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
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#46
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Forum Contributor Group: Members Posts: 1372 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
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. |
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Aug 6 2012, 12:32 AM
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#47
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Member Group: Members Posts: 599 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.
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Aug 6 2012, 12:33 AM
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#48
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Senior Member Group: Members Posts: 2082 Joined: 13-February 10 From: Ontario Member No.: 5221 |
Any reason it was tungsten specifically? Wouldn't lead work just as well (and be a bit cheaper)?
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Aug 6 2012, 12:36 AM
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#49
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Forum Contributor Group: Members Posts: 1372 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
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Aug 6 2012, 12:55 AM
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#50
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Senior Member Group: Members Posts: 2511 Joined: 13-September 05 Member No.: 497 |
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.
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Aug 6 2012, 01:06 AM
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#51
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Forum Contributor Group: Members Posts: 1372 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.
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