This is too cool: the UK is thinking about a space probe that will go to Mars, land on the tiny moon Phobos, and return a sample to Earth.
I love this idea. Phobos is weird. It has and extremely low density (prompting some scientists years ago to colorfully speculate that it was a hollow alien spaceship!), it orbits Mars in a very low retrograde orbit (atmospheric tidal drag is slowly dropping it, and it will impact Mars in a few million years), and it is heavily cratered with a whopper at one end. It’s almost certainly a captured asteroid, and is worthy of further study.
Update: Phobos is not in a retrograde orbit; but it is so low that it orbits the planet faster than Mars rotates, so from the surface it appears to go backwards in the sky — that’s what I was thinking when I wrote that. Thanks for the commenters who pointed this out.
Update 2: Sigh. Reader Alan Harris pointed out it’s tidal drag, not atmospheric drag, working on Phobos and dropping the orbit. D’oh!
February 11th, 2007 at 11:48 am
That’s an awesome idea! It’d be pretty cool to follow too… I just hope it will have less troubles than that japanese probe that landed on that asteroid… I forget the name of it.
February 11th, 2007 at 12:06 pm
Weren’t the Russians going to do something like this? I’m pretty sure they were sending something to Phobos, though I don’t recall if it involved a sample return. Let me see what I can find…
February 11th, 2007 at 12:07 pm
Yup, here it is:
http://en.wikipedia.org/wiki/Phobos-Grunt
February 11th, 2007 at 12:20 pm
Remember what happened the last time the British got involved with a Mars mission.
Remember Beagle 2?
February 11th, 2007 at 12:24 pm
Phobos is in a retrograde orbit?
I thought (and so does my astro program) that both Phobos and Deimos orbited in the normal direction. Counter-clockwise when viewed from above the ecliptic. The same way Mars rotates.
February 11th, 2007 at 12:46 pm
Phobos revolves around Mars faster than Mars itself rotates on its axis, so to an observer on the planet’s surface, Phobos will rise in the west, hurtle across the sky and set in the east about four hours after it rises. (I’m sure the Martian astrologers attach great significance to this fact.) The following anecdote is attributed to Ray Bradbury.
February 11th, 2007 at 12:49 pm
Phobos is NOT in a retrograde orbit, but its orbit is so low that its period is less than one Martian day, so, from the surface of Mars, it rises in the west and sets in the east.
February 11th, 2007 at 12:51 pm
Dang! I’m going to have to learn to type faster.
February 11th, 2007 at 2:10 pm
Is it atmospheric drag or tidal friction? Certainly tidal friction would cause it to inspiral because the orbit is less than synchronous radius (unlike our moon).
http://www.daviddarling.info/encyclopedia/M/Marsmoons.html
February 11th, 2007 at 3:14 pm
[...] “Phobos sample return?“, Uma missão a Phobos para recolher amostras de solo? soa muito bem. No Bad Astronomy; [...]
February 11th, 2007 at 7:16 pm
I’ve been in love with Phobos since KSR’s ‘Red Mars’, I would love to see a colony in Stickney (maybe I just have a thing for domed cities in craters) not in my lifetime I know….
February 11th, 2007 at 10:26 pm
What a cool project! Let’s hope it does better than the Mars Lander (and its weird music by Blur).
February 11th, 2007 at 11:47 pm
>>> and it will impact Mars in a few million years
They *so* have to YouTube that.
February 12th, 2007 at 1:05 am
Is it really atmospheric drag that’s dropping Phobos? It’s still up pretty high . . .
I always thought that Phobos was getting ahead of the tiny solid body tide that it produced in Mars, so that bulge was holding it back and dropping it to a lower orbit. With our Moon, the tidal bulge it produces moves ahead of the Moon because the Earth rotates more quickly than the Moon revolves, so our tidal bulge gets ahead of the Moon, acting to speed it up in orbit (making it spiral away) at the same time the Moon slows down the Earth’s rotation (conservation of angular momentum).
— Steve >>>>
February 12th, 2007 at 8:04 am
Yeah, it’s tidal forces. Prograde moons go down if they are below the stationary orbit, they go up if they are above the stationary orbit. Retrograde moons go down regardless.
February 12th, 2007 at 8:39 am
Ummm, low density. Quick, we need to write a SciFi story wherein Hoagland is a transplant from the alien vessel Phobos. That would surely explain why he’s so freaking wierd.
(quickly because those UKers wil obviously bury the evidence when they send their lander to Phobos,,,)
Gary 7
February 12th, 2007 at 9:36 am
Hope this goes well. Would be an interesting precursor to a Mars sample return.
Isn’t a hoped for mission for the CEV to fly by the Martain moons?
February 12th, 2007 at 2:51 pm
Low density? Possibly hollow?
Oh my God, it’s Rama!
(Thank you A. C. Clarke!)
February 12th, 2007 at 11:14 pm
Sounds cool. Britannia hasn’t had much success in previous Mars landers, best wishes to them and their mutton chopped über geeky top space scientist (his name eludes me).
February 13th, 2007 at 7:37 am
As I recall, it was Iosif Shklovskii who suggested that Phobos might be artificial and also Shklovskii who blamed the rate at which Phobos was dropping on drag.
Ritual disclaimer: I see no compelling reason to view either moon of Mars as artificial.
How _does_ an asteroid get captured by a planet? OK, with Jupiter you have the chance that interaction with the other moons will produce an orbit around Jupiter (although quite possibily a highly inclined and eccentric orbit) but in a simple interaction between a planet and a passing rock, how do you keep the rock around?
I suppose the double-world explanation for how Triton got captured (a gravitationally bound pair of KBOs pass by Neptune. One is ejected at a higher speed than it came in with and the other pays the Ek cost and sticks around) might work.
February 13th, 2007 at 8:23 am
“I just hope it will have less troubles than that japanese probe that landed on that asteroid… I forget the name of it.”
I believe that is Hayabusa and that despite having two frozen gyros and a good chance that the sample collector didn’t manage to collect any samples, the Japanese are trying to get it back for 2010.
February 14th, 2007 at 12:18 pm
Hayabusa was also a technology demonstrator anyway. It was intended to prove the concept, which it did. The hope is to repeat with new hardware on more missions. Not sure how that’s going yet.