SpaceX announces details on Falcon V

(McLean1382) :

Henry Spencer writes:


No. Such things have been discussed a lot, but they are not yet normal
practice. (Artemis more or less did this, but that was disaster recovery
rather than a deliberate plan.) One reason for that is that the long,
slow spiral up through the Van Allen belts is very hard on electronics in
general and solar arrays in particular.
--

There have been proposals to use SEP to ferry unmanned payload from earth
orbit
to lunar orbit, or up to high orbit for planetary missions. As far as I
can
tell, the solar arrays required to make this attractive are much ligher
than
current state of the art. Henry, can you comment on this?

Must it be solar cells? What about a solar-thermal generator setup - it
should have no problems with radiation.

Earl Colby Pottinger
--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp

In article ,
Earl Colby Pottinger wrote:
...the long,
slow spiral up through the Van Allen belts is very hard on electronics in
general and solar arrays in particular.

Must it be solar cells? What about a solar-thermal generator setup - it
should have no problems with radiation.

True, although you'd still have (lesser) issues with the other electronics.
Trouble is, the technology is poorly developed.

(It doesn't help that the main customers -- the comsat guys -- are the
most conservative market you can imagine, wary of almost any innovation.
They care much more about reliability than about price tag.)
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

In article , Dr. O
dr.o@xxxxx wrote:

So would NASA be interested in putting a man in to orbit for $12 million
(excluding capsule).

Of course they would, as long as the capsule costs $100 million.

--
David M. Palmer (formerly @clark.net, @ematic.com)

Henry Spencer wrote:
In article ,
Earl Colby Pottinger wrote:
...the long,
slow spiral up through the Van Allen belts is very hard on electronics in
general and solar arrays in particular.

Must it be solar cells? What about a solar-thermal generator setup - it
should have no problems with radiation.

True, although you'd still have (lesser) issues with the other electronics.
Trouble is, the technology is poorly developed.

(It doesn't help that the main customers -- the comsat guys -- are the
most conservative market you can imagine, wary of almost any innovation.
They care much more about reliability than about price tag.)

No, thats no really the problem - the problem is that they do it and at the
same time also don't fund microsats that could easily be used to explore such
technology issues and also be launched basicly free. It is better when comms
people worry most about reliability.

--
Sander

+++ Out of cheese error +++

On 14 Jan 2004 13:33:00 -0800, in a place far, far away,
(John Schilling) made the phosphor on my
monitor glow in such a way as to indicate that:

For chemical propulsion, it's never worth bothering with a tug. You wind
up carrying a substantial ammount of propellant all the way to GEO for
the sake of recovering some empty tanks with a bit of useful rocketry
and guidance hardware attached. Easier and cheaper to launch a new bit
of rocketry and guidance each time.

Even with aerobraking?

On Fri, 16 Jan 2004 03:16:58 GMT, in a place far, far away, Michael
Walsh made the phosphor on my monitor glow in
such a way as to indicate that:

OK, but if you are going to complain about big aerospace relying on
brochures and flip charts rather than actual hardware you should apply
the same standards to SpaceX.

The difference is the cost of the flip charts, and who pays for
them...

h (Rand Simberg) writes:

On 14 Jan 2004 13:33:00 -0800, in a place far, far away,
(John Schilling) made the phosphor on my
monitor glow in such a way as to indicate that:

For chemical propulsion, it's never worth bothering with a tug. You wind
up carrying a substantial ammount of propellant all the way to GEO for
the sake of recovering some empty tanks with a bit of useful rocketry
and guidance hardware attached. Easier and cheaper to launch a new bit
of rocketry and guidance each time.

Even with aerobraking?

Aerobraking doesn't help with the GEO deorbit burn, which is roughly
half the problem, and it does require carrying a TPS/aeroshell, etc,
as dead weight for the rest of the mission. It helps, but not enough
to make a pure chemical tug worthwhile.

Cheap propellant in LEO, as from an extraterrestrial source, would
make a chemical tug worthwhile, but even ET propellant isn't that
cheap by the time it gets to LEO if it made the trip by chemical
rocketry.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *

Rand Simberg wrote:

On Fri, 16 Jan 2004 03:16:58 GMT, in a place far, far away, Michael
Walsh made the phosphor on my monitor glow in
such a way as to indicate that:

OK, but if you are going to complain about big aerospace relying on
brochures and flip charts rather than actual hardware you should apply
the same standards to SpaceX.

The difference is the cost of the flip charts, and who pays for
them...

No argument with that and I don't doubt that SpaceX compares
quite favorably with Lockheed-Martin and Boeing on flip chart
costs.

Just pointing out that beyond their initial Falcon I vehicle that
should be getting close to first launch the later vehicles are in
the flip chart stage.

Mike Walsh

On 27 Jan 2004 12:16:04 -0800, in a place far, far away,
(John Schilling) made the phosphor on my
monitor glow in such a way as to indicate that:

Aerobraking doesn't help with the GEO deorbit burn, which is roughly
half the problem, and it does require carrying a TPS/aeroshell, etc,
as dead weight for the rest of the mission. It helps, but not enough
to make a pure chemical tug worthwhile.

Cheap propellant in LEO, as from an extraterrestrial source, would
make a chemical tug worthwhile

That was my next question.

but even ET propellant isn't that
cheap by the time it gets to LEO if it made the trip by chemical
rocketry.

But it may eventually be cheap enough.

In article ,
John Schilling wrote:
For chemical propulsion, it's never worth bothering with a tug. You wind
up carrying a substantial ammount of propellant all the way to GEO for
the sake of recovering some [relatively cheap bits of hardware]
Even with aerobraking?

Aerobraking doesn't help with the GEO deorbit burn, which is roughly
half the problem...

Somewhat less than half the problem if you're willing to go via a lunar
flyby, or just a leisurely loop up to very high altitude (where you make a
very small burn) and then back down. (Yes, it costs rather less to boost
from GEO to infinity than to drop from GEO to Earth.) Still not cheap,
though, and rather more time-consuming.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |