The NRAO Green Bank Telescope (GBT) and personnel supported the dramatic Phoenix Mars Lander entry, descent, and landing (EDL) on Sunday, May 25, directly observing transmissions from Phoenix as it entered and descended through the Martian atmosphere and successfully landed on the planet's surface.

The Phoenix Mars Lander mission in Green Bank was supported by a NRAO team led by Frank Ghigo and three radio science specialists from NASA's Jet Propulsion Laboratory. Special JPL data acquisition equipment sampled and recorded the signals from Phoenix that were collected by the GBT.

The three spacecraft orbiting the red planet -- Mars Reconnaissance, Odyssey, and Express -- were designed to receive the signals from Phoenix and then relay them to NASA's Deep Space Network antennas on Earth. The GBT directly monitored the Phoenix spacecraft as it descended through the atmosphere in case something went wrong with the orbiter relay or the Deep Space Network, or there was a malfunction in the complex Phoenix landing sequence. If a malfunction had occurred -- fortunately, it did not -- GBT data would have been vital for diagnostics.

The Phoenix mission data recorded by the GBT last Sunday are now being integrated with data recorded by the orbiters. This combined dataset will improve our knowledge of the trajectory Phoenix followed through the Martian atmosphere.

GBT support of the Phoenix mission also included radio frequency interference (RFI) mitigation. In March 2008, RFI was detected very near the frequency of interest for the Phoenix mission. The GB Interference Protection group researched possible interfering satellites, searched the local environment, and contacted NSF, JPL, and military spectrum managers. Two problem satellites were identified by the GB team, the agencies responsible for these satellites were contacted, and the potential RFI was mitigated during the critical Phoenix landing time window.

The GBT also supported preliminary Phoenix mission tests in December 2007 and March 2008, observing signals from the Mars Rovers, Spirit and Opportunity.