Lifeboats in Space

As I recall, Columbus left on his famous trip with three ships, but due to
various events, wound up coming back with partial crew on only the smallest,
the pinta.
So, multi-ship expeditions are a long-established technique.

"MSu1049321" wrote in message
...
As I recall, Columbus left on his famous trip with three ships, but due to
various events, wound up coming back with partial crew on only the
smallest,
the pinta.]

Actually, 4. 4th one sailed over the edge.


So, multi-ship expeditions are a long-established technique.

"Derek Lyons" wrote in message
...
"Jeff Findley" wrote:

This is what the original argument is all about. Does a lifeboat need to
do
more than keep the crew alive while they await rescue. We don't do it
for
ocean going lifeboats, so why are spacecraft much different? Assuming
the
lifeboat is in (or can get to) a stable orbit, why not wait for a rescue?

What keeps getting missed is two things; that it was formerly assumed
that lifeboats on oceangoing going vessels *would* seek to self
rescue, and that currently we have nobody for the rescuees to wait
for.

Or to put it more simply; crews on orbit today have more in common
with a ship at sea in 1704 than they do with a ship at sea today.
That will change, but it's unwise to ignore the fact the change hasn't
happened yet.

Although a stranded crew in LEO today is far better off than a crew on a
lifeboat in 1704. The stranded crew in LEO isn't "lost" in the sense that
NORAD knows exactly where they are, even if there is no communications. In
that case, it's just a waiting game.

From an engineering point of view, we have a trade off between a re-entry
system and the supplies to keep the crew alive until they can be rescued.
With the current shuttle and Soyuz flight rate, a re-entry capsule may be
the best bet, but we don't have that. If the shuttle or Soyuz develops
problems while you're in orbit and it can't safely re-enter, you're going to
wait at ISS for a rescue (i.e. ISS is your lifeboat). Even with the CEV, I
doubt this will change.

A large part of this trade-off is cost. Neither the US nor Russia can
afford to keep extra vehicles docked to ISS. As a matter of routine, they
go up and down with a full compliment.

Jeff
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Remove icky phrase from email address to get a valid address.

(Steve VanSickle) wrote:
Alternative: use all that spare cargo capacity and put it extra
propellant tanks for the OMS system. This one isn't probably as good an
idea. Have to plumb it it, the engineering starts looking formidable.

The plumbing already exists. However the sole 'extended endurance'
pallet, which contained H2 and O2 tanks as well, was lost with
Columbia.

D.
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Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL