Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/spacedig/V16_0/V16NO034.ZIP/V16NO034

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Date: Mon, 11 Jan 93 05:02:47
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #034
To: Space Digest Readers
Precedence: bulk


Space Digest                Mon, 11 Jan 93       Volume 16 : Issue 034

Today's Topics:
                       ** BUSSARD RAMSCOOP **
            Cheap Mars Rocks (was Re: Moon Dust For Sale)
                         future space travel
                      heat production of the sun
        HST Discovers Double Nucleus in Core of Active Galaxy
      Let's be more specific (was: Stupid Shut Cost arguements)
               Mars Observer Update - 01/08/93 (3 msgs)
           question on privately funded space colonization
                         russian solar sail?+
                    Saving an overweight SSTO....
                        Soviet space disaster?
                         Soviet space exhibit
                 Supporting private space activities
What Progress in Opening Up Galileo's Antenna? (was Re: Galileo Update - 01/08/93)

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

Date: Sun, 10 Jan 93 12:18:45 PST
From: Jason Cooper <[e-mail]>
Subject: ** BUSSARD RAMSCOOP **
Newsgroups: sci.space

[e-mail] (Chris Marriott) writes:

> In article <[e-mail]> [e-mail] writ
>
> >(if necessary) it might pipe protons out of the stream.  Thirdly, if we
> >were to STORE the antimatter, how would it be stored?  I have seen methods
> >for plasma, but can't seem to find antimatter storage.
> >
> >Any response welcome...
> >
> >                                                Jason Cooper
> >
>
> Storing antimatter should (in principle at least) be quite straightforward.
> Assuming it's charged, you can both store it and move it using
> magnetic fields.
>
> Chris
> --
> --------------------------------------------------------------------------
> | Chris Marriott                           | [e-mail]    |
> | Warrington, UK                           | BIX: cmarriott              |
> | (Still awaiting inspiration              | CIX: cmarriott              |
> |  for a witty .sig .... )                 | CompuServe: 100113,1140     |
> --------------------------------------------------------------------------
>

So, if we have an antiproton (p-bar, was it?) then does it have the SAME
charge as a proton?

                                                Jason Cooper

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

Date: 11 Jan 93 07:07:45 GMT
From: "David Hinz ([e-mail]" <[e-mail]>
Subject: Cheap Mars Rocks (was Re: Moon Dust For Sale)
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Henry Spencer ([e-mail]) wrote:
: In article <[e-mail]> [e-mail] (Anthony Datri) writes:
: >I must admit some skepticism wrt meteorites that are claimed to have been
: >ejected from Luna and Mars.
:
: The evidence for the lunar meteorites is pretty convincing.  The Mars ones
: aren't as solidly established, but they're getting there.

OK, someone has to ask...

By what mechanism do these rocks get here?  Volcanic action & random launching?
How do they acheive escape velocity?  Why do they end up so often in
Antarctica?  Or are they just more  visible there?  Do they come in swarms,
or randomly?  What is the meaning of life?  ((oops, sorry, got into question
mode, and, well, you know....))


--

Dave Hinz  -  Opinions expressed are mine, not my employer's.  Obviously.
Ask me if I have an opinion on this! \ Don't blame me; I voted for Perot!
SAAB - Because you get what you pay for.     \       Pherrets are Phun!!!

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

Date: Sun, 10 Jan 1993 22:49:36 -0600
From: [e-mail] (Phil G. Fraering)
Subject: future space travel

\Mars will be the only real place for a large colony, but then again,
/if there isn't anything there that's very interesting (like life or
\fossils) I can't see large colonies being placed up there.

You overlook the asteroids. A very big mistake.

\Seems like the future will see expanding development of robotic systems
/that will be used to explore every planet and moon, at a vastly
\reduced cost over sending humans.

But human costs could be lowered greatly too... in which case someone
might go just for the heck of it. Britian would probably be willing to
pay to send the current set of royals, one way...

\Maybe in the next 100-200 years biology will advance to the point
/where Venus could be altered with microbes.  Change the atmosphere
\so SOMETHING could live there.  It would be interesting to see what
/could live there if the temperature was reduced.

Actually, as has been pointed out before on this forum, energy concerns
make attempts to alter Venus untenable. _But_ that does not mean:

\I think science fiction has given people a false sense of the possible.

Not really. If anything, people have a too narrow sense of the possible.

\The space travel fiction of over 100 years ago neglected things like
/radio and computer electronics, and required a travelling human.
\TEchnology has superseded the human, and the information can be
/returned much more efficiently.

Information... that's not quite what we're after. I can read travel
book after travel book about New Orleans, none of which are likely
to convey the experience of living there.

\The urge to colonize the universe seems to come from an urge for
/terretorial conquest that has been with us for a long time.  It is
\interesting how old themes are constantly repeated in the present.
/It's too bad we can't interest some of our race (Serbians, Saddam, etc.)
\in coveting lunar instead of earthly real estate.

1. I can visit New Orleans and enjoy it without wanting to conquer
it. Exploration and colonization are not equivalent to conquest per
se: the europeans had been in the northern part of the New World
for at least a hundred years (and maybe more, depending on how far
back before Columbus you're willing to go: The Basque are shifty and
conniving in this matter) without any serious conflict with the
natives.

2. The Serbians, and Saddam, don't really want land. They want power.
If they can't kill or maim people in the process of taking said land,
or otherwise strengthen their power, they aren't interested. They could
do so in space exploration, but the rest of us are slightly hostile to
the idea.

Phil "No Fly Zone, No boost zone" Fraering


--
Phil Fraering         |"...Who in the valley shed the poison tear
318/365-5418          |no one knows...
[e-mail]|An old myth of a mythical hero..."

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

Date: Sun, 10 Jan 93 19:39:51 EST
From: John Roberts <[e-mail]>
Subject: heat production of the sun

-From: [e-mail] (Thomas Clarke)
-Subject: Re: *** BUSSARD RAMSCOOP ***
-Date: 5 Jan 93 19:25:07 GMT
-Organization: University of Central Florida

-> Not good enough, alas.  The pressure at the *center of the Sun* produces
-> only the most sluggish hydrogen reaction -- one that will take billions
-> of years to consume the Sun's hydrogen supply.

-I understand that a pile of human bodies (still alive somehow) as
-large as the sun would have about the same mass, but would produce
-more heat!!

Let's see - using the numbers from the frequently-asked-questions post,
the sun produces about 0.19 mW/kg. Unless I missed some decimal places,
that's roughly 1/10000 of the per-kilogram heat production of humans.

Of course, only a fraction of the sun's mass is undergoing fusion.

John Roberts
[e-mail]

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

Date: 10 Jan 93 18:54:34
From: Steinn Sigurdsson <[e-mail]>
Subject: HST Discovers Double Nucleus in Core of Active Galaxy
Newsgroups: sci.space,sci.astro

In article <[e-mail]> [e-mail] (Loren I. Petrich) writes:

   In article <[e-mail]> [e-mail] (Ron Baalke) writes:
   >     "The galaxy's active core presumably harbors a black
   >hole which has been re-fueled by the galactic collision,"
   >said Dr. Jack MacKenty, Assistant Scientist at the Space
   >Telescope Science Institute in Baltimore.

       I presume that what happens to a black hole in a galactic
   center is that it eats up all the stars on nearly radial orbits and
   tends to deprive itself of stars to consume, with new stars for it
   only arriving by their orbit parameters diffusing slowly to suitable
   parameters.

Yes, see Begelman et al Nature 287 307, and review bu Shapiro in
"Dynamics of Star Clusters" the black hole depletes a cone
in phase-space that is repopulated on a relaxation time scale (long!)

       An incoming galaxy would not suffer this depletion of suitable
   stars, and would presumably have some stars going head-on into the
   hole, with many more to come.

       Did I get it right?

Not quite, stars are not terribly efficient at fuelling AGNs - but
galactic collisions are efficient at torquing gas to the galactic
center, see eg Hernquist & Weil Nature 1992.

*  Steinn Sigurdsson               Lick Observatory          *
*  [e-mail]        "standard disclaimer"      *
*  The laws of gravity are very,very strict            *
*  And you're just bending them for your own benefit - B.B. 1988*

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

Date: 11 Jan 93 06:18:51 GMT
From: "Edward V. Wright" <[e-mail]>
Subject: Let's be more specific (was: Stupid Shut Cost arguements)
Newsgroups: sci.space

In <[e-mail]> [e-mail] (Jeff Greason ~) writes:

>>The "extreme mass ratio" is an aerospace legend.  We've been
>>building vehicles with similar mass ratios for the last 30
>>years.  The Shuttle external tank has the right mass.  So
>>did the Saturn S-IVB stage.

>I would love to see some convincing evidence of this, as this is the
>key risk to SSTO in my opinion -- If I get sold of this, I'll try to
>convince my Congresscritter.

So, contact the National Technical Information Service, get
the reports on Saturn Applications Single-Stage-to_Orbit,
Chrysler SERV, etc., and read them.


>1) A thermal protection system, capable of surviving multiple reentries
>   (many) suitable for reuse.  On previous vehicles, this is ablative and
>   non reusable, or (on Shuttle), heavy and only marginally reusable.

Nonsense.  The first US ICBM warhead (Atlas) used a nonablative copper
heat shield.  Copper's too heavy for SSTO, but there are many newer
refractory metals that would work just fine.  The problem is not that
there's no TPS available, it' choosing from among several alternatives.

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

Date: 11 Jan 93 02:19:47 GMT
From: Steve Collins <[e-mail]>
Subject: Mars Observer Update - 01/08/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

I turns out that the Mars Observer flight software and the new Mac OS
turned out to be almost identical in hex. The program can fulfill two
such different applications because the Mars Observer SCP (spacecraft
processor)
interprets the code as Mil-Std 1750A instructions instead of motorola
680x0 instructions. The the coincidence was the source of much amusement
when it was first discovered. It looks like the STAREX anomaly tiger team
might recommend code changes that would cause the two programs to differ
again, so we plan to continue our own development rather than waiting
for the next Apple update...
    Steve Collins MO Spacecraft Team (AACS)

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

Date: 11 Jan 93 02:26:20 GMT
From: Steve Collins <[e-mail]>
Subject: Mars Observer Update - 01/08/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

KaBLE is an engineering experiment to evaluate using Ka band to communicate
to deap space spacecraft. It can potentially support much higher data rates
than the X-band we currently use on MO. I don't know much about the details,
but the transponder on MO can receive and return the signal under the
right circumstances. There is a short window where we are on the High gain
antenna but are close enough to have the link-margin to do the experiment.

   Steve Collins MO Spacecraft Team (AACS)

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

Date: Mon, 11 Jan 1993 03:42:19 GMT
From: Dave Michelson <[e-mail]>
Subject: Mars Observer Update - 01/08/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]> [e-mail] (Steve Collins) writes:
>
>KaBLE is an engineering experiment to evaluate using Ka band to communicate
>to deap space spacecraft. It can potentially support much higher data rates
>than the X-band we currently use on MO. I don't know much about the details,
>but the transponder on MO can receive and return the signal under the
>right circumstances. There is a short window where we are on the High gain
>antenna but are close enough to have the link-margin to do the experiment.
>
>   Steve Collins MO Spacecraft Team (AACS)

I'm involved in some 20/30 GHz propagation work through ESA's Olympus
Propagation Experiment and NASA's upcoming ACTS so I'm interested
in MO's KaBLE, to say the least.  This has caught me by surprise - in a
pleasant way, of course.  Where can I get some more information on the
trials?  (i.e., experiment objectives, etc.)

Thanks.

--
Dave Michelson
[e-mail]

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

Date: Sun, 10 Jan 93 17:51:59 EST
From: John Roberts <[e-mail]>
Subject: question on privately funded space colonization

-From: [e-mail] (Henry Spencer)
-Subject: Re: question on privately funded space colonization
-Date: 10 Jan 93 05:34:23 GMT
-Organization: U of Toronto Zoology

-In article <[e-mail]> [e-mail] (John Roberts) writes:
->...Your complaint is that US citizens can't circumvent US safety
->regulations by going overseas. I don't see why they can't launch and also
->conform to the safety regulations.

-John, are you under the impression that safety is the only reason why the
-US government can refuse permission for a launch?

No, I've also heard of government objections or theoretical objections to
specific launch proposals on the grounds of national security, environmental
impact, and (to a widely varying extent) protection of the domestic launch
industry. (The last is not equivalent to forbidding overseas launches,
since at least *some* foreign launches are generally permitted, and since
a the hardware to be launched overseas could have been purchased in the US.)
Herman did not specify which existing laws he was referring to, but my
recollection from his posts of the last year or so is that one of his main
areas of complaint has been US organizations being subjected to US safety
regulations for foreign launches. I should have asked Herman to specify
which legal points he objected to, not just safety regulations.

-Would that it were so.
-If you want to fly a plane, that's more or less true.  But if you want to
-launch a rocket, they can refuse permission because it is "not in the
-national interest", they don't have to explain, and there is no appeal.

I don't claim to be an expert on US politics and law, but I've read millions
of words on those subjects, and I live in a part of the country where
the working of the US government counts as "local news". I've heard of
the US government blocking the activities of US citizens for many reasons,
including the reasons I mentioned above, but I've never heard of any
activity of US citizens being blocked by the US government with the
official reason being given as quote it is not in the national interest
unquote. Can anyone come up with a more concrete indication that such a
legal provision exists exactly as stated, and perhaps some discussion on
how it came about, and under which conditions it is likely to be used?

-For example, for some years it was government policy that any private
-remote-sensing satellite with ground resolution better than 30m would
-be denied launch permission.


That's on the grounds of military security, not some abstract, unspecified
"national interest". Allen says that there's been a recent change in this
particular policy, though I don't think he mentioned specific resolution
limits.

-One of the more interesting provisions of the late, lamented Commercial
-Space Incentive Act was a clause exempting launches carried out under it
-from DOT regulation *except* for safety.

->... And consider human rights issues - suppose
->US citizens set up a colony on the moon, and decide to revive the
->institution of slavery - would you say the US would have no legitimate
->interest in the matter?

-Suppose we stack the deck the other way.  US citizens set up a lunar
-colony.  The US then gets involved in a nasty little war in a country
-named, say, Nam Viet, and reinstates the draft.  Some of the residents
-of the lunar colony are draft-age, and they are ordered to report to
-an induction center.  They refuse, noting that slavery was abolished
-in the US over a century ago, and that the constitutional amendment
-which did it made no exception for the US Army.  The colony's government
                                                  -----------------------
Let's assume for the sake of argument that what you mean is more or less
equivalent to "national government" - so the colony is not just an
activity by a US corporation, for instance - it's a political entity,
which interacts with and makes agreements with the nations of Earth.

-backs them, noting that the Neocommunist revolutionary movement in
-Nam Viet presents no threat to the colony.  Does the US have a legitimate
-interest in *this* matter?

Well, let's look at historical precedent. Suppose the lunar government has
signed an extradition treaty with the US that includes extradition for
draft evasion. Then the US has a right to expect the evaders to be
returned (assuming they're still regarded as US citizens). If, however,
the lunar colony (let's call it Adanac [Note1]) has signed no such treaty,
then the US has little recourse to get the evaders back, and evaders who
manage to escape from the US and get to Adanac can reasonably expect to
be able to sit out the war, and perhaps even be pardoned several
administrations later. Of course, if the US-Adanacians start building
military bases and dropping rocks on the US, and this is condoned by
the government of Adanac, then the US might be inclined to try use of
economic or military pressure to alleviate the situation.

To try to get the topic somewhat back on track, I interpreted Herman's
post to suggest that Earth governments will always seek to control
establishment of humanity off-earth, out of an evil desire to suppress
human freedom. I theorized that if governments show an interest in the
form of government chosen elsewhere, the motives are not necessarily
always evil, and the results are not always guaranteed to be a net suppression
of human freedom.

[Note 1]: National anthem: "Adanac Ho!"

John Roberts
[e-mail]

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

Date: 10 Jan 93 23:53:53 GMT
From: David Goldschmidt <ida@atomic>
Subject: russian solar sail?+
Newsgroups: sci.space

[e-mail] (Henry Spencer) writes:

>Unfortunately, in the case of the heliogyro, there is a design constraint:
>having to feather the blades adds awkward complications at the hub, since
>now the hub ends of the blades must remain clear of each other through
>a 90-degree pitch change.  If you limit required pitch changes, the
>packaging problems at the hub are simplified, because you can stack the
>blades in multiple layers.  Since you want a large number of wide blades
>to compensate for the heliogyro's fundamental scaling disadvantage (area
>scales linearly, rather than quadratically, with diameter), packaging
>is a real problem at a modest-sized hub.  With 90-degree pitch changes,
>layers have to be separated by a full blade width.

 This must be solvable.  First, there is no reason why all of the blades
have to be attached to the hub at the same level (one could be above another)
This allows you to overlap blades and retain full control over blade angle.
Second, even if they were overlapping in the same plane, if you feather all
the blades at once, and in the same direction, they shouldn't interfere with
each other.  (like a venetian blind.) I admit it sounds risky (what if blades
catch?) but its no worse than any overlapping blades scheme.
 Another advantage of having 90 degree change is that it allows you to precess
the axis of the sail easily.  If you get the blades rotating with twice the
period of the heliogyro, so they are all horizantal on one side of the disk
and vertical on the other, this produce a constant torque with no additional
control inputs.  The only problem I see with this is a possible resonance
in the blades - oscillations could build up with each revolution.
  Are there any other ways to precess the axis?  The problem is that it is
very difficult to tilt the entire blade at once on a useful time scale.  By
the time the blade is doing what you want, it has rotated around to the other
side of the craft. (and is likely oscillating).
            Dave Patterson, guest on this account

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

Date: Mon, 11 Jan 1993 07:53:46 GMT
From: "Gregory N. Bond" <[e-mail]>
Subject: Saving an overweight SSTO....
Newsgroups: sci.space

Suppose DC-X works more-or-less as planned, and they go ahead and
attempt to build a DC-Y/DC-1.  And suppose the pollyannas are right
and it bloats and the dry mass goes up.

There are a couple of scenarios here:

1) It's overweight by some relatively small amount, say, 5000lbs.  This
leaves 5000lbs payload, still a worthwhile cargo.  And the price/lb is
double projections, but still a small fraction of ELVs.  So the
project is still a win, albeit smaller.

2) The mass overrun is a substantial fraction of payload, or exceeds
payload.  Then a possibility would be to delete the life support and
crew cockpit and use the thing unmanned.  This should get enough mass
back to get to case 1, perhaps with slightly lower reliability (due to
automated operation).  Costs would be higher than case 1 due to the
need to buy replacement DC-1s that the robots have totalled that
manned pilots wouldn't have, but could still be at least competitive
with existing ELVs.  The project is pretty much a wash, but valuable
experience is gained.

3) The mass overrun is much larger than that.  At this point, the
project is lost; however I suspect that (given the findings of the
various reports into the general feasability) this is much less likely
than the previous cases.

And in any case, you know a lot more than when you started, and you
can do it right next time!

Greg.
--
Gregory Bond <[e-mail]> Burdett Buckeridge & Young Ltd Melbourne Australia
            Dizzy Gillespie: RIP.

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

Date: Mon, 11 Jan 1993 03:05:24 GMT
From: Tom A Baker <[e-mail]>
Subject: Soviet space disaster?
Newsgroups: soc.history,sci.space,soc.culture.soviet

>>Charles Packer ([e-mail]) wrote:
>>: Somebody told me recently that they had read that the
>>: former Soviet Union had suffered a space disaster in which
>>: they had to leave one of their cosmonauts in orbit to die
>>: because they couldn't rescue him. My informant said that
>>: his information came from reading newspaper accounts of
>>: formerly secret material that was made public in the last
>>: couple of years during the unravelling of the Soviet system
>>: and the subsequent increase in openness of discussion and
>>: publication in Russia.

Ahhhhh.  During the Sixties there were indeed many persistant rumours
about heartless Communist space scientists launching cosmonauts in
unsafe capsules, and dead Soviets orbiting forever.  These rumours
never could be verified for my taste.

I wish I could quote exact references, but this kind of stuff was sort
of in the league of BOTH ufos and also propoganda.

I remember reading a Reader's Digest story about two young Italian
geniuses that loved to build radios.  They eavesdropped in on Mercury
flights, for instance, calculating the frequencies in use from a
picture of the Mercury antenna.

They also listened to Soviet flights, and tape recorded the
cosmonaut's heartbeat.  (Umm, you *DO* understand, don't you, that I
am relating this possibly untrue story as an example of the "rumours"?
I don't buy this tale, myself.)  They took the tape to a doctor, and
supposedly did not tell him what it was.  "This is the heartbeat of a
dying man," he was supposed to have said.

The point is that there were lots of stories like this.  Some even gave
names of the poor bastards that died in orbit before Gagarin's flight.
Put out for some Cold War reason, or just plain made up?  Or true?
Oh, well.
--------------------------------------.--------------------------------------
 Net - [e-mail]  __     | National Space Society is a nonprofit
uucp - uunet!world!tombaker   /  \  / | public organization dedicated to
 BIX - tombaker              /  O  /  | promoting the eventual establishment
 AOL - [e-mail]      /  \__/   | of a spacefaring civilization.
______________________________________|______________________________________

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

Date: Sun, 10 Jan 93 21:33:11 EST
From: John Roberts <[e-mail]>
Subject: Soviet space exhibit

This week's episode of "Inside Space" on the Sci-Fi Channel showed the
Soviet Space Exhibit in St. Louis. The report stated that this is the
last of four cities visited by the exhibit, after which it is to be
returned to Russia and disassembled.

John Roberts
[e-mail]

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

Date: Sun, 10 Jan 1993 15:14:46 GMT
From: Marc G Fournier <[e-mail]>
Subject: Supporting private space activities
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (David Pugh) writes:
>>The federal government paid the early airlines to carry mail. In some (most?)
>>cases, these mail subsidies were the only thing that made the airlines profitable.
>>So ... it seems reasonable to wonder if a similar program could be done for the
>>private launcher market. What I'm proposing is that the government agree to pay
>>$1000/lbs to deliver 1 million pounds to LEO each year from 1995 to 2015. At
>>$1 billion/year, this would be a fairly small program (by government standards).
>
>Congratulations, you've reinvented (more or less) the Commercial Space
>Incentive Act, which was proposed a few years ago.  Congress didn't like it
>and it didn't get anywhere.
>
>Even if you could get it passed, there is the non-trivial problem of
>convincing would-be launcher developers that it won't get repealed during
>their development period.  It *is* a relatively small expense, and it
>almost certainly *would* be extremely effective, but it's not the way
>Congress likes to do things.
>
>>... (I realize, of course,
>>that NASA would ever let it pass no matter what we did to it)?
>
>It's not NASA's decision.  Congress has passed bills that NASA didn't like.
>Forget NASA; the hard part is selling it to Congress.

    I'm confused.  Is the US the only country that has the 'environment' to
set up a launch site?  My understanding about why it is all done from Florida
is that it has to do with weather and easy of escaping Earth's atmosphere (lower
gravity?)

    Now, I know that the USSR(don't know which part has it now) has a space
 program, and that there are a few other countrys that also have their own
space programs.

    If the private sector was willing to/were to be convinced to fund a private
space program...why is the US the only place to do it?  Where their rules/laws/whims
are followed?

Marc
--
Marc G. Fournier      | R-node Public Access Unix running Linux 0.99p1
Etobicoke, Ontario    | 416-249-5366   24hrs 7 days/week   network email
voice: 249-4230       | shell accounts available  2500+ newsgroups  FREE
[e-mail] | Telebit WorldBlazer/SupraModem2400/Cardinal 2400

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

Date: Mon, 11 Jan 1993 03:20:17 GMT
From: "Loren I. Petrich" <[e-mail]>
Subject: What Progress in Opening Up Galileo's Antenna? (was Re: Galileo Update - 01/08/93)
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]> [e-mail] (Ron Baalke) writes:

>10. On December 29, after approximately 20 hours at the warming attitude, the
>DDA-5 windup/hammering activities commenced at 1455 UTC.  A total of 2160
>hammer pulses were executed along with three 20 second windup sequences. Data
>analysis indicated the ballscrew rotated approximately 360 degrees for a total
>ballscrew rotation beginning with the initial deployment attempt of
>approximately 6.4 rotations.  There was no indication of a rib release
>(see Special Topic No. 2).

    1 rotation added to 6.4 rotations.

    Not bad.

>11. On December 30, the spacecraft, under stored sequence control, was
>commanded back to a 5 degree off-sun attitude at approximately 1048 UTC.
>After the sun acquisition, sun gate data was collected to determine if an
>antenna rib is still obscuring the sun gate signal.  Preliminary data
>analysis indicates that the sun gate field of view is still obscured although
>the signature appears to have changed.  Initial analysis indicates that rib
>No. 2 may have moved out to a 43 degree angle.  Also, preliminary results may
>indicate that the antenna mesh is covering the sun gate field of view.

    "Rib No. 2"? What rib it is does not have much meaning unless
one knows which are the stuck ones.

    It was reported that 2 or 3 ribs had been stuck. If one of
them is now unstuck, then it's 1 or 2 to go, I suppose.

    Moving out to a 43-degree angle? Is that the angle that the
already-open ones are out to?

    "Signature appears to have changed" -- what's that?

>     Additionally, real-time commands were sent to open the star scanner (SS)
>shutter, reacquire celestial reference, and select scan type 6 to perform
>precise wobble estimation.  The wobble estimate indicated a change of 0.3
>milliradians which collaborated the motor current data indicating that no
>ribs released (see Special Topic No. 2).

    This change of 0.3 milliradians would presumably mean that the
ellipsoid of inertia has changed by some comparable fraction. I'm not
sure about Galileo's weight and dimensions, but I would presume that
if the spacecraft weighs 1 ton, then this wobble change corresponds to
a motion of a mass of about 300 grams across the dimensions of the
spacecraft.

>     After approximately two hours at the warming attitude, hammering of the
>HGA (High Gain Antenna) motors commenced.  Five 180 hammer pulse sequences
>were sent beginning at 2225 UTC and ending at 0442 UTC.  The motor hammering
>sequences were executed with the HGA motor temperature at 19.3 degrees C,
>29.8 degrees C, 34.4 degrees C, 36.2 degrees C, and 40.6 degrees C.
>Preliminary analysis indicated that the ballscrew was stalled with no
>appreciable ballscrew rotation.  There was some suggestion of minor rotation
>with the HGA motor temperature at 29.8 degrees C.  There was no indication of
>a rib release (see Special Topic No. 3).

    Disappointing.

    [Later such HGA motor hammering mentioned...]

    Any further results?

--
/Loren Petrich, the Master Blaster
/[e-mail]

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End of Space Digest Volume 16 : Issue 034
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