7 Minutes of Terror for Phoenix Spacecraft (Video)
Written by Nancy Atkinson
Are you ready for the Phoenix spacecraft to land on Mars? At the Jet Propulsion Laboratory, the Entry, Descent and Landing team for Phoenix has been hard at work getting ready, performing simulations to prepare for the real landing, scheduled for May 25, 2008 in a region above Mars' Arctic Circle. Emily Lakdawalla at the Planetary Society has an excellent post about Phoenix's landing elipse, with some great information from JPL's Rob Manning about all the variables the EDL team has to take into account for the landing, such as the spacecraft itself, its entry point, and the properties of the atmosphere. But if you're a more visual-type person, JPL has also put together a couple of videos about the 7 minutes of terror the spacecraft (and the EDL team!) endures from when the vehicle hits the top of the atmosphere, through parachute deploy, to touching down on Mars surface. The amount of anxiety is an upgrade from the six minutes of terror the Mars Exploration Rovers experienced, and it really is a scary time!
This video includes commentary from the engineers at JPL, describing all the events that take place during EDL:
And this video is visual only, no audio of EDL:
May 16th, 2008 at 7:14 am
An interesting approach for an immobile craft thats going to be searching for water on Mars. And I only say that because it would appear that thier using rockets to help land it on ice. wouldnt the rockets melt, at least some of the ice it will be landing on?
Idk. Maybe Im missing something here.
May 16th, 2008 at 7:46 am
@Emission Nebula
Most researchers believe that any significant amounts of water ice will be buried several centimeters (but possibly up to 1 meter) under the dusty and rocky surface of the northern plains of Mars.
The surface layer probably contains a small quantity of ice that is acting as a "cement" holding some of the dust and gravel together. The retrorockets may kick up some dust during descent, but as you see in the animation, they actually shut down while the lander is a meter or so above the surface and then the lander just drops.
Water ice isn't stable on the surface of Mars during the summer. If water ice is exposed it won't melt, it will sublimate (go from the solid phase to the gaseous phase). This will be a challenge if the lander is lucky enough to scoop up some subsurface ice with the robotic arm because the sample will be exposed to the atmosphere for several minutes as the arm moves to dump the sample into one of the onboard chemistry instruments for analysis.
The fact that the rocket blast never gets to close to the surface combined with the fact that any appreciable water ice is likely to be buried means that researchers don't expect the landing operation to cause much loss of ice. Even if there was some ice loss, it would probably only be directly under the spacecraft. The robotic arm will be digging in areas next to the spacecraft, not under it, so it should be okay.
Cheers
May 16th, 2008 at 9:34 am
I'm actually rather sceptical about this mission. If it works and finds what it's looking for (positive signs of past life, basicly) it'd be a huge deal, but there's too many things where it can go terribly wrong. If I were a betting man, I wouldn't put my money on its success, quite frankly.
Still, let's see. I hope I'm wrong.
May 17th, 2008 at 12:31 am
A look at the last stage where the craft is to jet down to a level landing fills me with massive doubt. Ive said it before…looks insanely complex and sort of 'wrong'.
If this thing lands on its feet Ill eat my hat.
As for life, or signs thereof…..I would have gone for a drill, not a scoop. Again….sort of seems 'wrong'
Nothing like making things really complex….millions of miles away.
If this thing lands OK AND finds signs of life….Ill eat my underwear as well.
Hope Im wrong.
May 17th, 2008 at 3:57 am
I bet on a successful landing,Its been done on Mars before and on the Moon by both us and the Russians.
May 18th, 2008 at 2:25 pm
When oh when are the Americans going to abandon all these antiquated units such as miles per hour and degrees Fahrenheit?
We've had one major Mars mission loss as a result of an Imperial-metric mix up, so for heaven's sake GO METRIC, in the name of all that's sane!
May 18th, 2008 at 7:51 pm
Yes, we'll get metric eventually.
I'm sure they tested the lander in Pasadena numerous times, or they wouldn't be attempting this, though releasing a video of that would be simpler and more convincing than the animation. What I doubt is whether that tiny little scoop is going to find anything terribly significant in the top centimeter of soil. We need to get some serious drills up there. Maybe they should call this the JSS lander, for "just scratching the surface".
May 19th, 2008 at 12:18 pm
@Kevin M:
From the Phoenix website:
"The RA will be 2.35 meters (just under 8 ft) long with an elbow joint in the middle, allowing the arm to trench about 0.5m (1.6ft) below the martian surface, deep enough to where scientists believe the water-ice soil interface lies. "
May 21st, 2008 at 5:01 pm
What I don't get is this: why jettison the chute and allow the craft to re-accelerate? Why not keep the chute longer and light the engines, just prior to loosing it? Maybe they're afraid of winds.
Also, in the second video, the engines blacken the earth ( the mars?) not only just beneath the lander, but also in a certain radius outside of the diameter of the lander on all sides, not to mention the sideways travel, and tilt of the craft just as it lands, effectively painting the ground with the torch of the engine exhaust as it passes over, right where the samples are going to be taken from. Seems to me that this would alter or destroy any water evidence in at least the first few centimeters of soil, which is what the video shows that cute little backhoe scraping up for testing.
They shoulda put some wheels on that thing.
May 25th, 2008 at 9:12 am
Congratulation. I have bet the whole farm on this safe landing..
June 4th, 2008 at 4:54 am
not a bad video. kina helps me understand how the hell they weregoing to get it to tyghe ground & all the things that could go wrong. Bet the guys at Control were having kittens during those minutes