Why aren't we digging deep for signs of life?
Why don't they ever include a deep drilling rig? Or controlled explosions would uncover fossils, if there are any.
There was good news and bad news for interplanetary exploration today. The bad news is that the heat shield for NASA’s Mars 2020 rover has cracked. Thankfully, it hasn't even taken off let alone attempted to land on Earth's sister world. The good news is that NASA and the European Space Agency (ESA) have signed an agreement …
Even on Earth, where fossils are (presumably) far more plentiful than they would be on Mars, it would be very difficult to pick a landing site from 40 million miles away, and be lucky enough to find fossils within a small area around the attempted landing zone.
"Even on Earth, where fossils are (presumably) far more plentiful than they would be on Mars, it would be very difficult to pick a landing site from 40 million miles away, and be lucky enough to find fossils within a small area around the attempted landing zone"
That's a very valid point and it gets worse than that. There was only a relatively short period during its earliest geological era when Mars was potentially conducive to the development of life so any biological remnants would be tiny microfossils which could be hard to identify. There just wasn't enough time for more complex life to evolve.
An upcoming mission to Mars will include a drilling rig... around 2 metres deep, if memory serves. There's more info on the latest episode of The Sky at Night, which is dedicated to Mars.
Shaped charges use a jet of plasma pushing once solid material out of the way like it were liquid... it'd dig you a nice hole for sure, but 1, it'd damage your sample, and 2, you're still left with the problem of getting your sample out of the hole.
The story: "The heat shield cracked whilst under stress testing specifically designed to see if it would break".
Reason: Original design flaw or (more likely) material develops age related changes - like microfractures or changes in structural properties - after standing at the back of a warehouse for ten years ...
This is all at the limit of space exploration technology and finding flaws before wasting one meelion/beelion dinar is what testing is designed to do. Test, inspect, learn, check budget, fix flaws, check budget again, repeat ... Ultimately spend as little as possible whilst still convincing the team "We're not at home to Mr Cock Up"
"The bit that surprised me in this article was that it was tested at only 120% of the predicted stress level it will need to survive. That would show an extraordinary degree of faith in their predictions, not to mention extremely fine design margins!"
Mars has been a graveyard of planetary missions with a very high mission failure rate. The example of the best Victorian engineers should be followed - the mechanics, shell and electronics should all be over-engineered and have multiple redundancies where appropriate.
For bridges and other buildings, a safety factor of around 3 is common, for airliners where just adding more material would quickly make them uneconomical to fly a factor of 1.5 (150%) is used. Given a Mars mission has more constraints in common with an aeroplane than it does a bridge 120% sounds about right. Remember, the calculations are taking into account worse case scenarios and erring on the side of caution to arrive at a figure, and then this figure is multiplied by 1.2.
Now eggheads at both space agencies will together try to figure out how to get those rocks back to our home world.
I suggest putting a dummy hand complete with extended thumb on the end of the arm. There's bound to be a car passing by that they could flag down. (Note that, as with all hitch-hiking arrival times are not guaranteed.)
all joking aside, the lack of a proper hitchhiking ring might prove to be a problem...
So maybe it's time to ship a few landers? And a robot mothership?
Here's the thing: Let's say a robotic lander has some kind of secondary booster, like the Apollo's LEM. It can be an SRB type, just to make it physically smaller. The booster would be designed to get the payload into Mars orbit, with some kind of guidance capability so you can at least get something predictable to happen. After getting into Mars orbit, "the robot mothership" would rendezvous with it, along with the "plethora of others", and then [eventually] put itself on a return course back to earth.
Getting samples into the landers shouldn't be too hard, given you have a) rovers, b) robotic arms, and c) the possibility of moving small buckets to/from the surface and into the landers. Buckets would be weighed when 'in place' (and covers locked down), and the relevant information would then be used to help calculate orbital 'whatever' because you'd need precise weight information to do that.
This probably means some of SpaceX's experience in remotely landing a rocket on its tail might prove to be useful. In fact, if the lander stage was also the guidance stage on launch, they could re-use some stuff and maybe cut back on the total weight. Still you're shipping a rocket to Mars that's designed to take off again, something we haven't done before. It should be interesting.
A few test runs to the moon might be worth doing, to work the bugs out.
Tintin managed a tail landing reusable rocket so it must be possible. "Explorers on the Moon"
The moon is easy, no atmosphere = use all the rocket power you want.
Landing on Mars is a pain, enough atmosphere that retro rockets stir up a lot of dust but not enough to slow you down.
The trouble is in order to get (eg) 1kg of samples back to Earth, you need a craft capable of returning to Earth from Mars (never been done). It'll probably also have to carry enough fuel to brake into Earth orbit, rather than parachute down and potentially break quarantine. Plus you need something that can take the samples from the surface of Mars and into orbit, probably to somehow automatically dock with the return craft in Mars orbit (again, never been done that far from Earth).
The biggest issue though is that both of these craft have to be carried all the way to Mars, and the orbital rocket has to be safely landed, and all of this takes a massive amount of fuel.
Then you add on the fun little problems, like building a rocket engine that can survive the months long trip to Mars, the landing, and also survive several days on Mars, and can still ignite successfully and reach orbit. Exactly what kind of fuel do you use that doesn't need heating or cooling or compressing for that long, whilst still being as efficient as possible?
All in all it's a tricky set of problems, and will probably cost a lot of money to do.
For more info, here's a look at a NASA plan for sample return from thirty years ago, which goes through some of the problems (eg taking a parachute all the way from Earth, to Mars and back again was too much mass, so they designed the return capsule to just crash).
"It'll probably also have to carry enough fuel to brake into Earth orbit, rather than parachute down and potentially break quarantine."
You could have the soil sample in a protective container with a small radio beacon attached hurtling towards the vicinity of Earth and intercept it with a separate craft launched from here. Obviously a craft that can get up to the speed of the returning sample has sufficient speed to fly to Mars anyway, but there's still a potential saving to be made: the point is that the equipment for landing on Earth (heat shield, parachute and so on) doesn't have to be slowed down into orbit around Mars and then accelerated away again; it just needs to meet up with the returning sample somehow, somewhere between here and there.
phuzz covered this well. The basic issue here is that the fuel requirement to launch a payload to orbit scales with the cube of the payload weight. With an out-and-return mission, you have to do this twice -- the fuel for the return mission is part of the launch mission's payload, so you're paying double for your return payload. (This is why the LEM had to be so lightweight.) Mars also has a relatively deep gravity well; not as deep as Earth's, but a lot deeper than the Moon's. The tyranny of the rocket equation strikes again.
This ignores the fuel requirements to get into interplanetary transfer orbits, but IIRC those are actually a fair bit smaller than what it takes to get to orbit to start with. This also doesn't include fuel needed to make a soft landing, but since Mars and Earth both have atmospheres you can use for aerobraking, that's not a large requirement. If you're clever and have a robust enough heat shield, you might even be able to slow down for orbital capture that way. But whatever you're using for your landing on Earth, you've got to lug it both ways, unless you're going to pick your sample up from orbit with another craft.
One way around some of this is to do what Apollo did, and leave some of your fuel (and maybe your Earth re-entry gear) in orbit while a smaller sampling craft descends to the surface. That helps with the fuel requirements, since you're not carrying all that fuel back up to orbit again, but it greatly increases your mission complexity; you'll need to do an automated orbital rendezvous and capture, on limited fuel reserves, and the round-trip communications time is too large for a manual override if it goes wrong. This is not easy.
@Orv - you're missing a trick - you may not not need to send all of the fuel needed for the return trip as payload to Mars. You could instead send just some hydrogen feedstock and a small chemical plant (IIRC from The Case for Mars, this wouldn't be very large at all, about suitcase sized) to create fuel from Mars' atmosphere. Thing is, once the lander gets to Mars, drills a hole and takes a sample, it isn't going anywhere for months - it has to wait until the next efficient Mars-Earth launch window. So you;ve plenty of time for the fuel plant to make the necessary propellant for the return trip.
I'm not 100% positive on this, but extrapolating from the Mars Direct plan for a manned Mars mission, it's possible that there's no need to send an orbiter AND a lander to Mars - just land the lot on the surface, which simplifies the mission, which then becomes - land everything on Mars, start fuel plant going, fire up drilling robot and send it on its way, place samples in return hold in main ship, return fuelled ship when Mars-Earth launch window arrives. No tricky orbital rendevous needed!
I've seen those proposals too, but I'd argue that building a chemical plant that will start up and run without problems, without human intervention, on another planet, is probably even riskier and more complicated than orbital rendezvous. Even when built on earth, chemical processing plants are finicky things.
"I suggest putting a dummy hand complete with extended thumb on the end of the arm. "
I really wouldn't. Somewhere in the galaxy, that gesture is a mortal insult and an accepted shorthand method of declaring war. Somewhere else, it means "Bring that Tesla coil over here and bugger me senseless, Big Borg". Somewhere else it means "Kill the defeated gladiator", elsewhere it means "NICE TITS", a few light-years away "Are there Donuts at the next exit?".
The stony silence and stillness of mannequins is probably the best choice in this case. One can't be too careful with gestures around unfamiliar cultures.
"Scientists hoping to get some real Martian muck under their microscopes should not hold their breath. ... Any potential mission involving posting materials back to Earth would therefore be some distance into the future, beyond the 2020 and 2021 robo-excursions.
Which means the zombie apocalypse is still some time off yet.
"Which means the zombie apocalypse is still some time off yet."
Probably even longer than that, the ESA Exomars rover was originally supposed to have launched by now. As with all massively complicated technological projects, a lot of system engineers appear to be channeling Douglas Adams and spending a lot of time listening for the whooshing sound that deadlines make as they go passed...
"Space engineering is hard. You might think it takes a long time to put up that shelf in the kitchen, but that's just peanuts to space..." (and so on.)
The team at Lawrence Livermore under John Whtehead did a lot of work on pumped systems, effectively fluidic oscillators which scaled down better than turbo pumps and were more powerful (IE much higher Isp) than pressure fed systems.
What they needed were a) Full thermal vacuum test b)Small, high pressure (IE 1000psi) combustion chamber.
With this IIRC something like SSTO to Earth was possible.
I did a quickie search on this and only found a summary of an article by Whitehead.
However from the summary I think I know what they're talking about: something smaller than one of those massive turbopumps they use on liquid fueled rockets nowadays. The article even suggests something piston powered.
I suggest a 'swashplate' design:
On one side, you have a swashplate engine, the other side a fuel pump. The engine would use a 2-part fuel, possibly ignited like a diesel engine [you could time fuel injection to prevent excessive knocking]. If a mechanical injector pump were used for the fuel injection [directly tied to the engine shaft] then all you would need to do is start it spinning [this would require a 'start gas' of some kind, maybe pressurized tanks of N2 or He or whatever]. Air starting of diesel engines isn't a new concept [it's done on submarines for example]. Then the fuel pump inlet valve would open and fuel would start-a-pumping. And so, you could apply start air to the fuel pump inlet (and make it work like a motor for the startup sequence), then the air shuts off when the engine fires up, then at the proper RPM the inlet valves open, and then the rocket fires up, etc.. Of course the lubricants and components need to work at cryo temps but this is more or less 'a given" being rocket fuel, etc..
As for the rocket engine itself as long as you can produce enough fuel volume for the engine to produce reasonable thrust, it oughta be a complete "no brainer".
Worthy of mention, an effective use of a swashplate engine:
NOTE: for a cooling system, you have some very cold fuel that could circulate around the engine before being pumped and/or burned by the fuel pump itself. This is already done with a typical rocket engine in which the fuel is circulated through the engine jacket prior to going into the combustion chamber. Additionally, the rocket bell could be cooled by forming a laminar layer of fuel along the inside surface, such that temperatures could actually exceed the melting point of the engine. At the expense of a small amount of fuel that forms the layer, you'd get to use a much higher burn temperature. [I don't know if this laminar layer trick is being used already, but most likely it is, as it's too obvious not to have it in a modern rocket's design].
There is a tiny chance there is life on Mars since the rule are in place to protect Mars from being infected by microbes from Earth. For the same reason probes are not allowed near likely places for life - the old probes were not sufficiently sterilised to permit that.
Why then will they permit bringing Mars rocks back to Earth where we know (right?) that there is in fact life here?
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