Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v15_6/v15no630.txt

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Date: Tue,  5 Jan 93 05:00:09
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #630
To: Space Digest Readers
Precedence: bulk


Space Digest                Tue,  5 Jan 93       Volume 15 : Issue 630

Today's Topics:
                 Aerospike Engines... what are they?
                       Aluminum as rocket fuel?
                     Data release delay? (2 msgs)
                     DC vs. Shuttle capabilities
                           DCX tech. info?
                      Earth-approaching asteroid
                      Energy production on Earth
                         fast-track failures
             How many flights are Orbiters designed for?
                       Media coverage of space
           Sea floor Planetary Protection really. (2 msgs)
      Shuttle a research tool (was: Re: Let's be more specific)
   Stupid Shut Cost arguements (was Re: Terminal Velocity (2 msgs)
                    What was NASA Thinking About?

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Date: Mon, 4 Jan 1993 13:44:26 GMT
From: "Herity D." <[e-mail]>
Subject: Aerospike Engines... what are they?
Newsgroups: sci.space

[e-mail] ("RWTMS2::MUNIZB") writes:

>In an spike nozzle the opposite takes place and the gas flow is directed
>inward from an annulus at some diameter away from the centerline.  This
>flow is directly exposed to ambient pressure and its expansion is thus
>directly coupled to the external environment (continuous altitude
>compensation with no moving parts).

As I understand it, the exhaust is confined between the spike and the
external airflow. So how can it work in a vacuum ? Can it ?
--
-----------------------------------------------------------|"Nothing travels   |
| Dominic Herity,  [e-mail],                      |faster than light, |
|Computer Science Dept, Trinity College, Dublin 2, Ireland.|except possibly bad|
| Tel : [phone] ext 1720 Fax : [phone]       |news"-Douglas Adams|

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

Date: Mon, 4 Jan 93 07:53:29 EST
From: John Roberts <[e-mail]>
Subject: Aluminum as rocket fuel?

-From: [e-mail] (Bruce Dunn)
-Subject: Re: Aluminum as Rocket Fuel?
-Date: 4 Jan 93 00:27:49 GMT
-Organization: MIND LINK! - British Columbia, Canada

-        Sorry for the sloppy wording.  I meant rather "when there is melted
-aluminum in the tank".  I am envisioning a system in which aluminum is
-premelted, possibly in a solar furnace, and poured into an insulated
-tank/valve/combusion chamber unit.  The aluminum will bring the whole system
-up to temperature, and melt any residual aluminum from the last firing.

Getting an aluminum engine that will work in single-use mode is the first big
step. Making one that can be restarted and reused is a significant further
challenge, which is not necessary to putting aluminum engines in service for
launch from the moon.

-I expect that it won't be too hard to insulate the assembly well enough to keep
-the temperature above the melting point of aluminum for days.  I don't think
-that a heater will be required.

That's probably correct, though you need to watch out for the possibility
of chemical reactions and leaks when storing molten aluminum for long periods.

-If heating is required for long term
-operation, the logical thing would be to admit a small amount of oxygen into
-the fuel tank to react with the aluminim and heat it.

If you do that, there's a very good chance you'll clog up whatever you're
using to inject the aluminum into the combustion chamber.

John Roberts
[e-mail]

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

Date: Mon, 4 Jan 1993 09:19:29 GMT
From: Ben Delisle <[e-mail]>
Subject: Data release delay?
Newsgroups: sci.space

    In a newspaper article I read a couple days ago, I saw that
NASA will delay the release of data and pictuers from the Mars Observer
when it arrives at Mars and begins it's job. Aparently the delay will
be of a year or more and live feeds that have been offered with previous
deep space probes will be restricted.
    Is there any truth to this, if so why has this policy been set
into force and by whom? This is unconscienceable and must be changed.
It is all out wrong. There is no reason.



--
[e-mail]


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

Date: Mon, 4 Jan 1993 15:37:58 GMT
From: Ed McCreary <[e-mail]>
Subject: Data release delay?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ben Delisle) writes:
>
>    In a newspaper article I read a couple days ago, I saw that
>NASA will delay the release of data and pictuers from the Mars Observer
>when it arrives at Mars and begins it's job. Aparently the delay will
>be of a year or more and live feeds that have been offered with previous
>deep space probes will be restricted.
>    Is there any truth to this, if so why has this policy been set
>into force and by whom? This is unconscienceable and must be changed.
>It is all out wrong. There is no reason.
>

Partly right, partly wrong.  The general release of digital data
from MO will be release approximately a year after they are returned.
Why?  To give the researchers first shot at analyzing the data.  This
has always been the case.  But, images of particular interest and
other scientific data will be released at the press conferences.

But, the researchers directly involved with the MO program will
have unprecedented access and control to their experiments.  Each
research group will have at least one workstation installed which
will provide access to the JPL database.  They can get data and
provide commands all from their local office instead of having to
go directly through JPL.  See the collection of articles on the
MO program in "The Journal of Spacecraft and Rockets" vol 28, no 5.


--
Ed McCreary                                               ,__o
[e-mail]                       _-\_<,
"If it were not for laughter, there would be no Tao."  (*)/'(*)

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

Date: 4 Jan 93 15:13:13 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: DC vs. Shuttle capabilities
Newsgroups: sci.space

In article <[e-mail]> [e-mail] ("Phil G. Fraering") writes:

\4. The servicing goals and rapid turnaround requirements of the vehicle
/are doable on paper, but have been held out as very risky by an
\independent study.

>An independent study which apparently had an axe to grind of its own,
>if you're talking about the TAC study.

If he is referring to the TAC assessment, there are even more problems.

TAC examined Max Hunters SSX design, not DC. Their main complaint about
turnaround was the active cooling being used in the Thermal Protection
System (TPS). They felt (with good reason) that the complex tubes and
pumps needed for this would make access difficult.

However, since DC doesn't use active cooling, most of the TAC complaints
regarding maintenance are moot.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------110 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 3 Jan 93 21:49:00 GMT
From: George Gassaway <[e-mail]>
Subject: DCX tech. info?
Newsgroups: sci.space

So much financial data being flung about here of late, could someone take
a time out to tell me hardware/flight details of the DCX? I did not
realize a test prototype was so far along that a flight is planned this
summer, I'd only heard of the general concept for the basic vehicle.

What is the size (height, diameter) and mass of this first test prototype?
Thrust?
Flight profile of the prototype - low altitude hop, suborbital, orbital?
Re-entry/landing - heatshield, parachutes, powered descent al-la-LM?
Launching and landing site(s)?

---
 This copy of Freddie 1.2 is being evaluated.


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

Date: Mon, 4 Jan 93 07:58:23 EST
From: John Roberts <[e-mail]>
Subject: Earth-approaching asteroid

CNN Headline News showed a radar image of the asteroid that flew by the
Earth on December 8. The commentator said that the image had 100 times better
resolution than any previously taken of an Earth-approaching asteroid (it's
still not as good as the Galileo images of Gaspra).

The asteroid appears to be very rough, and is composed of two large chunks
(possibly held together by gravity).

John Roberts
[e-mail]

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

Date: Mon, 4 Jan 93 09:11:33 EST
From: John Roberts <[e-mail]>
Subject: Energy production on Earth

Regarding the utilization of energy sources on Earth, which was discussed
in the context of importing energy from space:

A report on the radio this morning described a genetically engineered
bacterium, in which two genes were spliced in to allow it to do a very
good job of converting complex carbohydrates (including celluose) into
ethanol. Evidently the project is far enough along that there are plans
to build a plant in New York, to produce 15(?) million gallons of ethanol
per year from paper mill sludge.

Now, let's hope the bacterium doesn't get loose in the environment, or
that it requires something to live that's found only in the culture tanks. :-)

John Roberts
[e-mail]

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

Date: Mon, 4 Jan 1993 16:08:49 GMT
From: Brad Whitehurst <[e-mail]>
Subject: fast-track failures
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Shari L Brooks) writes:
>
>In article <[e-mail]>
>[e-mail] (Brad Whitehurst) writes:
>
>>In article <[e-mail]> [e-mail] (Edward
>>V. Wright) writes:
>
>>>You think a typical engineer earns $100,000 a year?
>>>
>>>I want to work for your company!
>
>>    By the time you also pay for FICA, pension, benefits, and
>>overhead, a $50,000 engineer can easily cost a company double his base
>>pay!  BTW, Ed, I ALSO help do the budgeting for my lab, so before you
>>ask, yes, I have some experience in this!
>
>Wow, your lab pays for FICA?  I'm impressed.  It takes up about a third
>of *my* salary, when combined with income taxes.  Right out of my pay.
>I was under the impression it came out of everyone's pay, that that was
>the idea behind "Social Security".
>
    Your employer also contributes an amount about equal (I think)
to that deducted from your paycheck.  So, yes, Social Security zaps
both you AND your employer!
--

Brad Whitehurst    |   Aerospace Research Lab
[e-mail] |   We like it hot...and fast.

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

Date: Mon, 4 Jan 1993 15:54:50 GMT
From: "John S. Neff" <[e-mail]>
Subject: How many flights are Orbiters designed for?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>From: [e-mail] (Allen W. Sherzer)
>Subject: Re: How many flights are Orbiters designed for?
>Date: Sat, 2 Jan 1993 17:15:39 GMT
>In article <[e-mail]> [e-mail] writes:
>
>>What's due to replace the shuttle in 2007 - the DC?
>
>NASA people have been responsible for two attempts to kill the DC
>program. However, Goldin hasaid that if it works, they will use
>it.
>
>>I *sincerely* hope
>>that the shuttle fleet won't be "run down" in anticipation of a 2007
>>cut-off, regardless of whether or not a replacement is *actually*
>>available by then!
>
>That's the rub. Shuttle and NASA procurement process are both so expensive
>that there simply isn't any money available for NASA to develope a
>replacement.
>
>>If NASA's historical record is anything to go by,
>>a replacement due to enter service in 2007 is unlikely to be ready by
>>then....
>
>DC could be available long before then *IF* we can get DoD to fund the
>proof of concept vehicle.
>
>  Allen
>--
>+---------------------------------------------------------------------------+
>| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
>|  [e-mail]     |  nothing undone"                                       |
>+----------------------112 DAYS TO FIRST FLIGHT OF DCX----------------------+

My view is that there better be a follow on to the shuttle if NASA does
not want to have egg on its face. I also think there will be pressure to use
as much of the shuttle hardware and operating systems as possible in order
to save money and time.

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

Date: Mon, 4 Jan 93 07:39:29 EST
From: John Roberts <[e-mail]>
Subject: Media coverage of space

-From: [e-mail] (Simon E. Booth)
-Subject: Re: Government-run programs  Was: Re: Justification for the Space Program
-Date: 2 Jan 93 04:54:16 GMT
-Organization: University of Texas at San Antonio

-Concerning public opinion about the space program, IHMO those opinions can
-and are greatly influenced by the media's depiction of space exploration.
-Next time watch news coverage of a shuttle flight.  Invariably some reference
-is made to the cost of that particular mission, plus any important technical
-information is either watered down or omitted.

-I've had people tell me that the media doesn't cover the space program very
-much because people aren't interested.

-But here's somethin to think about: did people lose interest and the media
-reduced it's coverage in response, or did the media cut back coverage and then
--convince people that they weren't interested in it?

It's true that there's not as much "big three" network coverage as there
used to be (other than occasional specials), but with the explosion of the
number of channels available on satellite and cable, there's a tremendous
amount of material being shown. Even not counting NASA Select (which every
space enthusiast should get if at all possible), there's  "Inside Space"
and "The Science Show" on the Sci-Fi Channel, space shows on the Discovery
Channel and the Learning Channel, PBS programming, a weekly science update
on CNN, etc. CNN Headline News had very good regular coverage of the Dante
mission (complete with video), until the fiber optic cable broke and the
mission was discontinued. (Incidentally, one of the NASA Select commentators
claimed that the purple color was chosen for Dante because it didn't frighten
the penguins, then admitted that was just a joke. The newspapers picked that
up and reported it as being the color penguins prefer. (Not many penguins
inside the volcano.))

The Washington Post gives very good coverage of space missions.

John Roberts              |       Portmeirion Village
[e-mail] |       Penrhyndeudraeth
                          |       Gwynedd LL48 6ER
                          |       WALES
                          |       (a vacation resort, the real address of
                          |       "the Village" from "The Prisoner")

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

Date: 4 Jan 93 15:21:27 GMT
From: Ed McCreary <[e-mail]>
Subject: Sea floor Planetary Protection really.
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Ed McCreary) writes:
>>... After it's mission is finished, MO will be raised to a high
>>enough orbit to prevent it's re-entry for X thousand years.
>
>This may be a little academic, since as I recall, as of its shutdown in
>1972, Mariner 9's estimated orbital lifetime was only half a century.

True, I should have checked my numbers.

The quarantine requirements state that the probability of impact
before Jan. 1, 2009 must be less than 0.0001.  The probability
of impact between Jan. 1, 2009 and Jan. 1, 2039 must be less than
0.05.  As a result, MO will be raised to a Sun-synchronous orbit
with an altitude of about 370 km after it's mission is complete.
--
Ed McCreary                                               ,__o
[e-mail]                       _-\_<,
"If it were not for laughter, there would be no Tao."  (*)/'(*)

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

Date: 4 Jan 93 16:11:00 GMT
From: Ron Baalke <[e-mail]>
Subject: Sea floor Planetary Protection really.
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Ed McCreary) writes:
>>... After it's mission is finished, MO will be raised to a high
>>enough orbit to prevent it's re-entry for X thousand years.

>This may be a little academic, since as I recall, as of its shutdown in
>1972, Mariner 9's estimated orbital lifetime was only half a century.

Mariner 9's orbit satisfied the Mars quarantine requirements that were in effect
at that time.  Once astronauts land on the surface on Mars, it is
impossible to guarantee that Mars will not be biologically contaminated.
In the early 1970's, people thought for sure that Man would set foot on Mars
within the next 50 years.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life.

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

Date: 4 Jan 93 15:08:00 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle a research tool (was: Re: Let's be more specific)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Francois Yergeau) writes:

>The shuttle system itself may not be considered R&D anymore, but it's
>the manifest that tells you whether it's doing research  or mere
>"operations."

No, the Shuttle is always doing operations unless it is Shuttle
itself which is being experimented on. When Shuttle carries spacelab,
it is engaged in operations *IN SUPPORT OF RESEARCH* but not research.

When somebody flies a roll during re-entry to see what happens, that
is research.

   Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------110 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Mon, 4 Jan 1993 15:03:49 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Stupid Shut Cost arguements (was Re: Terminal Velocity
Newsgroups: sci.space

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

>From all of the posts that I have seen in the last few months from you, it
>seems that you live in Allen's world.

I don't have much choice in that respect. I say again, one feature of Allen's
world is that I need to provide my customers a real return on their investment
of they won't hire me. At the same time, I need to bid projects so that all
our costs are covered. Unlike NASA, I can't simply decide to loose money
and expect the taxpayers to make good.

>This world is where you pick and choose your own numbers and play them the
>way you want to make your systems look desirable.

Dennis, I know this is hard to understand but I don't pick the vehicle I
like and then justify it. I pick the systems which can be justified and
support them. That is why, for example, I was a shuttle supporter until
about 83 when I concluded it simply wasn't working and dropped it.

My devotion is to a goal, not a launcher or an organization.

This is why I use the same numbers for launchers I use in my professional
life. As somebody who must earn his keep I know that our systems must
recoup ALL their costs one way or another.

>is just your accounting that are unrealistic, as you forget to charge against
>your vehicle, what you so decry me for not doing with the Shuttle.

I refer you to my recent breakout of DC vs Shuttle costs. I thought I
was bending over backwards to make Shuttle look good. In that posting
exactly what cost did I allocate to Shuttle but not to DC?

>The simple point that I was trying to make that you totally missed is that
>the marginal cost as described in the November 28-December 9 issue of
>space news for adding another mission is 37 million dollars maximum.

Oh no, I fully understand what marginal cost means. You however seem
to feel that is an excuse to ignore costs and charge what you want
to for arbitrary flights. That isn't acceptable in the real world.

I did agree to let you do it when you convince GM to sell you a
Corvet for the marginal cost of a Corvet. let me know when you do;
until then, I'll stick to assigning all costs to the project.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------110 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Mon, 4 Jan 1993 15:48:42 GMT
From: Brad Whitehurst <[e-mail]>
Subject: Stupid Shut Cost arguements (was Re: Terminal Velocity
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>In article <[e-mail]> [e-mail] (Brian Stuart Thorn) writes:
>
>Nobody puts people into space just for the hell of it. They are there to
>perform tasks. Given that, one can ask what those tasks are and wonder
>if there are cheaper ways to do those tasks. We can also decide if the
>tasks are worth doing at the price we must pay.
>
>I assert that there are no payloads which must fly on Shuttle and are
>worth flying. If you are going to disagree, please do so with a cost
>analysis or your arguement will be meaningless.
>
    If men are part of the payload, the Shuttle is (currently) the
only way to fly!  Now, we could just discontinue manned flight for the
next few years (I won't argue how many) until the wondrous DC-1 is
available, but some folks would argue there's plenty of value in
medical, operational, etc. research and development in the intervening
years.
N.B.: My opinion, your mileage may vary.

--

Brad Whitehurst    |   Aerospace Research Lab
[e-mail] |   We like it hot...and fast.

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

Date: Mon, 4 Jan 1993 13:47:16 GMT
From: Thomas Clarke <[e-mail]>
Subject: What was NASA Thinking About?
Newsgroups: sci.space

Wanting to refresh my somewhat rusty remembrance of things rocket,
I picked up "Rocket Propulsion Elements" by George Sutton
(1986, 5th ed, John Wiley and sons).
Therein I found the following interesting numbers:

Space Shuttle Main Engine    Saturn J-2 Upper Stage

Thrust (at alt): 470,000 lbs    230,000 lbs
Specific Imp (alt)   455 sec        426 sec
Dry Weight:         6335 lbs       3454 lbs
Thrust/Weight:          74             67
Mixture Ratio:           6          5.5

Now, I have been led to believe that the SSME is a large
advance over previous engines. The above seems to imply
that with a little work the 6 J-2s could have powered
the shuttle quite nicely.  Perhaps a 6:1 mixture would have
given it the same Isp as SSME - the J-2 thrust and thrust/weight
would have then been 246,000 lbs and 71.5.

Also:

       Space Shuttle SRB         Saturn F-1 First Stage

Thrust(at alt):     2,372,000     1,748,000
Specific Imp:   266 (average)      265 (grnd) - 305 (alt)

Now, the F-1 does not replace an SRB one for one, but its
no too far off.  Given its good record maybe the F-1 could
have been rerated to 135% throttle to equal the SRB.

Hence the question in the title of my post:  What was NASA
thinking about?  Apparently the Saturn engines could have
been used to build the shuttle vehicle.  Why weren't they?

A shuttle with 5 or 6 J-2s using 2 uprated F-1s in the recoverable
boosters would have taken advantage of a history of literally
dozens of successful flight firings.  Plus there would
have been a much wider range of abort modes.

Happy new year.  Let's hope for more rational future design.

[P.S. I tried posting this from home with a modem last week,
I didn't see it show up, so forrive me if its a duplicate]
--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
[phone], FAX: [phone], [e-mail]

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

End of Space Digest Volume 15 : Issue 630
------------------------------