Spacecraft Assembly

Ka-band communications system

April 3, 2008
In the last two weeks, we completed the electrical hook-up of the Ka-band modulator and tested it with the C&DH, installed the +Z panel of the spacecraft (the last major structural panel), and installed and tested CRaTER and Diviner. LEND has arrived, and we are preparing it for integration. The LOLA instrument is nearing completion of its thermal vacuum testing.

Joe Hammerbacher removes the bagging from the Diviner instrument in preparation for its first testing on the Orbiter. Joe is standing on the scaffolding about 8 feet above the floor. The CRaTER instrument is visible to the left of Diviner mounted on the vertical panel. The connectors in the foreground on the left side of the picture feed the Instrument Module. The cables are wrapped with copper to protect them from the charging effects of high-energy electrons.

April 10, 2008
This week, we completed integration of the Ka-band communications system, and we mechanically integrated the qualification battery. We will put the flight battery on the Orbiter shortly before shipping to the launch site. The late installation preserves as much life as possible in the flight battery.

Here is the avionics panel after integration of the Ka-band communications system. The gold box is the Ka-band modulator. The waveguide goes down from that to the Traveling Wave Tube Amplifier, then to the isolator, before it goes to the right around the corner of the Orbiter over to the fixture that simulates the mounting point on the High-Gain Antenna System. The modulator puts the data onto the radio signal. The amplifier boosts the signal to 40 watts. The isolator prevents reflected power from returning to the amplifier. Waveguide is used for high-frequency radio signals instead of coaxial cables because it is more efficient (not as much signal gets lost during transmission).

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