When he’s not on ham radio, Scott Tilley, VE7TIL, an amateur astronomer, hunts spy satellites. Using an S-band radio from his home in Roberts Creek, British Columbia, Tilley routinely scans the skies for radio signals from classified objects orbiting Earth, according to a recent article on Spaceweather.com. Since starting 5 years ago, Tilley has located dozens of secret or unlisted satellites. Earlier this month, while hunting for ZUMA — an undisclosed US government spacecraft lost in a January 8 launch mishap — when he saw the signature of IMAGE (Imager for Magnetopause-to-Aurora Global Exploration), a NASA spacecraft believed to have died in December 2005. The discovery has delighted space scientists.

“The long gone and nearly forgotten IMAGE spacecraft has come back to life and been detected by an amateur astronomer,” said Mission Manager Richard J. Burley at NASA’s Goddard Space Flight (GSFC), which confirmed that what Tilley spotted is, indeed, IMAGE. Amateur observer Paul Marsh, M0EYT, in the UK provided the first independent confirmation of the IMAGE signal.

NASA said on January 29 that observations from five sites were consistent with the RF characteristics expected of IMAGE. “Specifically, the radio frequency showed a spike at the expected center frequency, as well as side bands where they should be for IMAGE,” NASA said. “Oscillation of the signal was also consistent with the last known spin rate for IMAGE.”

But just to make certain beyond a shadow of a doubt, NASA will next attempt to capture and analyze data from the signal. The challenge to decoding the signal is primarily technical. The types of hardware and operating systems used in the IMAGE Mission Operations Center no longer exist, and other systems have been updated several versions beyond what they were at the time, requiring significant reverse-engineering.”

If data decoding succeeds, NASA will try to turn on the science payload to understand the status of the various science instruments.

After the spacecraft went silent, an unsuccessful 2007 effort was made to track IMAGE in the hope that a “long shadow encounter” would drain the battery enough to cause IMAGE to reset its control hardware. When that effort failed, the mission was declared to have ended. Space scientists now theorize that an even longer eclipse — or other event — did reset the system and bring the transmitter back to life. Yet to be determined is whether it’s possible to restore IMAGE to operation and to what degree.

Launched in 2000 on a mission to monitor space weather, IMAGE mapped plasma patterns around Earth, keeping tabs on the planet’s magnetosphere as it responded to solar activity; on-board ultraviolet cameras shot images of Earth’s auroras. “It had capabilities that no other spacecraft could match — before or since,” said Patricia Reiff, a member of the original IMAGE science team at Rice University.

“If revival occurs, the mission should be able to continue as before with no limitations,” NASA’s IMAGE Failure Review Board said in its 2006 report. Reiff said scientists stopped listening after the 2007 effort failed.

After seeing the radio signature, Tilley used a program called STRF to identify it. STRF deduces orbital elements from the Doppler shifts of their radio signals, and it immediately matched what Tilley saw to IMAGE.

Reiff said UC Berkeley still has a ground station that was used for real-time tracking and control and is scrambling to find the old software to see it they can get the spacecraft to respond.

“[IMAGE’s] global-scale auroral imager would be fantastic for nowcasting space weather, Reiff said. “Fingers crossed!” — Thanks to Alex Schwarz, VE7DXW; Spaceweather.com; NASA