henry@utzoo.UUCP (Henry Spencer) (10/08/87)
[Next in the multi-way tie for third place in space-related periodicals
is a pair: Planetary Encounter and World Spaceflight News. These are for
people who want the nitty-gritty details. No glossy color photos or
quotations from Chairman Carl to be found here, just page after page of
real hard solid information. PE covers planetary missions, WSN covers
near-Earth spaceflight. Aviation Leak spent one paragraph discussing
Joe Kerwin's medical report on the deaths of the Challenger crew; WSN
printed the whole thing. The NRC report on shuttle flight frequencies
etc. got about one column in AW&ST; WSN printed the whole thing. The
so-called International Comet Explorer got some polite coverage in various
journals (no exciting photos to be had, since it had no camera); PE spent
an entire issue on it, with diagrams, lists of experiments, an interview
with the mission director, etc. When the shuttle was flying regularly,
WSN printed things like payload manifests, activity schedules, and post-
mission assessment reports for EVERY mission. The same crew also puts out
a succession of extra-cost "special reports", containing things like NASA
technical documents on related topics. (Example: although I think they
may have had second thoughts due to poor sales on this, at one point they
were going to put out a multi-volume special report reprinting the entire
Critical Items List from the shuttle.) Highly recommended if you are
tired of the babytalk in newsstand magazines and want to know the gory
details. PE and WSN are at Box 98, Sewell NJ 08080. Each is nominally
monthly, although in fact they've been coming out less frequently for the
last year or so due to lack of news. Each is $30 for 12 issues sent First
Class to the US or Canada, elsewhere $45 for 12 issues sent Air Mail.]
Editorial commending the Ride report, and urging that it not get buried
in the White House bureaucracy. The National Commission on Space is
re-submitting its report in hopes that it will get attention this time.
Intelsat prepares for RFP for Intelsat 7 series. They will be smaller
than the enormous Intelsat 6s. The first 2-3 will be for the Pacific,
for launch in 1992-3, with possibly more for the Atlantic 3-4 years later.
Predictions of shortage of engineering talent in the Washington DC area
as NASA's space station contracts start hiring hundreds.
[*Just* what the space program needs, more bureaucrats.....]
Oops: the Shuttle-C shuttle-derived heavylift launcher may end up in
competition for funds with the advanced-SRB project.
Official release of the Ride report, calling for aggressive action and
[gasp] planning. "Without an eye toward the future, we flounder in the
present." NASA is giving it a lukewarm reception at best. NASA people
have been ordered to downplay it, and there was debate over whether it
should be released at all. (NASA is afraid of the reaction from the
Office of Mismanagement and Beancounting.)
Ride report endorses shuttle and station, but as tools rather than goals.
Shuttle-derived cargo vehicle should be developed immediately. Strong
consideration of a new *manned* expendable urged, for station logistics.
Strong emphasis on technology development, notably the Pathfinder program.
Ride report says US could return to Moon by 2000, base by 2005-2010. Mars
would take longer. Mars is clearly the ultimate near-future goal, but
"...we should avoid a `race to Mars'. There is a very real danger that if
the US announces a human Mars initiative at this time, it could escalate
into another space race. This could turn an initiative that envisions
the ultimate deployment of a habitable outpost into another one-shot
spectacular... Settling Mars should be our eventual goal, but it should
not be our next goal... We should adopt a strategy of natural progression
which leads step-by-step, in an orderly unhurried way... towards Mars.
Exploring and prospecting the Moon... would provide the experience and
expertise necessary for further human exploration of the solar system.
[We found] considerable sentiment that Apollo was a dead-end venture,
and that we have little to show for it. Although this task force found
some who dismissed [the lunar] initiative because `we've been to the
Moon', it found more people who feel that this generation should continue
the work begun by Apollo."
Meanwhile, the Soviet Union plans to launch by the mid-1990s one or more
dedicated asteroid missions with surface probes.
SDI's Innovative Science and Technology group to launch first space
experiment on sounding rocket in November, looking at problems of using
high-power electrical equipment in space. IST is looking at the "small
satellites" ideas and lightweight launchers, although it isn't funding
them yet. Advanced propulsion work includes a proposal to replace the
inert binder in solid rockets with a combustible fuel, and another to make
solid fuels with continuous rather than batch processes. Materials work is
looking at thin-film diamond as a semiconductor (it might be better than
gallium arsenide) and as a tough coating for optical surfaces.
Arianespace delays Ariane launch four days to give the launch teams some
rest. [Launch successful.]
Launch of Japanese H-1 booster carrying engineering test satellite slips
four days due to valve problem in second stage. [Launch successful.]
Chinese reentry capsule, carrying French experiment package, recovered
after five days in orbit. [Also, I made a mistake in reporting this one:
the capsule was of the type used for film-recovery spysats, but this
particular mission was all scientific.]
Inmarsat planning R&D program on navigation satellites.
AW&ST is running a multi-part series on South American aerospace, including:
Chilean space activity is modest but significant. Prominent in it is the
shuttle emergency-landing runway on Easter Island; this involved extending
the airport's runway and adding approach lights and landing aids. Chile
hopes to fly an astronaut on the shuttle eventually. Also of note are an
ozone-depletion experiment done jointly with the US and UK, and the first
South American ground station for the Sarsat (search and rescue) program.
Brazil's larger space program continues progress on building its own
launcher (roughly Scout-class), environmental and Earth-resources
satellites to go up on it, and a near-equatorial launch site for it. First
launch tentatively 1989.
ESA awards contract to British Aerospace for feasibility study of mobile
communications satellite system, possibly using Molniya orbits for good
coverage at high latitudes.
--
"Mir" means "peace", as in | Henry Spencer @ U of Toronto Zoology
"the war is over; we've won". | {allegra,ihnp4,decvax,utai}!utzoo!henrycrowl@cs.rochester.edu (Lawrence Crowl) (10/08/87)
In article <8727@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes:
)Aviation Leak spent one paragraph discussing Joe Kerwin's medical report on
)the deaths of the Challenger crew; WSN printed the whole thing.
I missed this. Can anyone post a short summary of what it said?
--
Lawrence Crowl 716-275-9499 University of Rochester
crowl@cs.rochester.edu Computer Science Department
...!{allegra,decvax,rutgers}!rochester!crowl Rochester, New York, 14627henry@utzoo.UUCP (Henry Spencer) (10/13/87)
> ... feasibility study of mobile > communications satellite system, possibly using Molniya orbits for good > coverage at high latitudes. I suppose I should explain this, since some people have asked about the term. Clarke (geostationary) orbit is the preferred one for comsats, but it has problems for ground stations at high latitudes. Clarke-orbit satellites are low on the horizon for such stations, and in fact are below the horizon for stations near the poles. This causes various problems. The Soviet solution to this is to use a different orbit for their Molniya comsats. The Molniyas are in highly elliptical orbits at high inclinations, with apogee over the northern hemisphere. This means that they spend most of their time moving quite slowly across the northern sky (and incidentally spend the low-altitude part of their orbits deep in the southern hemisphere, away from hostile nations). This isn't as good as Clarke orbit, since the Molniyas do move and stations need to track them continuously, but for high latitudes the results are better. The Soviets do now make some use of Clarke-orbit comsats as well, but the Molniyas remain important. There are a few other users of such orbits as well; I believe one of the upcoming amateur-radio satellites will use such an orbit. -- "Mir" means "peace", as in | Henry Spencer @ U of Toronto Zoology "the war is over; we've won". | {allegra,ihnp4,decvax,utai}!utzoo!henry
mac@idacrd.UUCP (Bob McGwier) (10/14/87)
in article <8760@utzoo.UUCP>, henry@utzoo.UUCP (Henry Spencer) says: > Xref: idacrd sci.space:3217 sci.space.shuttle:359 > >> ... feasibility study of mobile >> communications satellite system, possibly using Molniya orbits for good >> coverage at high latitudes. > > latitudes the results are better. The Soviets do now make some use of > Clarke-orbit comsats as well, but the Molniyas remain important. There are > a few other users of such orbits as well; I believe one of the upcoming > amateur-radio satellites will use such an orbit. > -- >Henry Spencer Molniya is usually applied to those orbits which are elliptical AND have high inclinations at just the right value to cause one of the principal perturbations to be zero (to first order). You are correct that this is used and has been extensively developed by the Soviets. OSCAR-10 (AMSAT's Orbiting Satellite Carrying Amateur Radio) DOES use an elliptical orbit and was scheduled for Molniya until the launcher did a rear end collision on us . We made it to 26 degree inclination so the argument of perigee precesses (the apogee swaps from north to south and back on its subsatellite point). Phase III-C, another in the oscar series will go up on the first Ariane 4 in the early part of next year. It is also scheduled for Molniya orbit. The need for a Molniya orbit is correctly explained by Henry. Bob McGwier, N4HY
karn@faline.bellcore.com (Phil R. Karn) (10/15/87)
> Phase III-C, another in the oscar > series will go up on the first Ariane 4 in the early part of next year. > It is also scheduled for Molniya orbit. Actually, while we would *like* a true Molniya orbit, what we get is actually just a close approximation. In a true Molniya orbit the inclination is 63.5 degrees. At this value, the secular perturbation on the argument of perigee vanishes. This means that the positions of apogee and perigee remain fixed in the orbit plane instead of slowly rotating. The argument of perigee is usually chosen to be near 270 degrees, so apogee occurs at maximum latitude (i.e., high over the Soviet Union). While the Soviets launch lots of stuff directly into this orbit, it is not used by the primary missions flying on the only launch vehicle available to us (Ariane). We must therefore make use of the Ariane's most common destination, geostationary transfer orbit (GTO). An Ariane GTO is typically 35800 km apogee by 200-250 km perigee, inclination 6 to 8 deg, and argument of perigee 180 degrees. This is designed to make it easy to get to a geostationary orbit with a single apogee kick motor firing. Unfortunately for us, it is difficult to get into a Molniya orbit from GTO. Most of our propellant is required just to raise inclination, and rotating the argument of perigee at the same time by 90 degrees is not possible. What we instead planned to do on Oscar 10 (and plan again for Phase 3-C) is to raise inclination to just a few degrees short of 63.5. Over the next several years, perturbations will slowly increase the satellite's argument of perigee, bringing the latitude of apogee higher into the Northern hemisphere over the lifetime of the satellite. Of course, once the arg of perigee gets to 270 degrees we would love to hold it there. Inclination changes must be done at the equator, however, and the burn would then have to occur at much lower altitude and higher velocity, making the fuel requirement unreasonable. On the other hand, it's entirely possible that we've overlooked some really clever trick. If anybody knows how to get from Ariane GTO into a *true* Molniya orbit with only 1500 m/sec or so of delta-V, please let Bob or me know! Ah, if we only had a dedicated launcher... Phil
henry@utzoo.UUCP (Henry Spencer) (10/16/87)
> )Aviation Leak spent one paragraph discussing Joe Kerwin's medical report on > )the deaths of the Challenger crew; WSN printed the whole thing. > > I missed this. Can anyone post a short summary of what it said? I posted one at the time, but don't have it handy (and probably wouldn't just repost it anyway). Very briefly: the crew died from the water impact; they were conscious for at least a few seconds after the orbiter broke up; it was not possible to determine for sure whether the cabin had lost pressure, but it seemed likely; if the cabin lost pressure, the crew would have lost consciousness fairly quickly and would not have regained it by time of impact. -- "Mir" means "peace", as in | Henry Spencer @ U of Toronto Zoology "the war is over; we've won". | {allegra,ihnp4,decvax,utai}!utzoo!henry