NASA to try launching shuttle next week

CAPE CANAVERAL, Fla. - NASA managers announced Thursday that they would press ahead with the first space shuttle launch of the year next week, three months later than originally planned because of a hail storm that pockmarked the spacecraft's external tank.

After a two-day meeting at the Kennedy Space Center, NASA officials agreed to launch Atlantis at 7:38 p.m. EDT June 8 on a mission to deliver a new pair of solar arrays to the international space station.

"The team is really pumped to get this done this time," said Mike Leinbach, NASA launch director. "We've been doing three months of down time due to the hail storm."

The launch had been set for mid-March, but the storm dropped golf-ball sized hail on the launch pad and damaged insulating foam on the external tank.

NASA managers are especially cautious when it comes to the external tank since a piece of foam fell off Columbia's tank in 2003 and hit the spacecraft's wing. Damage from the impact allowed fiery gases to penetrate Columbia during descent, killing all seven astronauts aboard.

After the hail storm, Atlantis was rolled back to the Vehicle Assembly Building, where technicians painstakingly repaired thousands of gashes in the tank's foam.

"We are extremely confident that we have done perfectly good repairs and have a tank that is safe to fly," said space shuttle program manager Wayne Hale.

Engineers have put the probability of foam coming off a failed repair area and causing critical damage to the shuttle at 1 in 650, Hale said, but "probability numbers I would take with a good grain of salt."

"All of that is good as a management tool," he said. "But I wouldn't take any of those numbers to the bank as a real indication of where you would put your money on the roulette wheel in Las Vegas."

Although a final polling of managers was unanimous to go ahead with a launch attempt, managers initially argued over whether bolt parts that hold in place pumps in the shuttle's main engines should be replaced because there was evidence that they could corrode with age. They eventually concluded that the pumps on Atlantis weren't old enough to have that problem and that an inspection of Atlantis' pumps had turned up nothing.

The postponement of Atlantis' launch forced NASA to cut the expected number of shuttle flights this year from five to four and pushed back the flight schedule for the rest of the year.

Astronaut Clayton Anderson was added to the previously six-person Atlantis crew so he can replace U.S. astronaut Sunita Williams on the space station. Otherwise, Williams would have spent eight months at the station, instead of the more typical six months. Her original return trip to Earth aboard shuttle Endeavour was pushed back from early July to late August.

Good question,, THanks for asking,. I don’t know. :-}

Those things do leave a mark tho, sort of.

Rocket Exhaust Leaves Mark Above Earth
http://www.space.com/scienceastronomy/shuttle_clouds_030610.html

http://www.space.com/scienceastronomy/shuttle_clouds_030610.html

By Robert Roy Britt

10 June 2003

Water-laden exhaust from a space shuttle can drift over the North Pole and create elusive high-altitude clouds visible only at night, according to a surprising new study.

The discovery was made serendipitously with data collected by a German satellite launched and retrieved eight days later during a Space Shuttle Discovery mission. Surprised scientists watched the clouds develop from water that had been shuttled into the upper atmosphere by the very craft that lofted the satellite into orbit. Ground-based observations helped confirm the exhaust plume’s travels.

The findings, from mission STS-85 in 1997, were reported May 31 in the journal Geophysical Research Letters.

The cloud type that developed, called noctilucent, also occur naturally. Scientists know little about how or why they form. The clouds are too thin to see from Earth during the day and become visible only after sunset, when the lower atmosphere darkens and the Sun continues to reflect off the clouds.

A shuttle’s exhaust is 97 percent water, a byproduct of liquid hydrogen and liquid oxygen. About half of the water vapor produced by the main fuel tank ends up in the thermosphere, Earth’s relatively warm and outermost atmospheric region that begins about 55 miles (88 kilometers) up.

An investigation of the satellite’s data, collected during eight days of orbits, showed that water vapor from the shuttle traveled to the Arctic in the thermosphere. The vapor then settled down to the chilly mesosphere, about 51 miles (82 kilometers) high.

In the mesosphere, where temperatures can drop below minus 220 degrees Fahrenheit (minus 140 Celsius), the vapor turned into ice particles, making clouds.

Drop in the bucket?

At first thought, it might seem like a shuttle’s exhaust would be a drop in the atmospheric bucket of moisture.

“Indeed, this was a surprise to us,” said study leader Michael Stevens, a physicist at the Naval Research Laboratory in Washington.

But the outer atmosphere is thin and tenuous. A little goes a long way.

“It’s a little like pouring a bucket of water onto your driveway — spatially, the repercussions can be quite widespread,” Stevens told SPACE.com. “Lower in the atmosphere, there is much more water, so it would be like pouring a bucket into a swimming pool.”

He noted that mysterious noctilucent clouds have been spotted since at least the late 19th Century, so rockets are not their only cause.

Much of the study was based on the Naval Research Laboratorys Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) instrument, which was aboard the satellite. The research was funded in part by NASA.

Contrail cousins

The shuttle-inspired clouds are not very similar to condensation trails left by commercial airliners, which are created just as the exhaust is emitted, and at much lower altitudes.

Jet contrails, as they’re often called, involve particles in exhaust that give water vapor a place to condense. While the exhaust can be humid, the process relies on water vapor already in the atmosphere.

A study performed in the days after the Sept. 11, 2001 terrorist attacks, when U.S. skies were clear of airplanes, found that contrails have a small but measurable effect on daily temperatures on Earth. The temperature range was more than one degree Celsius (about 1.8 degrees Fahrenheit) larger than when contrails were present, scientists reported in the journal Nature.

Meteorologists sometimes glean information from jet contrails. How readily one forms, and how long it persists, suggests how much moisture is in the air. Contrails also contribute about 1 percent of manmade greenhouse effects, a 1999 report showed.

More study needed

Stevens and his colleagues never intended to track Discovery’s emissions.

But over the mission’s first two days, they noticed signatures of the water vapor plume high above the Arctic that “got our attention, and one thing led to another. This was not the plan; the shuttle plume was never considered in any of our operations. Sometimes, some of the most interesting science comes to you.”

More work is needed to understand how the plume moved northward so quickly.

Also, with only one study of rocket-fueled clouds to go on, it’s not clear if the Space Age alters the atmosphere much beyond creating a few high, mostly invisible clouds. Stevens said the study found no evidence for any other environmental effects.

Other rocket launches might also contribute to the formation of noctilucent clouds, he said, but further study is needed to find out.

“The shuttle injects by far the most water per launch into the upper atmosphere of any launch vehicle currently operating,” Stevens said.

With dozens of other rockets going up in a typical year, his team would like to study their possible cumulative effect in generating the mysterious polar clouds.

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.