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Duncan Lunan
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Waverider Should you wish to contact the
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email: Imagine the problem: you're on the
International Space Station Alpha, at the climax of years of
training, embarked on six months of intensive research which
may be the foundation of your whole future career. Suddenly,
instead, you're faced with a medical emergency. You, or one
of your colleagues , becomes seriously ill, or is injured so
badly that it needs treatment on Earth. Worse still,
something really serious might happen: an on board accident,
or a collision with space debris, so bad that everyone must
return to Earth. But how do you manage it? In normal
operation the Space Station will be visited by a Space
Shuttle at 6-month intervals, on average. With only four
Orbiters, one of which is normally out of use for
modifications at any given time, there probably won't be one
available in an emergency. They'll be at various stages of
processing for the next missions planned for them: probably
the engines are being swapped between one Orbiter and
another - it happens all the time. It could be weeks before
there's one ready to launch, however great the emergency and
the dedication of the launch teams. So a lifeboat system is required,
kept docked to the Space Station, capable either of taking
off the entire crew, or of returning an injured or sick crew
person at need. Options such as a revived version of the
Apollo spacecraft have been considered, but the current
solution is to keep two Russian Soyuz spacecraft docked to
the Station, each capable of taking three people
off. But the Soyuz is designed to be
storable in space for only six months at a time. Seals,
batteries etc. have a set operational life, but the real
problem is the oxidiser in the liquid fuel propulsion
system, which becomes unsafe to use after six months. When
one is docked to the Russian Mir station for a long-stay
mission, the normal routine is for a short-stay crew to come
up in a new Soyuz, towards the end of the 6-month period,
stay for a few days and then take the previous Soyuz
back. The first crew to man the Space
Station, in 1998, have been named as the American William
Shepherd and Russian Sergei Krikalev. But with Shuttle
visits at 6-month intervals, more often during construction,
Station crew will normally travel on it. So the limited
space-storability of the Soyuz requires at least two
replacements per year to be launched from Russia, whether
the ones in space have been used or not, and the USA would
probably have to pay for them - a problem not anticipated
when the international agreements were drawn up. In addition, there are limitations on
the sizes of people which Soyuz can carry. NASA has been
treating these rules too casually and in November 1995 it
sent two astronauts to Russia to train for Mir visits, only
to have them sent back because one was too tall and the
other too short. It's now realised that 46% of the US
astronaut corps will not fit into Soyuz, and therefore can't
use the Station if Soyuz is to be the lifeboat. The Russians
have agreed to look into redesigning the Soyuz couches, and
to investigate the oxidiser problem, but whether either can
be solved remains to be seen. NASA therefore have assigned $500,000
to a prototype lifeboat, designated the XCRV - Experimental
Crew Return Vehicle. One of the 1970's 'lifting body'
research vehicles was refurbished for flight tests. Lifting
bodies are difficult to land - one of the early ones, the
M2-F2 vehicle, is seen crashing in the opening titles of The
Six Million Dollar Man - so the XCRV was intended to land by
parachute. The fins were removed for an experimental release
from the cargo bay of a C-130 transport aircraft, but the
parachutes became tangled and the vehicle crashed. At first
it seemed that no funds were available for a replacement and
the future of the project was unclear, but NASA's Johnson
Spacecraft Centre assigned $8 million to build a replacement
vehicle. A Russian spokesman commented that after so many
years the USA might not be able to build a man-rated
spacecraft, after so many experts from earlier programmes
had retired or died; but by June 1996 two new prototypes
designated 'X-38'
had been produced, for only $3 million. The second of these
was shipped to Johnson Space Centre, Houston, in November
1996. The parachute recovery system was tested in December,
with captive-carry tests under a B-52 bomber scheduled for
February 1997, with drop tests to begin in April. The European Space Agency is
considering the possibilities of a manned Crew Return
Vehicle/Crew Transportation Vehicle to take personnel to and
from the Station, starting in 2002. 'Phase A' studies of
feasibility and cost were authorised in July 1995, and joint
studies with NASA on rescue vehicles began in May 1996. The
CRV would be launched by Europe's new Ariane V booster, and
an engineering test payload is scheduled to fly on Ariane
V's second launch. The CRV would carry at least four people,
and be capable of staying docked to the station for several
months. But this would be a big, complex and expensive
vehicle: storing it in space for months at a time on the off
chance of an accident seems wasteful. The Japanese space agency NASDA is
developing a winged vehicle called Hope, to be launched by
their own H-2 booster for unmanned cargo deliveries to the
Space Station, and for obvious reasons they want to have it
considered as a Station lifeboat. A HY-FLEX test vehicle was
launched in February 1996 and sank after splash-down, but
the mission was otherwise a success. At the Woomera rocket
range in Australia, a test model has since been dropped from
a helicopter as a rehearsal for a rocket launch and land
recovery. But the fishing lobby in Japan restricts NASDA to
a launch season of only two months per year, which might not
tie in with the Station schedules. NASDA is negotiating with
the fisherman's unions for a more extended window, because
the present limit harms the commercial prospects of the H-2,
but the opposition is powerful. Page
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