ASTER DDL Update
In addition a cooperative effort is underway involving GSFC Earth Science Missions Operations (ESMO) Project personnel and representatives of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument to test the Direct Down-Link (DDL) capability to a DDL receiving antenna at the Earth Resources Observation and Science (EROS) ground station in Sioux Falls, South Dakota in case of SSR failure. The ASTER DDL would be used in a contingency situation. If directed by NASA Headquarters and agreed to by the Japan Ministry of Economic Trade and Industry (METI) and the Terra Science team, ASTER DDL could be also used in the event of complete failure of both Landsat 5 and Landsat 7 (Enhanced Thematic Mapper) instruments, i.e., DDL would potentially be used to acquire ASTER data over the contiguous US for every possible overpass, without impacting the total amount of data that ASTER currently collects over the rest of the world. In essence, the average 8% duty cycle would be increased by about 100 scenes per day. A secondary test objective related to the ASTER DDL activity is to determine if the DB stations in North America can successfully capture MODIS data via the I-channel using current ground station resources. To do this will require switching Direct Broadcast (DB) of MODIS data presently being accomplished on the “Q” channel to another data readout channel (the “I” channel). The concern is that the I-channel make not work well with the smaller (~2.5 meter) dishes used by several MODIS DB users. Representing the MODIS DB users is Liam Gumley from the University of Wisconsin and Vince Salomonson, MODIS Science Team Leader. A testing plan is nearing completion.