Mars rover Curiosity lands today
space.com
space.com
* An overview on CosmoQuoest.org: http://cosmoquest.org/blog/2012/08/curiosity-landing-remembe...
* A Google+ hangout that'll be covering the landing: https://plus.google.com/events/c7c2fbd2gil25fjimln1jnr1134/1...
* Conversion of the landing time into various time zones: http://timeanddate.com/worldclock/fixedtime.html?msg=NASA+Cu...
Awesome 3D live in-browser visualization of Curiosity's journey: http://eyes.nasa.gov/ [doesn't work on ubuntu :( ]
There are Curiosity landing parties going on around the world, see map: http://bit.ly/NFwMTk
Curiosity Twitter account: https://twitter.com/MarsCuriosity
NASA TV will stream landing live at: http://www.nasa.gov/multimedia/nasatv/index.html
Picture of the 3 generations of rovers next to people for size comparison: http://bit.ly/NZBKb3
A well-produced video of 7 minutes of terror, if you haven't seen it yet: http://www.jpl.nasa.gov/video/index.cfm?id=1090
https://plus.google.com/events/c5otcpguo0im3qmgblsf1fadeqs/1...
But if it works - oh, if it works! This really is the most exciting project in exogeology since men brought rocks back from the moon.
(Table of localized landing times: http://timeanddate.com/worldclock/fixedtime.html?msg=NASA+Cu...)
More info here: http://www.reddit.com/r/science/comments/xnoog/30_success_ra...
Any videos? Sure hope they did more than this with just a "lab test"
http://www.youtube.com/watch?v=89YfPWTpWN0
I'd be testing it by throwing it out of a plane and see if it can land intact?
ps. not a drop test but still interesting http://www.youtube.com/watch?v=vkGpnLrX-_g
That is not possible. Some things like gravity and atmospheric pressure/density cannot be replicated in the scale required to test here on earth. They have to rely on testing in parts and in some cases on calculations and data from previous visits and landings.
I find it impossible to believe it wasn't tested all together as a unit and just connecting individually tested parts.
Kind of strange they would not share such a video, which if made by a government entity is public domain anyway.
Believe it, because it's true.
No, having less atmosphere is a disadvantage in this case. This means just parachute wont work. Hence the whole sky crane thing. There is no feasible way to test the whole EDL (entry, descend, landing) phase here on this planet because simulating entry into mars's thin atmosphere is not possible out of computer simulations and whiteboards.
Worth a look, I promise. You get a sense of all the work to assemble a piece of hardware with this size and complexity.
Having said that, it still looks like the craziest Rube Goldberg set of hacked together systems I've ever seen for landing on a planet. Here's hoping it all comes off without a hitch. I have a feeling it'll become an object lesson in engineering whether it works or not.
It almost makes slamming into the planet and bouncing around in a giant airbag look like a perfectly reasonable and drama-free landing approach.
I spent a week of class periods building what looked like a replica of the Lunar Module with fins - the legs were springs to absorb the impact. It worked great when I tested it but failed on the testing day because the teacher was holding it upside down when he dropped it.
My friend, who goofed off the whole week drawing comics in class spent 5 minutes wrapping his bulb in straws, then crumpled up the paper, uncrumpled it and then wrapped that around the straws. A couple of loops of tape and he made a landing "vehicle" that worked every time.
Basically you have to ask the question "What science can I do at this stage?" so that during every possible outcome you extract the most data you can.
I find that a fascinating way to structure your thinking about a project.
The review board analyzing the loss of MPL could not narrow down the cause for certain, although they did identify a most likely cause. It was resolved in the future to have as much data collected as possible so that an unexplained loss could not occur again.
One key ingredient in this is line of sight to a relay orbiter.
But this is not a science driver, it is an engineering driver.
Fair point.
I can imagine a system where the capsule pitches up near the end of its run so that it starts gaining altitude and then deploys a parachute for landing once it has reached its apogee.
I appreciate that their system probably is the best design as they are a smart bunch, however I haven't heard the reason's why some of the more conventional mechanisms weren't used.
Another thing is the crane mechanism, which is to protect the rover from the debris kicked up from the rocket motors. I was wondering why the rover couldn't just be encased in a simple lightweight protective box and then placed directly on the deck?
Does anyone have any links to the other designs that were considered and rejected?
You can't land on Mars with just a parachute anyway, not with a 900 kg payload. The main problem with Mars is that its atmosphere is just dense enough that it complicates things but not dense enough that it's really helpful.
Regarding parachutes, is it not the case that if you need more performance, that you simply increase their size?
[1] http://www.youtube.com/watch?feature=player_embedded&v=S...
The effectiveness of a parachute grows at a square of your airspeed. This means that every planet has a minimum speed you can successfully slow down to using parachutes with a given system. For realistic loads and conventional materials, on Mars that is about 50m/s. Which is just too fast.
It's one thing to say it, it's another to design it such it has a chance of working. Telescoping mechanisms with deployable aerodynamic structures sounds very complicated to me, compared to the thrusters they're using.
> You could possibly then put a tractor rocket at the end of this shaft to slow descent and keep the rocket plumes away from the main body and the ground.
The sky crane already does this.
> Regarding parachutes, is it not the case that if you need more performance, that you simply increase their size?
'Performance' is lots of things, presumably you mean drag. Increasing the diameter does increase the drag, but it also increases the opening forces, which requires a stronger structure, which means more mass. You don't have the luxury of much margin when every gram in your landing system has cost the us taxpayer thousands of dollars and is a gram that you can't use for science.
Perhaps the most similar landing was by Viking, which made the final descent on rockets. Those thrusters were expressly designed (that is, compromised) to produce as little disturbance of the landing site as possible. The only thing Curiosity is doing that is really new is the sky crane. If there are any errors in understanding the dynamics of rocket plus lengthening pendulum in Mars gravity, then all is lost. I think it is likely that some extra attention has been paid to this part of the mission.
The martian atmosphere is really thin (I've heard it said that it would pass for vacuum in a high school science classroom). They've got that giant parachute doing as much deceleration-through-atmospheric-drag as possible, and it's still not enough. (And as a sibling post said, fancy atmospheric manoeuvring would require huge wings)
>Another thing is the crane mechanism, which is to protect the rover from the debris kicked up from the rocket motors. I was wondering why the rover couldn't just be encased in a simple lightweight protective box and then placed directly on the deck?
A box with rocket motors on? That'd still churn up the ground that the rover then has to drive through to go anywhere.
Or do you mean dropping it without the cable? The current rovers (MER) were deployed that way, with airbags, but this one's too big to do that with.
They do exactly that. But Mars' atmosphere is so thin that terminal velocity of the capsule is still supersonic.
> I can imagine a system where the capsule pitches up near the end of its run so that it starts gaining altitude and then deploys a parachute for landing once it has reached its apogee.
Parachutes don't help enough in 0.007atm. Even with the biggest chutes possible (remember: they're heavy!), you'd still be hurtling towards the ground like a missile.
> Another thing is the crane mechanism, which is to protect the rover from the debris kicked up from the rocket motors. I was wondering why the rover couldn't just be encased in a simple lightweight protective box and then placed directly on the deck?
Weight. Believe it or not, the sky crane delivers more payload to the surface.
> I appreciate that their system probably is the best design as they are a smart bunch, however I haven't heard the reason's why some of the more conventional mechanisms weren't used. > > Does anyone have any links to the other designs that were considered and rejected?
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2009000...
Also, that kind of blunt body is stable hypersonically, but unstable supersonically. As soon as you get to a mach number where a parachute can deploy stably (about mach 1.8 and below) you deploy it to stabilise the thing, and of course the drag is much greater than entry body alone.
>> Another thing is the crane mechanism, which is to protect the rover from the debris kicked up from the rocket motors. I was wondering why the rover couldn't just be encased in a simple lightweight protective box and then placed directly on the deck?
The point of the sky crane is not just to avoid kicking up dust, this notion seems to have become the received wisdom in the media though. The reasons include:
-Having rovers drive off from on top of things is difficult, it puts the CoG of the lander right up and if you have to drive off a sloped ramp having landed on a slope, the ramp can be really very sloped.
-Rocket forces nearer the ground can be quite an interesting control problem, in terms of the forces generated when you're near the ground and where all the exhaust goes.
-Having rocket fuel tanks landing on spikey rocks has the potential to really ruin your day.
-Knowing when to turn the rocket engines off (i.e. successfully detecting landing) is actually quite a hard problem. It's a very noisy problem, and getting it wrong was what destroyed Mars Polar Lander (i.e. it thought it landed when it was still up in the air, and so fell out of the sky). The skycrane has the rocket motors on the whole time and goes off an crashes.
Lots of this is explained in the video I linked to somewhere else in this family of comments.
http://www.jpl.nasa.gov/events/lectures_archive.cfm?year=200...
> I haven't heard the reason's why some of the more conventional mechanisms weren't used.
What's a conventional mechanism when you're landing on another planet?
A great day!