The MAVEN spacecraft, designed to investigate how Mars went from being a kinder, gentler world to one that’s cold, dry and with only the thinnest of atmospheres, has arrived.  It has begun to orbit the Red Planet, where it will sample its air for clues to this world’s past.
 
On September 17, SETI engineer Jon Richards used the Allen Telescope Array to search for telemetry signals from MAVEN and, as you can see in the plot above, found a transmission at 8446 MHz.  The signal appears as a diagonal streak in the plot, which graphs signal strength over a narrow range of radio frequencies vs time (frequency increases horizontally and time increases vertically).  The obvious drift of the signal to lower frequencies is caused by changes in the Doppler shift of the transmission due to Earth’s rotation.
 
This sort of observation is less about MAVEN than about the ATA.  It is a useful end-to-end test of the Array’s performance.