OFMM Science Goals - Surface: Discussion - Page 7 - Orbiter-Forum

**Urwumpe** · 01-09-2012, 12:49 AM

How much dV do you plan with? Depending on how we deploy it, we need different maneuver budgets for it.

When we release it during Earth-Mars-Transfer, we only need a little bit of dV for correcting impact site.

If we release it from Mars Orbit, we need much more dV for getting a steep enough reentry angle.

**Donamy** · 01-09-2012, 12:50 AM

Hope you don't break Mars.

**Cras** · 01-09-2012, 12:58 AM

Looks good! I think she will go boom quite adequately.

**Urwumpe** · 01-09-2012, 01:00 AM

Quote:

Originally Posted by Donamy

Hope you don't break Mars.

if it doesn't fit, use a bigger hammer!

**Woo482** · 01-09-2012, 01:01 AM

It has around 500 m/s dV with the current code, using solid motors for deorbit

**PhantomCruiser** · 01-09-2012, 03:04 AM

Quote:

Originally Posted by Urwumpe

if it doesn't fit, use a bigger hammer!

First rule of mechanical engineering?

**Loru** · 01-09-2012, 06:35 PM

somoeone might want to inspect impact crater after impactor hits mars surface:

MaverickSawyer · 01-09-2012, 07:08 PM

Good idea! no work needed to expose multiple layers of regolith. If we kick it out while in transit, then give it a slight nudge, and have it target near the planned LZ, it's a short hop away. However, we would need to have the sensors emplaced beforehand.

Could we place them on the cargo landers (the seismometers)?

**Loru** · 01-09-2012, 09:30 PM

Short before reentry

mojoey · 01-09-2012, 09:48 PM

Quote:

Originally Posted by MaverickSawyer

Good idea! no work needed to expose multiple layers of regolith. If we kick it out while in transit, then give it a slight nudge, and have it target near the planned LZ, it's a short hop away. However, we would need to have the sensors emplaced beforehand.

Could we place them on the cargo landers (the seismometers)?

how close to the LZ? If its too close, you run the risk of the guidance going kaput and you smashing the LZ to shreds. About 15-20 KM seems about far enough. Or am I missing something?

**Urwumpe** · 01-09-2012, 09:58 PM

Quote:

Originally Posted by mojoey

how close to the LZ? If its too close, you run the risk of the guidance going kaput and you smashing the LZ to shreds. About 15-20 KM seems about far enough. Or am I missing something?

If we have humans on the transit, we should be able to separate it a day before capture burn and still get its guidance within 800 meters accurate. We just need to track it from the main spacecraft to keep the navigation fixes correct.

Still, we don't want it to impact near the LZ, we want it at the right distance to get seismic data... 135° great circle distance to the seismometer array should do it.

Accuracy during landing is needed for another reason: It reduces the errors in the seismic data. We can reconstruct the impact zone from the seismic data, but we get more inaccuracy, the worse the impact accuracy is to start with.if we can monitor the impact visually from space with a telescope, we should be able to get much better impact data, but I can't tell the visibility during this work-load heavy phase.

Maybe we should coordinate the impact with a previously deployed Mars satellite.

mojoey · 01-09-2012, 10:01 PM

Quote:

Originally Posted by Urwumpe

If we have humans on the transit, we should be able to separate it a day before capture burn and still get its guidance within 800 meters accurate. We just need to track it from the main spacecraft to keep the navigation fixes correct.

Still, we don't want it to impact near the LZ, we want it at the right distance to get seismic data... 135° great circle distance to the seismometer array should do it.

Well, i'm more concerned with the guidance system failing and it not impacting on target or somewhere like the LZ... 135* circle sounds about right...

**Loru** · 01-09-2012, 10:13 PM

... and the impact zone:

**Urwumpe** · 01-09-2012, 10:17 PM

Quote:

Originally Posted by Loru

... and the impact zone:

Did you use the proper crater size?

It looks so big.

(BTW: In reality it is more deep than high, the crater rims are too steep and too high compared to the depth of the crater)

**Loru** · 01-09-2012, 10:19 PM

It's around 60 meter wide
Too big?

01-09-2012, 01:00 AM	#94
Urwumpe Not funny anymore	Quote: Originally Posted by Donamy Hope you don't break Mars. if it doesn't fit, use a bigger hammer! Last edited by Urwumpe; 01-09-2012 at 01:22 AM. Reason: Proper translation of German proverb

01-09-2012, 09:58 PM	#101
Urwumpe Not funny anymore	Quote: Originally Posted by mojoey how close to the LZ? If its too close, you run the risk of the guidance going kaput and you smashing the LZ to shreds. About 15-20 KM seems about far enough. Or am I missing something? If we have humans on the transit, we should be able to separate it a day before capture burn and still get its guidance within 800 meters accurate. We just need to track it from the main spacecraft to keep the navigation fixes correct. Still, we don't want it to impact near the LZ, we want it at the right distance to get seismic data... 135° great circle distance to the seismometer array should do it. Accuracy during landing is needed for another reason: It reduces the errors in the seismic data. We can reconstruct the impact zone from the seismic data, but we get more inaccuracy, the worse the impact accuracy is to start with.if we can monitor the impact visually from space with a telescope, we should be able to get much better impact data, but I can't tell the visibility during this work-load heavy phase. Maybe we should coordinate the impact with a previously deployed Mars satellite. Last edited by Urwumpe; 01-09-2012 at 10:01 PM.

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01-09-2012, 12:49 AM	#91
Urwumpe Not funny anymore	How much dV do you plan with? Depending on how we deploy it, we need different maneuver budgets for it. When we release it during Earth-Mars-Transfer, we only need a little bit of dV for correcting impact site. If we release it from Mars Orbit, we need much more dV for getting a steep enough reentry angle.

01-09-2012, 12:50 AM	#92
Donamy Beta Tester	Hope you don't break Mars.

01-09-2012, 12:58 AM	#93
Cras Spring of Life!	Looks good! I think she will go boom quite adequately.

01-09-2012, 01:01 AM	#95
Woo482 Moderator	It has around 500 m/s dV with the current code, using solid motors for deorbit

01-09-2012, 03:04 AM	#96
PhantomCruiser Wanderer	Quote: Originally Posted by Urwumpe if it doesn't fit, use a bigger hammer! First rule of mechanical engineering?

01-09-2012, 06:35 PM	#97
Loru Moderator	somoeone might want to inspect impact crater after impactor hits mars surface:

01-09-2012, 07:08 PM	#98
MaverickSawyer Acolyte of the Probe	Good idea! no work needed to expose multiple layers of regolith. If we kick it out while in transit, then give it a slight nudge, and have it target near the planned LZ, it's a short hop away. However, we would need to have the sensors emplaced beforehand. Could we place them on the cargo landers (the seismometers)?

01-09-2012, 09:30 PM	#99
Loru Moderator	Short before reentry

01-09-2012, 09:48 PM	#100
mojoey JapanAXA!	Quote: Originally Posted by MaverickSawyer Good idea! no work needed to expose multiple layers of regolith. If we kick it out while in transit, then give it a slight nudge, and have it target near the planned LZ, it's a short hop away. However, we would need to have the sensors emplaced beforehand. Could we place them on the cargo landers (the seismometers)? how close to the LZ? If its too close, you run the risk of the guidance going kaput and you smashing the LZ to shreds. About 15-20 KM seems about far enough. Or am I missing something?

01-09-2012, 10:01 PM	#102
mojoey JapanAXA!	Quote: Originally Posted by Urwumpe If we have humans on the transit, we should be able to separate it a day before capture burn and still get its guidance within 800 meters accurate. We just need to track it from the main spacecraft to keep the navigation fixes correct. Still, we don't want it to impact near the LZ, we want it at the right distance to get seismic data... 135° great circle distance to the seismometer array should do it. Well, i'm more concerned with the guidance system failing and it not impacting on target or somewhere like the LZ... 135* circle sounds about right...

01-09-2012, 10:13 PM	#103
Loru Moderator	... and the impact zone:

01-09-2012, 10:17 PM	#104
Urwumpe Not funny anymore	Quote: Originally Posted by Loru ... and the impact zone: Did you use the proper crater size? It looks so big. (BTW: In reality it is more deep than high, the crater rims are too steep and too high compared to the depth of the crater)

01-09-2012, 10:19 PM	#105
Loru Moderator	It's around 60 meter wide Too big?