| |
ZL2VAL > SPACE 01.03.04 12:10l 86 Lines 3726 Bytes #999 (0) @ WW
BID : 820575ZL2VAL
Read: GUEST DK3EL
Subj: Ariane launch delayed again
Path: DB0FHN<DB0RGB<OE5XBL<OE3XSR<OK0PBX<OK0PAD<OK0PPL<DB0RES<ON0AR<LZ3NP<
VK6ISP<ZL2TZE<ZL3VML<ZL2BAU<ZL1AB<ZL2AB
Sent: 040301/0921Z @:ZL2AB.#46.NZL.OC #:36864 [New Plymouth] FBB7.00g
From: ZL2VAL@ZL2AB.#46.NZL.OC
To : SPACE@WW
Foam Damage to Ariane 5 Delays Rosetta Launch
By Peter de Selding
Space News Staff Writer
posted: 09:20 am ET
27 February 2004
KOUROU, French Guiana -- The launch of Europe's Rosetta comet-chaser
satellite was delayed until March 2 or March 3 following the discovery
that a piece of foam insulation had fallen off the rocket's main
cryogenic fuel tank.
The delay, the second in 24 hours, further reduced the number of launch
attempts that can be feasibly undertaken before the final launch
deadline of March 17. Theoretically a launch window of a few seconds
exists each day. However, the availability of cryogenic fuel at Europe's
Guiana Space Center and the need to permit tired launch crews to rest
means that the rocket will have no more than six or seven realistic
attempts to launch Rosetta by March 17 - the last day it can be launched
and still reach its intended target, said Jacques Louet, head of science
projects at the European Space Agency (ESA).
Jean-Yves Le Gall, chief executive of the Arianespace launch consortium,
said Feb. 27 that this would be plenty of time to launch Rosetta, which
already missed its January 2003 launch window -- and was forced to find
a new target comet -- because of reliability issues that kept the Ariane
5 vehicle grounded early in 2003.
ESA Director-General Jean-Jacques Dordain said Feb. 27 that the agency
remains confident that Rosetta, whose total budget is 1 billion euros
($1.25 billion), will make its Ariane 5 launch deadline. "The problem is
identified and the solution is simple. We will leave a couple of days
later on a 10-year trip. The satellite is in good shape."
Le Gall said a piece of thermal protection covering the cryogenic fuel
tank was found on the launch platform during a routine inspection of the
area late Feb. 26. The rocket's pre-dawn Feb. 26 launch attempt had been
cancelled because of high winds in the upper atmosphere. The piece of
insulating foam, measuring 10 by 15 centimeters, had likely fallen off
the tank after the cryogenic fuel tank was emptied in response to the
24-hour weather delay.
The Ariane 5 rocket's main cryogenic stage contains about 158,000
kilograms of liquid oxygen and liquid hydrogen. The tank is fueled
several hours before launch. To keep the fuel cold and to prevent ice
from forming on the tank's exterior in the warm, humid air of this
equatorial launch base, the tank is covered with foam insulation.
Gases sometimes are trapped in the small spaces between the tank and the
insulation. Le Gall said it is likely that when the tank was emptied and
the tank's surface temperature rose, this gas expanded and forced the
separation of the foam insulation.
The rocket will be returned to its assembly hall and its entire
cryogenic tank inspected to assure that no other pieces of insulation
have become partially unglued. Replacement foam will be added to the
spot where the insulation fell off. Once added the replacement foam
takes about 36 hours to solidify.
Le Gall said even a small exposed area of the fuel tank cannot be
tolerated. If the missing piece had not been detected, ice would have
formed on the tank just before launch and could have become a danger to
the rocket if it fell off during launch.
=========================
73 de Alan, (Sysop ZL2AB).
AX25:ZL2VAL@ZL2AB.#46.NZL.OC
APRS:!3903.34S/17406.45E]
IP :zl2val@qsl.net
Message timed: 22:14 on 2004-Mar-01 (NZT)
Message sent using WinPack-AGW V6.80
Points to ponder
~~~~~~~~~~~~~~~~
Marriage
~~~~~~~~
Getting married is very much like going to a restaurant with friends.
You order what you want, then when you see what the other person has,
you wish you had ordered that
Read previous mail | Read next mail
| |
