Dr. Tony Phillips has a great piece on the Science@NASA site commemorating the 37th anniversary of the lunar landing.
Have a listen and enjoy.
http://science.nasa.gov/headlines/y2006/19jul_seaoftranquillity.htm.
By Marc S. Posner
SOAR Magazine
The Shuttle Discovery and her six-member crew returned to Earth this morning, landing in Florida at 9:14 a.m. EDT. The picture-perfect approach and touchdown ends a 13-day mission to the International Space Station.
Discovery, howevery, appeared to show the effects of re-entry more than other past missions, with markings over a wide area below Commander Steve Lindsey’s window visible on NASA-TV coverage. The apparent heat markings continued along the upper body of the craft toward the tail area, where — likely coincidentially &151; one of Discovery’s hydraulic systems had been slowly during the mission.
Some concern had been raised during in-orbit inspections that a thermal blanket near Lindsey’s window had come loose. Eventually, engineers determined that there was no safety risk to Discovery and the crew, and the shuttle was cleared to return. A similar concern was raised, and dismissed, during last year’s return-to-flight mission — also flown by Discovery. [Contribute to a discussion about Discovery's mission here.]
NASA waited over weather concerns until the last-possible minute before approving Discovery’s de-orbit burn, a point of no return for the space craft. Then, the space agency had Discovery change course and head for an alternate runway, something that’s never been done that late in a mission.
Even still, Commander Steve Lindsey reportedly couldn’t see the runway until a minute before Discovery landed.
It was just one of a series of grey-hair-producing moments during just the second mission after Columbia burned up in the atmosphere while attempting to return to Earth on February 1, 2003. There were also concerns over additional foam loss, a lost tool during a spacewalk, teathers that came loose during the first two spacewalks and a leak in a hydraulic system.
While technically designated as a test flight, mission STS-121 visited the International Space Station, where the crew delivered supplies, made repairs and even left one of their own members to join the Expedition 13 crew on the space station.
The ISS provides a safe harbor for the shuttles in case of damage to the orbiter that would prevent it from returning to Earth. The station is also the reason the shuttle program is still in existance. President Bush has called for the fleet — which now includes only three shuttles: Discovery, Atlantis and Endeavour — to complete the ISS’s construction and then be retired.
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From NASA
Discovery is targeted for a landing at 9:14 a.m. EDT Monday at the Kennedy Space Center in Florida. For that landing, Discovery’s engines would be fired at 8:07 a.m. EDT Monday to begin its descent. A second opportunity is available for Discovery to land at Kennedy on Monday, beginning the descent with an engine firing at 9:43 a.m. EDT and leading to a touchdown in Florida at 10:50 a.m. EDT. Flight managers do not plan to consider other shuttle landing sites on Monday.
The weather forecast for landing on Monday calls for a chance of rain in the vicinity of Kennedy’s shuttle runway that could be unacceptable for Discovery’s landing.
Discovery Commander Steve Lindsey and Pilot Mark Kelly checked the shuttle landing systems and steering jets early today. A test run of one of the three generators that power the shuttle hydraulics found that auxiliary power unit operating normally. A minute leak in that system has remained at expected levels. All three units are planned to be run as normal for landing.
The astronauts spent the rest of their planned final full day in orbit stowing gear and securing the shuttle for the trip home. Key events leading up to Discovery’s first landing opportunity on Monday include:
5:27 a.m. EDT — Discovery’s payload bay doors are closed
7:07 a.m. EDT — Discovery’s astronauts begin to strap in for landing
7:48 a.m. EDT — Mission Control “go” or “no-go” for the deorbit engine firing
Shuttle Discovery and the now-six-member crew undocked from the International Space Station just after 6 a.m., EDT, ending a 9-day visit that included repairs, delivery of supplies and transportation of a new crew member to the orbiting outpost.
Mission STS-121 is scheduled to end when Discovery returns to Florida on Monday.
from NASA
Mission Specialists Mike Fossum and Piers Sellers successfully completed STS-121’s third and final spacewalk at 2:31 p.m. EDT today. The demonstration of orbiter heat shield repair techniques was the objective of the 7-hour, 11-minute excursion outside Space Shuttle Discovery and the International Space Station.
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By Marc S. Posner
SOAR Magazine
Two Discovery astronauts are conducting a 6 1/2-hour spacewalk in which they will test NASA’s ability to repair damage to the shuttle’s heat-absorbing tile system while in orbit.
Mission Specialists Mike Fossum and Piers Sellers began the spacewalk at 7:20 a.m. EDT. It is the third spacewalk conducted by the STS-121 crew during Shuttle Discovery’s stay at the International Space Station.
The two astronauts are working on pre-positioned heat shield materials in Discovery’s the payload bay. Among the tools they are using are a space-certified caulk gun and a variety of spatulas to manipulate the test materials.
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By Marc S. Posner
SOAR Magazine
After reviewing video and photos taken during launch, ascent, orbit and approach to the International Space Station, NASA mission managers have determined that Discovery is fit to return to Earth at the end of the planned 12-day mission.
Just like last summer’s return-to-flight mission, there was concern raised about “protruding gap fillers” — cloth material used to fill the spaces between the thermal tile on the shuttle. One in particular caused concern because of its proximity to a door covering a connection point for the external tank.
The review of the evidence prompted mission managers to forgo a spacewalk similar to one conducted last summer to pluck the material from between the tiles.
“That is great news, that’s fantastic. And to get all that done by the end of flight day six when we did the focused inspection on flight day four is just amazing,” STS-121 Commander Steve Lindsey said after being told by Mission Control that the orbiter’s thermal protection system was 100% cleared for entry.
He also expressed thanks to the review teams.
From NASA
Astronauts from Space Shuttle Discovery prepared the International Space StationÂ’s rail car for restoration and tested a repair crane during a 7 hour 31 minute long spacewalk today, while their colleagues delivered a new oxygen generator and laboratory freezer to the station.
Mission Specialists Piers Sellers and Mike Fossum turned their spacesuits to battery power to officially start the spacewalk at 8:17 a.m. CDT. After they configured their tools and safety tethers, they moved to the S0 Truss and installed a blade blocker in the zenith Interface Umbilical Assembly to protect the undamaged power, data and video cable. Then they rerouted that cable through the IUA so the Mobile Transporter rail car could be moved into position on the truss for replacement of the Trailing Umbilical System containing the severed power and data cable during a spacewalk Monday.
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Discovery has docked with the International Space Station, just the second time a US spacecraft has visited the orbiting outpost since Columbia burned up in the atmosphere in February, 2003.
One of Discovery’s crew members will remain aboard the ISS while supplies will also be delivered during the 12-day shuttle mission. Two spacewalks will also include repairs to the station.
from NASA
At an evening press conference Tuesday at NASA’s Kennedy Space Center in Florida, Space Shuttle Program Wayne Hale reported that the external tank’s performance was greatly improved during the launch of Space Shuttle Discovery at 2:38 p.m. EDT.
“I have a good report,” Hale said. “The tank performed very, very well indeed.”
Based on early analysis of photographs taken during ascent, just a few items have been identified for further study. Some involve debris particles shed by the massive orange tank, which supplies liquid oxygen and liquid hydrogen to the orbiter’s three main engines during the climb to orbit. The particles observed are small, and all occur after the time frame — up to two minutes, 15 seconds into ascent — that engineers consider to be the most aerodynamically sensitive time for the shuttle.
About fifteen minutes into the flight, astronauts on board Discovery filmed a large piece of ice tumbling away from the orbiter. The ice, which forms on the exterior of the main engines, has been observed on previous flights and is not considered an issue.
“We don’t see any concern for the orbiter,” Hale reported, and added that in the coming days, the STS-121 crew will take a closer look at Discovery using the orbiter boom sensor system as well a slow back flip that will allow further photography of the orbiter from the International Space Station.