CAPE
CANAVERAL, Fla. NASA's planned launch of the space shuttle Endeavour tonight
isn't likely to form beautiful trails of glowing clouds like those of previous
liftoffs, weather experts at Kennedy Space Center (KSC) said.
NASA's June
space shot of Atlantis produced one
such striking display of the noctilucent -- or night-shining -- clouds, as
well as with the launch of the Mars-bound
Phoenix spacecraft last weekend. Weather experts here at KSC, however,
aren't crossing their fingers for a rare appearance of the clouds after shuttle
Endeavour launches at 6:36 p.m. EDT (2236 GMT) tonight.
"I'd
be surprised to see noctilucent clouds after this launch," said John
Madura, KSC's weather office manager. "We'll see the standard rocket
exhaust plume and that may be pretty, but we probably won't see the
clouds."
But Tim
Garner, a spaceflight meteorologist at NASA's Johnson Space Center (JSC) in
Houston, Texas is more optimistic about seeing the rocket-induced clouds 10 to
20 miles (16 to 32 kilometers) above Earth.
"The
launch is so close to sunset, I think we have a decent shot at seeing
some," Garner said. "The clouds will be diffuse, but we'll have a
good lighting angle."
Cloudy
recipe
Madura
explained that forming the glowing clouds from rocket exhaust follows a
sensitive recipe: Made mostly of water, the exhaust plume must freeze into ice
crystals and reflect sunlight just before sunrise or after sunset after
high-altitude winds blow them around.
"You
need the right moisture, the right altitude and the right angle of light coming
from the sun," he said. Too much sunlight hides the thin clouds, while too
little fails to light them up well enough to see in darkness.
Understanding
how natural
night-shining clouds form, however, continues to elude researchers.
"The
best knowledge we have suggests it's too dry for them to form, but they form
anyway," said KSC atmospheric scientist Frank Nerceret. "We need to
find out why that's happening, which is why we recently launched a new
satellite."
That
satellite, launched in April on NASA's Aeronomy of Ice in the Mesosphere (AIM)
mission, will monitor the natural formation of the clouds near the polar
regions of Earth to shed light on the mysteries of noctilucent cloud formation.
Endeavour's
STS-118 astronaut crew is commanded by veteran astronaut Scott Kelly and
includes NASA's first professional educator
astronaut Barbara Morgan, who first joined the agency in 1985 as the backup
for Teacher in Space Christa McAuliffe before the Challenger tragedy. The
planned 11-to-14 day mission will deliver fresh cargo, spare parts and a new
starboard-side truss segment to the International Space Station in Earth orbit.
Click here for SPACE.com's
STS-118 launch and mission coverage.
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