Author Topic: MSL Q&A  (Read 92868 times)

Offline Chris Bergin

RE: MSL Q&A
« Reply #40 on: 06/06/2007 05:35 pm »
And some video (cell phone). You have to open this in a quicktime player.
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Offline Jim

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Re: MSL Q&A
« Reply #41 on: 06/06/2007 11:54 pm »
Just a note, the sample handling hardware has changed

Offline MKremer

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Re: MSL Q&A
« Reply #42 on: 06/06/2007 11:57 pm »
Less complex, hopefully?

Offline Jim

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Re: MSL Q&A
« Reply #43 on: 06/07/2007 12:03 am »
all of it is on the turret of the arm.

The RCS and descent thrusters have changed and the mobility system is deployed during the repel

Offline tommy

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Re: MSL Q&A
« Reply #44 on: 06/07/2007 12:08 am »
IMAGE_00234.jpg is great. Looks like the Rover is looking at MSL with a look of "and you are??" ;)

Offline MKremer

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Re: MSL Q&A
« Reply #45 on: 06/07/2007 12:21 am »
Quote
Jim - 6/6/2007  7:03 PM

all of it is on the turret of the arm
So, more similar to what the Viking scoop/shaker did than the complex, multi-arm sample processing/transfers in the video?

Quote
The RCS and descent thrusters have changed and the mobility system is deployed during the repel
I already sort of figured the former would be in some flux until the final hardware construction contracts were signed.

Huh, interesting (concerning the suspension/mobility deployment timing). Wonder what made them decide to change the timing for that? (some risk of pyro signalling/activation while still mated to the descent module, maybe?)

Offline Jim

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Re: MSL Q&A
« Reply #46 on: 06/07/2007 12:49 am »
Quote
MKremer - 6/6/2007  8:21 PM

So, more similar to what the Viking scoop/shaker did than the complex, multi-arm sample processing/transfers in the video?


The arm turret will have the APXS, microscope imager, surface removal tool, powdering drill (instead of corer) and a handler that scoops regolith and receives samples from the drill.  The only things that remain on the rover body are the instrument inlets (3) and bit box for the drill.  the rock crusher has been eliminated

Offline MKremer

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Re: MSL Q&A
« Reply #47 on: 06/07/2007 01:46 am »
Thanks for the info.

Good thing the "corer" and "rock crusher" are no more - it was a lot of extra hardware mass (and less mass is a *good thing*) - plus eliminating all the descision-making software required to monitor each surface sample target to keep the corer/crusher from being damaged/destroyed by possible soft-then-hard/soft-then-waytoohard sudden transitions during coring.

I have to admit I looked wide-eyed in amazement as the video showed all the extra rotations the video-MSL  sample handling rotor had to make just to get the materials in position for both grinding and depositing, and then more contortions to deposite samples into the science instruments.



Offline Kaputnik

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Re: MSL Q&A
« Reply #48 on: 02/29/2008 01:07 pm »
http://www.space.com/news/ap-080228-flagship-mars-overruns.html

Erm, presumably it's a mistake when they write that MSL was supposed to use ET insulation???
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Offline renclod

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Re: MSL Q&A
« Reply #49 on: 02/29/2008 04:42 pm »
Quote
Kaputnik - 29/2/2008  4:07 PM

http://www.space.com/news/ap-080228-flagship-mars-overruns.html

Erm, presumably it's a mistake when they write that MSL was supposed to use ET insulation???

No, ET has/had SLA (super lightweight ablative) on feedline brackets.
"Foam and super lightweight ablative are being removed from the first four of the five brackets and replaced with foam only, Hale said. Less foam on the brackets is acceptable for the shuttle’s ascent, he added. Bracket foam is about one-inch thick while the underlying super lightweight ablative is about one-half-inch thick, but denser than foam. The final shape of the replacement foam is still under review." marshallstar.msfc.nasa.gov/8-30-07.pdf

Offline grakenverb

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RE: MSL Q&A
« Reply #50 on: 03/01/2008 05:30 pm »
Cool video,  but i have to wonder why they just don't put legs on the "sky crane" and have it land, then lower the rover to the surface once the whole thing has stopped moving.  I know that much smarter people than myself have conceived of this thing, but it all looks rather Rube Goldberg to me.

Offline Jim

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RE: MSL Q&A
« Reply #51 on: 03/01/2008 05:34 pm »
Quote
grakenverb - 1/3/2008  1:30 PM

Cool video,  but i have to wonder why they just don't put legs on the "sky crane" and have it land, then lower the rover to the surface once the whole thing has stopped moving.  I know that much smarter people than myself have conceived of this thing, but it all looks rather Rube Goldberg to me.

How would the "legs" fit in the aeroshell?  Short legs would have plume problems.   Apollo LM, Surveyor dropped that last few feet

the skycrane method is applicable to many packages.

Offline scienceguy

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RE: MSL Q&A
« Reply #52 on: 03/01/2008 06:16 pm »
How deep will MSL dig for its samples? I was just wondering because so far other Mars robots haven't detected Boron, Manganese, Molybdenum, Nickel, Copper, Zinc, or other micronutrients that plants need in the soils so far sampled. I was thinking that they just need to dig deeper.
e^(pi*i) = -1

Offline Jim

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RE: MSL Q&A
« Reply #53 on: 03/01/2008 07:15 pm »
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scienceguy - 1/3/2008  2:16 PM

How deep will MSL dig for its samples? I was just wondering because so far other Mars robots haven't detected Boron, Manganese, Molybdenum, Nickel, Copper, Zinc, or other micronutrients that plants need in the soils so far sampled. I was thinking that they just need to dig deeper.

It isn't going to dig.  It can make trenches with its wheels.

Phoenix will dig

Offline Kaputnik

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RE: MSL Q&A
« Reply #54 on: 03/01/2008 08:09 pm »
Quote
Jim - 1/3/2008  6:34 PM

Quote
grakenverb - 1/3/2008  1:30 PM

Cool video,  but i have to wonder why they just don't put legs on the "sky crane" and have it land, then lower the rover to the surface once the whole thing has stopped moving.  I know that much smarter people than myself have conceived of this thing, but it all looks rather Rube Goldberg to me.

How would the "legs" fit in the aeroshell?  Short legs would have plume problems.   Apollo LM, Surveyor dropped that last few feet

the skycrane method is applicable to many packages.

How do the plume issues scale with size? What I'm thinking of here is a larger, human scale, rover dropped via skycrane. With roof-mounted descent propulsion system would it be feasible to delete the whole bridle system in favour of a rigid system... sort of a 'roof rack' I suppose!
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Offline grakenverb

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RE: MSL Q&A
« Reply #55 on: 03/01/2008 08:18 pm »
I just hope that the "Keep it Simple, Stupid" theory hasn't been abandoned for some cool-looking, complicated, engineers delight.

Offline iamlucky13

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RE: MSL Q&A
« Reply #56 on: 03/04/2008 11:48 pm »
Quote
Kaputnik - 1/3/2008  1:09 PM

How do the plume issues scale with size? What I'm thinking of here is a larger, human scale, rover dropped via skycrane. With roof-mounted descent propulsion system would it be feasible to delete the whole bridle system in favour of a rigid system... sort of a 'roof rack' I suppose!

I can't answer that directly, but if a "skycrane" were chosen for larger rover missions, you can in theory just lengthen the tether. I think the main concern would be ensuring that you can pay out enough cable in the time you have been heat-shield separation and touch-down.

An overhead thruster has to fire at an angle to avoid blasting the cargo. The greater the angle, the greater the losses from opposing components of the thrust force. The longer the tether, the lower the angle you can use, both because the total clearance increases and the plume dissipates.

Another option is side-mounted thrusters, with the payload sitting in a protective enclosure that ends up suitably close to the ground, but then you end up with a much larger volume to package in the aeroshell and the launch vehicle, especially since the enclosure has to provide room to deploy the vehicle after landing.

By the way, MSL will weigh something like 800 kg. The Lunar rovers had a dry weight of only 210 kg and had a 500 kg payload capacity. Of course, the lunar rovers only needed to survive a few miles of driving and carry loads in 1/6 gravity, but an unpressurized human Mars rover might not weigh too much more than MSL. And with humans dexterity available, such a rover might be unpacked in decent-sized pieces from a more traditional lander and assembled on the surface.

Offline Jim

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RE: MSL Q&A
« Reply #57 on: 03/05/2008 12:45 am »
Quote
grakenverb - 1/3/2008  4:18 PM

I just hope that the "Keep it Simple, Stupid" theory hasn't been abandoned for some cool-looking, complicated, engineers delight.

The landing bag system is maxed out

Offline iamlucky13

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Re: MSL Q&A
« Reply #58 on: 03/05/2008 01:57 am »
Does anyone know whether the multi-mission RTG or a Stirling Radioisotope Generator (SRG) were chosen for power? Both were on the table a couple years ago, but I never heard anything more about it.

The SRG is much more efficient, and so requires less plutonium and a smaller radiator, but it also introduces more moving parts and some minor added vibrations and is (I believe) completely untested in space applications.

Offline Jim

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Re: MSL Q&A
« Reply #59 on: 03/05/2008 11:22 am »
MMRTG

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