# Landing on Phobos Rather Than Mars **URL:** \ **Category:** Factual Questions\ **Created:** [March 10, 2009, 5:28pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979 "2009-03-10T17:28:51Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![AndrewJRichards](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@AndrewJRichards](https://boards.straightdope.com/u/AndrewJRichards)\ **Post date:** [March 10, 2009, 5:28pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/1 "2009-03-10T17:28:51Z")
From Wikipedia: > [@](#): > > “Phobos has also been proposed as an early target for a Manned mission to Mars, since a landing on Phobos would be considerably less difficult (and hence, much less expensive) than a landing on the surface of Mars itself.” My question is why? I would imagine landing on the bigger object that we’ve visited already is easier, despite the atmosphere. What other advantages would there be to land on Phobos? To me, that would be like driving to Disneyland, hanging out in the parking lot, and then leaving. ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [March 10, 2009, 5:32pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/2 "2009-03-10T17:32:34Z")
at a guess, the gravity on Phobos would be much lesser than on Mars, meaning less fuel would be needed to control the descent and the take-off. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [March 10, 2009, 5:40pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/3 "2009-03-10T17:40:21Z")
Possible biocontamination might be considered. ---
**Author:** ![History\_Geek](https://avatars.discourse-cdn.com/v4/letter/h/b19c9b/32.png) [@History\_Geek](https://boards.straightdope.com/u/History_Geek)\ **Post date:** [March 10, 2009, 5:43pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/4 "2009-03-10T17:43:07Z")
As far as I can recall it was primarily the Soviets who had a fascination with Phobos. They sent a couple probes to it and everything. Since it’s nothing more than a captured asteroid there’s little reason to land on it, unless you’re looking to get data on asteroids. It’s useless as a moon and almost useless in Mars exploration. ---
**Author:** ![davekhps](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@davekhps](https://boards.straightdope.com/u/davekhps)\ **Post date:** [March 10, 2009, 5:48pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/5 "2009-03-10T17:48:29Z")
> [@History\_Geek](#): > > . . .and almost useless in Mars exploration. [Link](http://www.thespacereview.com/article/501/1). > [@](#): > > . . . On top of that, he said, Phobos offers a stable platform for observations of Mars and is a place where astronauts can teleoperate robots on the Martian surface with little time delay. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 10, 2009, 6:05pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/6 "2009-03-10T18:05:04Z")
> [@ilovetoberandom](#): > > I would imagine landing on the bigger object that we’ve visited already is easier, despite the atmosphere. Phobos is _tiny_. The surface gravity is less than 1/1000 G, compared to roughly 1/3 G for Mars and 1/6G for our Moon. Landing on Phobos is trivial compared to even landing on the Moon. If you recall, the first manned mission to the Moon was Apollo 8, which didn’t actually land on the Moon. It went around the Moon and then came straight back, to demonstrate/test the technology to at least get that far. A mission to Phobos would be similar, with the added bonus that you do get to do some science (e.g. bring back samples, and leave behind various instruments to monitor the Phobos/Mars environment). ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [March 10, 2009, 6:07pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/7 "2009-03-10T18:07:34Z")
You don’t really land on Phobos, it’s more like you dock with Phobos. ---
**Author:** ![wolfstu](https://avatars.discourse-cdn.com/v4/letter/w/d6d6ee/32.png) [@wolfstu](https://boards.straightdope.com/u/wolfstu)\ **Post date:** [March 10, 2009, 6:23pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/8 "2009-03-10T18:23:10Z")
Just for some context, an unmanned sample-return mission is already in development for Phobos. [Phobos-Grunt](http://www.esa.int/SPECIALS/ESA_Permanent_Mission_in_Russia/SEMIJFW4QWD_0.html) (‘Grunt’ is a transliteration of the Russian word for ‘soil’) will be a Russian mission with European participation. ---
**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:** [March 10, 2009, 6:50pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/9 "2009-03-10T18:50:22Z")
> [@](#): > > . . . On top of that, he said, Phobos offers a stable platform for observations of Mars and is a place where astronauts can teleoperate robots on the Martian surface with little time delay. But what advantage does landing on Phobos offer over just sitting in Martian orbit? ---
**Author:** ![fiddlesticks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiddlesticks/32/18129_2.png) [@fiddlesticks](https://boards.straightdope.com/u/fiddlesticks)\ **Post date:** [March 10, 2009, 6:54pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/10 "2009-03-10T18:54:23Z")
It’s something new. We’ve landed on and orbited Mars plenty of times, but we haven’t landed on an asteroid yet, which is basically what Phobos is. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [March 10, 2009, 7:20pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/11 "2009-03-10T19:20:52Z")
> [@Lemur866](#): > > You don’t really land on Phobos, it’s more like you dock with Phobos. Hell, if you really want to leave your mark, you could _carpet_ it. ---
**Author:** ![Argent\_Towers](https://avatars.discourse-cdn.com/v4/letter/a/e8c25b/32.png) [@Argent\_Towers](https://boards.straightdope.com/u/Argent_Towers)\ **Post date:** [March 10, 2009, 7:23pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/12 "2009-03-10T19:23:31Z")
I heard there is a portal to hell on Phobos. ---
**Author:** ![fiddlesticks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiddlesticks/32/18129_2.png) [@fiddlesticks](https://boards.straightdope.com/u/fiddlesticks)\ **Post date:** [March 10, 2009, 7:26pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/13 "2009-03-10T19:26:19Z")
> [@fiddlesticks](#): > > It’s something new. We’ve landed on and orbited Mars plenty of times, but we haven’t landed on an asteroid yet, which is basically what Phobos is. Oops…forgot all about NEAR-Shoemaker, which landed on the near-Earth asteroid Eros for its finale…even though it wasn’t designed to be a lander… [http://near.jhuapl.edu/](http://near.jhuapl.edu/) ---
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [March 10, 2009, 7:35pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/14 "2009-03-10T19:35:26Z")
> [@Argent\_Towers](#): > > I heard there is a portal to hell on Phobos. No, it’s just a Starbucks. ---
**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:** [March 10, 2009, 8:06pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/15 "2009-03-10T20:06:45Z")
> [@](#): > > Oops…forgot all about NEAR-Shoemaker, which landed on the near-Earth asteroid Eros for its finale…even though it wasn’t designed to be a lander… Which illustrates the point about just how easy it is to land on one. Don’t worry, **Argent Towers** , I understand some badass with a shotgun already took care of that about 15 years ago. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [March 10, 2009, 9:43pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/16 "2009-03-10T21:43:02Z")
> [@Chronos](#): > > But what advantage does landing on Phobos offer over just sitting in Martian orbit? Wouldn’t orbital stability be offered by association with the larger object, and you wouldn’t need to expend resources like occasional firing of thrusters to keep it in place? ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [March 10, 2009, 9:55pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/17 "2009-03-10T21:55:32Z")
> [@Argent\_Towers](#): > > I heard there is a portal to hell on Phobos. That’s just the Doom sayers. ---
**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:** [March 10, 2009, 10:29pm UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/18 "2009-03-10T22:29:38Z")
> [@](#): > > Wouldn’t orbital stability be offered by association with the larger object, and you wouldn’t need to expend resources like occasional firing of thrusters to keep it in place? You can also achieve orbital stability just by being in orbit, as long as you’re well above the atmosphere (and any reason why a high orbit would be a problem would also be a problem for landing on Phobos). ---
**Author:** ![History\_Geek](https://avatars.discourse-cdn.com/v4/letter/h/b19c9b/32.png) [@History\_Geek](https://boards.straightdope.com/u/History_Geek)\ **Post date:** [March 11, 2009, 2:00am UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/19 "2009-03-11T02:00:26Z")
> [@davekhps](#): > > [Link](http://www.thespacereview.com/article/501/1). Aside from the point about obtaining Earth-biocontaminate-free impact debris from Mars there’s nothing in that article that can’t be (or hasn’t already been) done in orbit around Mars, on our own moon, or with unmanned vehicles on other asteroids. The only valid reason I can see for choosing a Phobos-rendezvous over orbiting Mars would be to ensure you weren’t in the way of Phobos or Deimos. Any science about Phobos itself is secondary to actually landing on Mars. As Mr. Foust points out in his article there, going to Mars is expensive. Why duplicate that expenditure of time and resources? His suggestion that our technology is incapable of a successful Mars mission is just plain wrong. Yes, landing on Mars and returning to Earth is more expensive than going to Phobos and coming home. But Mars is more fascinating and more important than Phobos by (at least) an order of magnitude. None of which is to say that going to Mars and going to Phobos are mutually exclusive. If you’re going all that way anyway, why not stop off at every little tourist trap in Mars orbit? See some sights, get some postcards, that sort of thing. ---
**Author:** ![ArmenE](https://avatars.discourse-cdn.com/v4/letter/a/e9bcb4/32.png) [@ArmenE](https://boards.straightdope.com/u/ArmenE)\ **Post date:** [March 11, 2009, 2:40am UTC](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979/20 "2009-03-11T02:40:49Z")
> [@wolfstu](#): > > Just for some context, an unmanned sample-return mission is already in development for Phobos. [Phobos-Grunt](http://www.esa.int/SPECIALS/ESA_Permanent_Mission_in_Russia/SEMIJFW4QWD_0.html) (‘Grunt’ is a transliteration of the Russian word for ‘soil’) will be a Russian mission with European participation. Regarding the note on ‘grunt’ - it’s got the same root as the English ‘ground’ [Next page](https://boards.straightdope.com/t/landing-on-phobos-rather-than-mars/488979.md?page=2)