Phoenix EDL: The Seven Minutes of Terror thread

[ToSeek]

For me, the Yahoo feed reset to before the pressurization. I gave up on it.

[RedFive]

What a truly terrific day..!! I am not ashamed to say that I get emotional over this..!! Wonderful..!!

[aurora]

I had my peanuts.

I was switching back and forth between NASA and the Science Channel.

[Tuckerfan]

Twitter feed for the lander: http://twitter.com/MarsPhoenix

[ToSeek]

Originally Posted by 01101001

Did I hear 1/4-degree tilt?

That place is flat.

Reluctant Jerry! Did Phoenix hit "too hard"?

I didn't catch that, but several people at UMSF did - that's flat!

[Maksutov]

Originally Posted by 01101001

Did I hear 1/4-degree tilt?

That place is flat.

Reluctant Jerry! Did Phoenix hit "too hard"?

LOL!

Let's hear it for the blue collar workers!

[01101001]

University of Arizona:

Phoenix Has Landed!
May 25, 2008

Pasadena -- A NASA spacecraft landed in the Martian arctic today to begin three months of examining a site chosen for the likelihood of having frozen water within reach of the lander's robotic arm.

Radio signals received at 4:53 p.m. Pacific Time confirmed that the Phoenix Mars Lander had survived its difficult final descent and touchdown 15 minutes earlier. In the intervening time, those signals crossed the distance from Mars to Earth at the speed of light.

Mission team members at NASA's Jet Propulsion Laboratory, Pasadena, Calif.: Lockheed Martin Space Systems, Denver; and the University of Arizona, Tucson, cheered confirmation of the landing and eagerly awaited further information from Phoenix later tonight.

[KaiYeves]

Seeing as my social worker father knows no name for that feeling of extreme worry and extreme excitement and aprenension of something happy all at once, I will simply call it... Atmospheric Entry.

[ciderman]

Splendid!
For me (on Yahoo feed) first conformation of touchdown signal was from ToSeek...

[pumpkinpie]

Originally Posted by 01101001

Did I hear 1/4-degree tilt?

That place is flat.

Reluctant Jerry! Did Phoenix hit "too hard"?

I heard .25 degree tilt too!

[Van Rijn]

Originally Posted by pumpkinpie

I heard .25 degree tilt too!

Ditto. Wow. I wonder how soon someone will claim it was made that way?

[ToSeek]

Originally Posted by ToSeek

If I understand the schedule, we're coming up on 18 minutes of radio silence, during which Phoenix deploys its solar arrays.

My bad - there will be playback data from MRO and Mars Express at around 8:30 EDT (about 20 minutes from now). The next real-time data won't be until 9:43 EDT, about 90 minutes from now. But that might include photos!

[Sam5]

Here's a live NASA feed. Every now and then they have an interview:

http://www.nasa.gov/multimedia/nasatv/index.html

[HAVOC451]

Originally Posted by 01101001

Did I hear 1/4-degree tilt?

That place is flat.

Reluctant Jerry! Did Phoenix hit "too hard"?

Ah good, there will be no trouble when they deploy the pooltable!

[01101001]

Originally Posted by HAVOC451

Ah good, there will be no trouble when they deploy the pooltable!

It is a good omen for solar array deployment. Tilt makes it a little harder.

And energy is optimal when landed flat.

Edit: and... maybe that will wrap up the landing. Now that Phoenix is on Mars (how cool is that?) the action has moved to topic Phoenix on Mars. See ya'll there.

[Disinfo Agent]

I watched part of the coverage on CNN and BBC News. Very exciting. Congratulations!

[Jerry]

Originally Posted by 01101001

Did I hear 1/4-degree tilt?

That place is flat.

Reluctant Jerry! Did Phoenix hit "too hard"?

This was a powered landing! What is the fuel consumption rate? Our previous two powered landings (Viking I & II) consumed ~8% more fuel than expected in the final meters.

You can find the acceleration here:

ftp://naif.jpl.nasa.gov/pub/naif/PHOENIX/kernels/ck

Emily has an extracted graph on her blog:

http://planetary.org/blog/

Phoenix felt 9G's when the parachute popped; I think that is ~ 3G greater-than-expected. We know that the parachute deployed ~8 seconds late; meaning that it may have taken longer-than-expected to slow to the correct mach number for parachute deployment. The landing was slightly later-than-expected, three sigma 'downwind' in the landing oval. This is consistent with the shallowing we saw in the Doppler during the early descent. All of this is consistent with a thinner-than-expected upper atmosphere and thicker-than-expected lower atmosphere, which in turn, is consistent with a more centriod mass distribution (which would be highly inconsistent with the measured surface gravity and Newtonian mass predictions.)

The entire Phoenix entry is reminiscent of the early Doppler and accelerometer profiles of Huygens descent to Titan; and once again a sharp contrast to Venus soft landings.

But you have to have a complete picture - this is one accelerometer...or is it? There can be lever arm effects, frame bending and such, so it really takes an analysis by someone with a very good understanding of the probe design, planned entry corridor; Doppler pipelines and so forth. The Phoenix press release said the EDL reconstruction would take 'several months'. You should know by now 'several months' in NASA time is usually means several years. I still haven't seen complete EDLs for Spirit and Oppy...or the promised analysis of Oppy's heat shield.

[djellison]

Originally Posted by Jerry

I still haven't seen complete EDLs for Spirit and Oppy...or the promised analysis of Oppy's heat shield.

Stop lying Jerry - I gave you direct links to CSV's of accelerometer data and PDF reports from the JPL technical reports server covering both EDL's months and months ago.

And the 'promised' data on the study of Opp's heatshield was never ' promised'. I would not be surprised if it didn't fall under ITAR and thus would not make it into the public domain anyway.

Please keep your special discussion in the appropriate forum - which is NOT Space Exploration, but ATM.

[Jerry]

Originally Posted by djellison

Stop lying Jerry - I gave you direct links to CSV's of accelerometer data and PDF reports from the JPL technical reports server covering both EDL's months and months ago.

As I elaborated above, a complete EDL is much more than tables of accelerometer and Doppler readings. The best account I have found of Spirit's EDL is here:

http://www.spaceflightnow.com/mars/m...struction.html

Originally Posted by spaceflight now

Plunging toward Mars at 920 mph, Spirit's parachute deployed at an altitude of just 4.6 miles - a mile lower than expected - and its braking rockets fired a scant 34 stories or so above the surface in a flawless, but hair-raising descent that engineers are just now coming to fully appreciate.

The parachute deployed later than predicted because of a dust storm on the other side of the planet that affected the density of the atmosphere above Spirit's landing site. Engineers had instructed the lander's computer to take that into account, but they were surprised at the magnitude of the adjustment.

My bold. Just like many other Mars landers, the parachute was a little late - implying that the upper atmosphere is thinner than expected. Ok, a storm can do that, but as far as I know, there were not any storms during the Phoenix landing.

You are absolutely correct in stating this may all be due to happenstance. But don't try to tell me the descent of the Phoenix does not include some of the same peculiar aspects we have witnessed in prior Mars landings. Remember, I am responding to 01101001's jib that implies that the near-perfect Phoenix EDL should not raise any eyebrows. I say it is too soon to tell.

Continuing:

Originally Posted by Spaceflight Now

"It did it just right, but because of the very interesting atmosphere at Gusev at the time we landed, as a result of the dust storm, (parachute deployment) was about a mile lower than our target altitude, which kind of, as you can imagine, makes things a little bit more exciting toward the ground," quipped Rob Manning, Spirit's entry, descent and landing director.

Coming in at an angle, the lander's actual descent velocity was 152 mph, even with its parachute fully deployed. That's somewhat slower than expected, either due to updrafts or higher-than-expected atmospheric density, but still fast enough to cause white knuckles.

In the Phoenix EDL, the parachute also deployed lower-than-expected, which means the probe fell very fast longer than expected; so you should expect a sooner-that-expected landing. But Phoenix landed a little late. Like Spirit, did Phoenix experience a 'sudden updraft', or encounter a 'thicker-than-expected lower atmosphere? I don't think that Spirit had enough instrumentation to discriminate which answer is correct, but Phoenix should be able to tell us.

Originally Posted by Ellison

And the 'promised' data on the study of Opp's heatshield was never ' promised'. I would not be surprised if it didn't fall under ITAR and thus would not make it into the public domain anyway.

True. There was a NASA news release stating that the study of Oppy's heat sheild would keep engineers busy for many months, but NASA did not promised public dissemination of the data. Which is, I think we both agree, one of many sad, repressive effects of ITAR.

It is also true that Phoenix was expected to experience an acceleration of 9g's just after the parachute opened. (MY BAD - See http://www.spaceflightnow.com/mars/p...03preview.html )

Originally Posted by Ellison

Please keep your special discussion in the appropriate forum - which is NOT Space Exploration, but ATM.

The topic of Space Exploration undeniably includes observational evidence of what are, right now, our greatest space mysteries: The Pioneer anomalies, the gravitational assist anomalies, aurora electromagnetic sequencing, the helopause, cosmic rays, Enceladus jets, Titan surface composition and so on.

Using pixes or new physics to try to connect these events is ATM, identifying possible trends that may lead to a better un