Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_5/V15NO532.TXT

Internet Message Format | 1993-07-13 | 33KB

Date: Sat, 12 Dec 92 05:00:13
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #532
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat, 12 Dec 92       Volume 15 : Issue 532

Today's Topics:
              absolutely, positively overnight (2 msgs)
                          Asteroid Toutatis
           Cassini Undergoes Intense Design Review (2 msgs)
                           DC info (3 msgs)
                 DC vs Shuttle capabilities (2 msgs)
                         Goldin Speaks at JPL
                 GRAVITY-NEUTRALIZING AIR/SPACECRAFT
                 Koptev's visit to McD (was: DC info)
                            Saturn history
                           Spacehab on DC
                   stationary orbits over the poles
                   what the little bird told Henry

    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: Thu, 10 Dec 1992 17:28:52 GMT
From: Henry Spencer <[e-mail]>
Subject: absolutely, positively overnight
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Josh 'K' Hopkins) writes:
>I'm no expert on jet lag.  It just seems like going from breakfast to a late
>dinner in the time it takes to skim a good magazine would have to throw your
>system off.  Since jet lag is way off the subject...

Actually, not entirely off the subject.

The problem in jet lag is the timezone change from origin to destination.
How long it takes to get there is, to a first approximation, irrelevant.
Although the airlines often make some attempt to smooth the transition,
you can think of the situation as staying on origin time until you step
off the plane, at which point you suddenly have to shift to destination
time.

However, on closer examination, trip time is relevant... because a long
fatiguing trip can only make the problem worse.  The shorter the better.

>... On the subject of expense, the Concorde seems a
>good example.  It's never been profitable enough to make anyone else want to
>buy one and it's at least 1.5 orders of magnitude cheaper than I can see a DC
>type vehicle being.  So where's the motivation for passenger travel?

(I assume we're talking about surface-to-surface travel, not surface-to-space,
which is a very different market with a proven audience.)  I don't see DC-1
as a surface-to-surface passenger vehicle to any great extent.  Prices would
be high enough that you'd get only the cost-is-no-object crowd:  the really
rich and the people whose time is really valuable.  I suspect you could make
money by buying a couple of DC-1s, going all out on luxury interiors, and
running them on a charter basis.  It doesn't seem a promising basis for
regular scheduled service, though.

On the other hand, note that the Concordes seldom have many empty seats.
Their market niche may be limited, but they do make an operating profit.
You might be able to run scheduled DC-1 service on one or two well-chosen
routes.

I'm sure that if certification were suitable and appropriate facilities
were widespread, there'd be a few executive DC-1s bought.  The Saudi
royal family would surely buy one.  And then there's Air Force One...
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: 10 Dec 92 12:01:11
From: Steinn Sigurdsson <[e-mail]>
Subject: absolutely, positively overnight
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:

   I'm sure that if certification were suitable and appropriate facilities
   were widespread, there'd be a few executive DC-1s bought.  The Saudi
   royal family would surely buy one.  And then there's Air Force One...

I hate to raise this, but are there ICBM proliferation concerns
over open marketing of DCs? After all, it should have O(100 ton)
payload for IRBM ranges and multiton payload for ICBM ranges
and it can be arranged to come down hypersonically with what 1200 ft
targetting accuracy?

|  Steinn Sigurdsson    |I saw two shooting stars last night        |
|  Lick Observatory    |I wished on them but they were only satellites    |
| [e-mail] |Is it wrong to wish on space hardware?        |
| "standard disclaimer"    |I wish, I wish, I wish you'd care - B.B. 1983    |

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

Date: Thu, 10 Dec 1992 23:43:07 GMT
From: Ron Baalke <[e-mail]>
Subject: Asteroid Toutatis
Newsgroups: sci.space,sci.astro

From the "JPL Universe"
December 4, 1992

Asteroid to make close Earth approach Dec. 8

     One of the largest near-Earth objects, an asteroid named
"Toutatis," will make a close Earth approach Dec. 8, said Dr.
Donald Yeomans of JPL's Navigation Systems Section 314.
     The object, formally known as Asteroid 4179, will pass by at
about 3.6 million kilometers (2.2 million miles from Earth), said
Yeomans. The asteroid passes Earth less than one degree above
Earth's orbital plane every four years, making it an excellent
object for study, he said.
     Toutatis' orbit takes it almost to the distance of Jupiter's
orbit before the sun's gravitational attraction pulls it back.
     It will also make close Earth approaches in 1996 and 2000,
and in 2004 will come as close as about four lunar distances, or
less than a million miles.
     The asteroid, at 3.5 kilometers (two miles) diameter, is one
of the largest to cross the Earth's orbit on a regular basis.
     Yeomans said the ground-based viewing conditions for
infrared optical and radar observations just before, during and
well after the close Earth passage will be excellent and he notes
that astronomers in many areas of the world will simultaneously
study the body, using several different techniques.
     The approach of Toutatis this year and the one in 2004
represent the two closest Earth passages of any known asteroid
for the next 30 years, said Yeomans, head of JPL'S Near Earth
Object Center.
     Toutatis was discovered Jan. 4, 1989, by astronomer
Christian Pollas at Caussols, France, and was named after a
Gallic deity who was protector of the tribe.
                                   ###
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | The 3 things that children
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | find the most fascinating:
|_____|/  |_|/       |_____|/                     | space, dinosaurs and ghosts.

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

Date: Thu, 10 Dec 1992 23:39:23 GMT
From: Ron Baalke <[e-mail]>
Subject: Cassini Undergoes Intense Design Review
Newsgroups: sci.space,sci.astro,alt.sci.planetary

From the "JPL Universe"
December 4, 1992

Milestones, project-wide review in sight for Cassini
By Franklin O'Donnell

     JPL's Saturn-bound Cassini mission is in the midst of
passing several major milestones, with a critical project-wide
review planned next week and recent reviews of the spacecraft's
Titan probe and science payload.
     The critical design review, which will take an exhaustive
look at the mission and all major spacecraft systems, is
scheduled Dec. 8 at the Pasadena Hilton and Dec. 9-11 in JPL's
von Karman Auditorium.
     The mission's Huygens Titan probe, meanwhile, was the topic
of a system design review Oct. 12-16 at the Cannes, France,
facility of Aerospatiale, which is building the probe for the
European Space Agency.
     And plans among scientists whose instruments will ride on
Cassini solidified this fall when NASA formally confirmed the
mission's science payload.
     "All of the project's elements are moving forward very
briskly," said Cassini Project Manager Dick Spehalski. "The
critical design review will be an important step in the process
of designing and building the spacecraft."
     Next week's meetings will include a comprehensive review of
the project --spanning how it responds to science objectives, as
well as Cassini mission design, orbiter systems, probe and
launch-vehicle interface.
     In addition to JPL staff members, the review will include
presentations by Dr. Hamid Hassan, ESA project manager for the
Huygens probe, and Dr. Romeo Pernice of the Italian space agency,
which is contributing Cassini's high-gain antenna.
     JPL Cassini Project Scientist Dr. Dennis Matson noted that
science teams were very pleased by NASA's recent confirmation of
the Cassini orbiter's 12 experiments. Another six fly on ESA's
Huygens probe.
     Although the science instruments were tentatively selected
in 1990, they were then subject to scrutiny during an
"accommodation phase" during which the cost, weight and power
needs of each experiment were carefully eyed.
     Matson credited JPL organizations with delivering "excellent
packages" on plans for science instruments that were among the
most challenging to bring in on a tight budget.
     JPL's Office of Space Science and Instruments is building
the visual and infrared mapping spectrometer (VIMS) and the Titan
radar mapper, while the Observational Systems Division is
fabricating Cassini's optical cameras.Matson said science teams
are now turning their attention to the ground system "and more
detailed work on how we will go about flying this spacecraft."
     As for the Huygens probe, the green light at the October
meeting in France paved the way for work to proceed, leading up
to hardware deliveries in 1996 and 1997, according to Herb
Phillips, JPL's Huygens technical integration manager.
     In all, ESA will deliver three versions of the Huygens probe
to the United States.
     The first, an engineering model to be used during Cassini
integration in JPL's Spacecraft Assembly Facility, will arrive
on-Lab in February 1996.
     A second copy of the probe, called the structural thermal
pyro model, will be delivered at JPL in June 1996. This model
will be used for environmental testing in the Space Simulator.
     The third copy of the probe -- the actual flight model --
will be delivered directly to Kennedy Space Center in May 1997
for integration with the spacecraft at the launch site.
     The Cassini orbiter will be built up in JPL's Spacecraft
Assembly Facility between September 1995 and May 1996. It will
then undergo tests through spring 1997, when it will be shipped
to Florida to be prepared for its October 1997 launch.
     After flybys of Venus (twice), Earth and Jupiter as it loops
around the sun to pick up energy, Cassini will arrive at Saturn
in November 2004, beginning a four-year orbital tour of the
ringed planet and its 18 moons. The Huygens probe will descend to
the surface of Titan in June 2005.
                                   ###
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | The 3 things that children
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | find the most fascinating:
|_____|/  |_|/       |_____|/                     | space, dinosaurs and ghosts.

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

Date: Thu, 10 Dec 1992 17:40:01 GMT
From: Steve Flanagan <[e-mail]>
Subject: Cassini Undergoes Intense Design Review
Newsgroups: sci.space,sci.astro,alt.sci.planetary

I just want to point out a minor error in an otherwise informative post...

>     After flybys of Venus (twice), Earth and Jupiter as it loops
>around the sun to pick up energy, Cassini will arrive at Saturn
>in November 2004, beginning a four-year orbital tour of the
>ringed planet and its 18 moons. The Huygens probe will descend to
>the surface of Titan in June 2005.

The November '04 arrival date would apply only if the Titan IV SRMU is
not available at the time of launch.  If we can launch on the SRMU, our
arrival date is June 25, 2004.



Steve Flanagan
Cassini Mission Design Team
[e-mail]
Standard disclaimers apply,

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

Date: Thu, 10 Dec 1992 15:22:31 GMT
From: Paul Dietz <[e-mail]>
Subject: DC info
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:

> It is a separate engine which will be used for DC-Y if built. Some of the
> RL-200 engines will have extendable nozzles and will be sustainer engines
> for DCY and others will have non-extandable ones and will be used as
> boosters. Except for the nozzles, they will be the same.


Will all 8 engines be used for landing?  If not, it may make sense
(not in DC-Y, but in a subsequent generation of vehicles) to make the
booster engines different; in particular, make them burn a
hydrocarbon, not hydrogen.  Fuels burned early in the flight should be
dense rather than be optimized for high Isp, in order to increase
thrust at liftoff, reduce fuel cost and to reduce the mass of the
empty fuel tanks that must be lugged to orbit.

Question about the RL-10:  what intake pressure do its pumps require
to avoid cavitation?  Hudson emphasizes that reducing this pressure
is important in designing an SSTO, as lower pressure tanks can be
lighter.

    Paul F. Dietz
    [e-mail]

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

Date: Thu, 10 Dec 1992 17:12:24 GMT
From: Henry Spencer <[e-mail]>
Subject: DC info
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Michael F. Santangelo) writes:
>  I'm real foggy from this description as to what the RL200 engine is
>going to be.  Is it a name for many RL10-A5's grouped together through
>a common master nozzle of some form?  Or is it a seperate engine system
>used to augment the RL10-A5's on the latter DC systems during flight...?

No, it's a new engine, with some RL10 design heritage, relying on bits and
pieces that mostly have been tested already.  Only DC-X (and the proposed
DC-X' suborbital flyer) will use RL10s at all.  It's an excellent engine,
but a bit small for the full-scale DC-Y.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Thu, 10 Dec 1992 17:54:43 GMT
From: Henry Spencer <[e-mail]>
Subject: DC info
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (John Roberts) writes:
>A static test sounds like a good idea. Would that include "full throttle"?

I would assume so, but don't know for sure.

>And do the operational plans for DC call for a system like that used
>by the Russian spacecraft and the Saturn V, in which the spacecraft is
>held down until thrust is sufficient for launch?

I haven't seen details on the planned launch facilities for the "real"
DCs.  The hold-downs aren't absolutely necessary -- Thor did not use them
and I don't think its descendant, Delta, does.

The plus of hold-downs is that you get to find out whether the engines
are running satisfactorily before committing to launch (especially on a
craft which has all engines lit at takeoff).  The minus is that you use
precious fuel sitting there waiting for the hold-downs to be released,
fuel that could be used to start the climb.

For an SSTO, with limited fuel reserves and engine-out capability, I'd
guess hold-downs are not worth the trouble.  Better to handle troubles
in flight than to waste fuel just in case.

>-DC-X flies autonomously, not piloted from ground.  Ground monitors system
>-performance, initiates thrust termination
>
>Interesting approach. I suppose one motivation is to reduce the risk from
>communications problems.

Provided nothing goes wrong, automated piloting is clearly superior to
human piloting -- it's more precise and less prone to error.  Putting the
automation on board rather than on the ground likewise makes sense.

>A question - since it's an experimental design, will the DC-X have landing
>gear sturdy enough to support its weight fully fueled, or will it have to
>hover before landing on abort like the DC-1 is projected to do?

Don't know for sure, but DC-X's fuel load is not that big -- max takeoff
weight is only about double dry weight, unlike the real DCs where the
disparity is a *lot* greater -- so I'd suspect its gear can hold it.

>And if a
>DC-X / DC-Y / DC-1 does for some reason land fully fueled, would the
>spacecraft likely be destroyed, or would it just "crunch" the tail end
>a little? If the latter, what would be the expected magnitude of the
>repairs required?

Again, not sure, but my guess would be that it would be a major repair
job.  Unless you were pretty lucky, most of the crunching would be done
by the liquid hydrogen tank, which would probably have to be replaced,
and that's half the vehicle.

>So the DC-X, at least, will have a parachute...

I don't believe the later DCs are planned to have them.  DC-X can use
the backup, because unlike the later ones it only has four engines.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Thu, 10 Dec 1992 17:41:00 GMT
From: Henry Spencer <[e-mail]>
Subject: DC vs Shuttle capabilities
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Michael V. Kent) writes:
>>There appears to be no significant requirement to return large payloads.
>>I can't think of anything larger than a Spacelab experiment rack that
>>has to come down in one piece.
>
>I'd like to keep flying LDEF and EURECA (I know there are no plans for the
>former, but is the structure still intact enough to refly, or did they
>dissect it?).

LDEF could be reflown.  However, if you've got much cheaper transport for
smaller objects, why bother?  LDEF proper is a framework, a couple of
shuttle grapple fixtures, and a combination nutation damper and passive
stabilizer.  The experiment trays are independent and self-contained.
It wouldn't be difficult, time-consuming, or expensive to build a smaller
version that could carry a dozen of the trays and would fit in a DC-1.
Launching a few of those would be cheaper and better.

That would also be closer to the original intent of LDEF.  It wasn't
supposed to be a one-shot.  It was supposed to fly repeatedly, and to
be a way of getting simple, cheap long-duration experiments into space
with minimum hassle.  The organizers had such high hopes for it... :-(

>Here's a question that just popped into my head:  Would a modified Spacehab
>(note the "h") module fit in the cargo bay of the Delta Clipper?

I think it's too fat.  I could be wrong.  In any case, it needs more
infrastructure than the DC cargo bay provides -- for example, it has
no life support of its own.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Thu, 10 Dec 1992 19:37:03 GMT
From: Gary Coffman <ke4zv!gary>
Subject: DC vs Shuttle capabilities
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>None of these things is really a fundamental problem.
>
>Large payloads can go up in pieces for in-orbit assembly.  In fact, if
>you believe Fairchild's old Leasecraft study, this approach is superior,
>because plugging things together in orbit is easier than making absolutely
>sure they won't come unplugged during ascent.  Remember that NASA was quite
>happy, in the beginning, with a much smaller shuttle design.

Yeah, but I also remember how much harder in space assembly has turned
out to be than was originally expected. Hopefully they'll get better
at it with experience. I also know how hard it is to assemble and check
out complex systems down here on the ground in shirtsleeves. Anything
much beyond simple mating of standard modules in space is probably
stretching things too far. Insert tab A in slot B often turns out to
be an exercise in frustration down here with resort to a bigger hammer
being common. In space it's hard to swing a hammer effectively. :-)

I appreciate the ability to test and kickstart if necessary payloads
in orbit. That's why I support manned space. But intricate assembly
probably still belongs on the ground.

>DC-1's cargo bay will easily hold more crew than the shuttle can carry.
>DC-1 is not going to replace Shuttle+Spacelab -- it's too small and its
>stay time in orbit is too short -- but it could easily service a space
>station that would.  Hauling Spacelab up and down all the time is
>incredibly wasteful.

From the vague descriptions I've seen, the cargo bay would seem to
lack elementary things like an air lock. Does that mean that passengers
would ride up in a spacesuit and debark to a station? That plus the
short on orbit time seems to mandate an operating space station as
destination. Now I like space stations, but we don't have one yet.
Nor are we likely to have a functional one in the short timeframe
until DC-1 is projected to be operational. Doing vacuum transfers
of biological materials would seem tricky as well. With the crew
cabin in the middle, docking with a station would seem very difficult.

That's an interesting question anyway. How is docking with Freedom
supposed to be handled?

Gary

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

Date: Thu, 10 Dec 1992 23:40:46 GMT
From: Ron Baalke <[e-mail]>
Subject: Goldin Speaks at JPL
Newsgroups: sci.space,sci.astro,alt.sci.planetary

From the "JPL Universe"
December 4, 1992

`Take creative risks,' Goldin tells von Karman audience
By Karre Marino

     In a quick stop-over at JPL Nov. 25, NASA Administrator
Daniel Goldin told an overflow crowd of JPL personnel in von
Karman Auditorium of his concerns about the future of NASA
missions, precipitated in part by the looming possibility of
budget cuts as a new administration takes power.
     But he challenged his audience to be bold: "Use new
technology, take creative risks. Let's work on advanced concepts
and look to the future: whether that means composite structures,
(very lightweight) cameras or other nations' space programs. But
we have to put technology money where it has its biggest impact.
We need to do better in terms of commercializing space. We've
done better with privatization."
     Goldin said that analysis of the budget for NASA's Office of
Space Science & Applications  since 1987 "is cause for alarm" --
that NASA may be on the wrong path.
     "We're spending more and more money on operations and less
on cutting-edge technology to plant the seeds for the next
generation," he said. The number of scientific spacecraft on the
books is too few, and "we're using old technology to survive."
     Goldin said he is concerned that at the university level,
professors and students do not have the dollars to fund their
research. In fact, the question of federal monies was raised
often throughout Goldin's speech: "As we compete for increasingly
fewer dollars -- dollars we share with the National Institutes of
Health, the Department of Housing and Urban Development, paying
off the national debt -- NASA sees a smaller share of the federal
pot. Some of those funds are being diverted from NASA.
     "Maybe we have to do a better job informing the public why
we're vital, why our budget shouldn't be trimmed. We also have to
tell Congress the whole truth." If a budget is set for $1.4
billion, he said, "we shouldn't come back and ask for another $70
million to cover software costs. Let's be up front and tell them
exactly how much we need."
     The administrator also noted that President-elect Bill
Clinton expects a windfall from government-funded technology,
which must one day be used in the private sector to create more
jobs. "We should be a test bed of technology, bringing in people
from a variety of industries," he said.
     Goldin also discussed the possibility of working more
closely with other nations, and other space programs. For
example, "The Russians want to work with us." Their military
program may be under the knife, he noted, "but they won't give up
on their space program. This is a great opportunity to reach out
on an international basis and have scientists (from different
countries) work together. We could build more payloads here and
fly them internationally, or fly payloads of other countries on
our spacecraft."
     While NASA certainly has concerns about the future, the talk
was not all gloom and doom. Goldin cited a number of programs
that offer great hope: Mission to Planet Earth, Discovery, Space
Station Freedom. And throughout his address, he frequently
challenged JPL staffers to be creative, to submit their ideas to
management, to ensure that NASA engenders a successful marriage
of science and technology. "NASA and JPL can have great impact in
lifting the spirits of the nation and the economy if we take
risks and use cutting-edge technology. We can't be afraid to
fail."
     And while JPL is meeting Goldin's challenges, the
administrator will be busy making changes at the top: he plans to
cut out the layers of red tape. "The paperwork has become a
burden to scientists. We're going to fix that," he said. "We want
to spend our money and energy on technology."
                                  ###
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | The 3 things that children
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | find the most fascinating:
|_____|/  |_|/       |_____|/                     | space, dinosaurs and ghosts.

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

Date: Thu, 10 Dec 1992 17:21:17 GMT
From: Harald Hanche-Olsen <[e-mail]>
Subject: GRAVITY-NEUTRALIZING AIR/SPACECRAFT
Newsgroups: sci.math,sci.skeptic,sci.space

(This is my third attempt at posting this.  If our local NNTP host
won't accept it this time, then so be it.)

Why did you post to sci.math?

 >                        Gravity-NEUTRALIZING Air/Spacecraft
 >                          or ZERO/REDUCED-Gravity Chamber

I think sci.skeptic might be more appropriate.  Sci.skeptic readers,
if you want to flatten this scurry over to sci.math and read the
referenced article.  I find it very entertaining.  (What is this
program that sci.skeptic folks use to compute a bogosity index (or
whatever they call it))?

 >                NASA should build an experimental spacecraft based on
 >           U.S. Patent #3,626,605

Oh, what the heck -- I'll crosspost to sci.space too.  Followup to
sci.skeptic and sci.space, please...

- Harald

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

Date: Thu, 10 Dec 1992 16:17:03 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Koptev's visit to McD (was: DC info)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Paul Dietz) writes:

>Will all 8 engines be used for landing?

Not as part of a normal landing. Although in an emergency the pilot may
be looking hard for thrust wherever it can be gotten and to hell with
ISP.

>If not, it may make sense
>(not in DC-Y, but in a subsequent generation of vehicles) to make the
>booster engines different; in particular, make them burn a
>hydrocarbon, not hydrogen.

Funny you should mention that. The head of the Russian space program (Koptev)
was in LA last week visiting McDonnell Douglas. He met with the head of
the DC effort and they talked quite a bit about using the Russian RD-710
tripropellent engine.

I think Bruce Dunn posted a good analysis of what could be built with that
engine while still preserving the simplicity of the basic DC design. If the
RD-710 is reliable enough it could be an excellent addition.

BTW, when the briefing began, Koptev apparantly said that their studies
indicated that SSTO couldn't be done with today't technology and that
a reusable two stage vehicle was the way to go. After the briefing, he
had done a 180 and said he believes that DCY could work.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------135 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Thu, 10 Dec 1992 17:31:00 GMT
From: Henry Spencer <[e-mail]>
Subject: Saturn history
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:
>>The first Saturn I flew on 27 Oct 1961, actually.
>
>So if the Saturn I  was ready in 61,  why didn't they use it for
>Gemini?

The test flights needed to make it ready (by von Braun's standards) covered
the next several years.  For one thing, the first few flights had no upper
stage and were incapable of making orbit.
--
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  [e-mail]  utzoo!henry

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

Date: Thu, 10 Dec 1992 17:29:23 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: Spacehab on DC
Newsgroups: sci.space

[e-mail] (Michael V. Kent) writes:

>I'd like to keep flying LDEF and EURECA (I know there are no plans for the
>former, but is the structure still intact enough to refly, or did they
>dissect it?).

I don't know off hand whether the structure itself is still reusable but I think
it was originally designed to be.  Besides, LDEF doesn't need a single active
system so it ought to be trivial to build a new one if necessary.  By the way,
there's been some significant discussion of not flying EURECA again either. I
don't know what the current situation is or whether it will change.

>Here's a question that just popped into my head:  Would a modified Spacehab
>(note the "h") module fit in the cargo bay of the Delta Clipper?

Dimension wise I believe it would (assuming DC-1 is built and follows projected
dimensions).  However, given the number of modifications you'd need for power
and access and so on it may be more efficient to design a new one around the
new launcher.  However, since baseline proposals don't have Delta Clipper
capable of orbiting for more that a few days it may not be useful to orbit a
Space(l/h)ab type payload unless the launcher is redesigned too.

--
Josh Hopkins                                          [e-mail]
                        Ho^3     !=L

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

Date: Thu, 10 Dec 1992 16:16:33 GMT
From: "James B. Reed" <[e-mail]>
Subject: stationary orbits over the poles
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Tom) writes:
|> For the poles, forget about tethers.  What you want is some kind of giant
|> charged ring that you use sunlight to spin, creating a force from the
|> magnetic field of the Earth that balances gravity...

Yeah, but what happens next time the Earth's magnetic field reverses?

 :-) :-)

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

Date: Thu, 10 Dec 1992 19:20:26 GMT
From: Gary Coffman <ke4zv!gary>
Subject: what the little bird told Henry
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] ("Phil G. Fraering") writes:
>>BUT: if the main place where NASP materials seem to be being used is
>>the heat shielding, and its re-entry temperature is lower than the
>>shuttle's, wouldn't shuttle re-entry materials be just as useful?
>
>They'd probably work as well, but there is a durability problem.  Having
>to inspect every last damned tile is the last thing you want to do for a
>vehicle that's supposed to have rapid turnaround.

They're also heavy as I recall, something you don't need in a SSTO.
I appreciated the summary you gave earlier, Henry. It looks like they
have a better test program planned than what has been outlined here
before. I still think their schedule is extremely optimistic and
success oriented, but we'll see.

Gary

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

End of Space Digest Volume 15 : Issue 532
------------------------------