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Explorer Platform

Explorers are free-flying scientific spacecraft that
may be solar-, celestial-, or Earth-pointing.  Explorer
Platform missions will include missions like the Extreme
Ultraviolet Explorer and the X-Ray Timing Explorer.

     The Explorer Platform is a reuseable spacecraft based
on the Multi-mission Modular Spacecraft (MMS) and an
equipment deck.  The MMS, which has been used for both
solar- and Earth-pointing missions, provides all utilities
for its payloads and can be serviced in-orbit.  The Platform
can be launched on either a Delta-class expendable launch
vehicle or the space shuttle.  When launched on a
Delta-class vehicle, it can carry a 4,000-lb payload; when
launched on the space shuttle, it can carry more than 10,000
pounds.  It is designed to have a 10-year operational
lifetime, assuming on-orbit servicing and an occasional
reboost.  To accommodate more than one mission, it may be
converted on orbit and reused.  A typical scenario involves
retrieval of the Explorer Platform, changeout of its science
payload, then redeployment.

     A payload module is connected to an MMS through a
standard platform equipment deck.  The Platform includes the
following:

   (1) a standard triangular MMS structural subsystem,
   (2) one high gain antenna,
   (3) an MMS Modular Power Subsystem module,
   (4) an MMS Communications and Data Handling module
   (5) an MMS Modular Attitude Control Subsystem module, and
   (6) a platform equipment deck with solar arrays and six
equipment drawers.