Author Topic: ESA-Roscosmos: ExoMars 2016 updates and discussion  (Read 237972 times)

Offline Archibald

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #720 on: 10/21/2016 06:45 PM »
Quote
We can extrapolate based on the estimated descent speed prior to parachute separation (~80m/s), the period of thruster activation (~4s), maximum thrust (~3600N) and lander wet mass (~600kg, although it probably was quite a bit less at parachute release because of all the separation events until then), Mars gravity (~3.7m/s2) and the period during which Schiaparelli was apparently in free fall (~20s). The impact velocity would then be:

80-3600/600*4+3.7*20 = ~145m/s = 522km/h

Quote
Schiaparelli fell from a height of 2-4 km

Minimal mistake, maximum consequences. Welcome to Mars EDL challenge.

Seriously, better to have Shiaparelli crash rather than ExoMars. Hopefully lessons will be learned.
ExoMars is the name of the program, not the orbiter. The orbiter is just the Trace Gas Orbiter or TGO for short. Both the TGO and EDM are part of ExoMars 2016. The rover was ExoMars 2018 but it got delayed to the next Mars launch window in 2020 so it got renamed to ExoMars 2020.

thanks not lecturing me. I do know what the rover is, Exomars 2020. This thread needs a) serious cleanup and b)a lot of people calming down
« Last Edit: 10/21/2016 06:46 PM by Archibald »

Offline Mighty-T

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #721 on: 10/21/2016 07:15 PM »
Decent crater/blast radius with the MRO images.. Final impact splash about 25m x 25m round. Parachute seen about 900m south of Schiaparelli's crater.


Well, looks like Mars has two "Schiaparelli" craters now...

Offline redliox

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #722 on: 10/21/2016 07:31 PM »
There is some strange irony comparing Schiaparelli with Beagle 2.  Beagle 2 surprisingly landed intact, but was unable to communicate.  Schiaparelli was able to communicate well...up until impact.  Somehow, if the success of the former can utilize the relay ability of the later...maybe ESA would get a successful lander; that I mean as genuine encouragement since both landing attempts apparently had elements of "partial success" despite failing landing functionally on Mars (Beagle 2 apparently almost did, but didn't fulfill its function ultimately).

I don't think I could ever call Schiaparelli even a "partial success" (which frankly is just a PR-positive-spin on failure), but I will say in light of Beagle 2 and NASA's Mars 98 missions (orbiter, lander, and penetrators) it's an improvement.  ESA can at least pinpoint which point the lander's mission began to unravel...in similar fashion to how MRO pinpointed its black smear on Mars.  :-\

Two suggestions for ESA: 1) Keep trying, you're at least having slightly better luck than the Soviets did.  2) Talk to NASA again for more direct assistance.
"Let the trails lead where they may, I will follow."
-Tigatron

Offline meekGee

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #723 on: 10/21/2016 07:33 PM »
That's like saying the Titanic was 75% successful because it made it 3/4 of the way to New York.

This is a straw man argument

Only 80% straw.
ABCD - Always Be Counting Down

Offline wxmeddler

Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #724 on: 10/21/2016 08:09 PM »
Decent crater/blast radius with the MRO images.. Final impact splash about 25m x 25m round. Parachute seen about 900m south of Schiaparelli's crater.


Well, looks like Mars has two "Schiaparelli" craters now...

Clearly the lander became self-aware in it's harrowing descent and decided that it wanted to emulate it's namesake.

Offline tolis

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #725 on: 10/21/2016 08:17 PM »
I hope there were no martian microbes under that impact site.
If I were one, I wouldn't take kindly to umpteen kg of hydrazine
landing on top of me. But then again, maybe they drink the stuff.. ;D

Offline Nigeluna

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #726 on: 10/21/2016 08:25 PM »
For various reasons I find this all slightly (but only slightly) depressing. Yes, ESA has tried to land two probes on Mars on paper but they were as different as chalk and cheese.

Beagle 2 was knocked up by a group of British enthusiasts effectively in the evenings and weekends until very late in its development. It had minimal industrial support, except by goodwill, and was launched almost as an after-thought for political reasons. Everything was known to be marginal. Yet it almost worked and it seems that only a baulky deployment system, possibly due to the minimalistic airbags, stopped it opening completely and hence prevented comms. This was in the true tradition of the British amateur who almost makes it in an attempt to inspire others.

EDM was developed with full industrial support as part of a reasonably well funded international project (except for the US although I believe they contributed much expertise) from the outset. Definitely not developed on Colin Pilinger's kitchen table. Everything is reported to have worked well except, it seems, for the brain that seems to have gone a little crazy. Reports indicate that the relevant sensors were all providing the data that was expected therefore it seems to have been faulty digestion rather that tainted food.

I find myself hoping that the Airbus I fly and the reactors a few tens of miles from me have higher reliability in the control system department. Actually I'm sure they have but it would be nice if ESA find the failure was caused by something unforseeable. This is more in hope than expectation though. I await further news of the investigation with interest.

Offline jarnu

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« Last Edit: 10/21/2016 08:32 PM by jarnu »

Offline Hungry4info3

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #728 on: 10/21/2016 08:51 PM »
That seems awfully high up given that the event happened 53 kilometres away.

Online Alpha_Centauri

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #729 on: 10/21/2016 08:54 PM »
nm
« Last Edit: 10/21/2016 08:58 PM by Alpha_Centauri »

Offline curtquarquesso

Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #730 on: 10/21/2016 09:00 PM »
Based on where the lander impacted inside the landing ellipse, do we have any estimates on how far Opportunity is from the crash site? As the crow flies or based on a plausible transit path? Obviously, there are no plans to visit the crash site by NASA. I'm just entertaining my curiosity more than anything.

Offline eeergo

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #731 on: 10/21/2016 09:37 PM »
Pure especulation:
https://mobile.twitter.com/thomas_appere/status/789540027273445376

It seems the source is : http://mars.nasa.gov/mer/gallery/all/1/p/4528/1P530160317EFFCTARP2857L6M1.HTML


I can't find where I saw it, but it was already seen to be coincident with camera specks in other photos, which the enhancement makes appear something that aren't.
-DaviD-

Offline eeergo

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #732 on: 10/21/2016 09:43 PM »
Based on where the lander impacted inside the landing ellipse, do we have any estimates on how far Opportunity is from the crash site? As the crow flies or based on a plausible transit path? Obviously, there are no plans to visit the crash site by NASA. I'm just entertaining my curiosity more than anything.

If you look at the large scale picture posted by GalacticPenguin here: http://forum.nasaspaceflight.com/index.php?topic=31368.msg1602074#msg1602074 (second attached image, top section), the large dark crater on the right hand side of the picture is Endurance, on whose western rim Opportunity is roving right now. To give a sense of scale of the whole roved distance, take this map with mostly all of Opportunity's trek: https://upload.wikimedia.org/wikipedia/commons/thumb/e/ef/PIA19154oppmarch2015.jpg/600px-PIA19154oppmarch2015.jpg

It's about 40-50 km as the crow flies.
-DaviD-

Offline redliox

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #733 on: 10/21/2016 09:46 PM »
Clearly the lander became self-aware in it's harrowing descent and decided that it wanted to emulate it's namesake.

Exactly like the whale in Hitchhiker's Guide to the Galaxy...

...although if it was ALSO aware of Beagle 2's fate I think it'd be saying...

"Let the trails lead where they may, I will follow."
-Tigatron

Offline eeergo

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #734 on: 10/21/2016 09:54 PM »
Quote from: ESAoperations
orbit insertion near perfect: Now on 101000X3691km orbit (4.2 day), well within planned initial orbit - ready for science

Largest ever Mars probe, worth remembering.
-DaviD-

Offline BrakeFirst

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #735 on: 10/21/2016 10:31 PM »
...the large dark crater on the right hand side of the picture is Endurance, on whose western rim Opportunity is roving right now.

Opportunity is actually reported to be at Endeavour crater, the large one at the southern end of the trek.
http://mars.nasa.gov/mer/mission/status.html#opportunity

Endurance crater was at the beginning in 2004. If Opportunity had travelled north for its 43+ km to date, it would be very close to the impact site. I'm happier that Oppy is to the south and safely out of harms way.

Online Bob Shaw

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #736 on: 10/21/2016 10:43 PM »
Clearly the lander became self-aware in it's harrowing descent and decided that it wanted to emulate it's namesake.

Exactly like the whale in Hitchhiker's Guide to the Galaxy...

...although if it was ALSO aware of Beagle 2's fate I think it'd be saying...



Perhaps 'So long, and thanks for all the Euros...'

Online Kosmos2001

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #737 on: 10/21/2016 10:46 PM »
I've just made a little integrator in Python to calculate the final velocity at the moment of impact including drag.

I read in this blog that Schiaparelli's mass, once without the thermal shield, is about ~300 kg and its diameter 1.65 m.

Source from NASA.

Using this data:

g_m = 3.71            # Gravity on mars [m/s2]
C_d = 0.46            # Drag coefficient [-]
r = 1.65/2.0         # Radius [m]
A = np.pi*r**2.0      # Area [m2]
rho =  0.02            # Atmosphere density [kg/m3]
mass = 300.0         # Probe mass [kg]
T = 3600.0            # RR thrust [N]
t_T = 4.0               # RR burning time [s*]
v0 = 80.0            # Initial velocity [m/s]
t_ini = 0            # Initial time [s*]
t_fin = 20          # Final time [s*]
h = 10000            # Integration step [-]


V_impact = 102.6 m/s (369.4 km/h)

Feel free to correct any parameter that you consider not accurate enough.
« Last Edit: 10/21/2016 10:47 PM by Kosmos2001 »

Online Bob Shaw

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #738 on: 10/21/2016 10:48 PM »
I hope there were no martian microbes under that impact site.
If I were one, I wouldn't take kindly to umpteen kg of hydrazine
landing on top of me. But then again, maybe they drink the stuff.. ;D

One of the unfortunate issues with the Viking landers was, indeed, the rather poisonous nature of their landing rockets - a bit of an own goal for a spacecraft equipped with life-detecting experiments...

At least SkyCrane has the decency to run away and hide in a (new) crater having delivered a shiny rover (or two) to the surface!

Offline eeergo

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Re: ESA-Roscosmos: ExoMars 2016 updates and discussion
« Reply #739 on: 10/21/2016 10:50 PM »
...the large dark crater on the right hand side of the picture is Endurance, on whose western rim Opportunity is roving right now.

Opportunity is actually reported to be at Endeavour crater, the large one at the southern end of the trek.
http://mars.nasa.gov/mer/mission/status.html#opportunity

Endurance crater was at the beginning in 2004. If Opportunity had travelled north for its 43+ km to date, it would be very close to the impact site. I'm happier that Oppy is to the south and safely out of harms way.


You're right, I meant Endeavour (these pesky "End-" craters :) )
-DaviD-

Tags: Mars Exomars