The second of three major parts of the spacecraft that will launch into orbit on Orion’s first mission this fall is complete.
Work has been progressing steadily on all three main parts of Orion –
the service module, the crew module and the launch abort system – and
this month the service module joined the launch abort system in crossing
the finish line.
Orion’s service module sits below the crew module and above the
rocket that will launch Orion into space. The recently completed service
module, which will fly during Orion's first test flight, is a
structural representation and will lack many of the key capabilities of
the final service module. Service modules on future missions will
provide power, heat rejection, the in-space propulsion capability for
orbital transfer, attitude control and high-altitude ascent aborts. It
will also house water, oxygen and nitrogen for the trip. But because
Orion’s first mission will be a four-hour-long, unmanned flight test,
many of those systems aren’t needed just yet. Instead, this first
service module will primarily be responsible for the structural
support involved in carrying the crew module and launch abort system as
they’re launched into space.
Since the crew module and launch abort system together weigh more
than 37,000 pounds at liftoff, that’s no easy task. The crew module gets
some help with it from three massive panels, called fairings, that
encase the service module and shield it from heat, wind and acoustics.
They support half of the crew module and launch abort system’s weight
during launch and ascent, before they’re jettisoned more than 100 miles
up. After that, the loads on Orion are much lower and can be carried by
the service module alone.
To ensure that the service module and its fairings are up to the
challenge, it will spend two weeks in February undergoing tests.
Engineers will carefully apply small amounts of stress to the structure
to test its stiffness and verify it reacts as predicted. If it does,
they’ll up the ante, pushing and twisting it from multiple directions.
If it can withstand the strain, the engineers will know it’s ready for flight.
The launch abort system was completed in December, and the crew
module is coming right along. Engineers at Kennedy Space Center recently
completed the complex welding that’s required to make sure Orion’s
propulsion and life support fluid systems are leak tight.
To minimize the number of mechanical joints, which are invitations
for leaks, the fluid systems are welded together as one piece into a
virtual spaghetti bowl that surrounds the Orion pressure vessel. The
process required more than 260 individual welds in complicated
geometries, each of which was then X-rayed to ensure that it was good.
Over the next three months, Orion’s thermal protection system will be
installed – tiles on the top of the crew module and the largest heat
shield of its kind ever built. With that in place, the crew module,
service module and launch abort system will be ready to mate this
spring.
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