Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V10_2/V10_202.TXT

Internet Message Format | 1991-07-08 | 18KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/gZIcbvO00VcJ0DPk4r>;
          Sat,  4 Nov 89 02:04:28 -0500 (EST)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Sat,  4 Nov 89 02:03:44 -0500 (EST)
Subject: SPACE Digest V10 #202

SPACE Digest                                     Volume 10 : Issue 202

Today's Topics:
              Re: Jovian radiation belts
             Re: Jupiter Balloon
            Re: Voyager trajectory diagram
             Re: What do you do?
 Re: Manned Jupiter Mission (was Re: Condensed CANOPUS - August 1989)
              Re: Fragile Space Shuttle
            Jovian radiation belts
 Re: Manned Jupiter Mission (was Re: Condensed CANOPUS - August 1989)
               SPACE Digest V10
              RE: SPACE Digest V10 #177
             Re: Jupiter Balloon
             Re: PowerSat Options
         Re: Magellan Status for 10/31/89 (Forwarded)
            Re: Voyager trajectory diagram
             Voyager's last photo
              Astro/Space on CompuServe
----------------------------------------------------------------------

Date: 3 Nov 89 01:40:40 GMT
From: cs.utexas.edu!samsung!uakari.primate.wisc.edu!uwm.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu![e-mail]
Subject: Re: Jovian radiation belts


[e-mail] write:

> You said that travellers to Jupiter might want to head for under the Dragon's
>Teeth, as the Jovian belts are called.
>  You wanna go first?
>   :-)

Points that people have made about the radiation level of the Jovian
belts being quite high are well taken.  I guess that I had envisioned
somehow ducking in across the poles.  Energy wise, this would probably
not be an easy maneuver since you would have to quickly plant yourself
in such a low orbit.  I suppose aerodynamic breaking might actually
help here.

This does bring up the point that aerodynmic breaking would probably
not be useful when heading to Jovian moons since it would require a
couple of passes directly through the Jovian radiation belts.

-- Daniel Pommert
 ;-}

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

Date: 3 Nov 89 01:40:35 GMT
From: cs.utexas.edu!uwm.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu![e-mail]
Subject: Re: Jupiter Balloon


George W. Herbert ([e-mail]) writes:
>/* ---------- "Jupiter Balloon" ---------- */
>
>    A friend and I (George and Frank Crary) just worked out
>specs for a nuclear heated balloon for dropping into the Jovian
>atmosphere and leaving for an indefinite amount of time (years?).
>    ........
>    The altitude target would be the five-bar altitude, though
>the baloon should be able to handle from the two or three bar to the ten
>bar levels.
It is my understanding that the reason that biological life cannot be
expected to survive on Jupiter is because the convection cells go too
deep within Jupiter--so deep that any but the smallest molecules are
baked into atoms.  If this is the case, you would have trouble guiding
a balloon away from the down drafts and hense away from premature
distruction.

All this IMHO
-- Daniel Pommert

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

Date: 2 Nov 89 15:04:10 GMT
From: cs.utexas.edu!samsung!gem.mps.ohio-state.edu!rpi!crdgw1!crdos1![e-mail]  (Wm E Davidsen Jr)
Subject: Re: Voyager trajectory diagram

In article <[e-mail]>, [e-mail] (Henry Spencer) writes:
|  In black&white rather than pretty color, but larger and more legible
|  (and incidentally, much easier to reproduce).

  Don't suppose you have the stuff to scan that and convert it into
PostScript so you could share it, do you?
--
bill davidsen    ([e-mail] -or- uunet!crdgw1!crdos1!davidsen)
"The world is filled with fools. They blindly follow their so-called
'reason' in the face of the church and common sense. Any fool can see
that the world is flat!" - anon

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

Date: 2 Nov 89 17:42:06 GMT
From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!gem.mps.ohio-state.edu!wuarchive!uwm.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!m.cs.uiuc.edu!bucc2![e-mail]
Subject: Re: What do you do?


I'm an undergrad physics major at Bradley University who writes for an
amateur astronomical journal.

uiucdcs\
    noao>bradley!bucc2!moonman
   cepu/

Internet: bradley!bucc2![e-mail]
Arpa: cepu!bradley!bucc2![e-mail]

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

Date: 2 Nov 89 17:32:06 GMT
From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!gem.mps.ohio-state.edu!samsung!cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Manned Jupiter Mission (was Re: Condensed CANOPUS - August 1989)

In article <[e-mail]> [e-mail] (George William Herbert) writes:
>>... Human exploration of the outer solar system
>>is difficult, verging on impractical, unless propulsion is good enough to
>>let you forget about economy orbits and use fast ones instead.
>
>A friend did a design for a contest for a manned jupiter mission.  His
>solution was using NERVA rockets.  Nothing else works, realistically.

I'd consider even NERVA marginal, actually.  Its performance advantage
over good chemical rockets isn't that great.
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 2 Nov 89 18:44:24 GMT
From: cs.utexas.edu!samsung!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Fragile Space Shuttle

In article <[e-mail]> [e-mail] (Tom Neff) writes:
>Even commercial transport requires thorough checkout.  There just aren't
>any Public Affairs Offices keeping you informed on the maintenance being
>done on the 747 you'll be flying later in the week.

That's mostly because the manpower involved in said maintenance is several
orders of magnitude smaller.  747 "thorough checkout" and NASA "thorough
checkout" are enormously different things.  747 maintenance crews do not
remove, examine, replace/refurbish, and re-install 5000 components on
each engine after every flight.  NASA crews do exactly that for each SRB.

>My prediction is that we will never be allowed to stop checking spacecraft
>with a fine toothed comb...

Until we start designing them not to need fine-toothed-comb checkout,
this is trivially true.
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 2 Nov 89 08:25:06 GMT
From: bungia!orbit!pnet51![e-mail]  (S Schaper)
Subject: Jovian radiation belts


 You said that travellers to Jupiter might want to head for under the Dragon's
Teeth, as the Jovian belts are called.
  You wanna go first?
   :-)

UUCP: {amdahl!bungia, uunet!rosevax, chinet, killer}!orbit!pnet51!schaper
ARPA: crash!orbit!pnet51![e-mail]
INET: [e-mail]

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

Date: 2 Nov 89 23:56:24 GMT
From: uw-entropy!quick!thebes!polari!gtisqr![e-mail]  (Kevin Bagley)
Subject: Re: Manned Jupiter Mission (was Re: Condensed CANOPUS - August 1989)

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Brian Yamauchi) writes:
>>Are there any technical obstacles to a Jovian mission other than the
>>longer flight time (requiring more supplies, larger ships, etc.) and
>>the radiation around Jupiter?
        [stuff deleted]
>However, I'd say that the limitations imposed by Jupiter's Van Allen belts
>are the only technical problems that couldn't be solved with reasonable
>effort.

One of the major problems with a manned Jupiter mission would be the
general scope of the mission.  If we are ambitious enough to send people
to Jupiter, we will want to take as much advantage of that visit as
is possible.  Sending people there to orbit and collect data would be
a waste of the people sent on such a mission. We will definitely want to
land, retrieve samples, explore, set up long term experiments, etc. from
much more than just 1 Jovian moon. This would greatly complicate such a
mission since we would need to provide multiple use landing craft and
the required fuel for operating them.  The mission would also probably
be very lengthy in terms of the time we would stay in the Jovian system.
I wouldn't be suprized if such a mission were 100 times the cost of a
mission to Mars. (But wow, it would sure be worth it!)


>A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
>megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

--
   _____    Kevin Bagley  Global Technology Mukilteo WA 98275 [phone]
     )__) _   _   _       UUCP:uw-beaver!uw-nsr!gtisqr!kevin
   _/__) (_(_(_)_/_)_     ARPA:uw-nsr!gtisqr![e-mail]
  ____________/           Disclaimer: "I did not say this. I am not here."

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

Date:         Thu, 2 Nov 89  08:41:31 EST
From: Michael S Trauth <[e-mail]>
X-Title:      Asst Collection Mngr
Phone:        [phone]
Subject:      SPACE Digest V10
To: "space+" <[e-mail]>

Please discontinue my subscription to the space digest bitnet group please.

In-Reply-To:  note of 11/02/89 06:02

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

Date: Thu, 2 Nov 89 11:05 CST
From: [e-mail]
Subject: RE: SPACE Digest V10 #177

PLEASE remove me from this LIST-SERV...

Thank You!

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

Date: 2 Nov 89 20:02:35 GMT
From: agate!typhoon.Berkeley.EDU![e-mail]  (George William Herbert)
Subject: Re: Jupiter Balloon

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>>    A friend and I (George and Frank Crary) just worked out
>>specs for a nuclear heated balloon for dropping into the Jovian
>>atmosphere and leaving for an indefinite amount of time (years?).
>
>For heaven's sake don't tell the Christic Institute! :-) :-) :-)

Oops, gee, o forgot all about them... well, we need to keep them amused
_somehow_ :-)

-george

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

Date: 3 Nov 89 01:44:37 GMT
From: calvin![e-mail]  (John Sahr)
Subject: Re: PowerSat Options

[Hay mucho haranguing about power density in a powersat microwave downlink]
In article <[e-mail]> [e-mail] (Paul Dietz) writes:
>[deletions]     The microwave beam has low power density because it is
>diffraction limited (if it wasn't, we've made the transmitter too
>big).

All right.  For a standard powersat design, what is the antenna size and
frequency of operation?  It is not obvious to me that the beam would be
diffraction limited at the earth.  Suppose the transmit antenna has a
diameter of 2 km, and the frequency of operation is 3 GHz (lambda = 10 cm).
Then, the earth at 40,000 km distance would be on the border between near
and far field (Using D^2/lambda).

As an aside, for the 70 cm radar at Arecibo, the E region is still in
the near-field, 100 km away.

I recall that someone posted design quidelines for this system a while back;
I'm sorry I wasn't paying closer attention.

--
John Sahr,                   | Electrical Engineering - Space Plasma Physics
[e-mail] | Cornell University,         Ithaca, NY  14853

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

Date: 2 Nov 89 16:10:45 GMT
From: hpfcso![e-mail]  (Ross Cunniff)
Subject: Re: Magellan Status for 10/31/89 (Forwarded)

>    Velocity Geocentric                  66,573 mph
>             Heliocentric                883,205 mph

Boy, must be one helluva space/time warp it's passing through! :-)


                Ross Cunniff
                Hewlett-Packard Colorado Language Lab
                ...{ucbvax,hplabs}!hpfcla!cunniff
                [e-mail]

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

Date: 2 Nov 89 20:57:03 GMT
From: cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Voyager trajectory diagram

In article <[e-mail]> [e-mail] (bill davidsen) writes:
>  Don't suppose you have the stuff to scan that and convert it into
>PostScript so you could share it, do you?

Alas, I'm afraid not.
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 3 Nov 89 00:21:13 GMT
From: frooz!cfashap![e-mail]  (Bill Wyatt)
Subject: Voyager's last photo

I just got back from a lecture by Edward Stone, the Voyager Project
Scientist and Cal Tech prof. Wonderful pictures, but I thought I'd
pass his news (first real confirmation I've heard, at least) that
the camera will be turned on sometime next February for a last
look-back picture of the solar system.

Mercury will be too close to the Sun to distinguish, and Pluto is
too faint/dark, but all the others should be imaged. The inner planets
will be point sources, but the giants will be two or three pixels
across.
Bill Wyatt, Smithsonian Astrophysical Observatory  (Cambridge, MA, USA)
    UUCP :  {husc6,cmcl2,mit-eddie}!harvard!cfa!wyatt
    ARPA:   [e-mail]
    SPAN:   cfa::wyatt                 BITNET: wyatt@cfa

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

Date:         Fri, 03 Nov 89 00:58:03 EST
From: Leonard Abbey <[e-mail]>
Subject:      Astro/Space on CompuServe


There has been a great deal of discussion lately on both USENET and
BITNET concerning the availability of GIF images of the recent Neptune
encounter.  The "mother lode" of this sort of thing is CompuServe
Information Service.  The GIF format is a CompuServe product, which has
been placed in the public domain.

CompuServe operates both a Space and an Astronomy forum.  Between the
two there are over 300 GIF files (over 6 Megs), many of them Voyager
images.  GIF interpreters are available online as public domain
software for every major brand of computer.  There are dedicated
graphics support forums to assist with the reading of GIF and other
graphics files.

The Space and Astronomy forums have a combined membership of over
20,000.  Participants are private citizens, members of the academic
community, astronomers, and aerospace professionals from both private
industry and NASA.  Sky  Telescope magazine, Celestron, Meade, and
Televue maintain daily presence on the forums.

The data libraries (about 30 in all, I think) are truly massive, and
offer many, many megs of programs in addition to the GIF images.

Regular postings of late-breaking news are supplied by the Public
Affairs Office of the Jet Propulsion Laboratory as well as the NASA
Headquarters News Room.

The interactive communications facilities of the forums facilitate are
one of the most exciting facets of these formus.  Guest conferences in
which forum members can communicate directly with "celebrity guests" in
various astro- and space-related fields are regularly held.  Forum
members have been able to "talk" directly to astronomers such as  Clyde
Tombaugh, Tom VanFlandern, and Brian Marsden; astronauts Joe Allen,
Steve Hawley, and Jay Apt; authors Arthur C. Clarke, Larry Niven, Jim
Oberg, and G. Harry Stine; space advocates  Louis Friedman and Ben
Bova; as well as national policy shapers like former NASA Administrator
Dr. Thomas Paine and Professor Minoru Oda, former head of the Japanese
space program.  The cast of Star Trek has appeared too.  We've had
Soviet exchange students with us (members of the "Young Cosmonauts").

One group of students who are forum members has had space aboard a
future Shuttle mission donated to them to fly an experiment on
non-destructive materials evaluation which they have designed.

Users of BITNET and USENET are usually concerned about the cost of this
commercial sercvice.  Connecting to CompuServe is a local call from
most cities in the US.  The charge is $12.50 per hour at 1200 and 2400
baud ($6.00 at 300 baud, which is usually used for real-time
conferencing).  If a user is running one of the special dedicated
terminal programs (which automate almost all CompuServe functions) it
is possible to download 14K per minute at 2400 baud.  This very
reasonable when compared to long-distance charges usually incurred
when calling out-ot-town BBS.  And the really good Astro/Space BBS
do usually seem to be out of town!

USENET/BITNET users who are interested to trying out the CompuServe
forums can do so at no charge.  I have arranged for free "starter
kits", which contain instructions, local node phone numbers, and usage
credits good for a few hours.  This should allow anyone to size up the
situation for himself/herself.

If you are interested, drop a note to the forum's administrator, Dick
DeLoach at:

              CompuServe Space and Astronomy Forums
              3533 Chesapeake Avenue
              Hampton, Virginia 23661


======================================================================

Leonard Abbey
Georgia Tech
Research Institute
BITNET [e-mail]
UUCP [e-mail]
CIS 72277,566

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

End of SPACE Digest V10 #202
*******************