Columbia leaked hydrogen fuel during launch!
Chance of emergency landing loomed / safe return
to Earth / everything fine with Chandra
Hydrogen fuel was leaking from one of Columbia's three main engines
during the July 23 launch - and if the leak had grown, it could have
forced an emergency landing! The engine could have shut down abruptly after
overheating, and the orbiter would have had to make an unprecedented
emergency landing within minutes after launch - either back at the Kennedy
Space Center (Return to Launch Site) or in Africa (Trans-Atlantic Abort).
The leak of unknown origin, located in the cooling tubes of the engine's
nozzle where the hydrogen flows through, was discovered in hi-res photographs
of the launch. It was also the cause of the premature engine shutdown that
had left Columbia in a somewhat lower than planned orbit. What exactly had
happened in the engine is now being investigated after Columbia's safe
landing on July 28th.
The initial evidence that had pointed to a leak included a slightly higher
than normal temperature in the engine and launch photos showing a white
streak that could be escaping hydrogen. The initial inspection of the
suspect engine after landing has confirmed the leak: "It looks like several
of the tubes are damaged in the nozzle, and it looks like we had a real
hydrogen leak there," shuttle manager Bill Gerstenmaier said - in NASA-speak
that's "a significant failure." The same goes for the electrical problem that
occured seconds after lift-off. Commander Collins had reported that a
circuit breaker associated with an electrical bus on the Shuttle had popped
open during a transient short seconds after launch. The breakers will be
analyzed postflight to determine the exact cause of the problem. Meanwhile
the Chandra satellite is in excellent condition: Its own engine has started
to raise its orbit and all of Chandra's systems are functioning normally.
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Coverage of the fuel leak
from
CNN,
BBC,
ABC,
Florida
Today,
Space.com,
SpaceViews.
Chandra team ecstatic:
Florida
Today.
Short circuit just after launch doesn't faze Collins:
Florida
Today.
Tracking camera images
of Columbia's launch and pictures
from the
post-landing inspection.
SWUIS continues observations
from Columbia:
Homepage, a
CNN story.
Columbia returns safely -
but the problems were severe:
CNN
(first
engine check afterwards),
BBC,
ABC,
NYT,
Space.com,
SpaceViews
(engine check).
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Deep Space One's target gets a name: Braille
The target of NASA's Deep Space 1 mission now has a name: 9969 Braille, after
Louis Braille, the inventor of the language system that enables sightless
people to read. Astronomer Eleanor Helin, lead discoverer of the asteroid
formerly known as 1992 KD, selected Braille from hundreds of suggestions
submitted to The Planetary Society in a worldwide contest to name the object
that DS1 will encounter on July 29th. Kerry Babcock of Port Orange, Florida,
had submitted the winning name. His citation reads: "Louis Braille invented the
Braille language so those who could not see could obtain knowledge and explore
through the 'written' word.
Likewise, asteroid Braille provides knowledge about our universe and its
origin to the people of Earth, who through Deep Space 1, are also able to
explore and discover what previously they could not 'see.'" Mr. Babcock is a
software engineer at the Kennedy Space Center. A few years ago, he began to
learn to transcribe the braille system and was very impressed with Louis
Braille's achievement. Mr. Babcock gave his daughter the name "Braille," so
in a sense it is her namesake as well that is now traveling through the solar
system. According to a recent analysis of Braille's lightcurve by German
astronomers, the space rock measures about 1 x 2 km and rotates every 9.4
days. (DLR Press Release #46 of July 22nd and Planetary Society
Press Release of July 26th)
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Planetary Society Press Release.
Deep Space 1 Homepage at JPL.
Homepage at DLR.
July 25 Mission
Log.
Previews of the encounter from the
BBC,
ABC,
Space.com.
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The final week for the Lunar Prospector
has begun - and that's what's going to happen in the coming days:
- For July 26 a small orbit correction maneuver was planned to
raise periapsis up just enough (about 5 km) to last through the end of the
week. The velocity will be changed only 1.44 m/s and only 0.12 kg of
propellant will be used.
- On July 28, there was a lunar eclipse. This meant that for
several hours, the spacecraft did not see full sunlight even when it was on
the sun side of the moon, and so it was not able to fully recharge the
battery between nightside passes. Non-critical subsystems were turned off
to keep the battery from discharging below critical levels. First
indications are that the Lunar Prospector has survived the eclipse
and the - very cold - battery is recharging!
- On July 29, the spacecraft will be spun up to 23.7 rpm (from
nominal 12 rpm) at 15:30 UTC. This is in preparation for the velocity change
maneuvers later in the week which will target the spacecraft for impact.
Because these maneuvers will use the remaining usable fuel, the spacecraft
must be spun up to allow the fuel to reach the fuel lines to the jets.
- On July 30 at 08:15, a maneuver will be fired to raise apoapsis,
putting the spacecraft into a more elliptical orbit. Almost half of the
remaining propellant will be used to do this maneuver. This will be done so
that when we target for impact on July 31, we come in as steeply as possible to
hit the crater floor after passing over the rim of the crater.
- On July 31 at 09:16, the final maneuver will be fired to lower
periapsis beneath the lunar surface such that it will impact at the target
point of -87.7 deg latitude, 42 deg longitude. The velocity will be decreased
by 45 m/s, using 3.32 kg of propellant. The remaining 2.85 kg of propellant is
unusable, trapped in the propellant tank and lines. Because this maneuver
must be fired when the spacecraft is on the far side of the moon as seen
from earth, these commands will be loaded about an hour earlier with a time
delay built in so that they will occur at the proper time. If all goes
well, when the spacecraft passes behind the moon at 08:59 UTC, that will be
the last we hear from it. The impact site is so close to the pole, and the
spacecraft impact angle is so low (6.3 deg), the spacecraft will never be
in view of the tracking station before impact. The impact will occur at
09:51 UTC.
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"LunarImpact.com":
a special NASA
Website.
A major ground- and space-based
observing campaign of the impact is being put together right now:
Homepage.
Call for
Amateurs to try to observe the impact.
End of Mission
details -
and
fears
about the lunar eclipse.
News coverage of Prospector's possible eclipse problems from the
BBC,
SpaceViews.
A lunar burial for Gene...:
Homepage,
BBC,
Space.com stories.
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