Gut feeling... Options

[edstrick]

The EDL landing simulation video is 1.) time compressed, and 2.) overly dramatic. The on-engine wobbles and damn-near cavorting of the simulated lander, particularly just before touchdown, remind me of a T-Rex's hystrionical overacting in your typical cheap Dinosaur Dramatization.

Granted, a T-Rex could do a little scenery chewing.... but.

[dmuller]

The EDL landing simulation video is 1.) time compressed, and 2.) overly dramatic. The on-engine wobbles and damn-near cavorting of the simulated lander, particularly just before touchdown, remind me of a T-Rex's hystrionical overacting in your typical cheap Dinosaur Dramatization.

Granted, a T-Rex could do a little scenery chewing.... but.

I agree ... be mindful of that EDL movie. It has lander separation at something like L - 25 secs, but according to the published nominal timeline, lander separation is at L - 45 secs or so, giving it twice as much time to stabilize and then topple over at the last instance anyway. The timeline shown is also shorter than the nominal timeline, but still within its +/-46 seconds of possible deviations.

Chance of success - well it's gonna be interesting. Given that so many things have to go right at the right time (cruise stage sep, attitude, parachute deploy, legs deploy, radar, lander sep, retro-rockets pulse firings, stabilization & attitude, retro-rockets cut-off, venting, solar panel deploy) ... well why shouldnt it work.

Daniel

[ugordan]

I agree ... be mindful of that EDL movie.

I think edstrick might have had this movie in mind, not the EDL HUD simulation. In the former movie, the lander drops from the backshell a long way down, then ignites the engines (which don't pulse, btw) and wobbles crazily right up until one second before landing. Unecessary Hollywood-like dramatization if you ask me.

[Guest_Sunspot_*]

Nozomi: 15%
Beagle 2: 20%
MER A: 60%
MER B: 60%
Mars Express: 85%

Nozomi - 5%
MER A - 65%
MER B - 65%
MRO - 85%
Beagle 2 - 0%
Phoenix - 70%

I just didn't get excited at all about Beagle 2, when I checked the news to see if they had received the expected signal - and they hadn't- I didnt feel anything - no disappointement at all - weird.

Good Luck to everyone on the Phoenix team

[Guest_Zvezdichko_*]

Beagle 2 - I gave about 30%
MER A or MER B - 85%, I was quite sure they will succeed
As for Phoenix I give 70%, because the powered descent adds some risk.
And finally for MSL - 40%, the skycrane might or might not work.

[Doc]

A quote from the recent post on the Planetary Society site;

"The northern autumnal equinox will arrive on Mars on December 26, 2008, bringing winter darkness to the north pole. Phoenix will not survive past this date. In fact, it may not survive beyond November"

Can we hope otherwise......

[dmuller]

I think edstrick might have had this movie in mind, not the EDL HUD simulation.

Ah yes that one is hardcore Hollywood! Just watch the stars zip by in the cruise phase at Worp 5 I guess they gotta sell it to the masses ... most people probably dont get too hooked up on a 20 second lander separation discrepancy like us

[Doc]

As for Phoenix I give 70%, because the powered descent adds some risk.

I share your anxiety Zvezdichko. I tend to find powered descent very unreliable. Atleast the engineers have learned from MPL by programming the spacecraft to deploy its legs while attached to the back shell. So i'ld give Phoenix a resonable 75-80% chance of succeding.

This brings up a curious (or rather silly) question from me; why did many landers in the past fail. Is it because of the MPL error or what?

[Guest_Zvezdichko_*]

This brings up a curious (or rather silly) question from me; why did many landers in the past fail. Is it because of the MPL error or what?

Mars 2 failed because it entered the atmosphere in a very steep trajectory
Mars 3 failed on the surface
Mars 6 and 7 had microchip flaws.
Deep Space 2 - they were supposed to crash land

[Doc]

BTW-will the mission website provide realtime data of the signal strengh from Phoenix like they did with MRO when it arrived at Mars in 2005?

[dmuller]

This brings up a curious (or rather silly) question from me; why did many landers in the past fail. Is it because of the MPL error or what?

Whilst I share the 'fear' that the landing may go wrong, I dont see how recent history should contribute to the fear. Unless I miss something major, only one landing of US spacecraft post the Vikings went wrong: MPL. The record is quite good once you get to Entry Interface. Mars Observer and Mars Climate Orbiter didnt attempt to land, though the cause for the demise of Mars Observer (fuel pressurization) is yet to come for Phoenix. I dont know how comparable the technology / systems / economics were for Beagle 2.

Daniel

[SFJCody]

Seems strange that powered descent + landing legs has us so worried. Before Pathfinder airbags were seen as some weird Russian way of doing things that might not work!

[Guest_Zvezdichko_*]

I think it's because the powered descent hasn't been used successfully for decades (I'm not counting asteroid missions). Soviets used the powered descent on several lunar missions - the Lunokhods and Lunar Sample Returns. The airbag system has failed (Beagle 2, missions prior to Luna 9), and the Powered descent has failed in the past (MPL, Luna 15)...

[Doc]

I dont know how comparable the technology / systems / economics were for Beagle 2.

Daniel

From what I know, Beagle 2 had a lot of problems economically speaking as well as problems in management.
But how they managed to cram so many instruments int a 78kg cylinder is beyond me
That achievement merits a hats off. We can thank ESA for that

[Guest_PhilCo126_*]

Well, it's not just EDL but EDFL ( Entry + Descent + Freefall + Landing )...
Agreed on the "lessons learned" bit mentioned in other posts but it has been since Mars Polar Lander that they tried to land this way