Did Collision Cause Japanese Probe to Miss Venus?

A Japanese probe that failed to enter orbit around Venus Monday night (Dec. 6) may have been damaged by an impacting object, according to news reports.

Alternately, a problem with the spacecraft's engine nozzle could also be to blame for the probe's wayward journey.

The Akatsuki spacecraft, whose name means "dawn" in Japanese, is currently speeding away from Venus after failing to insert into the hellishly hot planet's orbit. But the probe will come close enough to make another attempt in late 2016 or early 2017, and officials with the Japan Aerospace Exploration Agency (JAXA) said they hope to try again.

"While we set up a new investigation team to study the cause and countermeasures, we will also review the Venus orbit injection plan again to take the next opportunity in six years when the Akatsuki flies closest to Venus," JAXA officials said in a statement.

Engines conked out

After more than six months of interplanetary travel, the $300 million Akatsuki spacecraft got to within 342 miles (550 kilometers) of Venus Monday night. At 6:49 p.m. EST (2349 GMT), the probe began firing its thrusters in an orbital-insertion burn, which should have slowed the craft enough to let Venus' gravity snag it.

After initiation of the burn, a communications blackout ? caused when Akatsuki swung behind Venus ? grew from the expected 22 minutes to more than 1 1/2 hours, suggesting that something had gone awry.

While JAXA scientists managed to re-establish contact with the probe, they announced Dec. 8 that Akatsuki had failed to enter Venus orbit. JAXA officials said that the thrusters failed to fire for long enough, burning for only two to three minutes instead of the expected 12, Japan's English-languageMainichi Daily News newspaper reported.

Akatsuki went into safe mode ? a sort of standby state that allows craft to weather various technical glitches ? which shut down the engines, according to an article in the journal Nature. JAXA officials have determined that Akatsuki started spinning before going into safe mode, suggesting the probe may have been hit by some object or had a problem with its engine nozzle, Nature reports.

Akatsuki doesn't have enough fuel to slam on the brakes and reverse course now, so it will continue on its long, looping path around the sun. It should come close enough to Venus to try another orbital-insertion burn in December 2016 or January 2017, JAXA officials said.

The probe should be able to survive until then, scientists said. Akatsuki was designed to operate for at least two years in Venus orbit, but its batteries can last for longer than that, and the spacecraft ?still has most of its fuel left. But JAXA officials are concerned that it could sustain heat or radiation damage on its trip around the sun, the Mainichi Daily News reported.

Akatsuki was the second robotic Japanese probe ever sent to visit another planet. Japan's first planetary mission, the Nozomi orbiter sent to Mars, also failed to enter orbit in late 2003.

A loss for astronomy

Akatsuki was supposed to study Venus' clouds, atmosphere and weather in unprecedented detail.

One main goal was to determine how Venus ? similar in so many ways to Earth ? veered off on such an extreme path, becoming an inhospitable world with thick sulfuric-acid clouds and surface temperatures hot enough to melt lead, JAXA officials have said. [Gallery: Beneath the Clouds of Venus]

"In so many ways, Venus is similar to Earth. It has about the same mass, is approximately the same distance from the sun and is made of the same basic materials," Akatsuki project scientist Takeshi Imamura said in a statement a few months ago. "Yet the two worlds ended up so different. We want to know why."

But now researchers will have to wait six more years to address these questions ? if they get to answer them at all. And in the meantime, that delay is a blow to the astronomical community.

"The Planetary Society regrets that the innovative Akatsuki spacecraft seems to have missed its opportunity to lock into an orbit of Venus," Bill Nye, executive director of the space-exploration advocacy group, said in a statement. "Although Akatsuki has already accomplished some remarkable things on its voyage, this setback reminds us how difficult space exploration can be."

Akatsuki's mission would have complemented and built upon the observations of Venus Express, a European Space Agency probe that has been orbiting Venus since 2006.

Akatsuki launched from Tanegashima Space Center in Japan on May 20 along with the solar-sail spacecraft Ikaros. Ikaros became the first craft to cruise through space propelled only by sunlight, and it's still going strong.

• Gallery: Beneath the Clouds of Venus
• Top 10 Extreme Planet Facts
• Japanese Spacecraft Misses Venus