# Mars walking **URL:** \ **Category:** Factual Questions\ **Created:** [February 4, 2003, 5:41am UTC](https://boards.straightdope.com/t/mars-walking/152662 "2003-02-04T05:41:46Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Yumblie](https://avatars.discourse-cdn.com/v4/letter/y/76d3ee/32.png) [@Yumblie](https://boards.straightdope.com/u/Yumblie)\ **Post date:** [February 4, 2003, 5:41am UTC](https://boards.straightdope.com/t/mars-walking/152662/1 "2003-02-04T05:41:46Z")
On the moon, gravity is so low that with every step the astronauts took they hopped off the ground. Since Mars more massive than the moon but still half the size of Earth, how would gravity affect walking on Mars? ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [February 4, 2003, 5:44am UTC](https://boards.straightdope.com/t/mars-walking/152662/2 "2003-02-04T05:44:17Z")
You’d weigh more than on the moon, but less than on Earth. You’d probably feel a little lighter, but not that much. –Providing highly specific answers since 2000 ---
**Author:** ![MEBuckner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mebuckner/32/2896_2.png) [@MEBuckner](https://boards.straightdope.com/u/MEBuckner)\ **Post date:** [February 4, 2003, 5:53am UTC](https://boards.straightdope.com/t/mars-walking/152662/3 "2003-02-04T05:53:50Z")
To be somewhat more specific, [surface gravity on Mars is 0.377 that of Earth](http://seds.lpl.arizona.edu/nineplanets/nineplanets/data2.html). ---
**Author:** ![MEBuckner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mebuckner/32/2896_2.png) [@MEBuckner](https://boards.straightdope.com/u/MEBuckner)\ **Post date:** [February 4, 2003, 5:55am UTC](https://boards.straightdope.com/t/mars-walking/152662/4 "2003-02-04T05:55:09Z")
…So a person who weighs 150 pounds on Earth would weigh about 56 pounds on Mars. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [February 4, 2003, 6:04am UTC](https://boards.straightdope.com/t/mars-walking/152662/5 "2003-02-04T06:04:27Z")
.377? I was thinking more like .80. Huh. Shows what I know, I guess. ---
**Author:** ![catdog](https://avatars.discourse-cdn.com/v4/letter/c/c6cbf5/32.png) [@catdog](https://boards.straightdope.com/u/catdog)\ **Post date:** [February 4, 2003, 6:17am UTC](https://boards.straightdope.com/t/mars-walking/152662/6 "2003-02-04T06:17:30Z")
… and the Moon’s gravity is roughly 1/6 or that of Earth. (I say roughly because I took the number from a kids science website) [http://www.sciencemonster.com/gravity\_inertia.html](http://www.sciencemonster.com/gravity_inertia.html) ---
**Author:** ![MEBuckner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mebuckner/32/2896_2.png) [@MEBuckner](https://boards.straightdope.com/u/MEBuckner)\ **Post date:** [February 4, 2003, 6:35am UTC](https://boards.straightdope.com/t/mars-walking/152662/7 "2003-02-04T06:35:47Z")
Figuring surface gravity can lead to some surprising results. (And _I_ certainly didn’t calculate any of this out; I just Googled.) Looking at the [physical data for the planets](http://seds.lpl.arizona.edu/nineplanets/nineplanets/data1.html), Mars is slightly over half of Earth’s diameter, but has only a bit more than 10% of Earth’s mass. Even if Mars were as dense as Earth, it would only have around 15% as much mass–mass varies according to the cube of the radius, so an object of equal density and exactly half the diameter will have 0.5 x 0.5 x 0.5 or 12.5% of the first object’s mass–and on top of that Mars is actually only about 70% as dense as Earth. However, [surface gravity is proportional to the object’s mass divided by its radius squared](http://photon.phys.clemson.edu/pjf/lec.black_holes.html#sgravity). So, Mars’ lower radius actually has the effect of making its surface gravity greater. (Conversely, even though Jupiter is over 318 times as massive as Earth, its “surface” gravity–that is, the gravity at its cloud tops, since Jupiter doesn’t really have any known “surface”–is “only” 2.364 times that of Earth, because an object at the top of Jupiter’s clouds is so much further away from the center of all that mass than an object on the surface of Earth is from the center of Earth’s mass.) ---
**Author:** ![Sock\_Munkey](https://avatars.discourse-cdn.com/v4/letter/s/aeb1de/32.png) [@Sock\_Munkey](https://boards.straightdope.com/u/Sock_Munkey)\ **Post date:** [February 4, 2003, 8:24am UTC](https://boards.straightdope.com/t/mars-walking/152662/8 "2003-02-04T08:24:01Z")
One thing I always think about when the subject of terraforming mars comes up is that if we can get the air pressure up to 10 psi or more, small pedal-powered aircraft would work quite well in the low gravity. Remember when the human-powered Daedelus aircraft flew across the english channel? ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [February 4, 2003, 1:28pm UTC](https://boards.straightdope.com/t/mars-walking/152662/9 "2003-02-04T13:28:09Z")
> [@](#): > > On the moon, gravity is so low that with every step the astronauts took they hopped off the ground. They hopped because walking was dam near impossible with the spacesuits. The hop was intentional and it was not a normal walking step that propelled them off the ground. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 4, 2003, 9:21pm UTC](https://boards.straightdope.com/t/mars-walking/152662/10 "2003-02-04T21:21:58Z")
To distill **MEBuckner** ’s post a bit, surface gravity is proportional to density times radius. So a planet (Mars) with half the Earth’s radius and about 70% of Earth’s density would have a surface gravity of about 35% of Earth. Which is about right for Mars. ---
**Author:** ![rhinostylee](https://avatars.discourse-cdn.com/v4/letter/r/bc79bd/32.png) [@rhinostylee](https://boards.straightdope.com/u/rhinostylee)\ **Post date:** [February 4, 2003, 10:02pm UTC](https://boards.straightdope.com/t/mars-walking/152662/11 "2003-02-04T22:02:24Z")
That means that it would be really easy to climb the pyramids on Mars . . . ---
**Author:** ![tsunamisurfer](https://avatars.discourse-cdn.com/v4/letter/t/a698b9/32.png) [@tsunamisurfer](https://boards.straightdope.com/u/tsunamisurfer)\ **Post date:** [February 5, 2003, 12:30am UTC](https://boards.straightdope.com/t/mars-walking/152662/12 "2003-02-05T00:30:48Z")
Heavy spacesuits are required on Mars. Hence, walking would be greatly affected. ---
**Author:** ![stockton](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@stockton](https://boards.straightdope.com/u/stockton)\ **Post date:** [February 5, 2003, 12:56am UTC](https://boards.straightdope.com/t/mars-walking/152662/13 "2003-02-05T00:56:11Z")
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