NASA’s Phoenix Mars lander will drop onto the Red Planet’s surface on May 25. JPL has put together a very cool video with animations and interviews with engineers about what this portable lab will go through on its way down. This is very well done (even if one guy talks about friction with the atmosphere, when really it’s compression of the air on Mars that slows the probe down), and gives you a real sense of why landing on Mars is hard. They even high a High Def version (but it’s 187Mb!).
I think it’s fantastic that folks at NASA (or at least JPL) understand that it’s stuff like this that gets people excited, and kudos for them on putting it online. But now if they would just allow embedding it! I couldn’t figure out how to do it. If someone else can, let me know, and I’ll plop it in here. But I can embed the one on YouTube!
Thanks commenters!
May 16th, 2008 at 10:39 am
Another one here
http://news.bbc.co.uk/2/hi/science/nature/7400375.stm
May 16th, 2008 at 10:45 am
This is one of the best NASA produced videos that I have ever seen. It fits in perfectly when teaching motion and forces to 8th graders (which I do)! Thanks for the link!
May 16th, 2008 at 10:47 am
The level of detail in the explanations/narrations is great.
I can forgive the friction thing, since “friction” is sometimes a pretty generic word. I have heard air resistance described by many as friction.
May 16th, 2008 at 10:51 am
I’d call it more than a “decent” video, I’d say it is excellent!!
May 16th, 2008 at 10:52 am
You can embed the YouTube version if you’d like:
http://www.youtube.com/watch?v=i2ucH1PT4LQ
Also, it’s “descent.”
May 16th, 2008 at 10:52 am
I hope it’s not an indecent video.
May 16th, 2008 at 10:56 am
That’s an impressive, well-made mini documentary. The complexities and rapid steps of the Mars entry and landing process for Phoenix made me wonder if the inflatable-airbag landing system used with the Rovers has safer parameters – but I imagine there’s an equal amount of potential dangers. Its going to be great when they get the signals then Mars data starts coming in.
May 16th, 2008 at 11:09 am
As I understand the landing problems, the more massive the lander, the less such techniques as the airbags help. Some suggestions for very massive landers, such as those for a human occupied craft, may be better served with orbital tethers, especially useful on MArs, since the gravity is only 2/5ths earths(less weight for the tether to support) and there is the possibility of using rotating tethers from low Mars orbit(as suggested by Arthur C. Clark) to deposit a payload in the upper atmosphere at a reasonable velocity. High mass landers have the problem on Mars that there is too little atmosphere to efficiently slow the craft before it hits the surface and too much atmosphere and gravity to efficiently use braking rockets(as we did on the moon).
All in all, a most interesting video.
GAry 7
May 16th, 2008 at 11:15 am
Impressive video overall – if only this was the kind of stuff that was shown on MTV and E! we might get more kids off their lazy asses and into science careers.
May 16th, 2008 at 11:16 am
Very decent descent video. Thanks for calling attention to it.
May 16th, 2008 at 11:19 am
My primary concern is that by using the system Phoenix uses to finish EDL, the lander is gonna disrupt the very surface it’s intending to sample. I’m positive they’ve thought this through to great extent, but it seems like you would want to sample as many depths as possible of the soil, and due to landing, you’ve blown away the top layer.
A very similar video was made for the rovers, but it was ‘6 minutes of terror’ instead of 7. That dang Phoenix…hogging all the terror!
May 16th, 2008 at 11:25 am
This is the work of Maas Digital (http://www.maasdigital.com/) who’s excellent CG work also gave a similar intro to the Mars Exploration Rovers right from launch to landing four years go. The final scene of that video with the rover trundling off into the distance in the fading Mars twilight can bring tears to your eyes.
May 16th, 2008 at 11:34 am
Okay, now I’m scared!
Great video.
Moreover, the compression energy gets (partly) converted to what is commonly described as friction heat, so it is convenient to put the cludgy “friction” label over the whole mess.
But as far as pedagogy goes, Phil’s comment is as usual for the win.
Possibly there’s a weight problem, as IIRC it is claimed that the next lander, Mars Science Laboratory is too heavy to land on (current technology) bags. It could also be a dress rehearsal for that.
But mainly I think the Phoenix mission, as the name suggests, is made by parts of the failed Mars Polar Lander, that probably was designed well before the Pathfinder technology proved itself (middle 1997 vs early 1999).
May 16th, 2008 at 11:42 am
cool video
May 16th, 2008 at 11:48 am
What could be better than science fiction video? Thats right, science faction video. I am about a year out from getting my BS is aerospace engineering, so this stuff gets me all kinds of excited.
May 16th, 2008 at 12:00 pm
Aerodynamic drag can be casually referred to as friction, but when it comes time to do some actual calculations it’s critical to clarify the difference. When two surfaces rub against each other, the coefficient of friction is a function partially of the normal force which presses the two surfaces together. In the case of an aeroshell plowing through the atmosphere, the drag *is* that normal force between the shell’s surface & the fluid piling onto it. Calling it friction is a lot like saying that friction presses my feet & the floor together. It’s just not the same thing.
May 16th, 2008 at 12:09 pm
John,
That’s a valid concern about contaminating the near environment. What the lander does have to mitigate this is an arm which will extend out about 8 feet, then drill core samples from as deep as about a foot and a half. If the landscape there really is frozen, then that should do the trick. There won’t be enough heat released by the landing rockets to melt off more than a veneer of ice within close range. Anything from just below the surface will be pristine ice.
May 16th, 2008 at 12:09 pm
Landing on Mars is one of the most exciting things I can imagine (One of ‘em) Which makes all the extra energy and adrenalin being pumped into this vid appear a little redundant but I understand they have to do that.
They’ve got to try and make it exciting for the non geeks. So they’ve turned the thing into a promo for 24!
What they really need to do is invent an English villain who’s trying to blow up Mars. Jack Bower has to track him down and interrogate him to reveal whether he’s switched the telemetry data to read out in imperial or metric measurements!
May 16th, 2008 at 12:18 pm
Some things just make you proud to be human.
May 16th, 2008 at 12:41 pm
Great presentation. It makes me think of watching the Apollo moon landings as a kid… I was never bored by the long shots of the mission control folks; they seemed so tense and intent. That same sense of skilled, trained people, dedicated and excited, comes from the Phoenix team.
May 16th, 2008 at 12:52 pm
also..
check out the Phoenix EDL Animation video at http://phoenix.lpl.arizona.edu/videos.php
it goes through the steps of what happens in “real time”..pretty neat..
cheers
jb
May 16th, 2008 at 12:54 pm
[...] Phoenix descent video. Bad Astronomy is on the scene with the phoenix descent video. Phoenix is the next Martian lander which is equipped with devices to look for water and do basic soil element detection. More at NASA Phoenix [...]
May 16th, 2008 at 1:07 pm
Near the North Pole of Mars?
Time to dig out Santa Claus Conquers The Martians…
J/P=?
May 16th, 2008 at 1:13 pm
@Mark: Thanks! I neglected to have a decent look at the instrument payloads, and a scoop on a stick sounds just about right. Let’s just hope there’s not much in the way of transverse motion on the burn. I wasnt so much concerned with melting as simply blowing off surface (since I had no idea what the rockets were using. I half figured it might just be compressed gas).
May 16th, 2008 at 1:56 pm
“This is the work of Maas Digital (http://www.maasdigital.com/) who’s excellent CG work also gave a similar intro to the Mars Exploration Rovers right from launch to landing four years go. The final scene of that video with the rover trundling off into the distance in the fading Mars twilight can bring tears to your eyes.”
For fun, the animators also recycled the MER CGI model and made a comedy variation of the scene where the MER extends its RAT and takes a sample of a rock. It puts the RAT to the rock and spins it for a moment, pauses a suitably comical period of time, and then starts wildly spinning as if the RAT has become stuck, with the typically cartoon-physics result (including a wheel flying off). It’s less polished — during the rotation, the MER passes through the terrain — but hilarious.
May 16th, 2008 at 2:09 pm
Calli: Where? Where? I’ve gotta see that!
Sounds reminiscent of the scene in Wallace and Grommit’s “A Close Shave” where Grommit comes flying into the factory in the sidecar plane and the robot dog grabs the propeller which results in the plane spinning instead.
May 16th, 2008 at 2:11 pm
Never mind. Found it: http://youtube.com/watch?v=Pb8riJ_mmio
May 16th, 2008 at 2:49 pm
It’s a really good video, the sort of thing that inspires interest.
May 16th, 2008 at 3:21 pm
Hmmm. Just before the “Entry” segment, when we see the probe with the twin solar panels still attached traveling thru space … , are those warping stars
Honestly, I love such videos and collect them and demonstrate them to others. On my iPhone I have an earlier video made for the same mission – without any dialogue – as well as a video for the Mars Science Laboratory mission.
May 16th, 2008 at 3:23 pm
Aw, you changed the title from “decent” to “descent”!
I actually got a chuckle out of what I thought was a pretty good pun!
May 16th, 2008 at 4:26 pm
Phil, the “friction” thing is another example of the scientific meaning of a word having a different meaning that the everyday meaning. The everyday meaning of the word friction is essentially “resistance”. Two coworkers can have friction with each other, and that produces “heat”, but that isn’t actually describing physical contact between the two of them, it is describing a clash of personalities.
So I disagree that the word friction is being used incorrectly. It’s just yet another word in English like “bat, bat, bat” or “theory, theory” or “heat, heat” (or any of a thousand other such words) that has multiple meanings, and you were wrongly assuming that the speaker meant one particular meaning over the other due to the ambiguous context of the statement.
May 16th, 2008 at 4:43 pm
gopher65, I disagree. Friction has a definite scientific meaning, dealing with rubbing between two surfaces (or something like that). The heating is due to compression of the air, not the air sliding over the surface. These are vastly different things.
May 16th, 2008 at 6:23 pm
Ummm. I loved the descent animation, and the interviews were informative and fun.
But…
I dunno, maybe I’m becoming a crank in my old age, but I really hated the video-game graphics, the super-dramatic text and fonts, the constant “swooshes” – heck, if I want to see that stuff, I could just watch the 6 o’clock news. And the jerky camera work, with all its unnecessary pushes on the interviewees, is exactly the sort of thing that makes me have a hard time watching Battlestar Galactica (the premiere, anyway) or 24 – if I want to see that stuff, I could just watch home videos I made with my camcorder. Of course, the popularity of those shows means that most people are able to get past those video peculiarities – or maybe even enjoy them.
I kinda felt like I felt when I watched the movie Spawn, that this something created for an audience with a 5-second attention span. People who would find a more straightforward presentation boring. So, hey, if it works, it works. I hope it works.
And I hope all goes well with the landing – on Towel Day, no less!
May 16th, 2008 at 6:34 pm
By the way, if one goes over to the NASA website to view this, it has closed captioning. But it’s done in a funny sort of way, because it has captioning which tells what the on-screen text says.
For example, at one point there’s narrative text which says, “Mission: Dig into the icy soil. Search for chemical building blocks of life. Study the history of water.” So the captioning says, “(Text on screen) Mission: Dig into the icy soil. Search for chemical building blocks of life. Study the history of water.”
May 16th, 2008 at 7:21 pm
Yeeaahh… I’m gonna have to go ahead and disagree with you on that Phil.
The heating during entry (or reentry if’n you’ve already been there) is due to aerodynamic drag. Aerodynamic drag can be broken into two components: induced drag and parasite drag. Induced drag is a byproduct of lift. Parasite drag can further be broken into two components: pressure drag (due to difference in pressure between the forward and aft sides of the vehicle) and, wait for it, skin friction! Skin friction is also called viscous drag and is due to the shearing force in the boundary layer between the gas and the surface of the vehicle. So, the word “friction” is used correctly by the folks at JPL. Although friction isn’t the only thing that slows the vehicle down.
The equation for total heat input to a reentry vehicle (assumes a few simplifications of course, I’m an engineer, what are you gonna do?) is:
Q=m/4*(Cf’*S/Cd*A)*(Ve^2-Vo^2)
m=mass of the vehicle
Cd=drag coefficient
S=surface area
A=aerodynamic area
Ve=entry velocity
Vo=impact velocity (hopefully small!)
Cf’=equivalent friction coefficient (based on local skin friction coefficient and gas properties)
So, two things: 1) the word ‘friction’ can definitely be use when speaking about drag (and therefore atmospheric entry) and 2) heating during entry is only partially due to compression of the gas to which the vehicle is entering.
May 16th, 2008 at 9:29 pm
“the word ‘friction’ can definitely be use when speaking about drag”
Oooo, nice take-down of the BA there, Robin.
I do have one nitpick with the video. The geeky dude with the brown shirt and glasses makes this statement:
“The outside can get almost as hot as the surface of the sun”
The very next statement is “the temperature of the heat shield can reach 2,600 degrees Fahrenheit”
According to Wikipedia the surface temperature of the sun is 5,778 degrees Kelvin = 5,505 degrees Celsius = 9,941 degrees Fahrenheit. So they are off by a factor of 3.8 unless the other parts of the exterior of the spacecraft become hotter than the heat shield which I somehow doubt.
May 16th, 2008 at 9:42 pm
Harold: It’s not just you. I can’t stand all that EXTREME FONT ACTION stuff; frankly I find it embarrassing. But! At least they did follow it up with some actual information, information which I very much enjoyed learning. And I agree that NASA shouldn’t be trying hard to reach out people like me. People like me already think this stuff is both important and fascinating; we’re not the ones who need convincing.
May 16th, 2008 at 9:47 pm
But as far as pedagogy goes, Phil’s comment is as usual for the win.
The complexities and rapid steps of the Mars entry and landing process for Phoenix made me wonder if the inflatable-airbag landing system used with the Rovers has safer parameters – but I imagine there’s an equal amount of potential dangers.
Possibly there’s a weight problem, as IIRC it is claimed that the next lander, Mars Science Laboratory is too heavy to land on (current technology) bags. It could also be a dress rehearsal for that.
I understand that the Mars Exploration Rovers (complete with landing platforms) were at the hairy edge of what the airbag system could tolerate — and as it is, they had to add a bunch of extra stuff to make it workable, including descent rockets to slow them down a bit more and a sophisticated landing guidance system to avoid rocks, since the airbags were highly vulnerable to punctures with all that mass behind them.
So yes, MSL will be much too massive for the airbag system. It will have to land using the old-fashioned retrorocket method.
May 16th, 2008 at 10:36 pm
Absolutely amazing. It’s hard for me to believe that this will actually work. Brilliant. I hope.
I’m looking forward to the landing.
May 17th, 2008 at 3:39 am
I don’t know, but possibly the closed caption repeat of the text in the video is for the benefit of blind people using screen readers (that convert text into spoken words.) The screen reader can easily read the caption text, but would have a very tough time extracting text from a video. At the minimum, it would have to construct stills from the video stream, OCR the text, and then notice when the text had changed while ignoring the rest of the video. The dynamic background would make OCR much more difficult.
Tom – possibly they were referring to the heated air outside the heat shield and not to the heat shield itself. Unless the heat shield is immersed in the gas long enough to achieve thermodynamic equilibrium (and clearly it isn’t), it will be cooler than the gas. Whether several thousand degrees cooler, I doubt, but maybe. You could tell by observing the color of the fireball, if you were suitably positioned on the martian surface
May 17th, 2008 at 7:10 am
This shows that science is so cool! I’m very excited for May 25. I hope nothing goes wrong this time and the mission is a huge success.
May 17th, 2008 at 10:22 am
Buzz Parsec,
That didn’t occur to me about the captioning, but it makes sense. Thanks.
May 17th, 2008 at 4:25 pm
My very minor nit with this great video is when the lander separated from the mothership there was a distinct “pop” sound. In space. Arrggghhhh! Just like essentially every SF movie/show except 2001. And this isn’t SF but (an animation of) the real thing.
A minor detail, but I’d expect NASA to get it right—especailly since the sound wasn’t even “needed” due to the music/voiceovers. (Kubrick was brave enough in 2001 to not hide the silence with background music et al.) Grumble, grumble, grumble…
May 17th, 2008 at 5:25 pm
I’m happy to see so many nice reviews for the video. While the Phoenix landing animation is Maas Digital, this video (storyline, graphics, interviews, music, etc) was produced and edited by Eric Tozzi at JPL. Videography by John Beck and Scott Hulme.
With tonight’s TCM (trajectory correction maneuver) coming up, you may want to watch this video which explains navigation: http://www.jpl.nasa.gov/videos/phoenix/phx20080124/
May 17th, 2008 at 7:29 pm
Wow. The Hi-Def version was well worth the download. Pretty good production values for such a short video. Hope it all goes down like it’s supposed to.
May 17th, 2008 at 9:41 pm
Did anyone else notice how much the Phoenix logo resembles the Firefox logo??
May 17th, 2008 at 11:26 pm
So sorry for the following downer, but I have to agree with Harold and Brian, and add a bit more.
On one level, it may be fine and dandy to jack up the metabolism to a ludicrous pace suited to marketing preconceptions on the attention-deficit of a generation jaded by whip-fast stimuli, and justifiable on another level to try to cram in as much as possible within a limited duration such breakneck back-and-forth between the talking heads and the fairly well-done cgi sequences in an editing tour de force…but for crying out loud already, this is getting ridiculous!
Worse, the PR departments at NASA and JPL are obviously buying into precisely the same sensationalist (clap)trap that Hollywood is famous for which you, Phil – and so many others – have worked so hard to try to rectify.
Phil, please, we can usually rely on your laser-like sharp eye to point out misrepresentations – especially gross ones – to keep us all straight, no matter what the source. Your mention of the inaccurate use of the word “friction” by one of the commentators is proper and a good point…just that ONE POINT.
But you leave an awful lot hanging there! For example, in the cgi sequence when the lander is released from the backshell the action is so ridiculously speeded up that it looks like it’s falling in a gravitational field of maybe 50 g’s! It looks as if it was shot out of a cannon toward the surface!
Come ON already!!! Doesn’t anyone ever notice this sort of shameless hyper-exaggeration anymore? What are kids to bring away from this video? That they have been given an accurate and informative sense of the actual events that will transpire during that “SE7EN MINUTES OF TERROR”???
Gimme a friggin’ break already. This trend of padding the material up for public consumption is grotesque beyond belief. The actuality is spectacular enough as it is. WHY are these lousy wrongheaded gimmicks being utilized? For improvement???
And what about all the many cool things that will actually have to happen that we are NOT seeing in this “very cool video”?
We don’t see how the lander is programmed to begin firing it’s thrusters a second after release.*
We don’t see how it’s programmed to maneuver “upwind” AWAY from the backshell/parachute in order to minimize the chance of recontact.
We don’t see MANY cool things that ACTUALLY will happen (hopefully, of course, along the lines of the desired plan).
What do we see instead in the moments before landing? Some peculiar guesswork gyrations that look like a major departure from the nominal – so much so that it looks like the lander is in major stability trouble or fighting an invisible dust devil.
As for the quality of the cgi parts in this video in general? The real-time paced sequences are fairly well accomplished. Maas Digital does superb work. But IMHO their work on the MER landing was BY FAR better done.
-
*Oh yeah, dropping the lander out of the backshell at a mere 3.72 m/s^2 or 0.38 g’s would have RUINED the “drama” of the preferred cannon-shot – “sciencefix”, pay attention now: one trusts that you don’t “teach motion” by referring to another similarly wildly imbecilic sequence that rarely icites a rolling of the eyes – in the film Apollo 13, when the LEM’s main engine is employed for a course-correction maneuver, we see the whole stack take off as if it was under the impulse of ALL FIVE of the F5 engines of the first stage. The word “ridiculous” doesn’t seem to have any meaningful impact when such a stupendous stupidity appears in a POPULAR film that did extremely well at the BOX OFFICE. (”OBVIOUSLY” it made MONEY which MEANS that it had the RIGHT RECIPE for SUCCESS, and INCIDENTALLTY it’s ONLY a MOVIE, ad nauseam). Meanwhile, we are all teaching the general public pure crap because we treat them like consumers rather than thinking, curious beings invested with something that resembles intelligence.
Ok. I’ve said it. SOMEBODY has to.
May 18th, 2008 at 9:53 am
Anchor, I agree. Other legitimate agencies, such as the NSF, the USGS, and so on, don’t resort to these tactics. They carry out their charters with some dignity and integrity. I remember when I was a kid, a film published by NASA was more an effort to teach me something than to push my buttons.
May 21st, 2008 at 10:16 am
Good video and concise information. Loved the animations that help you to understand what’s going to happen. This is exciting stuff.
Hope the chutes on Phoenix Mars lander remain intact upon deployment. Best wishes for the girl to land safely in a prime spot and best of luck for everything with the mission to go well. Those will be ten hour-long minutes while waiting for communication from the lander to say it’s down and everything is A-OK.
May 23rd, 2008 at 8:00 pm
[...] Fonte: JPL, Bad Astronomy [...]
July 3rd, 2008 at 10:25 am
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July 3rd, 2008 at 1:14 pm
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