Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V16_0/V16NO084.ZIP/V16NO084

Internet Message Format | 1993-07-13 | 31KB

Date: Thu, 28 Jan 93 05:04:26
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #084
To: Space Digest Readers
Precedence: bulk


Space Digest                Thu, 28 Jan 93       Volume 16 : Issue 084

Today's Topics:
                Biosphere 2 Oxygen and other Questions
      Clinton's Promises (space) in Charlotte Observer (2 msgs)
                        Elementary Ballistics
Fluidic envelope on a point gravitational source suspended in a uniform field
                       Galileo update? (3 msgs)
                                JIAFS
Lubrication problem (was Re: Galileo Stuck Ribs / Remote Manipulator?)
                            Nasa Press Kit
                      Nasa Select contact req ?
                     Orbital Mechanics--Careers?
       Precursors to Fred (was Re: Sabatier Reactors.) (3 msgs)
                    Saving an overweight SSTO....
                             TPS Systems
                    Using off-the-shelf-components

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----------------------------------------------------------------------

Date: Wed, 27 Jan 93 22:50:00 PST
From: [e-mail]
Subject: Biosphere 2 Oxygen and other Questions



Biosphere 2 Oxygen and other Questions
January 27, 1993

Sixteen months down and eight to go.

Sorry to be so long in posting answers to the many
questions, I simply have not been able to make enough time
in here.

We don't know where all the oxygen has gone. This is one
of the biggest mysteries so far. While the CO2 removal
system can account for some of the O2 loss, as oxidation
of organic material producing CO2, which was then
removed from the air by the system. The amount of CO2
removed from the air only accounts for about one fifth of
the total oxygen deficit. We have essentially two leading
theories, first is oxidation of reduced compounds that may
have been present at closure, like possibly a reduced iron.
The second is oxidation of organic material in the soil and
subsequent precipitation of the CO2 as a calcium
carbonate, the parent materials for this are abundant but
the necessary conditions are in question. We are also in the
process of doing small chamber experiments with soil
similar to that in Biosphere 2. Carbon and Oxygen isotopes
are also being extensively studied for clews to what is
going on. The soils are the main point of interest because it
is the only place in the biosphere big enough to hide 12,000
Kg of O2.

The CO2 is now at an average concentration of 3500 ppm,
with a 400 to 500 ppm diurnal swing. The sunny weather
we are having now is bringing the average CO2
concentration down at a rate of 80 ppm per diurnal cycle,
without any use of the CO2 removal system which is now
off.  This means that the draw down during the day is 80
ppm greater than the rise at night. To put 3,500 ppm in
perspective, a room with people in it and normal ventilation
can easily get this high. Also CO2 concentrations between
5,000 and 8,000 ppm CO2 is not uncommon in the space
shuttle and submarines. Human health difficulties seem to
begin at about 9,000 to 11,000 ppm. Increased CO2 does
result in faster growth rates with many plants.

There was no bias against the Sabatier or Bosch systems,
they were simply not considered necessary at the time. We
had no idea that the oxygen phenomena would occur. What
we did know was that during the winter we would have an
excess of CO2 and in the summer quite possibly a deficit.
We are able to put the CO2 back in the air during the
summer and have it made into plant material, thus
completing an annual cycle of CO2 storage and release.
The summer release of CO2 should stimulate plant growth
and replenish some of the oxygen. A basic problem with
the Sabatier or Bosch systems and our situation is that we
do not have enough CO2 in the air to significantly change
the O2 using a system that would liberate the O2 form the
CO2. Even in the summer with low CO2 in the air, the O2
loss is at about 0.26% O2 per month, while the average
CO2 concentration is fairly constant at only 0.12%. Even
converting all the CO2 in the air to C + O2 would have
little effect on the O2 situation. Using such a system to
drive the CO2 even lower would begin to reduce food crop
production rates, because the plants would become limited
by the availability of CO2. So there is no need to transform
the CO2, just temporarily store it in the winter. Note that if
we had constant high levels of light, like in space for
instance, this CO2 storage scenario would be mute
because we would have no need to try and survive a low
light season!

The CO2 removal system I designed uses sodium
hydroxide as a scrubbing fluid, removing a fraction of all
acid forming gasses in the air. This is done using a large
reaction column with a high air flow rate, even so we can
only remove 100 to 200 ppm per day with the system. On a
low sunlight day the CO2 can jump up 300 to 400 ppm, so
the system can only moderate trends. The sodium
carbonates formed from the CO2 and sodium hydroxide
are reacted with calcium hydroxide to form CaCO3
(limestone) which regenerates the scrubbing fluid back to
sodium hydroxide. The CO2 is thus stored as CaCO3 until
time to release the CO2, which is done by heating the
CaCO3 making CaCO and CO2. The CaCO can then be
re-hydrated with the water in the scrubbing fluid and all the
chemicals are restored and ready for the next winter. This
may not be the best system, but it works. It is too heavy for
a space application but may possibly be made from local
materials.

Also a basic problem with any system is the need to
process a large volume of air. If the CO2 was at 1000
ppm, then for every liter of CO2 removed, one needs to
process 2000 liters of air with a 50% efficient system. This
can be done either by pre-concentrating, which is difficult
with a volume as big as Biosphere 2, or processing the
whole air which is also hard. Ambient temperature
scrubbing of air in a reaction column, using a hydroxide,
can handle large volumes of air quite easily. A similar
system is used in space craft with solid lithium hydroxide.
Pressure swing systems are being considered for space
station using materials that adsorb CO2 at cabin pressure
and release the CO2 to space vacuum and/or with heating.

The smell is usually great. I have a pure air generator that
makes very clean air by pressure swing adsorption, air with
no smell. By breathing this air for a period of about 30
minutes, it tends to "zero" my sense of smell so for a short
time after, 4 to 10 minutes, I can smell the air in the
Biosphere. It smells like rich farm soil (not potting mix), a
sweet fresh smell. There are some exceptions to this, like
when the sewage system has a problem such as
inadvertent overflowing, but after cleanup the smell only
persists for one to three of hours. Also if a container of
some wet organic material is not tended, it can smell rather
bad.

Methane buildups have not occurred, this is probably due to
methanotrophic bacteria increasing to consume the
methane thereby keeping it in check. We have thus-far had
no problem with any trace compounds building up in
the atmosphere or water supply. We haven't even needed
to use the soil bed reactor system to clean the air. The soil
bed reactor is designed to force air through the soil in the
agriculture biome as a means of cleaning the air.

We are now at the two thirds mark, I am sorry to say that I
can not be more specific than to say that group dynamics
are quite exciting. Some studies I have seen say that in a
situation with a confined crew, the third quarter is usually
the most difficult time. Oxygen additions are continuing, we
are now at about 17.5%. The low light conditions that we
have had over the last two months may delay harvest times
with some crops as much as a month. The effect of this on
our total food production will not be fully seen until mid
March, at which time we will be able to evaluate the
situation decisively.


Taber MacCallum
Biosphere 2 Crew


------------------------------

Date: Wed, 27 Jan 1993 02:10:23 GMT
From: "Bruce F. Webster" <[e-mail]>
Subject: Clinton's Promises (space) in Charlotte Observer
Newsgroups: sci.space

In article <[e-mail]>
[e-mail] writes:
> In article <[e-mail]>, [e-mail] (Edward
V. Wright) writes...
> >In <[e-mail]> [e-mail] (rabjab)
writes:
> >
> >>>        B. Support completion of the space station Freedom.
> >
> >>Looks like Clinton is going to make some rather severe cuts in space
> >>projects.  And "supporting completion" doesn't mean actual completion.
> >
> >You don't understand.  NASA doesn't *want* Space Station Freedom
> >completed.
> >
>
> No you don't understand and your statement is a prime reason people like
> you are not listened to at NASA. Even looking at the proposition from a
> pragmatical political perspective, this statment of yours is false. Why?
>
> If NASA drags their feet and does not finish the station costs soar and
> nothing gets done.

Space Station Freedom was originally proposed in what? 1982?, was supposed to
be on orbit and operational in 1992, and was supposed to cost a total of $8B.
It is now 1993, not a single actual piece of Fred has been built (much less
placed on orbit), and the estimated total cost is $40B and rising. Q.E.D.

I used to work for NASA (as an employee of Singer/Link, the former contractor
on the Space Shuttle Flight Simulator at JSC) and also worked at the Lunar and
Planetary Institute next door. I have friends who are still heavily involved in
the space industry at various levels. I happen to think that the best thing
Clinton could do would be to kill SS Fred and offer $10B, tax-free, to the
first US corporation or consortium to put a station on orbit and keep it
staffed by at least X people for a year and day. He should also offer $5B to
the second corporation/consortium to do the same thing. The government would

spend less, create more jobs, and built an 21st century industrial base.
..bruce..

-------------------------------------------------------------------------------
Bruce F. Webster             |  We hackers linger by our leading edge
CTO, Pages Software Inc      |  Forgetting what is pending in the cache
[e-mail]           |  Till practice hurtles past us, and we crash.
#import <pages/disclaimer.h> |            -- Jeff Duntemann
-------------------------------------------------------------------------------

------------------------------

Date: 27 Jan 1993 15:58:06 GMT
From: Doug Mohney <[e-mail]>
Subject: Clinton's Promises (space) in Charlotte Observer
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Bruce F. Webster) writes:
>. I have friends who are still heavily involved in
>the space industry at various levels. I happen to think that the best thing
>Clinton could do would be to kill SS Fred and offer $10B, tax-free, to the
>first US corporation or consortium to put a station on orbit and keep it
>staffed by at least X people for a year and day. He should also offer $5B to
>the second corporation/consortium to do the same thing. The government would
>spend less, create more jobs, and built an 21st century industrial base.

Gosh, you been hanging out with Jerry Pournelle, huh?

He has expounded on the bonus plan to build a moon colony through the same
fashion.

I got some questions for you:

    A) Who owns possession of the technology used to develop the station?
    B) Who owns the data?
    C) How do you set the damned thing up without using goverment help
       in the first place? Guess who owns all the big launch facilities.
       (Unless, of course, you wish to disguise this as a Russian
        Marshall Plan, which is not necessary a Bad Thing. Just be say
        so up front).
    D) Does it have to be a U.S. corp? What if I use off-shore tech, say
       get the Italians into building my living modules?

IF, in exchange for the prize money, the government gets rights to the
"science" without infringing on trade secrets, it might work.


                    I have talked to Ehud, and lived.
  -- >                  [e-mail]                        < --

------------------------------

Date: Wed, 27 Jan 1993 07:49:20 GMT
From: Henry Spencer <[e-mail]>
Subject: Elementary Ballistics
Newsgroups: sci.space,sci.physics,alt.pagan

In article <[e-mail]> [e-mail] (Matt Healy) writes:
>Several people pointed out that LEO takes about 8 km/sec,
>minimum.  This is in the FAQ.  However, I haven't seen any
>posts giving the simple math behind the 8 km/sec figure,
>so I'll crack open Halliday & Resnick {Physics}:
>
>centripetal acceleration for a body following a circular
>path...  One standard "g" is 9.81 meter/second_squared...

Do remember, though, that the acceleration of gravity varies somewhat
with altitude.  The correct formula for circular-orbit velocity is
v = sqrt(GM/r), where G is the constant of gravitation, M is the mass
of the Earth, and r is the radius of the orbit.

(Actually, in practice, what you look up in a table is GM rather than
G and M separately.  The gravitational constant is a colossal pain to
measure because gravity is so weak, and it is known to only about four
digits.  The GM of a planet will typically be known far more precisely
than M, because GM can be determined directly from satellite orbits
but getting M requires dividing GM by the poorly-known G.)

The rule of thumb is that low orbit is at about 8 km/s, and you need
maybe 9.3 km/s to get from the surface to low orbit despite gravity
losses and air resistance.  That does assume relatively low velocity
during the climb through the thick low-altitude atmosphere, though,
or you lose much more to drag.

>But how would a *real* mass driver handle the problem of
>getting up *above* the atmosphere and then circularizing
>the orbit? ...

First, some terminology:  "mass driver" refers to a very specific type of
electromagnetic catapult -- one with recirculating payload-carrying
"buckets", a concept invented by Gerard O'Neill -- and is *NOT*, repeat
*NOT*, a generic synonym for "gun" or "catapult".

As for how gun/catapult systems handle circularization:  there has to be
some extra velocity change imparted by other means, e.g. an apogee kick
motor or a tether system.  Ignoring some fine points, an orbit always
passes through the point of the last velocity change.  If you want the
low point of the orbit to be above the atmosphere, there has to be a
velocity change done up there.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

------------------------------

Date: Wed, 27 Jan 1993 14:58:07 GMT
From: James Meritt <m23364@mwunix>
Subject: Fluidic envelope on a point gravitational source suspended in a uniform field
Newsgroups: talk.origins,sci.space

What would the characteristics be of the fluidic envelope (atmosphere and
hydrosphere) of a gravitational point source (say, the earth) if it were to
be suspended (through some magical method which would NOT affect the oceans)
in a uniform (or near-uniform) intense (approximately 6 meters per second
per second) gravitational field (say, from something that would become Saturn)?

Off hand, I wonder about the long-term status of the atmosphere.  Would the
escape velocity on the "near" side be reduced such that the molecular velocity
at "room temperature" be sufficient to "bleed off" the air?  What WOULD the
imposition of a uniform field over the inverse square field do the e.v.?
Someone care to perform the integral?

What would the physical distribution of the object be?  On the planetary
surface, the vector sum of the two fields would make "downhill" towards
the primary (except in a line straight through the center of mass of the
secondary (earth).  On the "near" point, 'g' would be reduced and on the
"far" point 'g' would be increased.  The equipotential surface would
be furthest from the center of mass of the secondary on the "far" side
and nearest to the center of mass on the "near" side.  How would this
affect things?  Would the lithosphere retain sphericality, or is the
material strength insufficient to prevent drastic redistribution to conform
with the equipotential shape (read: terminal earthquakes).  What would
the atmospheric pressure be, since the mass of the atmosphere would be
on the "far" side and the 'g' is reduced on the 'near' side?  Would the
partial pressure of O2 be sufficient for respiration?  Would there be
ANY oceans & lakes on the "near" side?


--
James W. Meritt:  [e-mail] - or - [e-mail]
The opinions above are mine.  If anyone else wants to share them, fine.
They may say so if they wish. The facts "belong" to noone and simply are.

------------------------------

Date: Wed, 27 Jan 1993 13:39:08 GMT
From: Jarno Kokko <[e-mail]>
Subject: Galileo update?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ron Baalke) writes:
>In article <[e-mail]>, Michael Petersen <[e-mail]> writes...
>>Could someone tell me if NASA has successfully deployed the high-gain
>>antenna on Galileo yet?   I heard that their most "aggressive" attempts
>>would occur after the the last Earth flyby.
>
>The recent hammerings have not opened the antenna.  The first hammering
>attempt turned the ballscrew an additional full rotation, but it has
>not budged since.  Despite 13,000+ hammerings at different frequencies
>and at various antenna temperatures, the ribs are still stuck.   One last
>attempt will be made by spinning up the spacecraft from 3 rpm to 10 rpm
>in March, but this is not expected to do much.  March has been designated
>as the deadline to open the antenna.  After that the focus will be
>on the Ida flyby in August and a low gain antenna mission.  One other
>event that may open the antenna is the Jupiter orbit insertion in December
>1995.  The solid rotor motor will fire for an hour and the resulting
>vibrations may jar the antenna loose, but this is to be considered a long shot.
>     ___    _____     ___
>    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
>    | | | |  __ \ /| | | |     Jet Propulsion Lab |
> ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Every once in a while,
>/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | try pushing your luck.
>|_____|/  |_|/       |_____|/                     |
>

Have people thought about combining hammering with the orbit insertion?
I think hammering when whole spacecraft is vibrating due to motor
firing would shake loose about anything :-) .. Or is it impossible
due to some minor technical detail?

- Jarnis <[e-mail]>

------------------------------

Date: 27 Jan 1993 16:25 UT
From: Ron Baalke <[e-mail]>
Subject: Galileo update?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Jarno Kokko) writes...
>Have people thought about combining hammering with the orbit insertion?
>I think hammering when whole spacecraft is vibrating due to motor
>firing would shake loose about anything :-) .. Or is it impossible
>due to some minor technical detail?

I don't think that would be a wise thing to do.  The motor firing has be
done at a precise time with the spacecraft in the proper attitude.  If the
hammering was done during the motor firing, and the antenna was to pop
open, it could change the spacecraft attitude enough to really mess up the
orbit insertion.  Besides, the spacecraft will very busy as it is during
the orbit insertion, collecting the probe data, performing a 1000 km Io flyby
and collecting science data on Jupiter.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Every once in a while,
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | try pushing your luck.
|_____|/  |_|/       |_____|/                     |

------------------------------

Date: 27 Jan 1993 17:22:00 GMT
From: Chuck Shotton <[e-mail]>
Subject: Galileo update?
Newsgroups: sci.space

In article <[e-mail]>,
[e-mail] (Ron Baalke) wrote:
>
> I don't think that would be a wise thing to do.  The motor firing has be
> done at a precise time with the spacecraft in the proper attitude.  If the
> hammering was done during the motor firing, and the antenna was to pop
> open, it could change the spacecraft attitude enough to really mess up the

What's to say it won't pop open anyway?

> orbit insertion.  Besides, the spacecraft will very busy as it is during
> the orbit insertion, collecting the probe data, performing a 1000 km Io flyby
> and collecting science data on Jupiter.

Will there be an attempt to open the antenna AFTER Galileo is in orbit (on
the assumption that the firing may have jarred things loose)?

------------------------------

Date: 27 Jan 1993 12:15:19 -0600
From: Harold Neal <[e-mail]>
Subject: JIAFS
Newsgroups: sci.space

Does anyone have any experience with the graduate program of the Joint
Institute for Advancement of Flight Sciences at Nasa/Langley, run by George
Washington University?
I'd hope to here about from someone who has been part of it.


------- -------
Harold Neal
[e-mail]
Engineering Mechanics, Virginia Tech

------------------------------

Date: Wed, 27 Jan 1993 08:07:31 GMT
From: Henry Spencer <[e-mail]>
Subject: Lubrication problem (was Re: Galileo Stuck Ribs / Remote Manipulator?)
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]> [e-mail] (Bill Higgins-- Beam Jockey) writes:
>> Who told you that loss of lubricant was the problem?  How about a
>> broken or cracked rib, or some other less obvious reason for the
>> jam?
>
>Loss of lubricant during truck travel is the best guess of Galileo's
>engineers...

It's important to note, though, that it remains only a theory, not an
established fact.  What's more, this theory seems rather low in predictive
power:  the same folks who told us that loss of lubricant was probably
the failure mode also told us that the heating/cooling turn sequence
would probably work the stuck ribs loose.  It didn't.

This is not to say that I have any better ideas, but do bear in mind
that the hard evidence is slim and our experience with such failures
essentially nonexistent.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

------------------------------

Date: 27 Jan 93 12:43:51 GMT
From: Philippe Colbach <[e-mail]>
Subject: Nasa Press Kit
Newsgroups: sci.space

How do I order Nasa's press kits?  Philippe

------------------------------

Date: 27 Jan 1993 16:09:07 GMT
From: Jim Lawson <[e-mail]>
Subject: Nasa Select contact req ?
Newsgroups: sci.space

Bill Higgins-- Beam Jockey ([e-mail]) wrote:
: In article <[e-mail]>, [e-mail] (Jim Lawson) writes:
: > My cable company is now under the impression that they need "permission"
: > to broadcast Nasa Select.
: > Do they ?
: No.  The government produces it and it's in the public domain.
: It *is* reasonable for the cable company to ask for written assurance of this.
: (From a source more authoritative than Bill Higgins, I mean.)

Kind of what I'm thinking, it might be my cable companys way of putting me off.

: > Who can I contact at Nasa Select to straighten this out ?
: This question has come up before-- should be in the FAQ-- but I don't
: have the answer handy.  Call the Public Affairs Office at NASA
: Headquarters and try to find out.  [phone].  If you get the
: answer, post it!

Thanks,
    I rang that number but it has been changed to [phone].
    I called that and they referred me to [phone]. I left
    a message and am awaiting a call back.

--
Jim Lawson    [e-mail]
        Alt:    [e-mail] or [e-mail]

Opinions/Comments expressed here are my own and no one elses !!

------------------------------

Date: Wed, 27 Jan 1993 07:02:42 GMT
From: My name is Nasser Abbasi <[e-mail]>
Subject: Orbital Mechanics--Careers?
Newsgroups: sci.aeronautics,sci.research.careers,sci.space,soc.college.grad

In article <[e-mail]>, [e-mail] (mark jones) writes...
>
>After u.g. major in math with lots of physics I'm trying to decide on
>masters/Ph.d in math or orbital mechanics.  What are the opportunities
>in orbital mechanics and will they still be there in 5 or 6 years.
>Any advice is greatly appreciated.  Reply via net or directly
>[e-mail]

since defense and aerospace are not doing too well, one would think
OM area might not be too hot. is there actually an MS in OM? or is
OM studied under control engineering? or mechanical engineering?

if however you study physics, you can do both, OM and math and many other
things too ;-)

\nasser

------------------------------

Date: 27 Jan 1993 15:43:29 GMT
From: Doug Mohney <[e-mail]>
Subject: Precursors to Fred (was Re: Sabatier Reactors.)
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] writes:

[Dennis tries to convince Allen that building hardware and flying it on
Spacelab is a good thing]

You're talking to someone who wants to burn shuttle and put in its place a
made-in-Russia tin can.

The wall will give you a better discussion Dennis, since Allen has already made
up his mind about the utility of anything (other than Freedom, which is needed
to assure the Soyuz/Atlas has a place to go) associated with the Shuttle is
patently Evil.


                    I have talked to Ehud, and lived.
  -- >                  [e-mail]                        < --

------------------------------

Date: Wed, 27 Jan 1993 16:58:12 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Precursors to Fred (was Re: Sabatier Reactors.)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:

>[Dennis tries to convince Allen that building hardware and flying it on
>Spacelab is a good thing]

No, Dennis it trying to convince me that space stations cannot be built
without doing lots of Spacelab flights.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------139 DAYS TO FIRST FLIGHT OF DCX----------------------+

------------------------------

Date: 27 Jan 1993 19:22:24 GMT
From: Doug Mohney <[e-mail]>
Subject: Precursors to Fred (was Re: Sabatier Reactors.)
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Allen W. Sherzer) writes:
>In article <[e-mail]> [e-mail] writes:
>
>>[Dennis tries to convince Allen that building hardware and flying it on
>>Spacelab is a good thing]
>
>No, Dennis it trying to convince me that space stations cannot be built
>without doing lots of Spacelab flights.

So how do you suggest NASA tests hardware and flight procedures before Freedom
goes up?

Thirty seconds on the vomit comet don't cut it.


                    I have talked to Ehud, and lived.
  -- >                  [e-mail]                        < --

------------------------------

Date: Wed, 27 Jan 1993 18:47:27 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: Saving an overweight SSTO....
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Pat) writes:

>How about this.  ping pong around.   HawaII to Ecuador. Ecuador to Spain.
>Spain to Tanzania.  Tanzania to India,  India to Australia,  Australia
>to Hawaii.

>You bounce around and just keep meeting cargos.


The problem is, that assumes an equal number of cargoes in all
locations, which wouldn't be the case.  You'd have a lot of
cargoes waiting for you in Hawaii, fewer in India and Australia,
practically none in Ecuador and Tanzania.

Ideas like this make sense when you're talking about expendable
artillery shells, and the emphasis is on maximum performance,
but when you're talking about airplanes -- or spaceships --
operational considerations must take precedence.

------------------------------

Date: Wed, 27 Jan 1993 07:33:23 GMT
From: Henry Spencer <[e-mail]>
Subject: TPS Systems
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Tim McDaniel) writes:
>Wasn't there at least one Chinese satellite that returned film (?) using
>a heat shield made of oak?

Yes, the Chinese reportedly use chemically-treated oak as an ablative
material.  Apparently it works pretty well.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

------------------------------

Date: Wed, 27 Jan 93 19:07:34 GMT
From: Ata Etemadi <[e-mail]>
Subject: Using off-the-shelf-components
Newsgroups: sci.space

G'Day

 Are there any companies out there whose off-the-shelf products are
space-qualified ? I ask this since a colleague at IKI told me that
they had flown many standard PC hard discs as onboard storage devices
and had great success. I just wondered what other components might be
out there which are standard and space-qualified. I don't imagine
for one minute that these components will be chosen for major space
missions since they are just not expensive enough. Maybe the UOSAT
folks will be willing to give them go...

    regards
       Ata <(|)>.
|               Dr Ata Etemadi, Blackett Laboratory,                          |
|               Space and Atmospheric Physics Group,                          |
|               Imperial College of Science, Technology, and Medicine,        |
|               Prince Consort Road, London SW7 2BZ, ENGLAND                  |
| Janet                        [e-mail] or [e-mail].c  |
| Internet/Arpanet/Earn/Bitnet [e-mail] or [e-mail]  |
| Span                              SPVA::atae       or     MSSLC:atae        |
| UUCP/Usenet                       [e-mail]        |

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End of Space Digest Volume 16 : Issue 084
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