Fred.McCall@dseg.ti.com - I don't speak for others and they don't speak for me.
------------------------------
Date: 26 Feb 93 20:29:51 GMT
From: Henry A Worth <haw30@macaw.ccc.amdahl.com>
Subject: Blimps
Newsgroups: sci.space
In article <C30pq7.322@news.cso.uiuc.edu> jbh55289@uxa.cso.uiuc.edu (Josh Hopkins) writes:
> nsmca@acad3.alaska.edu writes:
>
> >(Frank Crary) writes:
> >>
> >> Balloons are somewhat more difficult on Mars than on Earth, but they
> >> are very feasible. There will be one on the Russian Mars 94 mission
> >> (or so they say...)
> >>
>
> >I more like rigid balloons (deridgebles(sp)). Powered by beamed microwaves
> >either from the ground or from orbit..
>
> A _dirigible_ is a steerable vehicle. It doesn't have to be rigid. Rigid
> dirigibles are generally just called "rigids" (after you've established the
> context) or occasionally zeppelins after Count Ferdinand von Zeppelin.
>
> >Don't need to beam power directly at the Blimp, just to the tether that follows
> >behind..
>
> If you were going to use beamed power (which isn't obvious to me) you would
> almost certainly use the huge surface area of the thing to mount your receiver.
Missed the first part of this, our news feed must be acting up again.
So please forgive if I retrace previous discussion.
While it would be nice to use some of that power to run the propulsion
system, how about using the beamed power - be it microwave, laser, or
whatever (reflected sunlight? probably too weeak) -- to directly heat
the blimp's envelope? For instance if using microwave, have a metalized
layer in the envelope material that is etched into little tuned antennae
and loads? Take it a step further, and assuming a decade or more of
semi-conductor and materials science that we will have occurred
by the time any mission is mounted :-(, make the envelope a giant
integrated circuit with antennae, rectifiers, regulators, and storage
capactitors/batteries integrated into the fabric (or in the case of lasers,
a giant, amorphous, photovoltaic grid).
Another approach would be a rigid half shell above the envelope that
could contain the receivers and/or heat exchangers and would double as
a shelter for the envelope and gondola. Since a hot-gas blimp would
substantialy collapse when cooled, the shell could descend over the
envelope and gondola, be anchored against storms and perhaps even
include active aerodynamic surfaces is to counter wind loading and
pitching. If the more active heating approach is used, a reversible heat
pump might be used for both heating and to speed cooling and collapse
of the envelope.
Speaking of storms, any ideas on how much warning would be available?
Since a storm would be a threat not only to blimps, but rovers and landers
as well, I would assume a metorological net would need to be part of
the infrastructure for any mission more complex than a plant-the-flags-
and-dash. Have existing Mars proposals considered this in much detail?
I would suspect that storm warning time would be a limiting factor on
sortie range (giving blimps an additional advantage), and that a storm
may even require an abort back to orbit, at least until later long-term
missions that could build shelters for landers and other equipment.
Back to propulsion for a blimp (beam powered or otherwise).
Considering the thin atmosphere, and assuming a long-term/permanent
presence. If substantial subsurface water were found (almost a necessity
for a long-term presencence) any thoughts on what the preferable
propulsion method would be; ducted fan, steam jet, H2/O2 rocket,
or something even more exotic like an H2/O2 turbo-fan or a nuclear
rocket using H2 or even the atmosphere as a working medium?
--
Henry Worth
No, I don't speak for Amdahl... I'm not even sure I speak for myself.
------------------------------
Date: Thu, 25 Feb 1993 22:51:25 GMT
From: "Adam R. Brody " <brody@eos.arc.nasa.gov>
Subject: Cheap access to LEO
Newsgroups: sci.space,sci.space.shuttle
The current issue of Earth Space Review, vol2, no.1, has an abstract
for a paper in Space Commerce that apparently discusses how to get
to orbit for $22/pound. Edward L. Keith has analyzed Russian
experience with high rate of production space hardware and combined
this with an American ELV. The paper describes how to close the gap
between theory and engineering capability.
Anybody get a look at the article?
------------------------------
Date: 26 Feb 93 12:55:09 -0600
From: Bill Higgins-- Beam Jockey <higgins@fnalf.fnal.gov>
Subject: Chemical rovers? (was Re: Beamed power transmission on Mars?)
Newsgroups: sci.space
In article <1993Feb25.131408.17081@ke4zv.uucp>, gary@ke4zv.uucp (Gary Coffman) writes:
[lasers and powersats aren't all that great for Mars-roving vehicles]
> On board nuclear power is much better for this purpose and completely
> sidesteps issues of line of sight scheduling and complex systems in
> orbit with single point failure modes that can disable an entire ground
> fleet of vehicles and habitations.
Chemical systems (fuel cells, rockets, or internal-combustion) might
be pretty attractive too *if* you can make them on Mars. Some
scenarios for manned Mars landings envision production of fuels on the
earliest missions. The Case for Mars 1 workshop advocated
solar-powered production of O2 and CO from the atmosphere. Zubrin and
Baker's Mars Direct depends upon landing a fission-powered plant and a
supply of H2 to manufacture methane and O2.
How about landing a pilot plant for *unmanned* missions? For
instance, one launch lands a capable rover powered by CH4-O2 fuel
cells with solar-cell trickle backup. Another launch lands a filling
station with reactor which makes more fuel and oxidizer. The rover
can rendezvous with its initial fuel load, tank up, and keep exploring
indefinitely to the limit of its range.
Of course, we need to develop an automated docking and refilling
capability. (Where have I heard *this* before?) But this is
straightforward engineering, and easy to practice on Terra Firma.
Land more rovers and they can take advantage of the gas station. Or
land another gas station closer than the range limit and your rover
can cover even more territory.
You don't have to lug around a heavy nuclear reactor, or put up with
the low efficiency of RTGs. As another benefit, you get experience
with the Mars Direct apparatus, which can reduce cost and risks when
you finally send people.
I know Bob Zubrin wants to *go* to Mars himself, and soon, but his
ideas can be useful to a fleet of robots too. And it would strike a
blow for the use of extraterrestrial resources.
"Do you know the asteroids, Mr.Kemp?... Bill Higgins
Hundreds of thousands of them. All
wandering around the Sun in strange Fermilab
orbits. Some never named, never
charted. The orphans of the Solar higgins@fnal.fnal.gov
System, Mr. Kemp."
higgins@fnal.bitnet
"And you want to become a father."
--*Moon Zero Two* SPAN/Hepnet: 43011::HIGGINS
------------------------------
Date: 26 Feb 1993 18:19 UT
From: Ron Baalke <baalke@kelvin.jpl.nasa.gov>
Subject: JPL Mission Updates - 02/26/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary
PLANETARY MISSION STATUS
February 26, 1993
VOYAGER 1 and 2: The two Voyager spacecraft continue their
interstellar mission with fields-and-particles data acquisition.
Voyager 1 was launched September 5, 1977, is currently 7.7
billion kilometers (4.8 billion miles) from the Sun after flying
by Jupiter and Saturn in 1979 and 1980; Voyager 2 was launched
August 20, 1977, flew by Jupiter (1979), Saturn (1981), Uranus
(1986), and Neptune (1989), is now 5.9 billion kilometers (3.7
billion miles) from the Sun.
Contact: Mary Hardin, (818) 354-5011.
MAGELLAN: The Magellan spacecraft is continuing its survey of the
gravitational field of Venus, utilizing precise navigation of the
spacecraft in the near-Venus portion of its orbit through May 15,
1993. Magellan was launched May 4, 1989, aboard Space Shuttle
Atlantis with an IUS injection stage; it radar-mapped more than
99% of Venus's surface from September 1990 to September 1992.
Contact: Jim Doyle, (818) 354-5011.
GALILEO: The spacecraft is now en route to Jupiter, scheduled to
go into orbit there on December 7, 1995. Spacecraft performance
and condition are excellent except that the high-gain antenna is
only partly deployed; science and engineering data are being
transmitted via the low-gain antenna. The Project is now
planning the Jupiter mission and the August 1993 encounter with
asteroid Ida assuming dependence on the low-gain antenna.
Galileo was launched October 18, 1989, by Space Shuttle Atlantis
and an IUS, and flew by Venus in 1990 and Earth in 1990 and 1992
for gravity assists and asteroid Gaspra in October 1991 for
scientific observation.
Contact: Jim Wilson, (818) 354-5011.
ULYSSES: The spacecraft is in a highly inclined solar orbit, now
about 18 degrees south of the ecliptic plane, in transit from its
Jupiter gravity assist in February 1992 toward its solar polar
passages in 1994 and 1995. On February 14, 1993, Ulysses put
itself in the safe mode for unknown reasons, but normal operating
condition and performance, including cruise science, were
restored within three days. The Ulysses spacecraft was built by
the European Space Agency and launched October 6, 1990 aboard
Space Shuttle Discovery, with IUS and PAM-S stages.
Contact: Diane Ainsworth, (818) 354-5011.
TOPEX/Poseidon: The satellite is healthy, and all scientific
instruments are performing normally, typically providing three
playbacks per day. Initial results from the mission to map ocean
circulation are being presented at a press conference February
26. TOPEX/Poseidon was launched August 10, 1992, aboard Ariane 52.
Contact: Mary Hardin, (818) 354-5011.
MARS OBSERVER: Spacecraft health and performance are normal, and
Mars Observer is on its planned trajectory leading to Mars orbit
insertion August 24, 1993. It completed its second trajectory
correction maneuver of about 9.6 meters per second on February
10. It is now in the "outer cruise" flight mode, communicating
via the high-gain antenna. Mars Observer was launched aboard a
Titan III/TOS vehicle on September 25, 1992.
Contact: Diane Ainsworth, (818) 354-5011.
#####
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |__ M/S 525-3684 Telos | If you don't stand for
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | something, you'll fall
|_____|/ |_|/ |_____|/ | for anything.
------------------------------
Date: Fri, 26 Feb 1993 22:06:03 GMT
From: "Monaldo Francis M. S1R x8648 " <fmonaldo@aplcomm.jhuapl.edu>
Subject: Manned spaceflight vs science missions vs science?
Newsgroups: sci.space
I recently heard a talk about future justifications for the manned space
program which kindled soom thoughts I am submitting for your
consideration.
Over the years there have been numerous arguments about the relative
merits of unmanned vs manned space flight. Many of these arguments have
been replayed again and again in this news group. I don't want to
rekindled that debate, but I am interested in the structure of the
arguments.
The classical argument in favor of reduced emphasis on manned space
flight is that with unmanned mission we get more scientific bang for the
buck. If science is the motivation, then choose unmanned spaceflight.
However, lets suppose there is no manned space program to contend with
and we pour all the money into science. If the space science mission
were to compete with other science, eg the SSC or AIDS research or any
of a host of other projects would science space missions fare as well?
To carry the argument one step further, given a limited total pie,
would science research in general compete well against applied research
with more immediate returns, or against feeding th hungry.
I am not sure where this argument leads, except that if we focus too
much (too much of course) being a matter of judgment very littel science
gets funded
Frank
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Date: 26 Feb 93 03:14:58 GMT
From: Mark Smilor <msmilor@skat.usc.edu>
Subject: Question on getting to Mars??
Newsgroups: sci.space
Just two simple question on a some ideas I have read about on getting to Mars. The first one involves a plan put together by Buzz Aldrin. The article
I read was in Air&Space (Oct/Nov 1990). The plan involved a space craft that would take advantage of a natural earth/mars orbit. According to the article BuzzAldrin called the vehicles cyclers. Does anyone know where I could get some
solid information on this plan? The article was kind of sensational and void of any real data.
The second plan that I read was in the Final Frontier (July/Aug. 1992)
about a plan to 'travel light' to Mars. The plan was developed by Robert Zubrin at Martin Marietta in Denver. The quoted price was $50 billion, but was more
of a flag pole and footprint scenario. Still it was an interesting Idea, the article was called the 'Direct Route to Mars', anyone know where I could get some
more solid information on this program? I am interested in the vehicles (ie thrust, type of engines, size, fuel/oxidizer type, etc) as well as orbit used and what ever else. Thanks
Ms
*****************************
Mark Smilor
smilor@aludra.usc.edu
------------------------------
Date: 26 Feb 93 20:58:28 GMT
From: "Allen W. Sherzer" <aws@iti.org>
Subject: Reliable Source says Freedom Dead, Freedom II to be developed
Newsgroups: sci.space
In article <1993Feb26.165948.12214@aio.jsc.nasa.gov> kjenks@jsc.nasa.gov (Kenneth C. Jenks [GM2] (713) 483-4368) writes:
: Dime a dozen Dennis. Hell, I have friends at the Reston Program office
: who do that to amuse themselves on coffee breaks. Anybody who thinks
: a little about it can save $20 billion or so in life cycle costs without
: breaking a sweat.
: Getting the change implemented, THAT'S the hard part.
>Change costs money. Even if the change saves money in the long run.
If people (including Congress) saw the money being spent better they
may not gripe as much.
>Maybe more important is the idea that changing something which has
>already been approved implies that the managers who originally approved
>it made a mistake, and now you're correcting that mistake, putting egg
>on the faces of those going before you.
In a healthy organizational culture that's not the case.
