For the landing to succeed, hundreds of events have to go right -- many with split-second timing and all controlled by the spacecraft with no human intervention. Enter the Enter Descent and Landing (EDL) engineering team, whose mission was to design a flight plan and a craft that can go from 13,200mph to 0mph in seven minutes to land on Mars' surface. The critical challenges the team addressed included designing a heat shield that can resist temperatures of up to 1,600F and a supersonic parachute (the largest and strongest ever produced, according to JPL engineers) that can withstand 65,000 pounds of force and slow the craft down to 200mph.
Since even that speed can't accommodate a landing, the team also designed a rocket system that will help slow the craft even further, along with a diverter mechanism that will draw the craft away from the parachute and help reduce horizontal and vertical velocity. Operating rockets too close to the ground could cause giant dust storms that could damage the Curiosity's instrumentation and mechanics. Therefore, the team also designed a sky crane that will lower the rover on a 21-foot tether, deposit it gently on wheels to the surface, and cut the bridle so the rest of the craft can fly away and crash safely out of the rover's reach.
"There's an incredibly complicated, orchestrated set of maneuvers to get this thing on the ground, and it will happen all blind," Dave Taylor, vice president of Siemens PLM Software, told us. "By the time [mission control] finds out whether the rover got through the outer atmosphere of Mars, it will have either crashed or successfully landed."
The JPL standardized on Siemens PLM Software tools several years ago, so Teamcenter PLM served as the data management and design collaboration platform via the JT Open format. Overall product design was done in NX CAD, and NX CAE helped the team understand stresses and loads on all mechanical components, perform tolerance analysis, and make sure components fit together optimally.
This is a very complicated and strange landing sequence. It is, of course, dictated by the environment and size of the craft, but it is still fantastic. The only way to plan this out is simulation. That in itself is a big process. The delay in communications caused by the great distances in space has always made commanding interplanetary craft complex. You don't command it like a RPV. In effect, you send up a program that handles the maneuver, and hope it works. Here's hoping this one works on Mars.
There will no doubt be a ton of nail biting over this landing. It is so complex and in some ways, appears so convoluted, but I suppose that is what's necessary for this particular exploration. The whole notion that they are dark for seven minutes before knowing if the mission was a success or not is pretty mind boggling.
Wow, Beth – thanks for that article. What a difficult scenario to resolve! Two lines sum it up:
,,,,, seven minutes to travel from atmosphere to surface, but 14 minutes for a signal ,,,,,
,,,,,, By the time we get a signal back, it will have either crashed or successfully landed ,,,,,
Talk about the Kobayashi Maru!! Accordingly, the entire sequence has to perform autonomously, perfectly, and without any correctional interventions. What a fantastic challenge; I'll be watching Space.Com and other sites on August 5th for news on this!
Beth Stackpole: It does seem like a lot of things must go right. The most confusing thing to me(I understand why) is the crane. I just can't wait to see it on tv. Wish they had the swamp people camera crew there to film it, that'd be awesome!...lol
Not to go off subject, but if any cameramen are out there that knows how those swamp guys get those shots I would sure like to know. I can figure out most of them, but some just leave me thinking...how the heck did they do that?! It might be a strange show, but unbelievable camera work.
The crane is what they came up with to lower the rover on to the surface after vastly decelerating it with rockets. Apparently, if the rockets get too close to the surface, they kick up a dust storm that would ruin the equipment and rover itself, so they required a more streamlined and less intrusive way to lower the rover to Mars surface.
Actually, from watching the press conference last night, a bigger reason for the sky crane vs. a legged-lander (like Phoenix and Viking) is a legged lander would have to land on perfectly flat land, and perfectly upright, or it would most likely topple over. As a retrorocket approaches the ground - given the lack of air pressure and the unevenness of the ground, back-pressure from the rocket exhaust could spike unpredictably.
These two reasons make a legged-lander far less desirable than the sky crane.
The drop-bounce-roll landing (MER, MPF) is also unfeasible as we don't have any cloth - for airbags - that could withstand the impact of a metric ton hitting the ground.
I gather that they never actually tested a prototype of the 'crane' concept on Earth! That shows an incredible confidence in software!
I presume the fact that there are 8 rockets (2 in each corner?) indicates that there is redundancy in each corner, so only 4 actually need to work. It is going to have to fire the backup really fast if one of the mains fails...
This isn't such a far-fetched idea. It is VERY similar to the escape gantry used on all pre-shuttle manned space flights. The emergency system was designed to take a post-launch capsule to a sufficient altitude that the main parachute would function safely. This new system simply works in reverse sequence. NASA simply replaced the heavy, bulky metal superstructure with cables. So long as there are no tangles.....
Altitude is determined with a device similar to a laser range finder. At the appropriate altitude, the steps in the deployment/disengagement sequence are initiated.
This is gong to be fun to watch, once the rover is safely down. This lading sounds quite a bit different from the rover landing in the late 1990s, when the rover was enclosed in a big ball that bounced on the surface and then opened once it came to a rest.
I had forgotten we are this close to the landing. I think your great article is a "shining" example of how our country leads the world relative to engineering talent. We have the best schools, the best teachers and great opportunities to demonstrate engineering talent and resourcefulness. My great disapointment is our abdication of the manned programs and the loss of talent that will surely follow. Let's hope this landing is a total success.
At one time we did have the best schools, the best innovation, etc. Many of the senior scientists and engineers on this project were products of that period. Unfortulantly, according to every objective study, competitive exam, and evaluation, the US can no longer make such boasts. Our students lag behind even some formerly "backward" countries in math and science. The number of college grads per-capita, especially in science and engineering, has also fallen behind much of the world.
People who continue to make such jingoistic claims based on long-faded laurels demonstrate that we lag behind the rest of the world in honesty as well.
J-Allen, I'm going to overlook the fact that I have been called less-than-honest. If you evaluate our top engineering schools, and I do that on a regular basis, you will find that we do rank equivalent to those top schools in other parts of the world. NOW, I will admit, the caliber of student we send to those schools is dropping year by year. This is THE reason my wife and I have sent our three boys to private schools. The public educational system in this country is horrible, at best, and our so-called public servents don't really seem to worry that much about it. We are creating a class structure in this country which does worry me. I have a public education all the way--K through graduate school but then again, I'm 70. Things change. I read on a continuing basis the back-and-forth with our school boards, unions, teachers, etc and it is truly regreatable. I feel the answer is let's once again put the students first and the politicians last --- or at least close to last. Just a thought.
You are correct that American universities are still top notch, and they still attract the most talented students from here and abroad. That, however, was not the assertion in your comment. Also, I did not mean to impugn your honesty. I regret any suggestion that could be read that wa, especially now that you have clarified your position so well. I intended only to challenge those who, through blind nationalism, continue to insist that the US is "the best in the world" on every count. Here, too, some of the tortoises have overtaken the over-conficent hare.
I certainly agree with you that our country should put much more of its public resources into education and research, both pure and applied. We can regain our former leadership, but in order to do so we have to recognize the areas in which we have fallen behind. BTW, I am also about your age--69.
J-Allen, I agree completely and you are correct in that my origional statement was definitely not worded to indicate the basic issues we have as a country. I should have done better up front. I worry that, as a country, we have lost interest in those STEM courses that you and I "grew up on". I was absolutely amazed at the level of competence relative to our space program in those early years. Now, we seem to be comfortable in letting others take the lead. I think it all goes back to the level of prepardness at the secondary level. Over the years I have done work with several universities and have gotten to know professors overseeing projects. They indicate to me that the number of remedial courses necessary for in-coming freshmen have increased significantly due to necessary. More and more freshmen simply can't do the work at the university level. Your viewpoint is definitely a valid one. Many thanks..Bob J.
@Dave: I know. The model was valid and the mission a success so far. Apparently, from reports I've read, there was lots of nail biting during that seven-minute silence, but the rover's somewhat outlandish design proved to be what was required for such extreme circumstances.
FYI: Statement by the President on Curiosity Landing on Mars
(Taken from NASA Web site: http://www.nasa.gov/mission_pages/msl/news/obama_statement_curiosity.html)
I thought it was a pretty ringing endorsement of the work that NASA has accomplished. Just saying....
Tonight, on the planet Mars, the United States of America made history.
The successful landing of Curiosity – the most sophisticated roving laboratory ever to land on another planet – marks an unprecedented feat of technology that will stand as a point of national pride far into the future. It proves that even the longest of odds are no match for our unique blend of ingenuity and determination.
Tonight's success, delivered by NASA, parallels our major steps forward towards a vision for a new partnership with American companies to send American astronauts into space on American spacecraft. That partnership will save taxpayer dollars while allowing NASA to do what it has always done best – push the very boundaries of human knowledge. And tonight's success reminds us that our preeminence – not just in space, but here on Earth – depends on continuing to invest wisely in the innovation, technology, and basic research that has always made our economy the envy of the world.
I congratulate and thank all the men and women of NASA who made this remarkable accomplishment a reality – and I eagerly await what Curiosity has yet to discover.
I didn't want to turn it into a political hot potato, but on a related note, it seems that NASA and the space program in general is enjoying a big resurgence thanks to this successful landing. I read some really uplifting accounts of the years of work and then there's "Mohawk guy," the real-life Bobak Ferdowski, among those at the helm of mission control for the Curiosity landing and the new breed of NASA engineer who's quite a bit different than the suits of the past. Ferdowski is now an Internet darling and is widely being credited with helping make space exploration and STEM education "cool."
YES!! The design, the model, the testing, and the actual hardware appear to be validated. Great work from a team of great minds. I am really impressed that a scheme as complex as this one worked so well. There were quite a few places where being foo just a bit would cause a failure, but it seems that everything worked as planned.
Now they have something more to brag about. Right On.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.