Nasa lost satellite was discovered by the amateur astronomer is the IMAGE satellite, confirmed by NASA , II NASA confirms the identity of the lost IMAGE satellite and says it's still operational , II NASA SATELLITE MYSTERY SOLVED: NASA CONFIRMS AMATEUR ASTRONOMER HAS FOUND LONG-DEAD IMAGE SATELLITE—AND IT’S OPERATIONAL

NASA has confirmed that its long-dead IMAGE satellite was found January 20 by amateur astronomer Scott Tilley—and better still it looks like the spacecraft might be working.
Satellite hunter Tilley was been searching for the secret Zuma payload, believed lost earlier this month, when he stumbled on some strange signals that he believed could be NASA’s old IMAGE satellite. He described his results in a blog post.
Launched in 2000, IMAGE was designed to take pictures of the Earth’s magnetosphere. After a successful project and a mission extension, the agency lost contact with the craft in 2005. In 2007, NASA declared the mission was over.
After discovering Tilley’s findings, NASA scrambled to identify the source of the mysterious signals. The agency confirmed they looked like IMAGE signals on Monday.  Decoding this information and verifying the identity was another story altogether.
NASA

Outdated technology

The agency ran into a speed-bump during their initial testing. While they could measure the characteristics of the object's signals, they couldn’t decode their data. The old IMAGE mission center tech no longer existed. NASA's systems had been replaced and updated in the 12 years since the satellite stopped phoning home. NASA said understanding the data would take "significant reverse-engineering."
Yesterday, however, a NASA team at Johns Hopkins Applied Physics Lab in Laurel, Maryland, cracked in to some of the hidden information. They found a key piece of data—a tag labelled "166"—matching IMAGES's ID. NASA could now definitively confirm the signals came from the rogue satellite.

Still functional

The space agency was also able to confirm that the satellite was working—at least in part.
The agency announced yesterday: “The NASA team has been able to read some basic housekeeping data from the spacecraft, suggesting that at least the main control system is operational."
A team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, will continue to analyze signal data from the satellite. Still held back by a decade-long technology gap, the process should take a couple of weeks while NASA modernizes old software and databases.
Next, the agency will try and switch on the satellite’s scientific payload.
On 30 January, NASA said that at least the main control system of its IMAGE satellite, which was re-discovered by an amateur astronomer on 20 January, is operational.

IMAGE satellite which was lost decades ago.NASA.

Launched on 25 March 2000, IMAGE, short for Imager for Magnetopause-to-Aurora Global Exploration, was designed to image Earth's magnetosphere and produce the first comprehensive global images of the plasma populations in this region.
After successfully completing and extending its initial two-year mission in 2002, contact was unexpectedly lost on 18 December 2005.
After an amateur astronomer recorded observations of a satellite in high Earth orbit on 20 January 2018, his initial research suggested it was the IMAGE satellite.
NASA has now confirmed the identity of the satellite.
"On the afternoon of 30 January, the Johns Hopkins Applied Physics Lab in Laurel, Maryland, successfully collected telemetry data from the satellite. The signal showed that the space craft ID was 166 -- the ID for IMAGE," NASA said.
The NASA team was been able to read some basic housekeeping data from the spacecraft, suggesting that at least the main control system is operational.
NASA said it will continue to try to analyse the data from the spacecraft to learn more about the state of the spacecraft.
"This process will take a week or two to complete as it requires attempting to adapt old software and databases of information to more modern systems," the statement added.