|
|-
|Principle sources
|
|<ref>SpaceX. "[https://www.spacex.com/sites/spacex/files/making_life_multiplanetary-2017.pdf Slideshow: Making Life Multiplanetary]". 2017. </ref><ref>"[http://spacelaunchreport.com/bfr.html#config SpaceX Super Heavy/Starship Components]". 2019. Space Launch Report. December 9, 2019.</ref>
|
|<ref>"[http://web.archive.org/web/20191230093531/https://www.spacex.com/starship Starship]". SpaceX. 2019. </ref>
|-
| colspan="5" |* Indicates that this number is unofficial
† Diameter has always been the same for the first and second stages
|}

==Characteristics of Starship==
85-120 tonnes mass, 9m diameter, 100-150 tonnes of payload to LEO, 100-150 tonnes to Mars. These are target values, the lower the mass of the vehicle, the higher the payload mass will be. Payload volume of 1000 m3.<ref>https://www.spacex.com/starship</ref>

3 vacuum Raptor engines with 380s ISP and 3 atmospheric Raptor engines with 330s ISP. Nominal thrust of 2000 kN, (200 tonnes of force per engine) These numbers are subject to change as the engine and the vehicle concepts are under development.

120-160 day transportation time to Mars, using [[Aerobraking|aerocapture]] at Mars.

Fully reusable, rapid turnover and low maintenance vehicle.

Up to 100 passengers to Mars, although this has not been demonstrated yet by SpaceX.

==Enabling technologies==
The fundamental enabling technology of the Starship is [[Landing on Mars|supersonic retro propulsive]] landing on Mars. The use of supersonic retropropulsion in a critical phase of the Mars entry path allows the vehicle to land heavier payloads that previously thought possible. Although the exact details are not public, the current SpaceX Falcon 9 booster rocket has done flight tests that would confirm the flight path. <ref>AEROTHERMAL ANALYSIS OF REUSABLE LAUNCHER SYSTEMS DURING RETRO-PROPULSION REENTRY AND LANDING [https://elib.dlr.de/120072/1/00040_ECKER.pdf]</ref>

A second enabling technology is the capacity of refueling in orbit.

A third enabling technology is the use of methane as fuel, than can be provided by In-situ ressources production systems on Mars, and therefore allow for the re-use of the spaceship.

A fourth technology is a robust heat shield for Mars and Earth entry. This allows for fast re-use and lower costs, but also for faster transit times, reducing the radiation exposure to travellers. The Spaceship is not intended to use low energy Hoffman transfer orbits, but higher velocity orbits. These have lower transit times but leave the vehicle with significant velocity when it reaches Mars or Earth. The Starship must then use direct entry and aerodynamic braking to shed the kinetic energy from the extra velocity.

The NASA Ames research center trajectory browser can be used to explore transit times to Mars and other bodies in the Solar System. [https://trajbrowser.arc.nasa.gov/traj_browser.php Trajectory browser]

==References==
<references />

Starlink

2020-01-04T23:16:18Z

CZMatt:

'''Starlink''' is a [[satellite constellation]] currently being constructed by SpaceX to provide fast internet access worldwide.

==History==
The first concept of Starlink was first announced in January 2015<ref>''[https://www.youtube.com/watch?v=kcJcQA0-qDU Elon Musk Announces Plan for Internet Satellite Network 2015]''. YouTube.</ref> by Elon Musk. The project was kept closely under wraps for the next four years until scheduling the launch of the first batch of experimental Starlink satellites in May 2019.<ref>"[https://www.elonx.net/starlink-compendium/ Starlink Compendium]". ElonX. December 21, 2019. </ref> These sixty satellites launched aboard a Falcon 9 on 24 May 2019 from SLC-40 at Cape Canaveral Air Force Station.

==References==
<references />

2020-01-04T09:37:58Z

CZMatt: /* Development history */

[[File:Starship on booster.jpg|thumb|Starship and Super Heavy launch Stack]]'''Starship''' is the name of the 2019 version of the second stage of the [[SpaceX]] reusable super heavy lift vehicle, resting upon the [[Super Heavy]] booster. The term ''Starship'' may also be used to refer to the complete stack of both stages as well, however.

==Development history==
The origins of Starship were rooted in the Interplanetary Transportation System. This architecture was revealed in a 2016 speech by [[Elon Musk]] at the [[International Astronomical Congress]].<ref>Musk, Elon. 2016. ''[https://www.youtube.com/watch?v=H7Uyfqi_TE8 Making Humans a Multiplanetary Species]''. Guadalajara, Mexico.</ref> The concept was conceived as a two-stage spacecraft able to be reused a thousand times and to hold crews of over a hundred people with its primary intent to send people to Mars. The concept would depend upon tanker ships and orbital refueling, and it would extensively utilize [[in-situ resource utilization]] to produce the methane fuel required for the return voyage to Earth.<ref name=":0">"[http://spaceflight101.com/spx/ Interplanetary Transport System]". n.d. Spaceflight101.com. Accessed January 4, 2020.</ref>

The design was immense with a twelve meter diameter and depended upon forty-two methane [[Raptor engine|Raptor engines]] on the booster alone, allowing it to produce thrust of thirteen-thousand metric tons. The stacked system would measure one-hundred-twenty-two meters into the sky. Upon stage separation, the booster would return to the launch site, landing propulsively on the launch mounts so that the booster could quickly be refueled and again flown. The second stage, which in some launches would include a cabin, then had nine additional Raptor engines to accelerate the ship to Low Earth Orbit. In order to continue a trip to Mars, the second stage would have to bee refueled by one or more tankers.<ref name=":0" />

The proposal of the carbon fiber launch vehicle came with an estimated necessary cost of investment of ten billion dollars by Elon Musk, who suggested that a massive public-private partnership may be the best option for the vehicle. The original timeline of the proposal called for structures and propulsion development to complete in 2019, when ship testing and orbital testing were to begin. Orbital testing was to be completed in late 2022, and shortly thereafter Mars flights were to begin.<ref name=":0" />

Musk acknowledged that this timeline was incredibly ambitious, but he believed that it was not too unreasonable. Musk took pride in announcing that two components of the system had already been built and were undergoing testing: the twelve-meter carbon fiber tank to store oxidizer in the second stage<ref>"[https://twitter.com/spacex/status/780859793443401728?lang=en First Development Tank for Mars Ship]". 2016. Twitter. September 27, 2016.</ref><ref>Mitchell, Jacob. 2016. "[https://twitter.com/JandCandO/status/780862729204723713 Here Is the inside of This Tank for You Guys!]" Twitter. September 27, 2016. </ref> and the first development versions of the Raptor methane full-flow staged combustion engine.<ref>Musk, Elon. 2016. "[https://twitter.com/elonmusk/status/780275236922994688 SpaceX Propulsion Just Achieved First Firing of the Raptor Interplanetary Transport Engine]". Twitter. September 26, 2016.</ref> Initial tests of the carbon fiber tank proved to be successful, with Musk noting that his company had not "seen any leaks or major issues" when testing the tanks with cryogenic propellent.<ref>Milberg, Evan. 2016. "[http://compositesmanufacturingmagazine.com/2016/11/spacex-successfully-tests-carbon-fiber-tank-mars-spaceship/ SpaceX Successfully Tests Carbon Fiber Tank for Mars Spaceship]". Composites Manufacturing. November 29, 2016.</ref>

It was presented by Elon Musk during the announcement of Yusaku Maezawa' Dear Moon project, as an evolution of the BFR/BFS concept and Interplanetary Transportation System (ITS) concepts.

Originally planned to be constructed of carbon fiber composite, it was changed to a Stainless Steel design in January 2019 .<ref>Popular Mechanics article [https://www.popularmechanics.com/space/rockets/a25953663/elon-muhttps://www.popularmechanics.com/space/rockets/a25953663/elon-musk-spacex-bfr-stainless-steel/sk-spacex-bfr-stainless-steel/]</ref>

==Performance==
85-120 tonnes mass, 9m diameter, 100-150 tonnes of payload to LEO, 100-150 tonnes to Mars. These are target values, the lower the mass of the vehicle, the higher the payload mass will be. Payload volume of 1000 m3.<ref>https://www.spacex.com/starship</ref>

3 vacuum Raptor engines with 380s ISP and 3 atmospheric Raptor engines with 330s ISP. Nominal thrust of 2000 kN, (200 tonnes of force per engine) These numbers are subject to change as the engine and the vehicle concepts are under development.

120-160 day transportation time to Mars, using [[Aerobraking|aerocapture]] at Mars.

Fully reusable, rapid turnover and low maintenance vehicle.

Up to 100 passengers to Mars, although this has not been demonstrated yet by SpaceX.

==Enabling technologies==
The fundamental enabling technology of the Starship is supersonic retro propulsive landing on Mars. The use of supersonic retropropulsion in a critical phase of the Mars entry path allows the vehicle to land heavier payloads that previously thought possible. Although the exact details are not public, the current SpaceX Falcon 9 booster rocket has done flight tests that would confirm the flight path. <ref>AEROTHERMAL ANALYSIS OF REUSABLE LAUNCHER SYSTEMS DURING RETRO-PROPULSION REENTRY AND LANDING [https://elib.dlr.de/120072/1/00040_ECKER.pdf]</ref>

A second enabling technology is the capacity of refueling in orbit.

A third enabling technology is the use of methane as fuel, than can be provided by In-situ ressources production systems on Mars, and therefore allow for the re-use of the spaceship.

A fourth technology is a robust heat shield for Mars and Earth entry. This allows for fast re-use and lower costs, but also for faster transit times, reducing the radiation exposure to travellers. The Spaceship is not intended to use low energy Hoffman transfer orbits, but higher velocity orbits. These have lower transit times but leave the vehicle with significant velocity when it reaches Mars or Earth. The Starship must then use direct entry and aerodynamic braking to shed the kinetic energy from the extra velocity.

The NASA Ames research center trajectory browser can be used to explore transit times to Mars and other bodies in the Solar System. [https://trajbrowser.arc.nasa.gov/traj_browser.php Trajectory browser]

======References======
<references />

2019-12-08T18:55:49Z

CZMatt:

Sand is natural unconsolidated granular solid substance composed of grains the size of about 0.05 mm to 2 mm. Sand grains are produced from mineral particles, rock fragments, and, primarily on Earth, degradation of biological structure, such as coral. Most sand is composed of silicate minerals, primarily [[quartz]], or silicate rock fragments. Sand, being a natural mixture, is almost never pure. Sandstone is a rock made from consolidated sandstone.<ref>Sepp, Siim. n.d. [https://www.sandatlas.org/sand/ “What Is Sand?”] Sandatlas. </ref>[[Image:Cliffhanger Sand.png|right|thumb|300px|"'''Cliffhanger Sand'''" analysed by the rover [[Spirit]]]]

[[category:Materials]]

==Sand on Mars==

== Uses ==
Sand is used for concrete, glass, and construction.

==References==
<references />

Sand

2019-12-08T18:54:23Z

CZMatt:

User:CZMatt

2019-12-08T18:35:06Z

CZMatt:

Hello! I am CZMatt, a high school student with an immense interest in space exploration!

== Editing philosophy ==
Below is my editing philosophy, just in case someone happens to care.

=== Beyond Wikipedia ===
Since I come from Wikipedia, most of my philosophies originate there. However, Marspedia is a very different place from Wikipedia: Wikipedia is a generalized encyclopedia. As such, Wikipedia articles must reach a higher standard of notability. One is not going to find an article deeply specialized articles on Wikipedia about Martian igneous rock or early emerging technologies that can aid greatly on. This is what Marspedia is for. Thus, Marspedia is much more likely to be use by people with an active interest in space exploration. These people are much more likely to know the basics about space exploration, so the language of Marspedia may be much more science-oriented.

=== On boldness ===
I believe the best way to create many good articles quickly is for users to be bold and to make a change when they see a way for the wiki to be improved. I pretty much agree with the [[w:Wikipedia:Be_bold|Wikipedia policy on boldness]] here.

=== On citations ===
I believe that everything I write as fact on a wiki should have citations backing it up. Due to the nature of this wiki, that might mean me just linking to an essay explaining my reasoning somewhere in my user-space. '''This is a personal bar'''; I do not hold this expectation for other users because I believe that so much knowledge on this wiki will originate from life-long space exploration lovers that just their experience alone will allow for the material written to be reasonably credible for the purposes of this wiki.

Second, Marspedia expands beyond Wikipedia in that it is a place for the presentation of fact ''and'' discussion, while Wikipedia only intends to present fact, using discussion to decide how to best present that fact. Thus, much more on Marspedia is likely to be subjective. While these arguments must be reasonably construed, they cannot be expected to cite sources as factual information is expected to be referenced.

I do believe, however, that if there is a disagreement on the presentation of fact on Marspedia, then factual citations should be introduced, as if two or more intelligent individuals disagree on the presentation of fact, then external sources should be introduced to mediate the disagreement. I believe that Marspedia should work to be as credible as possible despite its specialized nature so that it can maintain status as a premier source of information about the Martian planet.

In this sort of specialized wiki, not everything will be able to be backed up by scientific papers or news articles. As such, forum threads, Reddit threads, explanatory YouTube videos, or original research should suffice for citable work. It is always preferable that published work is cited, but specialization makes this impossible.

Gravity

2019-12-08T18:02:50Z

CZMatt: CZMatt moved page Gravity on Mars to Gravity over redirect: I didn't see the talk page discussion about this. Sorry!

[[Mars]] has a mass of 6,419 · 1023 kg. Compared with [[Earth]] this is only a little bit more than a tenth. This results in a lower Gravity as the planet is also less dense than Earth.

The gravitational acceleration is 3,71 m/s², compared to 9,81 m/s2 on Earth. The resulting weight of any body on the surface of Mars is only a bit more than a third, compared with the same body on Earth. Mass and inertia remain the same, however.

==Impact on physics and nature==

*[[Dust storms]] on Mars reach high altitude. Scientists found the cause in the low gravity, allowing the [[sand]] grains to bounce much higher.
*The low gravity and lack of continental drift has allowed the growth of the highest mountain in the [[solar system]], e.g. [[Olympus Mons]].
*A rock thrown on Mars will fly much further than on Earth.

==Impact on humans==
The development of [[children|human embryos]] might be different. Also, the long term consequences for the health of human beings is unclear. Constant [[physical exercise]] has proven to be beneficial on the ISS to reduce calcium loss and maintain muscle mass. However the difference between no gravity and low gravity is still unknown.

==Impact on technology==

*The pressure on bearings for the same service is lower, causing less friction and abrasion. Or lighter bearings can be used.
*A [[space elevator]] is easier to build.

==Impact on plants==

*Plants have grown normally on the ISS and should grow on Mars. The effect on their internal structure of the low gravity is unknown.

[[Category:Gravimetry]]

Gravity on Mars

2019-12-08T18:02:50Z

CZMatt: CZMatt moved page Gravity on Mars to Gravity over redirect: I didn't see the talk page discussion about this. Sorry!

#REDIRECT [[Gravity]]

Talk:Gravity

2019-12-08T18:02:23Z

CZMatt: CZMatt moved page Talk:Gravity on Mars to Talk:Gravity over redirect: I didn't see the talk page discussion about this. Sorry!

The title, along with some others, is a bit vague. It should ratehr be "gravity on Mars" of "problems associated with Martian gravity" [[User:T.Neo|T.Neo]] 13:06, 17 June 2008 (UTC)
:Hi T.Neo, every article in Marspedia is related to Mars. I see no point in naming all articles "XXX on Mars", e.g. "gravity on Mars", "water on Mars", "sunlight on Mars", "greenhouse on Mars", etc. Okay, the article is a bit vague, indeed. It is only a start. Your commenting made me elaborate it a little more. Now it shows a variety of aspects. Still there is much more to write: problems, advantages, more facts and figures, thoughts, anything about gravity (on Mars). Some day the article will be very large, forcing us to divide it into several specialized articles, such as "human health problems associated with Martian gravity", "agricultural problems associated with Martian gravity", etc. By the way, I am glad, you're contributing to Marspedia. Welcome to the team! -- [[User:Rfc|Rfc]] 18:53, 17 June 2008 (UTC)

Thanks. I get you point with the names. Also, back to the subject of gravity, ''No one knows'' what 0.38x gravity does to the human body. And, if Mars were to be Terraformed, imagine the long and short term effects to animals and plants. [[User:T.Neo|T.Neo]] 09:37, 18 June 2008 (UTC)

Talk:Gravity on Mars

2019-12-08T18:02:23Z

CZMatt: CZMatt moved page Talk:Gravity on Mars to Talk:Gravity over redirect: I didn't see the talk page discussion about this. Sorry!

#REDIRECT [[Talk:Gravity]]

Gravity

2019-12-08T18:00:51Z

CZMatt: CZMatt moved page Gravity to Gravity on Mars: This article specifically discusses gravity on Mars, not in a more generalized context. However, it is still a good article. I will attempt to write a new, more generalized article for gravity in th...

2019-12-07T22:10:33Z

CZMatt:

A '''volcano''' is a point on a moon or planet's surface where the hot material from the interior of the body erupts onto the surface. Volcanos have been discovered on planets such as Venus, Earth, and Mars. Several moons also show signs of volcanism.

==Types of Volcano==

*[[shield volcano]]
*[[rift volcano]]

==Volcanos on Mars==
The [[Tharsis]] region contains a number of extinct volcanos. Notable examples include [[Olympus Mons]], [[Ascraeus Mons]], [[Pavonis Mons]], [[Arsia Mons]], and [[Alba Patera]]. 
The [[lava tube|lava tubes]] of an extinct volcano may provide an ideal [[volcanic cave settlement|settlement location]].
[[category:Areology]]
{{stub}}

2019-12-07T05:59:48Z

CZMatt:

An '''astronomical unit''' (AU) is the average distance between the Earth and the Sun. It is defined as exactly 149,597,871 km, and equals approximately 8 light minutes. The unit is most commonly used to measure distances within our and other solar systems.<ref>McClure, Brian. 2017. [https://earthsky.org/space/what-is-the-astronomical-unit “What Is an Astronomical Unit?”] EarthSky. October 23, 2017. </ref>

[[Mars]] is about 2.5 AU from the Sun, which means it is 2.5 times the distance from the [[Earth]] to the Sun, or approximately 375 million km from the Sun (149,597,871 km • 2.5).

== References ==
<references />