The size of MSL, Yep, it really IS that big! |
  |
The size of MSL, Yep, it really IS that big! |
 Aug 5 2012, 11:40 PM
Post
#46
|
|
|
Forum Contributor  Group: Members Posts: 902 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11  |
QUOTE (Marz @ Aug 6 2012, 12:29 AM)  Seems a shame to deliver an extra 75kg to mars that is dumb ballast. 5.7 hours and counting! The problem then is you'd have to safely land all the embedded rover/landers, have comms setup for them, and teams to run the submissions, all costing many many $$$. The throw away mass is what it is, it's a needed design feature. |
 |
 
|
|
Aug 6 2012, 12:32 AM
Post
#47
|
|
|
Member Group: Members Posts: 592 Joined: 26-August 05 Member No.: 476 |
Ballast is typically very dense material due to the mass and volume constraints. In some cases on aircraft, depleted uranium is used. Designing a payload into ballast is just not practical from either budget or schedule.
|
|
|
|
|
Aug 6 2012, 12:33 AM
Post
#48
|
|
 Member Group: Members Posts: 618 Joined: 13-February 10 From: Vancouver, British Columbia Member No.: 5221 |
Any reason it was tungsten specifically? Wouldn't lead work just as well (and be a bit cheaper)?
-------------------- To a body of infinite size there can be ascribed neither centre nor boundary... Thus the Earth no more than any other world is at the centre. -Giordano Bruno, 1584.
|
|
|
|
|
Aug 6 2012, 12:36 AM
Post
#49
|
|
|
Forum Contributor Group: Members Posts: 902 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
QUOTE (Explorer1 @ Aug 6 2012, 12:33 AM) Any reason it was tungsten specifically? Wouldn't lead work just as well (and be a bit cheaper)? To comply with the Planetary Protection Protocol they used fairly nonreactive tungsten. Lead is deadly poisonous. |
|
|
|
|
Aug 6 2012, 12:55 AM
Post
#50
|
|
|
Senior Member Group: Members Posts: 1041 Joined: 13-September 05 Member No.: 497 |
QUOTE (Explorer1 @ Aug 5 2012, 05:33 PM) Any reason it was tungsten specifically? Wouldn't lead work just as well (and be a bit cheaper)? Lead is too soft. Tungsten (or possibly a copper-tungsten alloy which is easier to machine) is much harder. Also, tungsten is denser, allowing volume savings. http://www.e-tungsten.com/top_10_tungsten_reasons.html I'm unaware of any planetary protection restrictions against lead or generally toxic materials. Consider the toxicity of Pu238... -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
|
|
|
|
|
Aug 6 2012, 01:06 AM
Post
#51
|
|
|
Forum Contributor Group: Members Posts: 902 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
The Pu238 is in protective ceramic cakes. It's highly unlikely to ever to pollute Mars. It also has a half life and will eventually decay into a less harmless compound.
|
|
|
|
|
|
Lo-Fi Version | Time is now: 19th May 2013 - 09:26 AM |
|
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE 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 a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here. |
|
