UPDATE: 7:55 p.m. EST

MRO project scientist Richard Zurek said that two of the eight science investigations set for NASA's Mars Reconnaissance Orbiter replace ones lost in 1999 aboard the Mars Climate Orbiter. One other mirrors one that was lost aboard the Mars Observer.

"So this is a very emotional time for me," Zurek said.

A navigation error sent the Mars Climate Orbiter plunging into Mars' atmosphere, where it burned up, instead of into a proper orbit in September 1999. Mars Observer was lost three days before entering orbit around Mars in August 1993.

NASA's post-orbital arrival briefing has ended. This concludes SPACE.com's live coverage of the Mars Reconnaissance Orbiter's red planet arrival. An updated wrap up of today's events will be posted to SPACE.com's home page shortly.

UPDATE: 7:33 p.m. EST

NASA's post-orbit insertion press conference for its Mars Reconnaissance Orbiter has begun.

"It's really great to be here right now, I've got to tell you," said James Graf, NASA's MRO project manager at JPL. "Today was picture perfect, I though today was a simulation because we were so right on."

SPACE.com's initial wrap up of today's Mars Reconnaissance Orbiter red planet arrival is available here.

UPDATE: 5:45 p.m. EST

NASA has ended its live webcast of the Mars Reconnaissance Orbiter arrival at Mars.

The spacecraft successfully entered orbit around Mars after a 27-minute engine burn that began at 4:24 p.m. EST (2124 GMT).

NASA will hold a press briefing on today's MRO arrival at 7:30 p.m. EST (0030 March 11 GMT).

You are invited to watch the briefing live using SPACE.com's NASA TV feed, which is available by click the link at left.

UPDATE: 5:45 p.m. EST

NASA's Mars Reconnaissance Orbiter is now the third U.S orbiter to enter Mars orbit and the fifth NASA probe to begin simultaneous operations at the red planet.

The probe joins NASA's Mars Global Surveyor and Mars Odyssey in orbit and the twin Mars rovers Spirit and Opportunity currently on the planet's surface. Europe's Mars Express orbiter is also actively studying the planet from orbit.

"Now we have a permanent scientific presence around another planet," said Charles Elachi, director of NASA's Jet Propulsion Laboratory (JPL), after MRO entered orbit.

James Graf, MRO project manager at JPL, lauded the efforts of his flight control team.

"I'm proud of all of you," he said just after MRO's orbital status was confirmed. "It went picture perfect...we couldn't have planned it better."

UPDATE: 5:37 p.m. EST

From SPACE.com Senior Space Writer Leonard David at Lockheed Martin Space Systems - builders of the Mars Reconnaisance Orbiter (MRO) - near Denver, Colorado:

MRO's team of spacecraft builders here at Lockheed Martin Space Systems are jubilant, given the word that the spacecraft has reemerged from behind Mars relative to Earth. The acquired signals from the Mars craft confirm that it was right on the money in its burn.

"Mr. O is in orbit," said one observer. "Yeah, for physics!"

The battery power on MRO is at 109 percent, which is terrific, said Steve Jolly, a spacecraft engineer here at Lockheed Martin Space Systems.

"We still have a long ways to go, but we're set up really well, said Joe Witte Payload Integration Lead for Lockheed Martin Space Systems.

The process of aerobraking will start at end of this month. "We call it toe-dipping," Witte told SPACE.com.

NASA's Mars Reconnaissance Orbiter has successfully entered orbit around the red planet, NASA said.

UPDATE: 5:20 p.m. EST

NASA's Mars Reconnaissance Orbiter has successfully entered orbit around the red planet, NASA said.

Flight controllers at NASA's Jet Propulsion Laboratory (JPL) erupted into applause on NASA Television and shouted for joy after receiving confirmation.

Mars Reconnaissance Orbiter flight controllers jumped for joy after receiving their first signals from their spacecraft since it passed behind Mars.

The spacecraft has survived its swing around Mars and flight controllers are checking its telemetry to determine whether the probe completed its Mars orbit burn successfully.

Several JPL flight controllers have shouted that MRO is "right on the money," though telemetry analysis continues.

UPDATE: 5:12 p.m. EST

James Graf, NASA's project manager for the Mars Reconnaissance Orbiter mission at JPL, said flight controllers can only wait to learn if their spacecraft is healthy and on track.

"We are in the dark, we're waiting to see," Graf said.

MRO should have completed the first part of a small manevuer to point it back toward the Earth. By 5:16 p.m. (2216 GMT), flight controllers expect to receive their first signals from the spacecraft since it past behind Mars.

"That just means it's calling home," Graf said, adding that it will take several additional minutes before flight controllers can determine whether MRO is on course and in Mars orbit.

UPDATE: 4:54 p.m. EST

According to its flight plan, NASA's Mars Reconnaissance Orbiter should have finished its orbital insertion burn and is coasting around the red planet.

Flight controllers at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California and MRO-builder Lockheed Martin Space Systems near Denver, Colorado still have more than 20 minutes to wait before learning whether the burn was successful.

UPDATE: 4:47 p.m. EST

NASA's Mars Reconnaissance Orbiter (MRO) has passed behind the red planet and flight controllers on Earth have lost contact with the probe.

The probe passed behind Mars at 4:46:23 p.m. EST (2146:23 GMT), according to flight controllers at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. Loss of signal was anticipated and MRO is expected to perform six more mintes of engine burn.

"It looked like it disappeared at the right time," said Steve Jolly, a Lockheed Martin Space Systems engineer at the firm's MRo control center near Denver, Colorado.

The probe should swing clear of Mars at 5:16 p.m. EST (2216 GMT).

SPACE.com Senior Space Writer Leonard David is reporting from Lockheed Martin Space Systems - builders of the Mars Reconnaisance Orbiter (MRO). Staff Writer Tariq Malik is writing from New York City.

UPDATE: 4:28 p.m. EST

BURN! NASA's Mars Reconnaissance Orbiter has ignited its six main engines and started the 27-minute burn to place itself in orbit around the red planet.

At JPL, mission controllers passed around the traditional jar of peanuts for good luck and erupted into applause as burn telemetry reached Earth. There is a 12-minute communications delay between MRO and earth due to the more than 300 million miles separating the two worlds.

The maneuver is scheduled to last about 27 minutes, though flight controllers at NASA's Jet Propulsion Laboratory in Pasadena, California and Lockheed Martin Space Systems - which built the probe - near Denver, Colorado will only be in contact with MRO for the first 21 minutes.

"This is the first sense of gravity since the spacecraft was launched," said Joe Witte, Payload Integration Lead for Lockheed Martin Space Systems near Denver, Colorado.

SPACE.com Senior Space Writer Leonard David is reporting from Lockheed Martin Space Systems - builders of the Mars Reconnaisance Orbiter (MRO).

UPDATE: 4:20 p.m. EST

From SPACE.com Senior Space Writer Leonard David at Lockheed Martin Space Systems - builders of the Mars Reconnaisance Orbiter (MRO) - near Denver, Colorado:

MRO has moved itself into the correct burn attitude, with the burn underway, Joe Witte Payload Integration Lead for Lockheed Martin Space Systems.

Propulsion engineers here are keeping a vigil on their monitors as the seconds fly and MRO continues to put on the brakes. Confirmation of the burn, however, is still to come as signals from the spacecraft race across space to Earth controllers.

MRO is expected to ignite its six main engines for today's orbital insertion burn at 4:24 EST (2124 GMT).

UPDATE: 4:16 p.m. EST

From SPACE.com Senior Space Writer Leonard David at Lockheed Martin Space Systems - builders of the Mars Reconnaisance Orbiter - near Denver, Colorado:

MRO's telecom system has transferred to low-speed mode as planned and NASA's Deep Space Network has locked onto the low-speed rate. So all continues to be "go" in readying for the braking of the spacecraft, said Joe Witte Payload Integration Lead for Lockheed Martin Space Systems.

"Everything is clicking along as expected," Witte said.

UPDATE: 4:10 p.m. EST

NASA reports that its Deep Space Network stations in Spain and California have picked up the Mars Reconnaissance Orbiter's (MRO) low-gain antenna signal. NASA is providing access to MRO's doppler signal live here.

At 4:07 p.m. EST (2107 GMT), MRO was slated to fire its small thruster jets to turn itself into the proper position for today's orbital insertion burn maneuver. The burn is set to start just past 4:24 p.m. EST (2124 GMT).

MRO navigation controllers at the Jet Propulsion Laboratory confirmed that the Mars probe began the turn manevuer.

UPDATE: 4:01 p.m. EST

MRO is less than three minutes from switching to its low-gain antenna.

UPDATE: 4:00 p.m. EST

MRO has cleared one of its first hurdles in today's Mars orbit insertion process by pressurizing its fuel tank with helium.

During the process, two small pyrotechnic charges blow to open valves in pencil-thin tubes and allow helium, a pressurant gas into MRO's fuel tank.

"That was easy," a flight controller said at NASA's Jet Propulsion Laboratory in Pasadena, as applause broke out.

Meanwhile, SPACE.com Senior Space writer Leonard David reports from Lockheed Martin Space Systems near Denver, where engineers anxiously awaited word that MRO's main tank had been pressurized. The firm designed and built MRO.

Applause broke out here after minutes of ground controllers holding their breath. The signal took 12 minutes to reach the control center here.

The key propellant line valve has opened, with pressure gauges rising to confirm the event.

"The pressurization has been confirmed," said Lockheed Martin engineer, Steve Jolly.

"We have pressurized, so everything is go," said Kevin McNeill, program manager at Lockheed Martin for MRO. "We are ready to capture into Mars Orbit. Everything is going really well," he said.

The next major event for MRO is to switch to its low-gain antenna. The probe's high-gain antenna - a 10-foot (three-meter) dish - can transmit signals faster, but must always be pointed at Earth. MRO will instead use its low-gain antenna to maintain continous contact with Earth before passing behind Mars. We are about 24 minutes from the start of MRO's orbital burn.

UPDATE: 3:45 p.m. EST

From SPACE.com Senior Space Writer Leonard David at Lockheed Martin's MRO Control Center in Colorado:

One might think that the Mars rovers - Spirit and Opportunity - have a ring-side seat to the Mars Reconnaissance Orbiter's insertion burn blazing bright in the martian sky.

They do, but the robots won't be turning their attention upward.

"We looked into this, but it's not possible, unfortunately," said Jim Bell, a Mars rover scientist at Cornell University. Part of the problem, Bell told SPACE.com via email, is that power is so low now on both vehicles - due to winter approaching fast -- that ground controllers can't "afford" the night-time operations to try to catch MRO's plume.

"Also, the plume is actually predicted to be pretty dim, though it would be fun and interesting to attempt," Bell added.

UPDATE: 3:30 p.m. EST

NASA's Mars Reconnaissance Orbiter (MRO) is less than one hour from firing its engines and thrusters in a maneuver to place it in orbit around Mars. The spacecraft is expected to light its engines at just past 4:24 p.m. EST (2124 GMT) for a 27-minute burn.

MRO launched toward Mars atop an Atlas 5 rocket on Aug. 12, 2005 and has spent the last seven months in transit. So far, the spacecraft has performed flawlessly, though orbital insertion is critical to the future of the mission. Live video from NASA's Jet Propulsion Laboratory is available via the link at the left.

NASA will be out of contact with the vehicle for the final six minutes of today's orbital insertion burn, while MRO swings behind Mars, then must wait until 5:16 p.m. EST (2216 GMT) when the probe emerges into range.