Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_3/V16NO323.TXT

Internet Message Format | 1993-07-13 | 35KB

Date: Wed, 17 Mar 93 05:08:54
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #323
To: Space Digest Readers
Precedence: bulk


Space Digest                Wed, 17 Mar 93       Volume 16 : Issue 323

Today's Topics:
                        20Khz Power supplies.
                     Charon & Pluto: definitions
          Extra Orbits (was Re: Magellan Update - 03/12/93)
                             Galileo HGA
                       GIFS of nightside (req)
                   Hobbies (was Re: Without a Plan)
                   Mars Observer Update - 03/16/93
                         NASA, DoD, Aerospace
                  NASA worships the God of paperwork
             Response to various attacks on SSF (2 msgs)
        Sisters of Mars Observer (was Re: Refueling in orbit)
          Venus and Mars, was Re: TIME HAS INERTIA (2 msgs)

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
    "Subscribe Space <your name>" to one of these addresses: listserv@uga
    (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: 16 Mar 93 19:07:31 GMT
From: Gary Coffman <ke4zv!gary>
Subject: 20Khz Power supplies.
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>
>Fred  as opposed to FRED the cut down space station.  You try to explain
>why a totally untested technology would be used on such a critical
>project.  Name 3 projects that have used 20Khz  power.  name 3 companies
>that produce 20Khz power components.

How about Lambda, ACDC Electronics, IBM, Apple, and zillions of Tiawan
clone makers. 20 kHz power is old hat. Likely the computer you are
reading this on uses 20 kHz, or higher, frequencies in it's power
systems. It's cheaper, smaller, and lighter than the old brute force
methods of Tommy Edison and Georgie Westinghouse. Even Nicky Tesla
thought higher frequencies were a good idea for power distribution.
DC was a technology of the 90s, the 1890s. Try to move into *this*
century Pat.

Gary

--
Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |                     |

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

Date: Tue, 16 Mar 1993 13:18:20 MST
From: "Richard Schroeppel" <[e-mail]>
Subject: Charon & Pluto: definitions

It's been suggested that Charon & Pluto be called "co-satellites" because
the system barycenter isn't inside Pluto.  This criterion depends too much
on the distance between the bodies.  The solar system barycenter is usually
not inside the sun; and if we were to move the moon 30% further away, the
earth-moon barycenter would be outside the earth.

Rich Schroeppel  [e-mail]

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

Date: 16 Mar 93 13:24:54 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Extra Orbits (was Re: Magellan Update - 03/12/93)
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]>, [e-mail] (Ron Baalke) writes:
>                          MAGELLAN STATUS REPORT
>                              March 12, 1993
>
> 1.  The Magellan spacecraft is operating normally, as it approaches its
> 7000th orbit of Venus next Tuesday.  (For those of you who have access
> to orbit numbers and are confused by the difference between the
> current orbit number and this count, remember that the first orbit
> after Venus Orbit insertion was 100 and an adjustment during the
> in-orbit-check-out added another 11.)

I wonder why this was?  Maybe the first 100 are JPL "center overhead?"

Bill Higgins, Beam Jockey              | What I want to be
Fermi National Accelerator Laboratory  | when I grow up:
Bitnet:           [e-mail]  | "Charismatic Leader
Internet:       [e-mail]  | of a Heavily Armed
SPAN/Hepnet:           43011::HIGGINS  | Religious Cult"

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

Date: 16 Mar 93 17:36:08 GMT
From: Henry Spencer <[e-mail]>
Subject: Galileo HGA
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>With the failure of hammering attempts to open Galileo's high gain antenna
>following the recent Earth flyby, and the decision to proceed with the mission
>using the low gain antenna, does this mean that no further attempts to open the
>high gain antenna will be made?

Not unless somebody comes up with a radically new approach.  Everything
that was thought to have a reasonable chance of success has been tried,
unsuccessfully.  The probability of getting useful results by repeating
the old techniques is minimal, and in some cases there is a significant
cost involved -- notably, heating and cooling turns require substantial
amounts of fuel.

Note that since much of the original mission can be flown using the
low-gain antenna, it is not permissible to endanger the spacecraft in
an attempt to open the high-gain antenna.
--
All work is one man's work.             | Henry Spencer @ U of Toronto Zoology
                    - Kipling           |  [e-mail]  utzoo!henry

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

Date: 16 Mar 1993 18:58:14 GMT
From: [e-mail]
Subject: GIFS of nightside (req)
Newsgroups: sci.space

My office mate is looking for GIFs of the nightside of the earth. Preferably
cloud free mosaics, either or both hemispheres (north preferred).  I'm sure
the light pollution people have lots of these.  In particular, he wants to
see if the jungle clearing fires in Central America are still as bright as
major cities.  Please respond with either ftp addresses or mailings.  You can
reply to me or him ([e-mail])

Clear skies.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Hey Timothy's about cannibalism, when was THAT popular?"
     Crow - Monster a Go-Go

Kenn Lippert    Alcoa Technical Center    [e-mail]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

Date: 16 Mar 93 07:40:41 GMT
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: Hobbies (was Re: Without a Plan)
Newsgroups: sci.space,talk.politics.space

In article <[e-mail]>, [e-mail] (Pat) writes:
>
> Wow.  This is a hard one for me.  Defending Szabo.  ack....
>
> But the guy has one critical valuable point to make.
> That is a sustainable economy must be the basis of space  activities.
>
> Any non viable system, remains a hobby.

That sums it up.  I agree heartily with Pat and Nick on this point.
Nothing wrong with having "hobbies," but the solar system holds some
promise to sustain spaceflight activities by bringing economic
benefits to humanity.  If we exploit this promise space science,
technology, development, exploration, and colonization will blossom.
If we don't, space will remain an expensive sideshow indefinitely.

I think it is rational to make plans to open these doors.  Fred McCall
evidently doesn't.

Bill Higgins, Beam Jockey              | Bartlett's
Fermi National Accelerator Laboratory  | Most Familiar Quotation
Bitnet:           [e-mail]  | (according to W. H. Leininger):
Internet:       [e-mail]  | "Say, that's pretty good!
SPAN/Hepnet:           43011::HIGGINS  | Mind if I use it?"

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

Date: 16 Mar 1993 19:02 UT
From: Ron Baalke <[e-mail]>
Subject: Mars Observer Update - 03/16/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from the Mars Observer Project

                       MARS OBSERVER STATUS REPORT
                              March 16, 1993

The Flight Team reports that spacecraft subsystems and the instrument
payload are performing well.  The spacecraft is in Array Normal Spin in
outer cruise configuration, with uplink and downlink via the High Gain
Antenna; uplink at 125 bps, downlink at the 2 K Engineering data rate.
The DSN (Deep Space Network) is providing continuous coverage to Mars
Observer in support of TCM-3 (Trajectory Correction Maneuver #3) activities.

Flight sequence C7 B continues clocking out through shortly before 8:00 AM,
Thursday March 18.  Activation of C8 containing TCM-3 occurs at 8:00
AM, also on March 18.  The TCM-3 maneuver itself occurs at 2:00 PM that
afternoon.  TCM 3 is planned to produce a velocity change of .46 meters per
second.

Flight Team members have completed maneuver parameter updates to the
sequence, which has been successfully VTL tested.

The Maneuver Assessment Meeting is scheduled for 4:00 PM on Monday,
March 22.  The Navigation and Spacecraft Teams will present their
analyses of the results of TCM-3 at that session.

Today, the spacecraft is 30,378,028 km (18,876,032 mi.) from Mars
travelling at a velocity of 3.31 kilometers/second (7404 mph) with
respect to Mars.  One-way light time is approximately 444 seconds.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Don't ever take a fence
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | down until you know the
|_____|/  |_|/       |_____|/                     | reason it was put up.

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

Date: Tue, 16 Mar 93 14:45:56 EST
From: Tom <[e-mail]>
Subject: NASA, DoD, Aerospace

From: Mary Shafer <[e-mail]>

[e-mail] sez:
>>yes, the nasa culture is sick.
>>but not as sick as the entire aerospace industry!

TomM> Can you make such a distinction?  How much of the aerospace
TomM> industry exists soley because of NASA?  How many of it's problems
TomM> can be traced to their biggest customer, NASA?  Seems like a lot
TomM> of it.

>NASA is not the biggest customer of the aerospace industry--the
>Department of Defense is.  NASA's total budget is at least an order of
>magnitude smaller than DoD.

Duh!  OK, I should have known that.  But, still, the question applies.
When shuttle launches DoD stuff, even if not all of it, or NASA gets
some of it's funding based on National Defense grounds, can you really
call DoD, NASA, and aerospace seperate enitites?  Don't NASA, DoD,
and Aerospace Industry (if it's really One), all share R&D here and
there as well?

-Tommy Mac
-------------------------------------------------------------------------
Tom McWilliams | 517-355-2178 (work) \\     Inhale to the Chief!
[e-mail]  | 336-9591 (hm)\\  Zonker Harris in 1996!
-------------------------------------------------------------------------

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

Date: 16 Mar 93 09:23:24 GMT
From: Pat <[e-mail]>
Subject: NASA worships the God of paperwork
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (David B. Mckissock) writes:
|
|In article <[e-mail]>, [e-mail] (J. D. McDonald) writes...
|>
|>was doen correctly .. for example, the paperwork for the (last)
|>challanger launch was in perfect shape: it was OK to launch in cold weather.
|>This was official, agreed to by management. That it was not the
|>opinion of the people who knew did not matter.
|>
|
|I'm responding, not because I think I can change your mind, but
|for the benefit of other readers on sci.space.
|
We always welcome attributed conversations here.
anonymous ones are more controversial:-)
Certain things are religious,  but engineering arguments can
often be thrashed out.  You should have seen the roaring on the
DC-1 proposals.

|First off, I don't understand the logic supporting the position
|of "who cares about the shape of the paperwork, I want to know
|how the hardware works." The "paperwork" defines the requirements

Dave.  Here we have two people hearing two different things from one
statement.  The paperwork oftentimes does define the requirements,
but it's often used to disguise the problems.
"Alter the documentation"  is often times a response to hardware
or software problems.  Rather then fixing the problems, the
requirements get re-scoped.  Look at the problem plagued B-1
bomber.  In design since 1977, it was delivered, and still has
serious operational problems.  The paper work is right,  but the
damn thing is very problematic.  The Terrain avoidance radar gets
jammed by the ECM system.   it flys either nap of the earth, or
jamming but not both together.  It's a real problem.

When the Space station was first proposed,  the proposal was 8 people.
8 billion dollars, by 1988.  No matter what,  we aren't seeing that.
NASA has a very detailed quality assurance system, but it's not
working well.  For all the money spent on tracking systems,  shuttle
missions, sometimes don't know if engines have been properly reconditioned.
Three people can sign off on a task, and things are undone.

This is what one perceives as paperwork not working.


|
|agree that some of the NASA "paperwork" burden is probably
|excessive, and could be cut-back without comprimising the
|safety or performance of the project. To become a "devil's

80% of the paperwork could be tossed, if people would
be willing to take responsibilty for things getting done.
That includes contractors and NASA management.   Look at
the early days.  From proposal to Build in less then a year.
Mercury was built in 13 months.  The little Joe test vehicle
was done in 12.  Gemini was a fast program.  Apollo had
defined work blocks.  Each contractor was responsible for
stages, and when it didn't work, they took it on the chin.
The S-IV stage was a real fight in weight budget, so was the LEM.

|advocate" for a moment and cite an example, I become frustrated
|when I go to meetings and some ya-hoo says "let's create a new
|document to record this-and-that and such-and-so", & I argue
|that stuff is already written down in two other places, what
|a stupid waste of resources to create a third document to
|record these things.
|
Not only that, but usually the documents become out of sync,
and that's where integration problems become a bear.

|So, yeah, parts of the NASA "paperwork" system can be reformed,
|but I don't believe one can ignore the "paperwork" all together.
|
No, but the requirements book could be 10 pages.
The army contract for the Chinook helicopter in 1961, was 16 pages.
Today,  the blackhawk contract is 6 thousand pages.

|Finally, I disagree that the paperwork for Challenger was in
|perfect shape. In a Systems Engineering seminar I took a few
|years back, it was noted that part of the Challenger tradegy
|was due to a requirements traceability failure. The Shuttle
|Level II requirements document contained a requirement
|establishing a wide temperature range on the entire vehicle.
|This requirement was incorrectly flowed down to Thiokol,
|resulting in the SRB's being designed, qualified, and tested
|to a smaller temperature range. The contention is, if the
|Shuttle Level II folks had their paperwork in-order, then
|this error in requirements flowdown would have been caught.
|


Yes,  but the problem was in NASA management.  Thiokol didn't
want to sign off,  NASA pressured them.  Rockwell also was real
hesitant to sign off on launch,  NASA pressured them too.

And look what happened after it blew up,  cover ups,  obfuscation,
blame avoidance.  Dozens of other serious problems finally got
worked during the stand down.  Landing gear issues,  better brakes,
Computer updates,  stronger attach points, valve improvements.

Simplicity and professional devotion to task  are the best guide
to requirements planning.

On the SRB design,  the contracts specified,  field joints and
factor joints,  but Nothing pointed to ASTM guidelines,  so Thiokol
was in violation of ASTM guidelines, when they bored all the holes
in the clevis joints.  Had the booster, ripped like a postage stamp
it would have been all over.

This was a serious item for the ISRM fix.  All the requirements matrices
in the world, dont track to basic guidelines of engineering practice,
and that's a serious NASA management problem.

NASA requirements specs are often times directed at performance issues
without considering design practice.

I am curious,  do any of the SSF documents Cite NEC, or IEEE standards?
or ASME or ASTm standards?

pat

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

Date: 16 Mar 93 08:58:29 GMT
From: Pat <[e-mail]>
Subject: Response to various attacks on SSF
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (David B. Mckissock) writes:
>In article <[e-mail]>, [e-mail] (Pat) writes...
>>
>>And who is responsible for integrating their work?  How come
>>that's a major management issue?
>The Space Station Program Organization is similar to the
>Apollo & Shuttle organizations. Level I, based at NASA
{stuff deleted}
Dave,  You mention that Level 2 is responsible for integrating
the level three centers and contractors, but what I read in the trade press
is that there is a feeling that there is a lack of integration,
and that no contracts have been let to ensure all the work packages
and systems  interface completely.

Given the incredible diversity in centers contractors and work packages
and flight packages,  it is possible for something small to get dropped
on the floor, and be a large problem.

The saudis built King Khalid and Rhiyad cities  as separate contracts.
Blocks were built by different companies,  so funny things were happening,
like cables coming into manholes,  but not having any final connections.
The wires were all there, but noone had the authority or responsibity
to tie everything together.

Plus  different engineering standards were used.  Each company would use
say  100 pair cables,  but one cable would be circular, the others
elliptical,  so standard connectors wouldn't fit.

Three phase cables were run,  but some were delta wired,  others Y.
with different legs grounded.

A major problme in the DOD is that nothing is well designed to
interoperate.  Air force tankers can't refuel Navy fighters.
European Jets oftentimes can't use US fuel pumps.

While these issues are often being worked,  they have been a real
operational problem.

Is there a single contract that specifies integration?  Reston doesn't
have the man power to conduct integration, to the best of my
knowledge.


>>
>>>key part of our Contracts with these folks are their
>>>requirements documents. Each NASA center tailors the
>>>requirements in the PDRD for their individual contract, and
>>
>>And how many requirements got dropped on the floor between the
>>three tailoring jobs?  Who has the contractual obligation
>>to the whole thing?
[ stuff abou;flow down process deleted]
I don't dispute that there are a lot of requirements and
a detailed tracing system,  but oftentimes requirements
run to two different contractors,  or two different systems.
The only way to make sure it's really met is to have the
parties working together,  and given the management structure,
horizontal flow is restricted.

Small teams are often highly productive, because they can
communicate with each other.

>>IF the requirements document is such a holy bible,  how come
>>Moorehead had to re-establish two-fault tolerance into vital
>>stabilization and propulsion systems?
>>
>>That was a part of the work package 2 cost over-run.
>>I am not impressed with people waving and screaming about the
>>quality of the paper trail.  I llok at the work.
>>
>Your premise is: SSP 30000 required two-fault tolerance
>in the stabilization & propulsion systems, WP-2 wasn't meeting
>that requirement, Moorehead "re-established" the requirement,
>and then WP-2 had a cost over-run.
>
>Wrong premise. The program failure tolerance requirements
>were reduced to save money (either during the Turbo team
>activities in 1990 or as part of Restructuring in 1991, I
>can't remember exactly). Mr. Moorehead put-back in the
>two-fault tolerance requirement as part of an Engineering
>Design Council suggested changes. The requirement was never
>being ignored, it was simply deleted and then re-instated.

Does it really matter wether the requirement was dropped
and restored or not met in the first place.
Engineering judgement specified two fault tolerance.
SHouldn't it have been in there all the time?

>>I dare you to justify 3 things:
>>
>>    1)  20 KHz power developement.
>First, two disclaimers. One, I'm a systems engineer, & therefore
>focus on the 'big picture', and I'm not an expert in 20 kHz.
>Second, although I'm from Lewis Research Center, I'm currently
>working at NASA Headquarters, so I don't have access to all of
>my files from the Phase B activities where we studied the system
>impacts of using 20 kHz, nor access to the LeRC library, with
>proceedings from conferences like IECEC (where papers on the
>benefits of 20 kHz have been presented).
>

What is your degree in?  and actually studying the big picture
should make you look at this issue.  AS a systems engineer you need
to look at major design issues:

    power,
    life support,
    module size and design.
    orbit selection and dynamics.
    Science objectives.
    Propulsion and navigation.
    Standards & codes.

    I would expect the systems people to go to experts, to get
detailed evaluation,  and  then conduct the trade off studies and
form criteria  for management.

    I would expect in a project of this size, cost, weight, size,
power and consumables budgets would be estimated +- 10% for each system,
and then the experts would be told to see if it's do-able.  Then any critical
problems would come back for re-budgeting or re-design and impact.

    My question, is that i never heard about any criticalities that
drove an initial selection of 20Khz power.  it would be one thing if the
initial design was 400 Khz,  it turned out the mass budget was in real
trouble,  and a move to 20Khz was viewed as helping in this problem.
Instead, 20 Khz was put on the table to start and only killed after it
proved totally unworkable.

    From what I read of the intial design, the big risk area of the
program was closed cycle life support.  Cost considerations dropped that.
Solar dynamic power was also a risk item, but those were ditched very
quickly too.   Given that the rest of the design seemed to be
fairly conservative,  what was driving this rather unusual design
proposal across the boards?

>As I recall from the Phase B studies, using a 20 kHz distribution
>frequency for the SSF resulted in lower weight, better efficiency,
>and better safety characteristics than 400 Hz and/or DC systems.
>

Lower weight,  but how much lower then 400 Hz.  From what I heard,
only 5%.  not much.

Better efficiency,  but again,  not much.  400 Hz, three phase is pretty
good.  ANd if efficiency and mass is such an issue, why not go to
6 Phase power.  I know a fair bit of work was done on this for utility
work,  and the existing three phase gear can be mostly clommed for this.

>As I stated in an earlier e-mail, LeRC has run a testbed with
>20 kHz components for a long time. And, to preclude another
>rebuttal from Dennis, I'll acknowledge that MSFC apparently had
>problems running 20 kHz components in their lab, although I
>am unaware of their specific problems.

There is a real big difference between running in a lab, and running
in hundreds of environments on thousands of pieces of hardware.
Aside, from some lab gear, I've never heard of anyone using
20Khz.  Look at all the problems existing gear has in strange conditions.
High Voltage gear has real trouble during sun spots.  These were not
well understood phenomena for a long time.

>>
>>    2)  Non Metric (english)  component selection with the
>>    european modules being Metric.
>I don't see that this is that big of a deal. I had to learn
>both sets of units in school. I remember a Change Request
>being processed several years ago to modify the units to use
>metric on all SSF drawings, schematics, analyses, etc.
>The CR was reviewed and costed by the work packages, and Level II
>ended up rejecting the CR, due to the high estimated costs to
>implement the change.
>
COnversion is not a problem.  Wrenches and connectors are a problem.
When somebody is outside, and needs to carry two toolkits, that's a
problem.   When something breaks, and you can't cannibalize between
systems,  that's a problem.   English, metric, Mayan numbers.  it
should be standard between all modules.  fasteners should be standardized.
connectors should be standard.

During emergencies you often times need to hook strange things together.
Look at Navy boats.  During fires,  they often tap the bilge pumps
to help in fires.  Good thing they all use standard fittings and
flanges.

THis is a systems engineering issue, and to have not addressed
this up front was amajor failure.  It's like NASA has not considered
one DOD initiative in this area.

Things can work fine,  but in an emergency one can really regret
incompatabilities.  look at apollo 13.
Wouldn't it suck to have to abandon the station because they need
some adaptors?

>>
>>    3)  Total failure to practice EVA until this year.
>Another common fiction on sci.space. NASA has two facilities
>for practising EVA's in water tanks, one at JSC, and another
>at MSFC. WP-4 has tested many of our EVA procedures in these
>facilities. For example, in December 1992, we tested 22
>[stuff deleted]

I didn't know Water counted:-)  seriously.  Water is just not
the same thing as zero-g.  It's good for analyzing real manpower
problems,  but still the real nitty gritty occurs in space.

I haven't seen anyone testing small truss builds,  or docking excercises.
AS allen pointed out.  Flying dummy segments,  and practicing docking
with them, and mating manuevers.

pat

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

Date: 16 Mar 93 18:22:50 GMT
From: Mark Littlefield <[e-mail]>
Subject: Response to various attacks on SSF
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (David B. Mckissock) writes:
|> In article <[e-mail]>, [e-mail] (Pat) writes...
|> >
|> >>You obviously don't understand how NASA operates. For the SSF
|> >>program, NASA has three Contractors responsible for building
|> >>SSF hardware (McDonnell Douglas, Rocketdyne, and Boeing). A
|> >
|> >And who is responsible for integrating their work?  How come
|> >that's a major management issue?
|> The Space Station Program Organization is similar to the
|> Apollo & Shuttle organizations. Level I, based at NASA
|> Headquarters, is responsible for the overall management...

Lots of description deleted....

I'd like to thank David on his fine description of some of the system
and management issues wrt SSF.  Alot of people on this list either
aren't aware, or choose to ignore the fact that SSF, like most other
manned space projects, is a very complex system and requires VAST
amounts of documentation.  Many ideas are proposed, tested, and either
rejected or implemented into a workable system and ALL of it needs to
be documented.  Requirements, documentation and management may not be
the most romantic aspects of the space program, but without them,
nothing will fly.

--
=====================================================================
Mark L. Littlefield              Intelligent Systems Department
internet: [e-mail]
USsnail:  Lockheed Engineering and Sciences
          2400 Nasa Rd 1 / MC C-19
          Houston, TX 77058-3711
====================================================================

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

Date: Tue, 16 Mar 1993 17:36:26 GMT
From: Eric H Seale <[e-mail]>
Subject: Sisters of Mars Observer (was Re: Refueling in orbit)
Newsgroups: sci.space

[e-mail] (Henry Spencer) writes:

>... There's no particularly good reason why a commercial
>comsat or something of that ilk couldn't function perfectly well around
>Mars or Venus, with minor adjustments to things like the size of the
>solar arrays.
Speaking as a spacecraft-type, these "minor adjustments" have a very
nasty tendency to snowball.  At first glance, all you have to change is
the size of your solar arrays and high-gain antenna.  But wait -- now
your solar arrays generate TOO MUCH power while you're at Earth (gotta
resize the power control circuitry).  And the longer comm distances mean
you have to have higher-power communication gear (make the solar arrays
bigger again...).  It's cold at Mars, too -- add some insulation and

heaters (darn, those arrays are getting bigger again).  Long comm delays
mean the spacecraft has to be more autonomous than its terrestrial
cousin (bigger, more reliable flight computer = more power + more weight
+ more cost).  Oh, and the bigger arrays / comm gear / computer mean the
structure needs to be beefed up some (and of course, a commercial
satellite isn't built to handle the loads imposed during escape from
Earth's gravity).  And did you remember to add the extra propulsion gear
to get into Mars' orbit?

It's not at first apparent, but by "customizing" an existing spacecraft,
you can easily end up with a more expensive bird than if you had just
started from scratch.  Look at it this way -- say you drive a Pinto but
want a Cadillac.  Easy -- just replace the engine (of course, now the
transmission needs to be replaced); oops! now the suspension needs to be
upgraded...

>... Unfortunately, while MO *is* based on a commercial bus
>(the one RCA builds for low-orbit weather satellites),...
Actually, to be fussy, GE (but I think they bought RCA's spacecraft
branch).

>...there have been
>many, many, many, many, many changes and the cost has skyrocketed.
See point 1, above.


Eric Seale
#include <disclaimer.std>

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

Date: Tue, 16 Mar 1993 18:32:01 GMT
From: Paul Dietz <[e-mail]>
Subject: Venus and Mars, was Re: TIME HAS INERTIA
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ata Etemadi) writes:

 > Talk about a sledgehammer to crack a nut. Plain old moss loves the
 > constituents of the Venus atmosphere, and is highly resistent to
 > attack from UV, acid etc..  If its spores were released at high
 > altitude on Venus, they would happily float around converting the CO2
 > to Oxygen. It would take roughly 100 years for the spores to reach the
 > surface of Venus, by which time the atmosphere would also have been
 > converted. I think terraforming is really a branch of bioengineering.
 > Other approaches just don't make economic, or practical sense.

A small bit of thought shows this is nonsense.  The problem with Venus
is that the atmosphere is too damn thick.  The surface pressure is 90
bars.  Converting that to oxygen and (say) carbon would give you 60
bars of oxygen -- hardly healthy.  In reality, any reduced organic
matter that could be produced by putative cloud-living organisms would
be quickly reoxidized back to CO2.

To really terraform Venus, you have to somehow get rid of most of the
atmosphere, either by removing it to space (by massive rapid heating
with nuclear explosives, for example) or reacting it with rocks to
form carbonates.

    Paul F. Dietz
    [e-mail]

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

Date: 16 Mar 93 19:18:39 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Venus and Mars, was Re: TIME HAS INERTIA
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Ata Etemadi) writes:
>In article <[e-mail]>, [e-mail] (Eric H. Taylor) writes:
>
>Talk about a sledgehammer to crack a nut. Plain old moss loves the constituents
>of the Venus atmosphere, and is highly resistent to attack from UV, acid etc..
>If its spores were released at high altitude on Venus, they would happily float
>around converting the CO2 to Oxygen. It would take roughly 100 years for the
>spores to reach the surface of Venus, by which time the atmosphere would also
>have been converted. I think terraforming is really a branch of bioengineering.
>Other approaches just don't make economic, or practical sense.

There are the little matters of 90 bar pressures, 860F temperatures, and
basically no water to address. Roasted, crushed, and dehydrated moss probably
doesn't reproduce well. If there were any free oxygen, any moss would burn.
Unless you address the problems of removing 98.888888% of the existing
atmosphere, and supplying oceans of water, you're not going to terraform
Venus, no matter what orbit it's in.

Gary

--
Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |                     |

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

Date: Tue, 16 Mar 93 13:05:29 MST
From: [e-mail] (Stephen Horan)

>Sometime ago I read an article in Sky and Telescopy about the discoverer of
Pluto,
>Clyde W. Tombaugh (may be I have mispelled his name). He contended that,
based
>in his earlier work and from gravitational data from the Pioneers and
Voyagers
>spacecraft,  there was NO planet beyond Pluto  howeverJhe did not came
forward
>with an explanation for the perturbation in the orbits of Uranus and
Neptune! So
>here you are, certain astronomers, in order to explain deviations in the
orbits of
>these two planets,   postulate the existence of a 10th, yet undetectable,
planet in the
>solar System  and comes Pluto's discoverer and say that there is no 10th
planet but
>does not offer any explanation of the orbit deviation of the other planets.
How
>come??? Is there anyone in the NET who can explain Tombaugh's position???

------------------------------
Clyde W. Tombaugh is still alive and kicking here on the NMSU campus.
 Tombaugh's position is not derived from positional information over a
fraction of an orbit but from his extensive blink comparisons of the sky
and his personal estimates that any object large (massive) enough to cause
orbital perturbations would have sufficient size to appear on the plates.
Tombaugh spent many years after the Pluto discovery searching for other
objects but found nothing larger than Pluto from our solar system in the
search.  For more, details see his book.

Stephen Horan

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

End of Space Digest Volume 16 : Issue 323
------------------------------