Space Shuttle Atlantis thundered into a hazy blue sky at Florida's Kennedy Space Center on Monday, on its way to rescue the Hubble Space Telescope, whose batteries, cameras and gyroscopes are badly in need of replacement.
Seven astronauts are on board the shuttle, led by Cdr. Scott Altman. Despite one warning signal right after liftoff, they safely reached orbit within eight minutes. They are flying at more than 17,200 miles per hour.
If all goes well, they will catch up with the Hubble, 350 miles out in orbit, on Wednesday. Then they will begin five days of space walks to repair the telescope.
This mission --designated STS 125 by NASA -- is the last chance to save the Hubble -- and it's a mission that nearly didn't happen at all.
Astronauts and scientists had to fight to restore the mission.
Shaken by the Columbia disaster in 2003, NASA actually cancelled the planned fifth Hubble repair mission, as they thought it was much too dangerous because there was no easy way to rescue the crew if something damaged the space shuttle.
"The bulk of the people said this is crazy," astronomer Sandra Faber said. "It is not that much risky. Nobody in my community really bought the risk argument. And to compound the issue was the fact that at that time there were 27 flights scheduled to finish the space station, which astronomers can't see that much use for. The astronauts are chomping at the bit to go fix Hubble because they love it."
Astronauts like John Grunsfeld say Hubble's potential is infinite.
"Each time we go back to Hubble we re-invent the telescope, we bring up new instruments allowing Hubble to see new areas we have never seen before," he said. "And so what I always think about is, when we put the new wide-field camera in or the cosmic origins spectrograph in -- two of the new instruments -- what will be that next great discovery that no one has thought of before?"
Grunsfeld will be making his fifth spaceflight on this mission, and this is his third trip to Hubble.
But when NASA talks about the risks facing the astronauts, they don't just mean the possibilty of debris hitting the orbiter during launch, which was what happened to Columbia. They also mean the threat of micro-meteorites hitting the orbiter while the astronauts are fixing Hubble.
Hubble orbits about 350 miles above Earth, in an area with a higher density of debris. Earlier this year two satellites collided over Siberia, which has increased the risk even more, as junk from that collision drifts lower.
As soon as Atlantis fixes Hubble, and releases it back into orbit, it will immediately maneuver to a lower altitude to reduce chances of getting hit by space junk.
The most dramatic step NASA has taken to reduce risk is the preparation of a full-scale rescue mission.
In the event that Atlantis sustains damages the crew cannot repair, a second space shuttle, Endeavor, is standing by on another launch pad at the Kennedy Space Center to rescue crew members.
STS 400 can be ready in three days if a rescue is necessary.
Spacewalker Mike Massimino, a member of the Atlantis crew, admits the risk.