henry@utzoo.uucp (Henry Spencer) (11/11/88)
Japan launches CS-3B comsat on H-1 booster Sept 16.
Amroc completes maximum-duration (70 s) firing of its hybrid rocket motor.
This was the last major test before a suborbital test, set for spring.
Big items of pre-shuttle-launch coverage. NASA believes it can build to
12-14 flights per year eventually; Morton Thiokol thinks 8-10 is a better
estimate.
There has been internal debate within NASA on policy issues arising from
the new crew-escape system. In some main-engine-failure situations,
there is a choice between aborting into the ocean and pushing remaining
engines to emergency maximum to try to reach a runway. The latter
preserves the orbiter and payload as well as the crew, *if* the extreme
throttle setting doesn't cause an engine explosion. The astronauts and
Houston originally recommended abort and bailout. NASA HQ overruled
them, citing the non-trivial risks of bailing out in mid-Atlantic where
rescue would be difficult. [Granted that NASA HQ does have ulterior
motives, this argument does have some validity.]
NASA has also reversed pre-Challenger policy on abort modes, which
favored Return To Launch Site over TransAtlantic Abort. TAL is now
favored. RTLS remains the only option early in the flight, when the
shuttle can't make the TAL sites, but it calls for making a U-turn
at Mach 7 -- really -- and this untested maneuver is now considered
chancier than TAL when there is a choice. [As I observed a long time
ago, it says something about the "operational" nature of the shuttle
that one of its primary abort modes has never been tested. Come to
that, TAL hasn't been tested either.]
The STS-26 trajectory was chosen to give the safest possible abort
modes in the event of engine failure. Discovery went up more steeply
at first, taking it to an altitude of 69 nm quite early, after which
the orbiter actually flew slightly nose-down and descended 9 nm in
the course of further acceleration.
One new measure that has been approved is use of a steeper reentry
angle, if needed to reach a TAL landing site. This is controversial
because of the higher heating, but it does stretch the range 500 nm.
There remain "black zones" in the trajectory, where a multiple engine
failure is invariably fatal. For example, between Mach 8 and Mach 10,
the orbiter is moving too fast to safely descend to lower altitudes,
but is not high enough to decelerate enough before descent. A major
post-Challenger simulation effort has defined the black zones much
more precisely, and given the astronauts much better guidance on how
to deal with extreme emergencies that border on black zones.
Lockheed is offering a new small launcher to military customers, based on
the Poseidon sub-launched missile that is being phased out in favor of
Trident. (Lockheed builds both.) Lockheed's board of directors has
approved internal funding for development of a three-stage launcher, using
the first and second stages of a late-model Poseidon plus a Star 48 solid
motor as the third stage. Lockheed says the launcher could be ready in
two years and could put 770 lb into low orbit. It would not be commercially
available, and potential military customers would be responsible for getting
Navy approval to use surplus Poseidon stages.
General Dynamics and ESA are both pursuing ways to launch small payloads
piggyback on their big boosters. Small secondary payloads flew on GD's
Atlas-Centaur a number of times in the 60s, using side-mounted cargo pods;
GD is asking potential users whether they are interested in a revival of
the idea. ESA is planning a demonstration launch with Amsat's "Microsat"
small satellites mounted on a ring in unused space low in the payload
fairing of a large Ariane.
DoD is pursuing several small-satellite programs for launch in the next
few years. DARPA has bought a Pegasus launch for a cluster of small
experimental UHF comsats. The Navy's Spinsat program, developing four
small experimental satellites (the only one mentioned explicitly is
called Profile and will be used for locating radio interference sources),
is considering Scout, Pegasus, or piggyback launch on a USAF booster.
SDI is working on a small satellite (details not given) to be tested
from a submarine, using a missile adapted for use as a booster. NASA
will launch part of its CRRES (Combined Release and Radiation Effects
Satellite) project on a Scout in March 1991. (The other part goes up
on an Atlas; originally both were one larger shuttle payload.) Several
other small satellites are reported to be under construction for some
of the more obscure agencies, notably the CIA. DARPA is pursuing its
Lightsat project despite high-level opposition. Apart from the idea
of small satellites per se, DARPA would like to find out whether small
satellites can be built economically: current military satellites can
cost $100,000 per pound, twelve times the price of gold, and DARPA
thinks this is ridiculous. Military commanders support Lightsat concepts
because current centralized satellite systems have been officially
superseding systems that were under more local control, like long-range
reconnaissance aircraft and weather aircraft; the result has been large
central resources that more often than not are too heavily loaded with
"high priority" traffic to provide effective support to forces in the
field.
Picture from the NOAA-10 polar-orbit metsat: Hurricane Gilbert hitting
Yucatan. An enormous spiral of clouds with a tiny eye. Pressure at
the eye was 891 millibars (one "standard" atmosphere is 1013), with
winds gusting to 200+ MPH.
Israel launches its first satellite Sept 19, using a small solid-fuel
booster and launching *west* across the Mediterranean. The satellite
is named Offeq-1 ("Horizon 1"); the booster is called Shavit (Comet)
and is thought to be a derivative of the Jericho ballistic missile.
Offeq-1 is a test satellite with no useful military capabilities, but
Israel's primary objective is believed to be launching its own small
spysats. [Flight International, 3 Sept, reports that Israel badly wants
its own spysats. It has been getting satellite pics from the US since
the Yom Kippur War, but the US has denied its request for direct ground
links to the satellites, and Israel is not happy about getting edited and
sometimes dated information. A further consideration, possibly of some
significance, is that Israel has an election coming up.]
[The 1 Oct issue of Flight had some more details, including a picture of
Offeq-1. The western launch meant an orbital inclination higher than
anything since some NASA test launches in 1966. Launching against the
Earth's rotation cuts into payload, but it was the only way to avoid
overflying Arab nations. Flight shows the flight path nearly due west,
overflying Sicily and Gibraltar but avoiding other land. Moshe Ortass,
head of Israel Aircraft Industries' electronics division, says total
development costs of launcher and satellite were $190M, most of it out
of company R&D budgets. He says there will be another launch within
two years. [The first spysat?]]
The planned Oct 7 Ariane launch has been postponed to the 27th because
the German TVSat has encountered thruster problems, and the Ariane
payload is the very similar French TDF-1.
Senate approves Wirth bill to limit third-party liability of US commercial
launchers. The bill is similar to one that passed the House. The White
House likes neither, since they transfer financial responsibility to the
government rather than setting absolute limits.
Letter from Dennis Jenkins, observing that the Martin Marietta / McDonnell
Douglas flyback booster for ALS looks strikingly like the MM/McDD proposal
for a flyback booster for the shuttle, circa 1970.
--
Sendmail is a bug, | Henry Spencer at U of Toronto Zoology
not a feature. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu