North Korea’s first spy satellite is “alive”, a Netherlands-based space expert said on Tuesday, after detecting changes in its orbit that suggested Pyongyang was successfully controlling the spacecraft - although its capabilities remain unknown.

After two fiery failures, North Korea successfully placed the Malligyong-1 satellite in orbit in November. Pyongyang’s state media claimed it has photographed sensitive military and political sites in South Korea, the United States and elsewhere, but has not released any imagery. Independent radio trackers have not detected signals from the satellite.

“But now we can definitely say the satellite is alive,” Marco Langbroek, a satellite expert at Delft University of Technology in the Netherlands, wrote in a blog post.

From Feb. 19-24, the satellite conducted manoeuvres to raise its perigee, or the lowest point in its orbit, from 488 km to 497 km, Langbroek said, citing data from the U.S.–led Combined Space Operations Center.

“The manoeuvre proves that Malligyong-1 is not dead, and that North-Korea has control over the satellite - something that was disputed,” he said.

South Korea’s Defence Ministry said it too had assessed that the satellite was in orbit, but said it would not comment further on individual analyses. On Monday, Defence Minister Shin Won-sik said the satellite was not showing any signs of performing other tasks or engaging in reconnaissance.

“While we indeed currently cannot be sure whether the satellite does successfully take imagery, it at least performs orbital manoeuvres, so in that sense it is functional,” Langbroek wrote of Shin’s comments.

The orbit-raising manoeuvre was a surprise as the presence of an onboard propulsion system was unexpected and previous North Korean satellites never manoeuvred, he said.

“Having the capacity to raise the satellite’s orbit is a big deal,” Langbroek said.

That meant that as long as there was fuel in the satellite, North Korea could prolong the satellite’s lifetime by raising its altitude when it got too low because of orbital decay, he concluded.