Author Topic: MSL Q&A  (Read 75772 times)

Offline CriX

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Re: MSL - The Next Generation Mars Rover
« Reply #20 on: 06/04/2007 05:44 AM »
Is there any remaining controversy (amongst decision makers) on the inclusion of the RTG?

Offline Jason Davies

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Re: MSL - The Next Generation Mars Rover
« Reply #21 on: 06/04/2007 03:28 PM »
Quote
Mogster - 3/6/2007  4:04 PM

I wonder how well the crane can hover in a strong crosswind.

Do they have crosswinds on Mars? (I have no idea).

Offline Jim

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Re: MSL - The Next Generation Mars Rover
« Reply #22 on: 06/04/2007 07:15 PM »
Quote
CriX - 4/6/2007  1:44 AM

Is there any remaining controversy (amongst decision makers) on the inclusion of the RTG?

nope, just need to finish the paperwork

Offline Jim

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Re: MSL - The Next Generation Mars Rover
« Reply #23 on: 06/04/2007 07:16 PM »
Quote
Jason Davies - 4/6/2007  11:28 AM

Quote
Mogster - 3/6/2007  4:04 PM

I wonder how well the crane can hover in a strong crosswind.

Do they have crosswinds on Mars? (I have no idea).

A cross wind is a wind from an other direction than headwind

Online Chris Bergin

RE: MSL Q&A
« Reply #24 on: 06/04/2007 07:20 PM »
This is becoming a useful thread, so it's now changing call signs to MSL Q&A.

Offline jabe

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Re: MSL - The Next Generation Mars Rover
« Reply #25 on: 06/04/2007 07:32 PM »
Quote
Jason Davies - 4/6/2007  10:28 AM

Do they have crosswinds on Mars? (I have no idea).

If I rememebr correctly if one of (or both(?)) the MER rovers didn't have an option to correct for some cross winds it may have crashed on landing.  I believe the gusts were strong right before landing...
I saw a vid somewhere of animation of a simulated crash due to high gusts just before landing.. neat but scary.. (forget where I saw it!!)
I read a concern of the MSL rover was having it coming down and getting dragged sideways and "breaking the wheels"..as opposed to being dragged forward and back and have the wheels move... I'm fascinated by the crane..be cool if it works (I'm giving them benefit the doubt and say it will :) )..opens up some neat possibilites!!
cheers
jb

Offline Jim

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Re: MSL Q&A
« Reply #26 on: 06/04/2007 07:37 PM »
MER added a system to deal with winds, TIRS

Offline rsp1202

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Re: MSL Q&A
« Reply #27 on: 06/04/2007 08:33 PM »
"TIRS, the Transverse Impulse Rocket System, was designed to add a last-second attitude correction to protect the landing craft's airbags from self-induced excess horizontal velocity resulting from multibody excitation due to wind shears and gusts."

MSL looks to be using a robust RCS system to handle such contingencies, rather than a retro-pack.

Offline Kaputnik

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Re: MSL Q&A
« Reply #28 on: 06/04/2007 10:32 PM »
How confident can the designers be that there won't be a pendulum motion that would send the rover smacking into the surface sideways? What sort of horizontal velocity do they expect to achieve?
Waiting for joy and raptor

Offline MKremer

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Re: MSL Q&A
« Reply #29 on: 06/04/2007 11:54 PM »
I would guess that they've already compensated for leveling out the descent stage prior to lowering the lander, and that they've got more than enough lateral control to minimize oscillations at the altitudes prior to touchdown/release.

This isn't hit-or-miss - these folks have done lots of work to prove this system.
IOW - if it doesn't work, it will be something well beyond what they could have planned for... a sudden support hardware or thruster failure, a total failure to one of the pyro primary/backup signal lines, etc.

Compared to the MER EDL complexity to land and deploy, MSL entry/descent/landing is overall actually simpler hardware/reliability-wise.


Offline NotGncDude

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Re: MSL Q&A
« Reply #30 on: 06/05/2007 01:43 AM »
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MKremer - 4/6/2007  7:54 PM

Compared to the MER EDL complexity to land and deploy, MSL entry/descent/landing is overall actually simpler hardware/reliability-wise.


What do you mean? MSL EDL seems much more complex with that crane. Do you mean that all the mechanisms behind deploying the airbags and then the rovers were more complex? (not to sound antagonistic, i'm just curious)

The software (control) side of the MSL EDL does seem much more complex. I'm sure they'll debug it thoroughly.

Offline Stowbridge

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Re: MSL Q&A
« Reply #31 on: 06/05/2007 02:38 AM »
Is there any word on test schedules? I'm assuming the crane will require some form of testing before flying?
Veteran space reporter.

Offline MKremer

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Re: MSL Q&A
« Reply #32 on: 06/05/2007 02:44 AM »
Do a Google search for:
six minutes of terror
six minutes of hell
...to read about all the entry/deployment/landing parameters/pyros/configuration each of the MER landers (not to mention to rovers themselves) had to survive.

With MSL, once the parachute deploys, and the heatshield goes away, there's only 5 *major* things needed to accomplish a successful landing - descent thrusters ignited and positive thrust; suspension deployment and release of the MSL itself (from the descent stage and lowered via the cables); touchdown and release of the suspension cables; rover mast elevation and other vehicle deployments.
Then drive away.

With the MER EDL, once the main parachute deployed and location/drift was computed there were extra necessary steps - airbag pyro ignitions and inflation; lander cable cut at the correct point (retro/drift rockets fired); computation that the bouncing/rolling had stopped and it was OK to deflate the airbags; retract the airbags as much as possible; lander petal opening; rover mast elevations and other vehicle deployments (solar panel 'wings'); rover elevation for wheel/suspension deployment; pyro charge cut of lander cable connections to the rover; rover movement off the lander and to Mars' surface.
Then drive away.

Compare the two.


Offline Jim

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Re: MSL Q&A
« Reply #33 on: 06/05/2007 05:06 AM »
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Stowbridge - 4/6/2007  10:38 PM

Is there any word on test schedules? I'm assuming the crane will require some form of testing before flying?

There is no "crane"  It is the descent stage.

They are current testing the repelling portion of the sequence with the "scarecrow" rover and having land on different terrain

Offline MKremer

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Re: MSL Q&A
« Reply #34 on: 06/05/2007 06:35 AM »
BTW, looking at the pic Jim posted, the top of the 'triangle' in that picture is around 6 feet high - MSL is a *BIG* rover.

Offline savuporo

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Re: MSL Q&A
« Reply #35 on: 06/05/2007 11:09 AM »
Quote
Stowbridge - 4/6/2007  5:38 PM
Is there any word on test schedules? I'm assuming the crane will require some form of testing before flying?
After watchig Armadillos LLC1 test video, i was thinking they could do the exact landing sequence tests with VTVL vehicles like these. However Pixel currently only takes a payload of 25KG which falls way short of lifting the MSL.
Orion - the first and only manned not-too-deep-space craft

Online Chris Bergin

RE: MSL Q&A
« Reply #36 on: 06/06/2007 03:04 PM »
Some cool photos that have been provided to us:

Offline hyper_snyper

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Re: MSL Q&A
« Reply #37 on: 06/06/2007 03:06 PM »
Wow, they weren't kidding.  That thing is huge.

Offline Launch Fan

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Re: MSL Q&A
« Reply #38 on: 06/06/2007 04:12 PM »
You could drive to work in that! Huge.

Offline Marsman

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Re: MSL Q&A
« Reply #39 on: 06/06/2007 04:54 PM »
I'll give em' 45K for it   :bleh:  The look on my coworker's faces when they see it in the parking lot will be well worth it.

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