Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v11_5/v11_556.txt

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Date: Sat, 23 Jun 1990 01:48:03 -0400 (EDT)
Subject: SPACE Digest V11 #556

SPACE Digest                                     Volume 11 : Issue 556

Today's Topics:
              Re: Full Funding for NASA
            Re: What makes a nebula glow??
            Mars Rover Update (Forwarded)
                Re: SpaceList
             Re: Satellite round-trip...
               Re: Model rocket contest
             Re: Escape velocity
       Re: Immune system depression: Isolation or microgravity?
               Re: 10 psi overpressure

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription notices,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 21 Jun 90 15:53:22 GMT
From: mentor.cc.purdue.edu!l.cc.purdue.edu![e-mail]  (Herman Rubin)
Subject: Re: Full Funding for NASA

In article <[e-mail]>, [e-mail] (Gregory Fedor) writes:
> I received this via e-mail, but thought I'd reply to it here:
>
< >From @po5.andrew.cmu.edu:[e-mail]  Tue Jun 19 14:58:56 1990
< >From: "Jon C. Slenk" <[e-mail]>
< >To: [e-mail] (Gregory Fedor)
< >Subject: Re: Full funding for NASA!
< >
< >I, for one, do not want my taxes going to anything other than the explicit
< >protection of my rights. I do *not* consider funding NASA (in general) to
< >be such: if NASA were purely military then I could justify it, but NASA is
< >also doing (and preventing) what should be *entirely* comercially done.
< >
< >-Jon.
< >(Donning Acme Flame-Proof Suit already...)
< >
>
> No flames...we are adults.
>
> I don't believe that the commercial sector is ready to undertake the full
> mission of NASA.  Yes there are several areas that started out as NASA
> exclusives, but have matured enough that private industry can see profit in
> pursuing them (don't forget the country is based on capitalism).
>
> In my work here at Lewis (one third of NASA's research arm), I've heard
> several stories that state that private industry _wants_ NASA to do the basic
> research and initial testing, then turn the technology over to them for
> commercial development.

I agree that the PRESENT private firms are not willing to undertake the
necessary basic space work, nor do I think they should be willing to do
more that some investment and contribution to it.  But if the government
allowed free rein, the necessary non-profit and profit corporations would
arise.  Before WWII, most of the research done was not directly funded by
governments, and much of it had at best indirect government support.  I do
not know the situation in Europe, but, for example, the large telescopes
built before WWII were all financed by non-governmental sources.

The funding can be obtained, but only if the government gets its restrictive
paws off.
--
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907
Phone: [phone]
[e-mail] (Internet, bitnet)    {purdue,pur-ee}!l.cc!cik(UUCP)

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

Date: 21 Jun 90 16:30:38 GMT
From: uoft02.utoledo.edu![e-mail]
Subject: Re: What makes a nebula glow??

In article <[e-mail]>, [e-mail] (Robert W Murphree) writes:
> The answer is: BOTH.  In the star nursery of a molecular cloud environment
> there is both flourescence and reflection.  When in close proximity to a
>               ^^^^^^^^^^^^ - already descrbied well in another post
                                 ^^^^^^^^^  Just to clarify, the reflection
is due to dust grains in the nebula scattering the light into our
line of sight.  The best reflection nebulae are those where the star
is at the edge of a dusty cloud but they may be imbedded as well.
The dust also heats up and reemits in the infrared ("Extended Red
Emission - ERE").

Robert Dempsey
Ritter Observatory

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

Date: 21 Jun 90 16:30:07 GMT
From: usc!elroy.jpl.nasa.gov!forsight!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Mars Rover Update (Forwarded)

NASA'S JET PROPULSION LABORATORY TESTS PLANETARY ROVER

     Scientists and engineers at NASA's Jet Propulsion
Laboratory, Pasadena, Calif., have begun an extensive period of
field testing of a semi-autonomous navigation system on a
computer-operated robotic vehicle prototype for possible use in
future planetary explorations.

     Brian Wilcox, supervisor of the Robotic Sensing and
Perception Group, said the summer-long testing program would be
carried out mostly in the Pasadena Arroyo, a dry river bed,
adjacent to JPL.

     Developing new technologies, including a new generation of
planetary rovers, is seen as critical to the success and cost
effectiveness of the Space Exploration Initiative (SEI) program
announced by President Bush last July.  The Planetary Rover
project will develop systems for the manned and unmanned vehicles
needed for surface transportation.

     Surface transportation systems required by SEI include
unmanned rovers for outpost site survey and for regional robotic
exploration and science, piloted rovers for transportation both
locally and long range, and unmanned cargo handling, construction
and mining.

     Increased traverse distance, longer life and autonomous
operations are required for the unmanned roving vehicles for the
program.  Traverse distances of up to several kilometers per
Earth day and a mission life from 1 to 5 years are desired for
the next generation of robotic exploring vehicles.

     The operation of an autonomous unmanned rover in a location
remote from the Earth, such as the surface of Mars, with round-
trip communications time, at the speed of light, between 8 and 40
minutes, involves an entirely unproven technology.

     Two advanced forms of unmanned rover navigation are under
development at JPL.  They are computer-aided remote driving
(CARD) and semi-autonomous navigation (SAN).

     The CARD technique allows a human operator to remotely drive
a vehicle by planning and identifying an extended (10s of meters)
obstacle-free path with a three dimensional display of images
from stereo cameras aboard the vehicle.  The path then is
transmitted to the vehicle for atonomous execution.

     The SAN technique allows a human operator to determine a
nominal extended route (10s of kilometers) for the vehicle, with
the specific path taken by the vehicle around local obstacles
determined automatically from the rover's sensor data and stored
data base.

     JPL's prototype rover made its first, continuous semi-
autonomous navigation (SAN) traverse, in rough natural terrain,
on May 7, 1990.

     The navigation testbed is a six-wheeled, three-body,
articulated vehicle the experimenters call Robby.  It is about
13-feet long, 5-feet wide and more than 6.5-feet high.  Its 35-
inch diameter wheels and articulated body permit it to go over
obstacles a meter high.

     The 2,500-pound vehicle contains two computer systems, one
for perception and planning and one for control of the actuators
in the wheel drive and arm control.  The robotic arm has six
links and 6 degrees of freedom with an additional pivot axis and
gripper providing two more degrees of freedom.

     There are four cameras on the pan-tilt head capable of
stereo correlation to provide three-dimensional images of
objects.  A motor generator provides 3,500 watts of power and
batteries provide 24 volts.

     Other parts of the rover program include the development of
advanced mission operation, mobility and power technology at JPL;
the development of an innovative legged vehicle concept, as
opposed to using wheels, at Carnegie Mellon University in
Pittsburgh, Pa.; mission operations research at the Ames Research
Center, Moffett Field, Calif.; and piloted rover technology at
the Marshall Space Flight Center, Huntsville, Ala.
       _   _____    _
      | | |  __ \  | |       Ron Baalke           |  [e-mail]
      | | | |__) | | |       Jet Propulsion Lab   |  [e-mail]
   ___| | |  ___/  | |___    M/S 301-355          |
  |_____/ |_|      |_____|   Pasadena, CA 91109   |

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

Date: 21 Jun 90 20:48:47 GMT
From: concertina![e-mail]  (Steve Hix)
Subject: Re: SpaceList

In article <[e-mail]>, [e-mail] (Brian or James) writes:
>
>     Defining one gravity as 9.8 m/s**2 has alway grated on me
> slightly. I'm aware of the source for the 1-g value, but we don't
> *have* to tie our measuring system to arbitrary natural phenomena.
> 10 m/s**2 would so much tidier to work with.
>     I bet this goes over as well as my suggest to dump the
> 1 day = 86400 seconds in favour of 1 day = 10**5 seconds :)

Leaving the second (and day...) tied to an arbitrary natural phenomena.
Or maybe ending up with "days" drifting with respect to local planetary
"sunrise"/"sunset"/"midnight"?

Tidy one thing up...ruffle various related items.

(I should think that not having to deal with slugs and pounds and ounces
and inches and feet and yards and so on would enough of an improvement.
Perhaps one could choose appropriate numeric radices to make the calculations
come out more neatly.)

------------
  The only drawback with morning is that it comes
    at such an inconvenient time of day.
------------

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

Date: 22 Jun 90 15:38:18 GMT
From: cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Satellite round-trip...

In article <[e-mail]> [e-mail] writes:
>Was there ever a satellite designed to make a close pass by some inner planet,
>or perhaps the sun itself, and rendezvous with the earth again elsewhere in
>time and space so that it could be retrieved and studied for effects (whatever
>effects they may wish to look for )...

It's been talked about -- e.g., there has been some discussion of eventually
retrieving Giotto -- but has not been done.  The propulsion requirements are
too severe and the returns too limited, and most of the planetary missions
flown to date have had mission plans incompatible with return.
--
As a user I'll take speed over|     Henry Spencer at U of Toronto Zoology
features any day. -A.Tanenbaum| uunet!attcan!utzoo!henry [e-mail]

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

Date: 22 Jun 90 19:05:08 GMT
From: milton!unicorn![e-mail]  (Worth Henry A)
Subject: Re: Model rocket contest


     One aspect that I have not seen mentioned in the discussion on whether
a guidance system can be left out is RANGE SAFETY. If you can't afford the
weight of a guidance system, than what about range safety devices?
If the press was ever to develop even the perception (justified or not), that
there was a cavalier attitude toward safety, they would CRUCIFY the project
(and model rocketry, as well) on page one of every newspaper and at the top
of every newscast.

    You must be very...very careful not to generate the percepion that
you are a bunch of "BIG-BOYS PLAYING with their TOYS" (and possibly
endangering public saftey). The Project Solar Sail supporters have
expressed concerned about this in their book; a promising sign that
they may have the political savvy it takes to pull-off such a project.

    Remember, that in politics, perceptions are more important than
substance...sigh. Be very careful what kind of Congressional hearings
you generate.

P.S. If you really want to make a political statement (and avoid the DoC
and FAA), launch in Libya or Iraq... :-)

HW
6/22/80

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

Date: Fri, 22 Jun 90 17:21:09 EDT
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Escape velocity


>From: eru!luth!sunic!tut!kaakkuri![e-mail]  (Karri Tapani Palovuori)
>Subject: Re: Aim For The Moon - model rocket contest

>The escape velocity is not the velocity needed to escape!

>A rocket that would climb 1 m/s would eventually reach the moon (yes, it
>would take some time). Isn't this quite natural?

>The escape velocity is the _theoretical_ (starting) velocity that would be
>needed for a bullet to escape the gravity field generated by earth (solar
>system, galaxy - there's many different 'escape velocities'). It is also the
>speed gained by an object which is accelerated by corresponding gravity field
>from infinitely far away.

That's true, but misleading. With chemical rockets, it's very difficult to
get into orbit or beyond at all. If you don't take off as fast as your
rocket and payload can stand, you're wasting fuel. This is because effective
acceleration on takeoff is theoretical acceleration minus 1g, and because it
is to your adventage to get rid of as much weight as possible (including
lower stages and fuel) as low in the gravity well as you can. The result
is that most rockets reach peak velocity and cut off thrust while they are
still relatively close to the ground (though out of the worst of the
atmosphere). It's almost as if they were shot out of a gun. For most
launches of this type, "escape velocity" is indeed a matter of considerable
interest.

For maneuvers in space, it seems to be more common to refer to the "delta V"
needed to complete the maneuver. I suspect this is usually computed in terms
of one or a number of instantaneous velocity changes.

(I did enjoy the launch scene in the movie "The Mouse on the Moon". The rocket
lifted up a few feet, paused until they increased the thrust a bit, then
slowly rose into the sky at several miles per hour. The justification was
that they had virtually unlimited power to waste, and didn't want to worry
about aerodynamic stresses. :-)
          John Roberts
          [e-mail]

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

Date: 23 Jun 90 02:25:43 GMT
From: zaphod.mps.ohio-state.edu!samsung!umich!ox.com!kitenet![e-mail]  (Russ Cage)
Subject: Re: Immune system depression: Isolation or microgravity?

In article <[e-mail]> [e-mail] (Mike Van Pelt) writes:
>Is there any evidence that the immune system depression experienced by
>the MIR cosmonauts is greater than that experienced by Antarctic
>researchers?  Maybe this isn't due to zero-g after all.

The immune-system depression begins immediately upon entry
to microgravity, and is seen as a reduction in the rate of
immune-cell production.  Activity of immune cells in culture
is also reduced by tumbling them.  Orientation to acceleration
seems to be essential to certain processes.

These effects are seen in VERY short missions (days), so
a lack of novel challenges to the immune system is not a
likely factor in the short-term immune depression.

On the flip side, hyper acceleration environments appear
to improve immune function.  Maybe sleeping in a waterbed
at 2G will make up for working in zero-G for 8 hours.

This is what I recall from _Analog_, corrections cheerfully accepted.
--
  I am paid to write all of RSI's opinions.  Want me to write some for you?
[phone]        Forewarned is half an octopus.
Russ Cage, Robust Software Inc.            [e-mail]

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

Date: 22 Jun 90 04:21:11 GMT
From: skipper![e-mail]  (Mary Shafer)
Subject: Re: 10 psi overpressure

In article <[e-mail]> [e-mail] (Ralph Reid) writes:
[In reference to Challenger]

   As I remember, at some point a signal was sent to blow up what
   remained of the shuttle to keep large pieces from falling into
   populated areas.  No doubt this contributed to the ultimate
   destruction, although the shuttle may have been in several pieces by
   the time the destruct signal was sent.

Well, yes and no.  The Shuttle itself has no range safety package;
deliberate destruction isn't possible.  The SRBs have range safety
packages, however, and these were activated.

NASA doesn't put range safety packages on manned vehicles nor on every
unmanned vehicle.  But I'll concede that putting one on the SRB, which
is on the Shuttle, looks a lot like putting one on a manned vehicle.

--
Mary Shafer  [e-mail]  ames!skipper.dfrf.nasa.gov!shafer
           NASA Ames Dryden Flight Research Facility, Edwards, CA
                     Of course I don't speak for NASA
 "A MiG at your six is better than no MiG at all"--Unknown US fighter pilot

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

End of SPACE Digest V11 #556
*******************