Arrival Time Nears For New Mars Probe

by Leonard David, Senior Space Writer

Date: 24 February 2006 Time: 04:39 PM ET

NASA's Next Mars Probe Takes Aim at Red Planet

This is an artist's concept of the Mars Reconnaissance Orbiter during its critical Mars Orbit Insertion process. In order to be captured into orbit around Mars, the spacecraft must conduct a 25-minute rocket burn when it is just shy of reaching the planet. As pictured, it will pass under the red planet's southern hemisphere as it begins the insertion. Image
CREDIT: NASA.

NASA is ready to add one more spacecraft to the constellation of orbiters and landers exploring the red planet.

The Mars Reconnaissance Orbiter (MRO) is ready to put the brakes on, slowing itself down for insertion into orbit around the planet. Arrival time is March 10 as MRO fires its main thrusters to slow itself enough to be captured by Mars' gravity.

Launched last August, the instrument-loaded spacecraft has journeyed across the vacuum void and will soon begin its unprecedented surveying of Mars.

MRO has been performing extremely well during its cruise to the red planet, said Doug McCuistion, NASA Mars Exploration Program Director at NASA Headquarters in Washington, D.C.

Given earlier Mars missions that have failed to reach the planet, McCuistion cautioned: "Mars is hard. Mars can be unpredictable." Getting into Mars orbit is not an easy task, he said during an MRO press briefing held today at NASA Headquarters.

"We're 95 percent there," said James Graf, MRO Project Manager at the Jet Propulsion Laboratory (JPL) in Pasadena, California. JPL is managing the $720 million mission for the NASA Science Mission Directorate.

Crucial maneuver

To slip into Mars orbit, MRO will fire its thrusters for about 27 minutes--decreasing the velocity of the spacecraft by 18 percent. That maneuver is crucial; otherwise the probe will sail right past Mars.

The process of slowing down MRO at Mars is going to be a nail biter for ground controllers.

"We're doing a lot of first events," Graf explained. First, the propellant system to fire MRO's thrusters must be pressurized. In addition, there are software patches onboard the spacecraft that have not been used before, he said.

Once MRO is firing its thrusters, it will go behind Mars--out of contact with mission controllers. "We'll be out of touch for the next 30 minutes...so we will not see the end of the burn itself," Graff said.

Start of the suspenseful Mars Orbit Insertion (MOI) thruster firing is 1:25 p.m. Pacific Standard Time, with MRO coming out from behind the planet at 2:16 p.m. PST.

Deep dipping

Given a successful MOI, the spacecraft will spend half a year dipping in and out of Mars' atmosphere in a process tagged as "aerobraking"--adjusting its initial 35-hour elongated orbit into a nearly circular, two-hour loop around Mars.

MRO's aerobraking is to take place from March into October and calls for hundreds of precision-controlled dips into the upper atmosphere of Mars. Those dips have to be deep enough to slow the spacecraft by atmospheric drag, but not so deep that the orbiter becomes overheated.

The primary science-gathering phase of MRO is slated to start in November 2006 and last for over two years.

"MRO opens a new chapter in the history of Mars exploration," said Bob Berry, Director of Space Exploration Systems at Lockheed Martin Space Systems Company near Denver, Colorado. The aerospace firm designed, built and operates MRO. The spacecraft carries six instruments and features a set of solar arrays that stretch tip-to-tip some 46 feet (14 meters), he said.

Berry said that MRO carries enough propellant and energy supply to last more than 10 years.

Over and under observations

MRO totes powerful instruments that can investigate every level of Mars: From underground layers to the top of the planet's atmosphere.

For one, the Mars-bound spacecraft is hauling the most powerful telescopic cam?era ever sent outward to scan another planet. That gear can spot rocks the size of a small desk.

MRO will chart water-related deposits in areas as small as a baseball infield. The Italian space agency supplied the mission with a radar designed to probe for buried ice and water.

Also, a weather camera will monitor the entire planet daily, while an infrared sounder is assigned the duty to gauge atmospheric temperatures and the movement of water vapor.

JPL's Graf said that MRO will return more data than all previous Mars missions combined.

Swimming in the data stream

Thanks to the huge amount of data streaming from MRO, scientists can expect a real intellectual leap forward in better understanding the red planet, said Michael Meyer, NASA Mars Lead Scientist at NASA Headquarters.

Along with revealing Mars as never before, Meyer said MRO will guide future mission decisions too.

MRO's powerful sensors can scope out the landing spot near the northern polar ice cap where NASA's Phoenix lander is slated to touch down in 2008, as well as the exploration zone in which the space agency's next rover--the Mars Science Laboratory--will head for after its launch in 2009.

Even those "little rovers that just won't quit"--NASA's Spirit and Opportunity robots--can be seen by MRO, said NASA's McCuistion. MRO can also provide, he added, useful data for some of the early decision-making as to where future human explorers can safely land on Mars.