NASA’s last-ever space shuttle, Atlantis, rocketed skyward Friday, carrying four astronauts into space. The Associated Press reports:

Atlantis and four astronauts rocketed into orbit Friday on NASA’s last space shuttle voyage, dodging bad weather and delighting hundreds of thousands of spectators on hand to witness the end of an era.

It will be at least three years — possibly five or more — before astronauts launch again from U.S. soil, and so this final journey of the shuttle era packed in crowds and roused emotions on a scale not seen since the Apollo moon shots.

After days of gloomy forecasts full of rain and heavy cloud cover, the spaceship lifted off at 11:29 a.m. — just 2½ minutes late — thundering away on the 135th shuttle mission 30 years and three months after the very first flight. The four experienced space fliers rode Atlantis from the same pad used more than a generation ago by the Apollo astronauts.

The shuttle was visible for 42 seconds before disappearing into the clouds.

The Post’s Brian Vastag was in Cape Canaveral to watch the launch Friday. He writes:

Riding a column of flame and smoke, space shuttle Atlantis glided skyward this morning at 11:29 a.m., the roar of its rockets building to a ground-shaking rumble as cheers erupted at the Kennedy Space Center’s storied countdown clock.

Carrying the burden of history, Atlantis pierced the low cloud deck that threatened to scrub this final space shuttle launch, its tail glow lighting a ring beneath the clouds as the craft slipped skyward.

Before liftoff, the clock froze at 31 seconds, leaving the crowd standing for an extra 21 / minutes of will-she-or-won’t-she anticipation as engineers faced a final, minor hiccup. After confirming retraction of a vent arm at the launch pad, mission control gave the go-ahead, sending Atlantis on its way.

Eight and a half minutes later, soaring at 17,000 miles an hour above Earth, Atlantis shut off its main engines for the last time, having achieved orbit for a final 12-day mission, carrying Commander Chris Ferguson, pilot Doug Hurley, and mission specialists Sandra Magnus and Rex Walheim.

“This is mission control Houston,” said liftoff announcer Rob Navias from mission control in Houston. “Atlantis is safely in its preliminary orbit.”

Read Brian Vastag’s tweets from Cape Canaveral here

The Post’s Joel Achenbach reminds us that the space shuttle flights are a dangerous business. He writes:

Human spaceflight is dangerous — and it’s about to get more so, according to former Johnson Space Center director Christopher Kraft, who says NASA is making a mistake by retiring the space shuttle.

Kraft has co-written a letter, endorsed by a number of Apollo-era NASA veterans and astronauts, contending that the international space station will become more hazardous for astronauts without the shuttle’s resources as an emergency backup.

“I think they’ve got their head in the sand,” said Kraft, who was NASA’s first flight director.

He said the shuttle’s robotic arm has no duplicate on the Russian Soyuz spacecraft, which NASA will need to rely on for several years as the private sector develops new vehicles for getting astronauts into orbit. Nor can the Soyuz permit two astronauts to conduct spacewalks simultaneously, Kraft said. Such spacewalks might be necessary if the station lost power or underwent decompression.

“In a worst-case scenario, deterioration and loss of systems on an abandoned ISS could result in an uncontrolled, catastrophic reentry with risks to populated areas around the world,” the letter states.

Robert L. Crippen, pilot of the first shuttle mission in 1981 and one of the letter’s endorsers, said the shuttle’s retirement will make it impossible to replace large components on the station should they fail. The Soyuz payload capacity is much smaller than the shuttle’s.

“If it runs into any significant problem, it could be the demise of the station,” Crippen said.

As the shuttle era ends, Brian Vastag says that questions loom for the shrinking astronaut corps. He writes:

When astronaut Garrett Reisman returned from an 11-day space shuttle mission last May, he knew he was headed to the back of the line. If he wanted to return to orbit, he would have to wait at least five years for a second tour aboard the international space station, which he had called home for 95 days in 2008.

And even if he were offered a chance to return to space, Reisman would have to fly aboard a cramped Russian capsule, not an American space shuttle. After NASA’s Atlantis rolls to a stop later this month, the Soyuz will be the only ride to space — and slots are limited.

For the foreseeable future, NASA plans to send just four to six astronauts — American and international — to the space station each year, paying Russia up to $56 million per seat.

Instead of waiting, Reisman joined a steady flow of astronauts drifting away from NASA like so many untethered spacewalkers.

More from the Washington Post

Full coverage of the shuttle launch

NASA endangering space station by retiring shuttle

Q and A with former astronaut

Space station research ramps up as shuttles return to Earth

NASA space shuttles have traveled more than 500 million miles since 1976