BY JUSTIN RAY

Follow the arrival of NASA's Mars Reconnaissance Orbiter at the red planet! Reload this page for the latest on the mission.

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0245 GMT (9:45 p.m. EST)

After a seven-month voyage from Earth, NASA's Mars Reconnaissance Orbiter successfully fired its main engines for 27 minutes today, slowing the craft by some 2,200 mph and putting it into a near-perfect elliptical orbit around the Red Planet.

Read our full wrap-up story.

0034 GMT (7:34 p.m. EST)

"Today was picture-perfect," MRO project manager Jim Graf is saying at the post-arrival press conference right now. "It was just a wonderful day."

2255 GMT (5:55 p.m. EST)

NASA is planning a post-arrival news conference with MRO officials at 7:30 p.m. EST. We'll pause our live updates until then.

2253 GMT (5:53 p.m. EST)

The spacecraft has successfully completed all of the activities for orbit insertion, mission control says. Soon MRO will switch back to its high-rate communications.

2247 GMT (5:47 p.m. EST)

No problems are being reported from the various controllers in the post-burn status poll.

2247 GMT (5:47 p.m. EST)

Mission control reports the burn lasted 1,641 seconds vs. the projected 1,608 seconds. The propulsion system is maintaining good pressure now, indicting no leaks.

2239 GMT (5:39 p.m. EST)

MRO becomes the third American spacecraft now orbiting Mars, joining Mars Global Surveyor and Mars Odyssey. The European Space Agency's Mars Express orbiter is there, too. Down on the surface, the never-say-die Mars rovers Spirit and Opportunity continue their missions of explorations.

"We really have a permanent presence at that planet," says JPL center director Charles Elachi. "This is a long term program of understanding another world."

2232 GMT (5:32 p.m. EST)

"I am very relieved. It was picture-perfect," MRO project manager Jim Graf says.

"We went behind the planet just when we thought we would. Clearly, we terminated the burn exactly when we thought we were going to. And then (the spacecraft) appeared almost to the second when we thought we were going to reacquire the signal."

2231 GMT (5:31 p.m. EST)

Controllers are beginning to analyze the system telemetry coming back from the spacecraft. The team members will be polled in about 15 minutes to report how everything is working.

2225 GMT (5:25 p.m. EST)

IN ORBIT! The Mars Reconnaissance Orbiter is truly an orbiter now after successfully swooping into orbit around the Red Planet today, mission control confirms!

2219 GMT (5:19 p.m. EST)

Deep Space Network tracking stations in Madrid, Spain and Goldstone, California have locked on the spacecraft's signal. It will take a few minutes for enough data to be received from the spacecraft via the low-data rate to determine state of health and the orbit achieved.

2217 GMT (5:17 p.m. EST)

It is a moment of relief and excitement in mission control. "Nice comm(unications) system, dude," one controller could be heard saying.

2216 GMT (5:16 p.m. EST)

CONTACT! Communications have been restarted with the Mars Reconnaissance Orbiter!

2213 GMT (5:13 p.m. EST)

The spacecraft is supposed to be pointed back at Earth now. Communications are expected in three minutes or so.

2212 GMT (5:12 p.m. EST)

MRO should 1,890 miles above the surface of Mars and traveling at 7,650 miles per hour.

2210 GMT (5:10 p.m. EST)

If the burn has gone according to plan, MRO will have entered a very elongated elliptical orbit just 250 miles above Mars at its closest point and stretching as far as 27,340 miles at the highest point. It will take the spacecraft 35 hours to complete one orbit.

Over the next five months, MRO will perform more than 500 "aerobraking" maneuvers in which it dips into the upper fringes of the planet's atmosphere to reshape the orbit into a low-altitude circular one.

2203 GMT (5:03 p.m. EST)

MRO should have completed the first part of its turn back to Earth. This initial maneuver is designed to protect the spacecraft's instruments from facing the sun.

2202 GMT (5:02 p.m. EST)

Mission control has just dispatched a "ping" signal that when it arrives at Mars in 12 minutes the spacecraft should hear it.

2200 GMT (5:00 p.m. EST)

Once communications are reacquired with MRO, the spacecraft will send a basic report, including the burn duration and the amount of slowing the probe thinks it achieved. The Deep Space Network on Earth will listen for MRO at 5:16 p.m. EST.

"There will be jubilation on the team," Rob Lock, MRO lead mission planner, predicts for the moment the signal is heard again. "It will mean out spacecraft has survived. Unfortunately, we won't know anything more than that. After about five minutes, enough telemetry will collect with our flight team to understand how well the maneuver performed -- did it burn right, the right amount of time, things like that. It will take a few minutes.

"Within about a half-an-hour, we'll have tracking information for our navigators to say what kind of orbit we are in."

2155 GMT (4:55 p.m. EST)

"We still have a ways to go," project manager Jim Graf says with caution.

2155 GMT (4:55 p.m. EST)

MRO should be performing a programmed turn to point back at Earth for communications once it emerges from the backside of Mars.

2153 GMT (4:53 p.m. EST)

Propulsion engineers report that the burn appeared to be about one percent off the projections at the time the spacecraft went behind the planet. But that is within the acceptable margin. The difference probably was caused by a cooler than expected internal temperature.

2151 GMT (4:51 p.m. EST)

The burn should now be complete. However, communications with MRO are not possible at this time because the spacecraft is behind the planet as viewed from Earth. Controllers must wait until 5:16 p.m. EST to restore their radio link with the probe and begin reviewing data to determine if orbit has been entered successfully.

2149 GMT (4:49 p.m. EST)

MRO should be back in sunlight after passing through the brief eclipse period.

2148 GMT (4:48 p.m. EST)

At the point of contact being lost, MRO has achieved 1,552 mph of slowing or 69 percent of the total.

2146 GMT (4:46 p.m. EST)

LOS. The loss of signal period has started as MRO passes behind Mars. The rest of the engine burn will occur out of communication with Earth. Mission control expects to reestablish contact with the spacecraft at 5:16 p.m.

2145 GMT (4:45 p.m. EST)

Contact with MRO is about to be interrupted.

"We will move behind the planet of Mars, and all our radio signals will stop, and we won't be able to see the spacecraft for about half an hour," explains Rob Lock, MRO lead mission planner.

2145 GMT (4:45 p.m. EST)

Mars Reconnaissance Orbiter is now beginning to pass into the planet's shadow. This means the spacecraft must switch from the twin solar panels to its onboard nickel-hydrogen batteries.

2144 GMT (4:44 p.m. EST)

The spacecraft has obtained about 63 percent of the slowing needed to enter orbit.

2144 GMT (4:44 p.m. EST)

All engines are still burning well.

2141 GMT (4:41 p.m. EST)

MRO is 280 miles above Mars. Everything still looks good.

2137 GMT (4:37 p.m. EST)

The burn continues to progress normally, mission control reports.

2135 GMT (4:35 p.m. EST)

This engine firing imparts the force of about 1/12th of Earth's gravity on the spacecraft.

2133 GMT (4:33 p.m. EST)

The spacecraft's main engines were originally built for the Mars lander slated to launch in 2001. But that mission was cancelled after the Mars Climate Orbiter and Mars Polar Lander failures in 1999. The engines each produce about 170 newtons (38 pounds) of thrust.

2132 GMT (4:32 p.m. EST)

MRO has achieved 295 mph of slowing, or 13.2 percent for the burn.

2130 GMT (4:30 p.m. EST)

Doppler tracking of the spacecraft indicates good thrust. And the telemetry from the catalyst beds shows a temperature for all six main engines up and running.

2128 GMT (4:28 p.m. EST)

MRO has obtained over 80 mph of speed change so far, or 3.7 percent of the burn objective.

2126 GMT (4:26 p.m. EST)

MRO is 1,315 miles from Mars, traveling at 10,740 mph.

2125 GMT (4:25 p.m. EST)

The burn began by firing small thrusters for 30 seconds to push propellant to the back of the tank.

2124 GMT (4:24 p.m. EST)

MOI IGNITION! Flying backward with the Red Planet looming near, the Mars Reconnaissance Orbiter has ignited its cluster of engines for the 27-minute orbit insertion burn. This engine firing will slow the spacecraft's speed by 2,200 mph, enabling the planet to capture the probe before sailing past.

2123 GMT (4:23 p.m. EST)

Controllers and managers are passing around peanuts, a good luck charm at JPL.

2122 GMT (4:22 p.m. EST)

All spacecraft sub-systems are "go."

2121 GMT (4:21 p.m. EST)

Mission control confirms MRO is in the proper configuration for the burn.

2121 GMT (4:21 p.m. EST)

MRO is 1,860 miles from Mars and traveling at 10,300 miles per hour.

2120 GMT (4:20 p.m. EST)

MRO has completed its turn. The craft has achieved the orientation for the burn.

2119 GMT (4:19 p.m. EST)

Five minutes from ignition. The orbit insertion burn is performed by the spacecraft's six main engines. A valve is electrically opened to route fuel into the engines, flowing over high-temperature catalyst beds that cause the propellant to ignite and blast through the cluster of nozzles at very high speed.

2117 GMT (4:17 p.m. EST)

MRO is 2,300 miles from Mars and traveling at 10,000 miles per hour.

2114 GMT (4:14 p.m. EST)

Main engine start is now 10 minutes away.

2112 GMT (4:12 p.m. EST)

The turn should be complete at 4:19 p.m.

2110 GMT (4:10 p.m. EST)

The spacecraft has begun its reorientation turn to the position needed for the engine burn. MRO is doing all of these activities autonomously based on pre-loaded commands.

2108 GMT (4:08 p.m. EST)

Standing by for confirmation that the spacecraft's turn to the burn attitude has started as planned.

2107 GMT (4:07 p.m. EST)

MRO is 3,600 miles from Mars and traveling at 9,300 miles per hour.

2105 GMT (4:05 p.m. EST)

The handover has occurred. Now 19 minutes to the burn ignition.

2103 GMT (4:03 p.m. EST)

Mars Reconnaissance Orbiter is now switching its communications mode from the precise high-gain antenna to the low-gain antenna. The low-gain allows the spacecraft to receive and send signals without having to directly point the antenna at Earth. The telemetry data will be 160 bits per second.

2052 GMT (3:52 p.m. EST)

The propulsion system has been pressurized as planned. The flight control team was just told they can stand down from their contingency plans.

2050 GMT (3:50 p.m. EST)

Pressurization has begun, telemetry from MRO indicates, prompting boisterous applause in the control room.

2047 GMT (3:47 p.m. EST)

The next critical step -- pressurizing the spacecraft's propulsion system -- begins three minutes from now. The pressure level will increase from 190 psi to 235 psi for pushing the propellant to the engines. This is done by firing two small pyrotechnic charges to open valves in the pencil-diameter plumbing between the helium gas pressurant and main fuel tank. This system pressurization is a first-time event for MRO, so naturally that creates an anxious moment for the ground team.

2042 GMT (3:42 p.m. EST)

The spacecraft is now inside 7,000 miles from the planet.

2037 GMT (3:37 p.m. EST)

MRO is 7,500 miles from Mars and traveling at 8,210 miles per hour.

2024 GMT (3:24 p.m. EST)

Now one hour from ignition of the Mars Orbit Insertion burn. At this point in the sequence, Mars Reconnaissance Orbiter is scheduled to begin warming up its engines from their current 35-degree temperature to 140 degrees F for the upcoming burn.

2000 GMT (3:00 p.m. EST)

Mars Reconnaissance Orbiter currently weighs 4,784 pounds. That is 22 pounds less than it did at launch because of the propellant consumed during trajectory correction maneuvers performed after leaving Earth. But the course was so accurate that navigators saved 60 pounds budgeted to adjust the flight path if needed. Those savings translate into fuel for the spacecraft to perform an extra seven months of science operations at the end of the mission, according to Howard Eisen, MRO flight systems manager.

The 27-minute orbit insertion burn will guzzle up 1,726 pounds of fuel, about two-thirds of the spacecraft's entire propellant supply.

1921 GMT (2:21 p.m. EST)

Mars Reconnaissance Orbiter should be in orbit two-and-a-half hours from now, capping its 310-million mile cruise from Earth.

"It's a great feeling," Doug McCuistion, Mars exploration program director, said today. "I can't wait also for the scientists in a few months to be able to take control of the orbiter and see what we find. They're gonna be like a bunch of kids with a new microscope, I think, being able to look at things they haven't seen before. And I just can't wait to hear all the 'wows' coming from the science community, it will be quite exciting.

"First thing we have to do it get into orbit -- not an easy task. NASA has about an average grade of C in doing this. It is not a simple thing to do. But these guys will do it. It is a great team."

1850 GMT (1:50 p.m. EST)

"I'm very excited about what's going to happen today," Howard Eisen, MRO flight systems manager, said at today's mission status briefing. "I'm very happy to report that at the current time, the Mars Reconnaissance Orbiter is safe and stable with fully charged batteries pointing at the Earth in full communication with us. We have good gyroscopes and a good star tracker and the flight teams in both Denver and here in Pasadena are working no issues whatsoever."

1830 GMT (1:30 p.m. EST)

"What a fantastic week for NASA. First, Enceladus discovery announced yesterday, and today we're here to insert the most-capable orbiter ever put at another planet into orbit around Mars," Doug McCuistion, Mars exploration program director, said at today's noon EST news conference.

The orbit insertion burn begins at 4:24 p.m. EST.

"It is a little bit nerve-wracking even though it is exciting. It is a big event and not a simple activity."

1800 GMT (1:00 p.m. EST)

After a seven-month voyage from Earth, timers aboard NASA's Mars Reconnaissance Orbiter are counting down to a make-or-break 27-minute rocket firing this afternoon to slow the craft enough to slip into a looping elliptical orbit around the Red Planet.

Read our full story.

1704 GMT (12:04 p.m. EST)

The Mars Reconnaissance Orbiter is tracking on the proper course for its rendezvous with the Red Planet today, mission officials are reporting at a status news briefing from the Jet Propulsion Laboratory at this hour. Navigators deemed two contingency course-correction maneuvers were not needed yesterday and today.

The probe is 33,000 miles from Mars and traveling at 7,000 mph. That speed should reach 11,000 mph by the time the orbit insertion burn begins, as the spacecraft essentially falls into the planet's gravity influence, said Rob Lock, MRO lead mission planner.

The Deep Space Network tracking station in Spain is monitoring the spacecraft now. The Goldstone station in California will be acquiring as the day goes on.

WEDNESDAY, MARCH 8, 2006

These are tense days at the Jet Propulsion Laboratory and Lockheed Martin spacecraft control centers where engineers are guiding the Mars Reconnaissance Orbiter to Friday's maneuvers for entering orbit around the planet.

The 27-minute firing of the six main engines on MRO will slow the craft, allowing Mars to capture the instrument-laden probe into an initial looping orbit. If the burn doesn't occur or gets cut short by a problem, the probe would be doomed to fly right past Mars.

"We have a tremendous amount of anxiety and concern at this particular point in time, which is what you'd want us to be," Jim Graf, the MRO project manager, said Wednesday, adding that his teams need to keep looking under rocks to ensure potential pitfalls don't go undiscovered and bite the $720 million mission.

"At the same time, I feel confident. We have a very good spacecraft. It's been performing extraordinarily well. We have an excellent, well-trained team that's ready to go forward. So I am both concerned because I have to be as a good project manager, you have to be. But I'm also confident that we've done the right things and we've got the right people in place to be able to be successful."

The Lockheed Martin-built spacecraft was 325,000 miles from Mars at midday Wednesday, traveling 6,400 miles per hour. That speed will double as the spacecraft gets closer to the planet, Graf said.

All of the computer sequences needed for Friday's insertion into orbit around Mars have been uplinked to MRO. The spacecraft will be running completely on its own for the engine burn, since commands from Earth take 12 minutes to reach Mars.

"We're clearly very excited about the potential of MRO doing science around Mars. But, at least for me, my heart rate is going up for a different reason," said Fuk Li, Mars program manager at JPL. "The mission is entering into a very dangerous phase in the next several days. If you look back at the history of exploration of Mars and all of the missions sent by all of the nations since the dawn of the space age to the Mars, only about a third of them succeeded."

NASA has lost two of its last four spacecraft intended to enter Mars orbit since 1993.

"Those are very sobering numbers and indicate to us how tough it is to get this mission operating correctly around Mars," Li added.

The Mars Observer disappeared a few days before reaching the Red Planet, apparently because of a fuel system pressurization mishap, and the Mars Climate Orbiter was off course due to a navigational error in 1998.

The Mars Global Surveyor and Mars Odyssey probes safely arrived in 1997 and 2001, respectively, and continue to perform their scientific research today.

Here is a timeline of Friday's major events (in Earth-received Eastern Time):

10:24 a.m.: Final trajectory correction maneuver if needed

04:07 p.m.: Start spacecraft turn to orbit-insertion orientation

04:19 p.m.: Turn complete

04:24 p.m.: Orbit insertion rocket firing begins

04:45 p.m.: Spacecraft enters Martian shadow; on battery power

04:47 p.m.: Loss of signal as MRO passes behind Mars

04:51 p.m.: End of orbit insertion burn

05:13 p.m.: Spacecraft turns for Earth pointing

05:16 p.m.: Acquisition of signal

MRO will enter a very elongated elliptical orbit just 250 miles above Mars at its closest point and stretching as far as 27,340 miles at the highest point. Over the next five months, MRO will make more than 500 "aerobraking" maneuvers in which it dips into the upper fringes of the planet's atmosphere to reshape the orbit into a low-altitude circular one.

"Aerobraking is like a high-wire act in open air," Graf said. "Mars' atmosphere can swell rapidly, so we need to monitor it closely to keep the orbiter at an altitude that is effective but safe."

The science-collecting near-polar orbit is planned to be only 158 miles above the planet's surface at its closest and 199 miles at the furthest point.

The mission's main science phase runs from November 2006 to December 2008, enabling the on board cameras, spectrometer, climate sounder and subsurface radar to gather an unparalleled amount of data about Mars. The instruments on MRO will offer a sharper focus than earlier spacecraft, giving scientists hope for revolutionary discoveries.

Featuring the largest telescope to orbit another planet, MRO's high-resolution camera can spot rocks as small as three-feet across and surface layering that will be critical to Mars research as well as selecting safe but interesting sites for future landers.

"This mission will greatly expand our scientific understanding of Mars, pave the way for our next robotic missions later in this decade, and help us prepare for sending humans to Mars," said Doug McCuistion, director of NASA's Mars Exploration Program. "Not only will Mars Science Laboratory's landing and research areas be determined by MRO, but the first boots on Mars will probably get dusty at one of the many potential landing sites the Mars Reconnaissance Orbiter will inspect all over the planet."

But MRO needs to get into orbit to fulfill its mission. Watch this page for live updates throughout the dramatic activities on Friday.

FRIDAY, FEBRUARY 24, 2006

NASA's $720 million Mars Reconnaissance Orbiter mission faces a make-or-break milestone March 10 when it fires its main engines for nearly a half hour, slowing the craft enough to slip into orbit around the Red Planet.

Read our preview story.

Additional coverage for subscribers:
VIDEO: MARS ARRIVAL PREVIEW NEWS BRIEFING DIAL-UP | BROADBAND
AUDIO: LISTEN TO THE NEWS CONFERENCE FOR IPOD
MORE: MARS RECONNAISSANCE ORBITER COVERAGE
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