NASA's
gleaming new Ares I-X rocket grew an odd-looking hood Wednesday as it launched
skyward on a suborbital test flight — a telltale sign of a rocket going
supersonic.
The hood was
actually a vapor cone, sort of like a man-made cloud, created as the long,
slender Ares I-X rocket hit Mach 1 and broke the sound barrier. Photographer Scott
Andrews caught the moment 39 seconds after the 327-foot (100-meter) rocket blasted
off from NASA's Kennedy Space Center in Florida. It can also be seen in NASA's video
of the Ares I-X launch.
The phenomenon
is not well studied, but has been seen on jet aircraft and spacecraft,
like NASA's space shuttles and the massive Saturn V rocket, as they surpass the
sound barrier. The vapor cone is also referred to as a shock egg or shock
collar.
Scientists think
the phenomenon is caused by something called the Prandtl-Glauert singularity
and starts when a layer of water droplets is trapped between two high-pressure
surfaces of air. In humid conditions, condensation can gather in the trough
between the two crests of sound waves produced by a launching rocket or flying
jet. It does not always coincide with breaking the sound barrier.
Photographers
caught a vapor cone on the 363-foot (110-meter) Saturn V rocket that launched
the Apollo 11, NASA's first manned moon landing mission in 1969. NASA
cameras also capture the phenomenon every now and then during space
shuttle launches, such as the STS-106 flight of Atlantis in 2000.
NASA's Ares
I-X rocket is a trial version of the new Ares I booster slated to launch the
crew-carrying Orion capsules that the agency plans to use once the shuttle fleet
retires. The prototype consisted of a four-segment solid rocket booster
(recycled from the space shuttle fleet's inventory) capped with a dummy fifth
segment and mock-ups of a second stage, Orion capsule and abort system.
NASA expected
the rocket to hit a maximum speed of Mach 4.7 before its first
stage separated from a dummy upper section two minutes after launch.
The first
stage carried parachutes to slow its return and splashed down in the Atlantic
Ocean to be recovered by a retrieval ship. The dummy second stage, however, was
discarded after separation. It crashed in the ocean further
downrange as planned.
The launch
test demonstrated the feasibility of the Ares I rocket design, mission managers
said. NASA's plan of using Ares I and Orion craft to replace the shuttle fleet
and return
astronauts to the moon by 2020 is currently under review by the White
House.
Click
here for SPACE.com's full Ares I-X mission coverage.
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