[meteorite-list] Rosetta Launch Delayed

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:28 2004
Message-ID: <200402261634.IAA20879_at_zagami.jpl.nasa.gov>

http://www.newscientist.com/news/news.jsp?id=ns99994722

Launch of comet-chasing spacecraft delayed
Maggie McKee
New Scientist
February 26, 2004

Strong, high-altitude winds forced the launch of Europe's comet-chasing
Rosetta spacecraft to be called off early on Wednesday morning.

The launch was halted 20 minutes and 40 seconds before Rosetta was scheduled
to blast-off at 0436 local time from Kourou in French Guiana.

Mission managers will attempt the launch again on Thursday at about the same
time, but if more problems develop, they can try once every day until 17
March.

Winds between 10 and 15 kilometres above the launch site arose about two
hours before the scheduled lift-off at 0736 GMT. But managers of the
Ariane-5 launch rocket were concerned about the direction of the wind, not
its force.

"The launch vehicle can fly whatever the speed of the wind," said Jean-Yves
Le Gall, chief executive officer of Arianespace, the rocket's manufacturer.
"The concern is where the debris will fall down if we have problems in
flight."

ESA science director David Southwood took the news in his stride but says he
felt like he was "all dressed up and nowhere to go". Still, he acknowledged
the importance of following the protocol for possible debris damage. "You
have to think of every eventuality," he said. "Better safe than sorry is a
good approach."

Rainy season

Usually there are two launch opportunities per day, each separated by 20
minutes, from this site just north of the equator. But to maximise the use
of fuel on the launch vehicle, Rosetta has just one chance to launch per
day.

Gravitational calculations have set Thursday's launch for 0736 and 50
seconds, one second after Wednesday's intended time. The launch window to
reach Rosetta's target - Comet 67P/Churyumov-Gerasimenko, or Chury - will
end on 17 March. Mission planners had aimed for the earliest launch
opportunity in case problems arose.

Roberto Lo Verde, a spokesman for ESA, says that lightning and low clouds
that block mission controllers' view of the launch vehicle are other weather
factors that can scupper a launch. The launch window to reach Comet Chury
falls during the rainy season in Kourou, and the hours preceding Wednesday's
scheduled launch were filled with rain.

"You come to the tropics, and it rains and you get winds," said Southwood.
"Everything was looking good two hours ago. Tomorrow is another day."

Gravitational fields

Rosetta has suffered more than its share of delays. Originally conceived in
1985, the mission was approved in 1993 and was due to launch in January 2003
to rendezvous with Comet Wirtanen. But Rosetta's managers decided to
postpone the mission after a new version of the Ariane-5 launch rocket blew
up in December 2002. The mission was redesigned entirely with a new flight
path and a new comet.

This is the first mission to attempt to orbit and land on a comet. Rosetta
will take ten years to reach Chury. During its long voyage it will fly three
times round the Earth and once around Mars, using the gravitational fields
of these planets to slingshot itself into the correct path for the
rendezvous.

A few months after the spacecraft meets Chury, it will release a small
cube-shaped lander on to the comet's icy core. The orbiter will then spend
two years circling Chury as it travels back towards the Sun.
Received on Thu 26 Feb 2004 11:34:18 AM PST