I hadn't realised Colin Pillinger had died. I've found the news oddly affecting considering I never met the guy. :(

(For anyone interested in the background to the Beagle2 probe, 'Backroom Boys'[1] includes a great chapter on it, and Prof Pillinger's involvement .)

[1]: http://www.amazon.co.uk/Backroom-Boys-Secret-Return-British-...

Thumbs up for that book. The section about the development of mobile telephony is great.

The section on Elite was pretty interesting as well - I can remember being amazed playing it on an Acorn Electron in '84/'85.

Colin Pillinger seemed like a great bloke though, I really did feel sorry for him when the probe failed.

Yes, I loved the Elite section - I bought the book after reading an excerpt from the Elite chapter in the Guardian [0] - and the Concorde section.

I had also missed the news of Colin Pillinger's death; RIP.

[0] Probably this one, should anyone else be curious: http://www.theguardian.com/books/2003/oct/18/features.weeken...

Yes, great chapter. I like the bit about after the fall of Soviet Union the KGB tries to sell satellite images of Great Britain to be used by Vodaphone for radio planning.

This seems like something right out of The Martian (which I am 75% through reading, and highly recommend) - http://www.goodreads.com/book/show/18007564-the-martian

Love the book. Scared about the movie. Matt Damon seems an odd cast for the role. He's not that kind of funny.

You should watch Dogma, I know it's been quite a while but he's absolutely hilarious in it.

The character is a clown who is stuck in a serious situation. He's a funny guy, a joker, and that keeps him alive.

Matt Damon is a serious actor, who can do a serious character. Put a serious character into a funny situation, and it can be very funny. But put a serious character actor into a funny man role, and well... I'm hopeful, but worried.

You didn't say 'bless you' when I sneezed.

It's Ridley Scott doing a Mars shipwreck movie. I hope the humour is at a minimum.

It wont be a very accurate adaptation if it is! Mark Watney's a fun guy!

In my head Mark Watney was Sam Rockwell, maybe beacuse of Moon , similar theme different plot.

Matt Damon has been cast? Not sure about that decision!

If you like that kind of thing I'd recommend Rocket Girls (the novels rather than the animé), and Moondust: In Search of the Men Who Fell to Earth (nonfiction).

The final act is definitely a stretch in terms of plausibility, but it's a fun book. Recommend as well.

If Matthew mcConaughey docked to a spinnig station and sandra bullock re-entered to earth like that, then Matt damon can survive that, also Andy Wier reseached a lot about the plausability of every situtation, but I'm sure "hollywood" will make this stupidly unbelievable or magically believable.

In an interview, he said the most implausible / impossible thing in the book was actually the very first scene when there is a storm that can knock things over.

Yes, my first flippant thought was, well send Mark Watney by for a quick repair... (I recently finished the Martian too, good read!)

One time in a interview I got asked "If two robots are lost on mars and can't communicate with one another, how do they find each other? - please write a program outlining your thoughts"

I just want to be clear it took an actual space agency 11 years to pull this off and the company I interviewed at just backed up data for people.

If they can't communicate with each other, why would they want to meet?

Assuming Mars is featureless (if it has features, they can both climb Olympic mons, for instance, as Mike Ash already said) and they cannot leave Mars (if hey do, they could have agreed before to meet in a bar in, say, Paris), the solutions I can think of all are a bit impractical:

- both dig a hole to the center of Mars and wait there for the other to arrive.

- both spread themselves out over half the area of Mars.

- both self-replicate until they cover the surface.

- at least one of them starts annihilating Mars.

If they are allowed to discuss strategy beforehand, the following will work:

Both walk straight ahead along a great circle. When (not if; great circles cannot not intersect and not be the same) they meet the trail of the other, the slower one stops at the intersection, and waits for the faster one to return on its path.

It's easier to go to the North or South Pole, instead of the center of the planet, because you don't have to dig so much. As a guide you can use a gyrocompass that don't need a magnetic field for orientation: http://en.wikipedia.org/wiki/Gyrocompass IANARS

I'm guessing one stays put and the other does a grid pattern search.

How does each robot decide whether to stay put or not if it can't communicate with the other?

Ha, good point. Could be pre-arranged. But if something can be pre-arranged, I like mikeash's answer.

Most of them have means to leave marks on the ground. Would that count as communicating for that exercise?

That might work on the moon, but on Mars... http://www.universetoday.com/14892/mars-dust-storms/

>> Because the planet’s atmosphere is only about 1% as dense as Earth’s only the smallest dust grains hang in the air.

It should be possible to move a few larger rocks, maybe? Spirit, Opportunity and Curiosity have robotic arms. Good image processing might or might not recognize patterns in the stones.

(http://nssdc.gsfc.nasa.gov/image/planetary/mars/vikinglander... for an example what most images I saw look like. I imagine it looks like this after a storm: http://nssdc.gsfc.nasa.gov/image/planetary/mars/vikinglander...)

(Of course, compared to mikeash's answer, this is overengineering and only applicable if their conditions are not met (prearranged meeting point; we have a map and know our location))

Start by solving the problem for two robots lost on Earth. Mars will be a bit more dusty but there is a much smaller search space to cover.

Both go to a prearranged meeting point (e.g. the north pole).

This seems too easy. Did I miss something?

thought the same thing, the devil would be in the details of the robot itself, the "how to get to same place" bit seems fairly straightforward

Nice answer!

Part of me hears stuff like this and just goes "let's get Curiosity to motor on over and..."

I am kind of hoping that at some point we'll drop a high-speed rover of some sort on Mars. Even if you took 6 months or a year, being able to cover a decent chunk of the planet would be a heck of a capability.

.. or one inside a mesh cage that can roll and jump in a chosen direction. :)

Was it just chance that the cameras would pass over that location, or was fuel spent, or other priorities diverted to discover this? That would be interesting to know, because I somewhat hope someone had to make sure we got these images and answers.

It looks like it might be as simple as one of the solar panels not flipping out to expose the radio. Such bad luck. Really goes to show how many things on a mission like this has to go right.

Hindsight is 20/20, but maybe they should have planned for a less than perfect landing.

They did actually, the thing was designed to drop on a random angle and bounce around for a while on airbags until it came to a full stop, before said airbags would deflate and it would self-right itself by opening up. Here's an image with it having landed on an uneven surface: http://freespace.virgin.net/michael.jennings1/beagle.jpg

This is a good 'accidental' postmortem and provides a good example of how to not design a probe. Having many large parts move before radio contact is possible is bad design.

I have a new project: compare designs of Martian missions that succeeded, and contrast against those that didn't.

Easy to say, but given the shoestring nature of the budget, perhaps more risk had to be taken.

Look north(?) of the probe about 6m. There's a white spot that seems to match the probe.

After reading the description regarding incomplete petal opening, it appears that one of the petals separated.

I think that's unlikely based on the design. Beagle 2 was in a flattened cylinder, a bit like a hat box, that was sealed shut to protect it on entry. After becoming stationary, the 'lid' would flip open and the round solar petals would unfurl.

If the lid opened allowing one of the petals to unfurl and break off during landing I wouldn't expect the rest of the petals to unfurl perfectly.

Is there any chance it still works at all? Probably not but I'm just curious. They said the problem was that the antenna was blocked under the solar panel.

The only thing that separates this place from reddit is the down-voting of jokes since submissions are largely cross-polinated.