WEEKLY WHINE

Meet the Pegasus

Coming up tonight at 22:45 PDT, the High Energy Transient Explorer 2, HETE-2, will be launched from a Pegasus booster. HETE-2 is a replacement for the original HETE satellite that was lost on MON 04 NOV 1996 when the third stage of the Pegasus failed to release HETE-1 and the Argentine satellite SAC-B.

The new HETE satellite will also be launched on a Pegasus, built by Orbital Sciences. The Pegasus is a three stage launcher that is now preparing for its thirtieth flight. HETE-2 has a mass of 125 kg [Earth weight 275 lb] and will be launched into a 650 × 600 km [404 × 373 mi] orbit at an inclination of 2°.

Because the Pegasus is normally incapable of launching a satellite of that size into such an orbit, this mission will be carried out from a new launch site. Kwajalein Missile Range in the Marshall Islands will serve as the base for this Pegasus launch. It is the first launch of a space satellite from KMR, which previously had been a site for testing of US missiles. Meanwhile, the launch control center will be in Florida, at Cape Canaveral Air Force Station. As a result, three communications lines between KMR and Cape Canaveral have been installed, even though one would have sufficed. Nonetheless, problems in the lines forced a launch delay on FRI 06 OCT 2000 while the connections are repaired.

KMR will represent the sixth different site from which a Pegasus has launched, including sites in California, Florida, Virginia, and the Canary Islands. The Pegasus's flexibility arises from its launch pad: an airplane. The Stargazer L-1011 aircraft carries the Pegasus beneath its belly. Five seconds before ignition, the Stargazer releases the launcher and banks to the side awaiting the Pegasus's ascent into space. Whereas most launch vehicles can only lift off from one or two different sites, the Pegasus can launch from anywhere that the twenty five or so technicians can reach and connect to a fully equipped launch control station. That gives the Pegasus the ability to launch satellites into equatorial orbits, as is the case tonight; inclined orbits; or polar orbits depending upon the launch site.

Live video of the launch can be obtained at http://science.ksc.nasa.gov/payload/missions/hete-2/ starting at 22:00 PDT tonight.