Mars probe poised for 'hair-raising' orbit entry
The Mars Reconnaissance Orbiter must fire its thrusters for 27
minutes to enter orbit around Mars (Illustration: NASA/JPL-Caltech)
Related Articles
Web LinksNASA'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 hourFor 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 sitesThe 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. FROM: http://www.newscientistspace.com/channel/solar-system/dn8777 |
||||||
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 craft slams on its brakesA 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. Reuters
|
||||||
. . . . . . . . . . . . . By Gina Keating LOS ANGELES (Reuters) - The Mars Reconnaissance Orbiter on Friday returned the first test images from its super high-resolution cameras, the most powerful photographic equipment to be trained on the Red Planet in NASA's search for water and life. The black-and-white photos, taken by three cameras, show deep channels and layered surface debris around the planet's midsection, features that probably were formed by water, said Alfred McEwen, a mission scientist and University of Arizona professor of planetary science. The images were taken from an altitude of 1,547 miles above the surface, about three times higher than the orbiter will be when it formally begins its science mission in November. The spacecraft, which reached orbit on March 10, is to map about 1 percent of the Martian surface for future landings by robotic probes and human astronauts. The resolution of the test images is comparable to those captured by the less powerful cameras of three other orbiters circling Mars, but the tests show that cameras survived the seven-month space trip that began in August. NASA scientists will use the images to calibrate the cameras, and will later combine the images to create broader view and to add color. They are available for viewing at www.jpl.nasa.gov. Over the next seven months, the orbiter will "aerobrake," dipping into Mars' atmosphere and gradually changing its elliptical orbit into a near-circle about 185 miles above the planet's surface. In the lower orbit, scientists will be able to distinguish surface objects as small as 3 feet (1 meter) wide, McEwen said. The Mars Reconnaissance Orbiter has a suite of onboard instruments to map the planet's subsurface minerals, monitor its atmosphere and look for evidence of subsurface ice or water. "At this point we have an idea that water is probably abundant on Mars in the form of ice," McEwen said. "It's not a matter of finding water on Mars but learning its importance in climate change ... and clearly it has been important to shaping the landscape." The orbiter's first mission is to find landing sites for the Phoenix Mars Lander, set to arrive on Mars in May 2008 to dig for subsurface water ice, and for the 2009 arrival of the Mars Science Laboratory, a larger version of the twin robotic geologists Spirit and Opportunity, which have been traversing the planet's surface since 2004. The Mars Reconnaissance Orbiter has the most advanced and powerful
instruments of any of the four science satellites circling the planet
and will return more than 10 times the quantity of data than all other
probes combined, McEwen said. |
||||||
NASA’s
new red planet probe, the Mars
Reconnaissance Orbiter
(MRO), has relayed spectacular test
images using its super-powerful camera leaving mission scientists
and engineers more than pleased with the initial
imagery.
The views from MRO's High
Resolution Imaging Experiment (HiRISE) camera, which has called
the most powerful camera ever sent to red planet, reached Earth early
Friday. “The quality of the images is fantastic!”
HiRISE principal investigator Alfred McEwen, of the University of
Arizona, told SPACE.com. “This demonstrates that both the
HiRISE camera and the spacecraft pointing performed superbly.” After
the test shots using HiRISE wrap up on Saturday, the camera will be
turned off while the spacecraft “aerobrakes”
- a technique whereby the MRO spacecraft repeatedly dips into the
upper atmosphere more than five hundred times to scrub off speed. By
doing so, the spacecraft will drop into successively more circular
orbits.
MRO “People have been saying ‘oooh’ and
‘ahhh’ a lot while examining the first images,” said Loretta
McKibben, a spokeswoman for the HiRISE operations at the University of
Arizona in Tucson. MRO
quest: persistence of water The
orbiter is hauling an array
of science instruments,
including a radar device designed to probe the subsurface of Mars for
layers of ice, rock and, perhaps, liquid water that might be
accessible from the surface. NASA’s MRO is on a quest to find supportive
evidence that water persisted on the surface of Mars for a long period
of time. While other Mars missions have shown that water flowed across
the surface in Mars’ history, it remains a mystery whether water was
ever around long enough to provide a habitat for life. Equally happy about HiRISE early images is Jim Graf, Project
Manager for MRO at NASA’s Jet Propulsion Laboratory (JPL) in
Pasadena, California. Earlier, Graf told SPACE.com that other
MRO instrumentation will undergo checkout too. These are the Context Camera (CTX) that provides wide area views
of Mars terrain to help scientists appreciate the context for close-up
photos, as well as a trial-run of the Mars Color Imager (MARCI) - a
weather camera that eyes clouds and dust storms. Third time's the charm Another key instrument on MRO is to be turned
on later today – the Mars Climate Sounder (MCS). Getting this
instrument to the red planet has been tough-going. The device flew on the ill-fated Mars
Observer that was lost just before Mars arrival in August 1993.
Then it was onboard the metric-challenged mission of the Mars
Climate Orbiter that was lost in September 1999 when one
engineering team thought metric while another figured in English
units. Daniel McCleese is the principal investigator
for the MCS, a scientist at the Jet Propulsion Laboratory (JPL) in
Pasadena, California. He told SPACE.com that MCS will be
powered on this evening as MRO is near apoapsis – that’s the
farthest the spacecraft now swings by Mars. At that time, a brief period of taking test
data with MCS is slated. The device will be turned off as MRO nears
periapsis – a part of its orbit that brings the probe closest to the
red planet early Saturday, McCleese explained. Checkouts and calibrations MRO is also flying the Compact Reconnaissance
Imaging Spectrometer for Mars - CRISM for short. The instrument is
another high-tech detective that will help seek traces of past water
on the Martian surface. It isn’t grabbing images yet, as its cover
is still on. But the testing has gone well, advised Michael Buckley, a
spokesman at The Johns Hopkins University Applied Physics Laboratory
(APL) in Laurel, Maryland. The APL-led CRISM team conducted three
successful checkouts of the instrument during the cruise to Mars.
According to APL’s Scott Murchie, the principal investigator for the
instrument, the device is working very well. This summer, the CRISM team will continue
planning for the next round of spacecraft checkouts and instrument
calibrations -- which begin when MRO’s aerobraking phase ends in
September -- and refining the software it will use to operate the
instrument and collect data. “In fact, we expect the first data –
images -- in mid-September, when the cover is opened,” Buckley told SPACE.com. Following several months of aerobraking to
achieve a circular, polar orbit, MRO will begin its primary mission
starting in November 2006 and run through November 2008. The primary
mission is followed by a communications relay phase, currently planned
to run through December 2010. |
||||||
| MARS
DATABASE - all pages reside on greatdreams.com
DREAMS OF THE GREAT EARTHCHANGES - MAIN INDEX
|
