IPB

Welcome Guest ( Log In | Register )

3 Pages V   1 2 3 >  
Reply to this topicStart new topic
Michael Meyer, about Phoenix and MSL
Cugel
post Sep 25 2006, 10:01 AM
Post #1


Member
***

Group: Members
Posts: 153
Joined: 11-December 04
Member No.: 120



http://www.marsdaily.com/reports/Managing_...ssions_999.html

Michael Meyer, lead scientist for NASA's Mars Exploration Program, spoke at the recent Viking anniversary celebration. One remarkable quote:

"Considering how long the Spirit and Opportunity rovers have lasted beyond their design lifetimes, it almost boggles the mind to think how long MSL could last. It may be there to greet the astronauts when they arrive on Mars."

That's what I call optimism.
I always thought that the lifespan of an RTG was pretty predictable and that in case of MSL it lasted for about 2 earth years. Maybe he's talking about the solar array powered version?
Go to the top of the page
 
+Quote Post
djellison
post Sep 25 2006, 10:02 AM
Post #2


Founder
****

Group: Chairman
Posts: 14431
Joined: 8-February 04
Member No.: 1



Or the sort of failures we're seing on MER - actuators, motors etc.

Doug
Go to the top of the page
 
+Quote Post
climber
post Sep 25 2006, 11:07 AM
Post #3


Senior Member
****

Group: Members
Posts: 2917
Joined: 14-February 06
From: Very close to the Pyrénées Mountains (France)
Member No.: 682



Do we know for sure whether MSL will be solar or RTG's?
OR
When will we know? Did they past the critical desgin yet?


--------------------
Go to the top of the page
 
+Quote Post
Cugel
post Sep 25 2006, 02:12 PM
Post #4


Member
***

Group: Members
Posts: 153
Joined: 11-December 04
Member No.: 120



Apparently not.
According to Meyer the project is still in a 'conceptual' phase.
That sounds a bit scary, doesn't it?
Go to the top of the page
 
+Quote Post
Jim from NSF.com
post Sep 25 2006, 04:47 PM
Post #5


Member
***

Group: Members
Posts: 321
Joined: 6-April 06
From: Cape Canaveral
Member No.: 734



MSL has its PDR in June. MSL DEIS briefings are this week.
Go to the top of the page
 
+Quote Post
climber
post Sep 25 2006, 05:38 PM
Post #6


Senior Member
****

Group: Members
Posts: 2917
Joined: 14-February 06
From: Very close to the Pyrénées Mountains (France)
Member No.: 682



QUOTE (Jim from NSF.com @ Sep 25 2006, 06:47 PM) *
MSL has its PDR in June. MSL DEIS briefings are this week.

Those accronyms again! I've just got "june" and "week" biggrin.gif
Well, MSL too, but can you help with this Jim ?
BTW, I understand this week is important.


--------------------
Go to the top of the page
 
+Quote Post
Guest_AlexBlackwell_*
post Sep 25 2006, 05:43 PM
Post #7





Guests






QUOTE (climber @ Sep 25 2006, 07:38 AM) *
Those accronyms again! I've just got "june" and "week" biggrin.gif
Well, MSL too, but can you help with this Jim ?
BTW, I understand this week is important.

He's referring to the MSL preliminary design review and the draft environmental impact statement.
Go to the top of the page
 
+Quote Post
Guest_Analyst_*
post Sep 25 2006, 06:55 PM
Post #8





Guests






QUOTE (Cugel @ Sep 25 2006, 10:01 AM) *
I always thought that the lifespan of an RTG was pretty predictable and that in case of MSL it lasted for about 2 earth years. Maybe he's talking about the solar array powered version?


The funny thing about RTGs is there predictable power reduction. They don't die instantly like an empty battery (after i.e. two years). The output decreases very gracefully. The Voyager RTGs are generating today more than half of their output at launch in 1977.

So if MSL uses a RTG (I can't imagine it using solar panels and I can't imagine this decision hasn't been taken already.) and if it behaves like the Voyager RTGs and if all the other rover subsystems keep working and if the rover can work with 50 percent power (like MER) it can still be arround after 30 years.

A lot of if's. But also a beancounters nightmare. Imagine the 15th mission extension. smile.gif

Analyst
Go to the top of the page
 
+Quote Post
helvick
post Sep 25 2006, 08:25 PM
Post #9


Dublin Correspondent
****

Group: Admin
Posts: 1799
Joined: 28-March 05
From: Celbridge, Ireland
Member No.: 220



QUOTE (Analyst @ Sep 25 2006, 07:55 PM) *
... if it behaves like the Voyager RTGs and if all the other rover subsystems keep working and if the rover can work with 50 percent power (like MER) it can still be arround after 30 years.

That might be the case for the RTG's itself but I'm certain that the RTG will be used to charge up a battery sub-system that will act as a buffer for power demands of the rover's main sub systems. It's less likely that the battery\power mangement sub system will be good for 30 years.

On the issue of solar vs RTG - I assume that this is being kept vague simply to avoid attracting the ire of the anti nuke crowd. I can't see how a solar panel solution would be sufficient given the power requirements and mission duration. The MER's survival for 2+ years through good luck does not change the fact that MSL's power requirements would require _huge_ panels (>8m^2) in order to ensure that it could survive the full blown Martian dust storms that it's mission duration absolutely requires that it needs to be able to survive.
Go to the top of the page
 
+Quote Post
Stephen
post Sep 26 2006, 01:31 AM
Post #10


Member
***

Group: Members
Posts: 307
Joined: 16-March 05
Member No.: 198



QUOTE (helvick @ Sep 25 2006, 08:25 PM) *
The MER's survival for 2+ years through good luck does not change the fact that MSL's power requirements would require _huge_ panels (>8m^2) in order to ensure that it could survive the full blown Martian dust storms that it's mission duration absolutely requires that it needs to be able to survive.

Using solar panels would also presumably limit the MSL to equatoral regions like the MERs (or else increase the panel acreage required even more).

======
Stephen
Go to the top of the page
 
+Quote Post
lyford
post Sep 26 2006, 04:06 AM
Post #11


Senior Member
****

Group: Members
Posts: 1281
Joined: 18-December 04
From: San Diego, CA
Member No.: 124



Maybe they are planning to use the ChemCam to zap the solar panels clean? I kid! tongue.gif
I can't see how this mission could be solar powered and still be the MSL we have come to expect in 2009.
I would also imagine that all things being equal electro-mechanically, a RTG mission lifetime would be very predictable, with none of the power budget uncertainty the MERs face.


--------------------
Lyford Rome
"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test
Go to the top of the page
 
+Quote Post
edstrick
post Sep 26 2006, 09:40 AM
Post #12


Senior Member
****

Group: Members
Posts: 1870
Joined: 20-February 05
Member No.: 174



I do not know the possible engineering constraints on "supplementary" solar cells, but if the weight of a square meter or two on advantageously oriented surfaces on top of the rover wasn't a big problem, it seems that they might be useful as a supplementary power source. There's additional power handling hardware and cabling and the like, but it might be worth it.
Go to the top of the page
 
+Quote Post
Jeff7
post Sep 26 2006, 11:39 AM
Post #13


Member
***

Group: Members
Posts: 477
Joined: 2-March 05
Member No.: 180



QUOTE (helvick @ Sep 25 2006, 04:25 PM) *
That might be the case for the RTG's itself but I'm certain that the RTG will be used to charge up a battery sub-system that will act as a buffer for power demands of the rover's main sub systems. It's less likely that the battery\power mangement sub system will be good for 30 years.

They managed to squeeze more than 15 years out of Hubble's batteries, and they get recharged about every 90 minutes, if memory serves.
Go to the top of the page
 
+Quote Post
helvick
post Sep 26 2006, 04:23 PM
Post #14


Dublin Correspondent
****

Group: Admin
Posts: 1799
Joined: 28-March 05
From: Celbridge, Ireland
Member No.: 220



QUOTE (Jeff7 @ Sep 26 2006, 12:39 PM) *
They managed to squeeze more than 15 years out of Hubble's batteries, and they get recharged about every 90 minutes, if memory serves.

Those are very different beasties. Hubble uses pressurised Nickel Hydrogen batteries. Those have excellent life time and recharge cycle characteristics but are relatively inefficient from a power storage\density POV. The MER's use Lithium Ion\Lithium Polymer batteries and MSL almost certainly will too.



Go to the top of the page
 
+Quote Post
Spacecadet
post Dec 23 2006, 07:30 AM
Post #15


Newbie
*

Group: Members
Posts: 4
Joined: 20-December 06
Member No.: 1498



MSL is an RTG powered rover.

Keep in mind there are two other benefits from RTG's.

1. Lots of waste heat which can be used to heat the rover. This is a significant power savings.

2. No batteries.. = mass savings ;)
Go to the top of the page
 
+Quote Post

3 Pages V   1 2 3 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 28th March 2024 - 10:07 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member.