Japanese space probe Akatsuki fails to enter Venus orbit+

TOKYO, Dec. 9 Kyodo -
The Japan Aerospace Exploration Agency said Wednesday that its space probe
Akatsuki failed in its attempt Tuesday to enter orbit around Venus, and is
believed to have passed the planet.
As for the cause of the failure, the agency, known as JAXA, said the probe
vehicle went off balance and its engine stalled during engine reversal to slow
it down so it could be pulled into Venus' gravitational field and enter into
orbit.
But the probe vehicle, which was launched aboard a rocket May 21, will still
have a chance if it can continue flying until it comes close to Venus again in
six years' time, JAXA said.
If Akatsuki had succeeded in entering into orbit, it would have been the first
time Japan had placed a space probe in orbit around a planet other than Earth,
after a failed attempt between 1998 and 2003 to place a probe into orbit around
Mars.
''I'm sorry that we failed to meet the expectations of the public,'' said
Masato Nakamura, Akatsuki project manager, in a press conference at JAXA's
Institute of Space and Astronautical Science in Sagamihara, Kanagawa
Prefecture.
But JAXA will try once again to put the probe, developed at a cost of 25.2
billion yen, into orbit when it approaches Venus, he said, adding, ''Speaking
optimistically, I think the likelihood (of success in six years) is high.''
Space engineers at JAXA worked through the night to receive and analyze data
from Akatsuki, after it lost contact with Earth shortly after starting to
reverse its engine Tuesday morning Japan time as a final step before entering
into orbit around Venus.
JAXA has partially restored communication with the probe, and said it has found
no trouble with its main unit.
Under the plan, Akatsuki, which was about 550 kilometers above Venus on
Tuesday, was to reverse its engine for 12 minutes to slow down so it could be
pulled into Venus' gravitational field and enter into orbit.
But Akatsuki's engine stalled 2 minutes, 23 seconds after it went into reverse
thrust, JAXA said later in the day. When it attempted to slow down, Akatsuki
lost its right posture and went as if it had been rolling, it said.
Being unable to slow down sufficiently, the probe had passed over Venus, it
said, adding it was impossible to make Akatsuki return to the planned orbit
even if all of the remaining fuel was used.
Nakamura said JAXA will carefully analyze why the engine trouble happened as it
will try to put Akatsuki into Venus orbit in six years' time by using the same
engine.
Akatsuki is designed to observe the atmosphere of the planet for over two years
in an elliptical orbit taking 30 hours per revolution at altitudes of 550 to
80,000 km.
Shedding light on meteorological phenomena in Venus will help in understanding
why Venus and Earth, the two planets most similar in size and distances from
the sun, have very different environments, researchers say.
Junjiro Onoda, head of the JAXA institute, said Akatsuki's failure to enter
into orbit around Venus was ''extremely regrettable, as it comes at a time when
the public has started to show greater support for the country's space
development programs after the success of (the asteroid explorer) Hayabusa.''
Akatsuki is Japan's first planetary exploration mission since an unsuccessful
stint by the Mars probe Nozomi, which was launched in 1998. In 2003 JAXA gave
up trying to put Nozomi into orbit around the planet after a series of
technical glitches.
JAXA officials said they used lessons learned from Nozomi's failure in the
development of Akatsuki, such as adopting a more cautious method of
communicating closely with Earth in attempting engine reversal.
When the Akatsuki project team concluded early Wednesday morning that it had
failed to put it into orbit around Venus, project manager Nakamura told its
members, ''It's hard to find words, but let's keep on protecting Akatsuki for
the next six years,'' they said.
==Kyodo
2010-12-09 00:06:40