to arrive at Mars - 3-10-06

update 7-17-08

compiled by Dee Finney



Mars probe poised for 'hair-raising' orbit entry

  • 11:26 27 February 2006
  • news service
  • Maggie McKee
The Mars Reconnaissance Orbiter must fire its thrusters for 27 minutes to enter orbit around Mars (Illustration: NASA/JPL-Caltech)
The Mars Reconnaissance Orbiter must fire its thrusters for 27 minutes to enter orbit around Mars (Illustration: NASA/JPL-Caltech)
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NASA's Mars Reconnaissance Orbiter is preparing for a "hair-raising" entry into orbit around the Red Planet on 10 March, mission managers say. If successful, the spacecraft will spend seven months spiralling towards the planet until it skims just 300 kilometres from its surface – where it will study the planet's geology and climate in unprecedented detail.

The spacecraft has travelled 459 million kilometres (285 million miles) – 95% of the way to Mars – since its launch from Florida's Kennedy Space Center, US, in August 2005. It has already fired its thrusters twice to correct its course towards Mars. Those firings were so successful that mission managers cancelled two further trajectory tweaks that had been scheduled.

"We're right on the money now, heading towards our encounter at Mars on the 10th," James Graf, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena, California, US, said at a press briefing on Friday.

But that encounter is very risky, he said: "We're starting to enter into the realm where we've lost two spacecraft in 15 years." NASA's Mars Observer spacecraft fell silent in 1993 when it approached the planet – probably because of a leak caused when its propulsion system was pressurised.

And the Mars Climate Orbiter is thought to have broken up in the planet's atmosphere in 1999 due to the accidental use of both metric and Imperial units by collaborating teams, which scuppered a critical manoeuvre.

Nervous half hour

For MRO's orbit insertion at 2124 GMT, it will aim its main thrusters forward and fire them for 27 minutes to slow down by 18%. "If we don't succeed in firing the thrusters, it will be a flyby spacecraft," Graf said.

But mission controllers will not know immediately whether the manoeuvre worked, since the spacecraft will travel behind the planet as seen from Earth for about 30 minutes before the end of the thruster firing and will therefore be out of radio contact.

If the "hair-raising" orbital insertion is successful, the spacecraft will then begin a seven-month "aerobraking" phase, said Michael Meyer, the lead scientist for NASA's Mars programme in Washington DC, US.

During this phase, it will dip into the Red Planet's atmosphere hundreds of times, using the friction of atmospheric drag to move from a 35-hour orbit that extends 35,000 miles (56,000 kilometres) above the planet to a two-hour orbit that skims just 190 miles (300 kilometres) above its surface. At that point, it will begin to collect "more data than all of the previous missions combined," Meyer said.

Landing sites

The spacecraft will use a suite of six instruments - including the most powerful camera ever sent to another planet, which will image objects as small as 1-metre wide and should be able to snap pictures of the Spirit and Opportunity rovers – now on opposite sides of the planet. The instruments will track the planet's weather, geology and mineralogy, and even probe about a kilometre beneath its surface to hunt for water.

The mission will collect 34 trillion bytes of data from Mars. "That's about as much as in a video store," said Meyer. "It will revolutionise our understanding of the planet." He adds that it will also help determine where future missions – including the Phoenix lander due to launch in 2007, the Mars Science Laboratory (MSL) rover set to launch in 2009, and eventually a human mission – should land.

The spacecraft will focus on science for two years after aerobraking manoeuvres are completed. After this pure science phase, it will begin its "relay" phase. During this time it will continue to take science data but will give priority to relaying data from other Mars missions, such as Phoenix and MSL, to Earth. The spacecraft carries an antenna that will be able to transmit 10 times as much data per minute as any previous spacecraft. The probe's expected operational lifespan is 10 years.


Arrival Time Nears For New Mars Probe
By Leonard David
Senior Space Writer
posted: 24 February 2006

 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 cam­era 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.

Mars Reconnaissance Orbiter: Home
Mission official site. Features mission updates, goals overview, spacecraft details, and data.

Mars craft slams on its brakes

March 12, 2006

A NASA spacecraft achieved orbit around Mars yesterday, successfully completing a make-or-break manoeuvre in its two-year mission to scour the red planet for evidence of life and landing spots for future astronauts.

Mission controllers at NASA erupted in loud cheers when the Mars Reconnaissance Orbiter, which left Earth in August, signalled it had dropped into a perfect orbit.

To achieve this, the craft had to turn its main thrusters forward and fire them for 27 minutes, effectively slamming on the brakes while cruising at more than 17,600 kmh.

If it had failed to get into orbit, it would have flown past Mars and off into outer space

The craft is designed to spend two years searching for signs of life on Mars and scouting possible landing spots for future missions. It is equipped to send back 10 times as much data as all previous probes put together.

But missions to Mars are notoriously difficult, with two of the past four attempts by NASA to put a craft in orbit around the planet ending in failure.

"Mars is just for some reason harder to get a mission to than other places in the solar system," lead mission planner Rob Lock said.

The Mars Reconnaissance Orbiter program will cost about $US720 million ($983 million), including $US450 million for the spacecraft, $US90 million for the launch and $US180 million for data processing and support.



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