Author Topic: A Closer Look at NASA's New Exploration Architecture  (Read 29554 times)

Offline Flightstar

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RE: A Closer Look at NASA's New Exploration Architecture
« Reply #80 on: 10/14/2005 12:34 AM »
Of course. However T/Space's plans are flawed for such 2+2 missions. You have to double contigency on both elements for it to be workable, thus making twice as much extra redundancy. Imagine you have two cups, both filled with water. One spills, there's no help from the other cup. So they are sending two half full cups. That is the best analogy I can think of for their plans. It would be cheaper and more efficient to send a full cup with a good lid!

Offline nacnud

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RE: A Closer Look at NASA's New Exploration Architecture
« Reply #81 on: 10/14/2005 12:43 AM »

I thought the idea was that for a 2+2 mission that the other half of each vehicle was filled with science gear etc that could be dumped in an emergency allowing a single ship to carry 4.

Yes there is extra inefficiencies involved but there is a lot of extra safety as well. Think of Columbusís first American voyage, multiple ships for redundancy. Perhaps not the best analogy but you can see the similarities.


Offline Flightstar

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RE: A Closer Look at NASA's New Exploration Architecture
« Reply #82 on: 10/14/2005 12:54 AM »
Nicely put.

However, I'm thinking as an Orbiter tech, as I would. I'm trained to know that every lb of weight taken uphill has to be nessasary in the absolute. I worry about SpaceX 2+2 systems as they are appear to reducing capacity for redundancy at a ratio that goes past my personal beliefs of efficiency and cost. There are factors alone with a tandem mission such as theirs. I have not seen there plan where a rescue would involve 'creating' redundancy through dumping cargo (which is risky in its own right). I'll have to look at that.

Offline Avron

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RE: A Closer Look at NASA's New Exploration Architecture
« Reply #83 on: 10/14/2005 03:06 AM »
On the redundancy issue... three options I can see..

1) Take the risk   --- Not going to sit well with the public
2) Full redundancy including propulsion -- mass/complexity issue
3) Redundancy of all life support PLUS a Rescue mission on standby

Rescue mission all depends on two factors, where the CEV is going and how long you can keep a Rescue CEV stacked and ready to roll - cannot be that bad if its based on SRB's in terms of rollout and pad processing.

Full redundancy is fine as long as any failure does not impact the backup system (thinking back to Apollo13 - O2 was redundant as still the CM was left with close to zero ) -
Thus may also require a standby rescue mission.

Online Chris Bergin

Now unsticky (as I believe everyone who wanted to be invovled has seen it now).

Will move to the CEV section later today.

Offline kraisee

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RE: A Closer Look at NASA's New Exploration Architecture
« Reply #85 on: 10/27/2005 04:20 PM »
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Flightstar - 13/10/2005  8:54 PM

Nicely put.

However, I'm thinking as an Orbiter tech, as I would. I'm trained to know that every lb of weight taken uphill has to be nessasary in the absolute. I worry about SpaceX 2+2 systems as they are appear to reducing capacity for redundancy at a ratio that goes past my personal beliefs of efficiency and cost. There are factors alone with a tandem mission such as theirs. I have not seen there plan where a rescue would involve 'creating' redundancy through dumping cargo (which is risky in its own right). I'll have to look at that.

I agree that the tandem mission profile isn't the ideal.   That's why I think they'll use the continuously replaced redundant system they use with Soyuz to the ISS currently.

An initial lander will be sent to the moon unmanned.   The first expedition crew will arrive in another LSAM.   But they will return home using the "oldest" LSAM, leaving the "newest" LSAM as the escape vehicle for the next expedition.

Further crews will continue to replace the oldest craft with a newer one which remains "on-surface".   That way you always have a backup which is as new as reasonably possible.

If there is ever a significant problem with the older craft, then crews can abandon it, and the newer one becomes the "emergency" crew return vehicle.
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Offline kcowing

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RE: A Closer Look at NASA's New Exploration Architecture
« Reply #86 on: 10/31/2005 03:53 AM »
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kraisee - 27/10/2005  11:20 AM

Quote
Flightstar - 13/10/2005  8:54 PM

Nicely put.

However, I'm thinking as an Orbiter tech, as I would. I'm trained to know that every lb of weight taken uphill has to be nessasary in the absolute. I worry about SpaceX 2+2 systems as they are appear to reducing capacity for redundancy at a ratio that goes past my personal beliefs of efficiency and cost. There are factors alone with a tandem mission such as theirs. I have not seen there plan where a rescue would involve 'creating' redundancy through dumping cargo (which is risky in its own right). I'll have to look at that.

I agree that the tandem mission profile isn't the ideal.   That's why I think they'll use the continuously replaced redundant system they use with Soyuz to the ISS currently.

An initial lander will be sent to the moon unmanned.   The first expedition crew will arrive in another LSAM.   But they will return home using the "oldest" LSAM, leaving the "newest" LSAM as the escape vehicle for the next expedition.

Further crews will continue to replace the oldest craft with a newer one which remains "on-surface".   That way you always have a backup which is as new as reasonably possible.

If there is ever a significant problem with the older craft, then crews can abandon it, and the newer one becomes the "emergency" crew return vehicle.

Uh no - not exactly. If that was the case then they'd only land at one location - and many locations are under consideration for landings.

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