The North Korean satellite launched into space last week appears to be tumbling in orbit and is most likely dead, astronomers are reporting. The evident failure will not cause the spacecraft to fall quickly back to earth but seems to represent a major blow to the North's portrayal of the launching as a complete triumph.
"It's spinning or tumbling, and we haven't picked up any transmissions," said Jonathan McDowell, a Harvard astronomer who tracks rocket launchings and space activity. "Those two things are most consistent with the satellite being entirely inactive at this point."
North Korea's state-run news media said nothing about the satellite's dysfunction, focusing instead on the event the launching was supposed to honor: the somber first anniversary of the death of Kim Jong-il, the longtime leader. As part of the coverage, state television broadcast video of his daughter-in-law — her first public appearance in more than a month — that appeared to confirm that a new member of North Korea's notoriously reclusive Kim dynasty is on its way.
The images showed Ri Sol-ju, the wife of Kim Jong-il's son and successor, Kim Jong-un, dressed in a dark flowing dress and walking slowly beside her husband inside the Kumsusan Palace of the Sun, the mausoleum in Pyongyang, the capital, where Kim Jong-il and his father, Kim Il-sung, lie in state. Although she was wearing a high-waisted, loose-fit, traditional "hanbok" dress, and there was no official mention of pregnancy, South Korean media detected what they considered a visibly swollen belly. The South Korean news agency Yonhap quoted a government source as saying that birth was "imminent."
State media has been describing the satellite launching as a triumphal achievement of the young leader, completed despite worldwide criticism and United Nations sanctions on the North's ballistic missile program. On the day of the launching, the mission director, Kim Hye-jin, told reporters that the satellite was broadcasting in orbit "Song of Gen. Kim Il-sung" and "Song of Gen. Kim Jong-il."
The satellite, about the size of a washing machine, reportedly carries an on-board camera to observe the earth. That mission requires the spacecraft to remain quite steady.
Dr. McDowell said tumbling would imply that on-board systems meant to control and stabilize the craft had failed.
He added that radio astronomers had picked up no signals from the satellite and that optical astronomers had observed it brightening and dimming as it slowly rotated through space end over end.
"It's clear that the rocket part of this mission worked very well for the North Koreans," Dr. McDowell said in an interview. "They ended up in the right orbit. But the preponderance of the evidence suggests that the satellite failed either during the ascent or shortly afterwards."
North Korea fired the small satellite into orbit last Wednesday atop a long-range rocket, a first for the impoverished nation. The official Korean Central News Agency hailed it as demonstrating "indomitable spirit and massive national capabilities."
Last week, rumors circulated in Washington that the satellite was malfunctioning. Astronomers who turned a variety of telescopes on the sky have now gathered evidence that supports that finding.
Greg Roberts, a retired professional astronomer who lives in Cape Town, South Africa, reported Sunday on an Internet site that he was able to observe the satellite flashing through repeated cycles that would brighten and dim.
The spacecraft, he added, "appears to be doing a regular tumble." On Monday, he added that new observations showed the satellite reaching its maximum brightness roughly once every 16 seconds.
In an e-mail, Mr. Roberts cautioned that he still needed to make more observations to confirm the evident tumbling.
The glaring absence of any signals or other signs of life from the spacecraft suggests it is dormant or dead.
The radio silence stands in contrast to North Korea's early wave of excited proclamations.
Robert Christy, a British radio astronomer who has tracked satellites for decades and runs an observers' Internet site, said in an e-mail from England that for days after the launching he listened for the satellite but could hear nothing and found no plausible signals.
"I still wouldn't rule out it turning up," Mr. Christy said. But he noted that North Korean officials have already missed an opportunity to make "any real propaganda out of it transmitting."
Ted Molczan, a sky watcher in Toronto who is also tracking the satellite, said tumbling would have little if any impact on the orbit's decay and the satellite's re-entry through the atmosphere, where the blistering heat of friction will eventually cause it to burn up.
"It's going to be up there for at least a few years," Mr. Molczan said. "The real question is whether the satellite is functioning. Right now, it looks like it's rotating aimlessly."
William J. Broad reported from New York, and Choe Sang-hun from Seoul, South Korea.
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