Dropping through a clear sky under a huge orange-and-white parachute, the charred Soyuz descent module landed upright and on target near the town of Arkalyk at 1:23 a.m. EDT (11:23 a.m. local time).
"And the search and recovery forces now report the Soyuz TMA-18 has landed," said Rob Navias, mission control commentator at the Johnson Space Center in Houston.
"The soft landing engines are reported to have worked perfectly. Alexander Skvortsov, Tracy Caldwell Dyson, and Mikhail Kornienko are back on Earth after 176 days in space," Navias said.
Russian recovery forces, including NASA flight surgeons and support personnel, rushed to the landing site from nearby staging areas to assist Skvortsov, Kornienko, and Caldwell Dyson as they began the process of re-adapting to Earth's gravity after 176 days in space.
But all three appeared relaxed and in good spirits after they were assisted from the spacecraft, enjoying fresh fruit and chatting with the recovery team.
After initial medical exams, all three crew members were to be flown to Karaganda for a traditional Kazakh welcome. Skvortsov and Kornienko then planned to head for Star City near Moscow, while Caldwell Dyson was scheduled to fly back to the Johnson Space Center in Houston aboard a NASA jet.
Strapped into the Soyuz TMA-18 spacecraft, the same vehicle that carried them into orbit April 2, Skvortsov, Kornienko, and Caldwell Dyson undocked from the space station's upper Poisk module at 10:02 p.m. Friday.
An attempt to undock Thursday night was blocked by problems with a sensor in the docking mechanism holding the Soyuz to the Poisk docking port. After extensive troubleshooting, station flight engineer Fyodor Yurchikhin installed jumper cables that emulated the expected signals from a bypassed "hatch locked" sensor, restoring the docking system to operation.
There were no problems during the second undocking exercise Friday, and after moving the Soyuz a safe distance away, Skvortsov fired the ship's braking rockets for four minutes and 21 seconds starting at 12:31:17 a.m. Saturday. That slowed the craft by about 258 mph and put it on course toward the targeted landing site.
After a half-hour free fall, the Soyuz TMA-18 descent module fell into the discernible atmosphere at an altitude of about 63 miles at 12:59 a.m. Parachute deployment was normal, and the capsule touched down without incident.
The most dramatic moments of the crew's six months in space came at the end of July, when one of the space station's two coolant loops shut down because of an ammonia pump failure.
Forced to power down numerous space station systems to prevent overheating, the station crew quickly geared up for a complex three-spacewalk repair job by Caldwell Dyson and Douglas Wheelock.
"What would historians write about this increment? Well, certainly the headline would be the pump module remove and replacement--the day the ammonia stopped flowing in loop A and the three dramatic spacewalks and all of the work that was involved to change those out in the limited amount of time we felt we had," Caldwell Dyson said before undocking.
"I think historians could write a whole lot about that, everything from the problem itself to how this space station is so robust that it can withstand a failure like that," Caldwell Dyson said.
After the successful spacewalks, Caldwell Dyson told CBS News the experience was "awe inspiring."
"You know, for the last four or five months I've been looking out our cupola window at the sunrises and sunsets and been brought to tears by the multitude of stars once the sun goes down," she said. "And I wondered just how I would feel when I went out there.
"For me, my first [walk] was a culmination of 12 years of training and being here and watching and learning and having a huge desire to do that. And so the feeling I was having out there, being on structure, outside the space station, was as emotional as you can get in [a spacesuit], looking out at the sunrise for the first time. It was, like I said, a culmination of so much desire and years of training; it was a feeling I'll never forget."
In an interview last week with ABC News, Caldwell Dyson said she would miss her two crewmates "because as soon as we land...I get on a plane and I come right back to Houston. And my two Russian crewmates, who I spent all my time with, I won't be able to see for a couple of weeks.
"I'm definitely going to miss the views," she added. "I don't think there's a time I could enter the cupola with the intent of staring at the views and not get a little choked up thinking this might be the last time. But then I'm also encouraged by the fact that not too many people get to see that view, and I try to take it in (so) I can help describe it to folks when I come back, and help them feel a little bit of it.
"The one thing I'm not going to miss is the lack of longevity in my toothbrush. I'm really looking forward to having running water," she laughed.
The departure of Soyuz TMA-18 left the International Space Station with a crew of three: Expedition 25 commander Wheelock, Yurchikhin, and Shannon Walker.
They will have the station to themselves for the next two weeks before the arrival of three fresh crew members aboard an upgraded Soyuz TMA-01M spacecraft scheduled for launch Oct. 7.