Mars Lander Beagle 2 Remains Silent
for National Geographic News
|December 29, 2003|
Scientists are clinging to hope that Europe's first probe to land on Mars will speak up and be heard, though no signal from Beagle 2 has been received since it touched down on the red planet Christmas Day.
The British-built probe was jettisoned from its mother ship, Mars Express, on December 19. Upon landing on the red planet December 25, Beagle 2 was to relay a signal of its success via NASA's orbiting Mars Odyssey spacecraft.
However, repeated attempts to hear the Beagle 2's call with Mars Odyssey and an array of powerful radio telescopes on Earth have failed, including the latest try earlier today.
Despite the spacecraft's disappointing silence, Collin Pillinger, lead scientist for Beagle 2, told reporters Saturday in London that he remains optimistic the probe's call will be picked up by Mars Express when it enters a polar orbit on January 4.
"Mars Express is our primary route of communication. It's been the one we spent most of our time over the last four years testing," he said.
At present, Mars Express is in a high orbit around the red planet's equator. On Tuesday, mission controllers will fire its engines to gradually place it in a polar orbit as low as 125 to 155 miles (200 to 250 kilometers) above the Martian surface.
The orbit around one of Mars' poles will allow the spacecraft to survey the entire planet with a high-resolution camera and radar that can look for underground water. It will also be in position to communicate with Beagle 2.
In the meantime, scientists will continue to listen for the as yet unheard from probe with Mars Odyssey and radio telescopes at Jodrell Bank Observatory in Cheshire, England, Stanford University in Palo Alto, California, and possibly other locations, including the Parkes telescope in Sydney, Australia.
Scanning for Signals
The 73 pound (33 kilogram), pocket-watch shaped Beagle 2 was scheduled to land in a 19-mile by 3-mile (30-kilometer by 5-kilometer) lowland basin called Isidis Planitia on December 25 on a mission to search for signs of past or present life.
The pocket-watch design of the probe meant that it would rest upright irrespective of how it landed on Mars. Soon after landing it was to open up and begin sending transmissions to Mars Odyssey.
The orbiting spacecraft did not hear the lander on its first pass over the landing site nor has it on any subsequent pass.
Mission scientists at Lander Operations Control Center at the University of Leicester have established a "tiger team" of engineers to help explain some of the possibilities for why Beagle 2's signal has fallen on deaf ears.
San Diego, California-based Malin Space Science Systems has provided the Beagle 2 team with a picture of the landing site taken by the camera on the Mars Global Surveyor 20 minutes after the spacecraft's scheduled landing.
The image shows a crater inside the landing zone that measures three-fifths of a mile (one kilometer) wide. Scientists say there is an outside chance Beagle 2 could have touched down inside this crater, making it unable to communicate.
The image also indicates good weather, dismissing the possibility that inclement conditions interfered with the landing.
Other possibilities include incompatible communication systems aboard the Mars Odyssey and Beagle 2, an off course landing, or that the lander's antenna is pointing in the wrong direction.
A potential problem the team has ruled out is a glitch on the lander's onboard computer that reset its clock, causing it to send out its signal at the wrong times.
On December 26, the team made Mars Odyssey send a command to Beagle 2 to reset its clock. It is not known if the lander took the command, but there have been no successful communications with Mars Odyssey in subsequent flybys.
If the lander is unable to establish contact with Mars Odyssey before January 4, it is programmed to enter an auto transmission mode, where it will send a continuous on-off pulse signal throughout the Martian daylight hours.
At this time Beagle 2's mother ship, Mars Express, will be positioned to pick up Beagle 2's signal.
"We haven't played all our cards," David Southwood, the European Space Agency's director of science, told reporters Saturday in London. "The baby, we believe, is down on the surface, and the mother is very anxious to get in touch."
Currently, Beagle 2 should be sending a ten-second on-off signal once every minute. This signal should reach Earth 9 minutes later after a journey of 98 million miles (158 million kilometers).
Even though the transmitter's power is only five watts, little more than that of a cellular telephone, scientists believe the signal should be detectable by powerful radio telescopes scanning the planet's surface.
Although the ground-based radio telescopes will not be able to send a reply to Beagle 2, detection of a transmission would help mission controllers pinpoint the spacecraft's location. This in turn would allow the communications antenna on Mars Odyssey to be directed more accurately toward Beagle 2 on subsequent overhead passes.
Getting spacecraft to Mars has historically proved a difficult tasktwo out of every three missions to the red planet has failed. Most recently, NASA's 1999 Mars Polar Lander was lost during landing.
Lord Sainsbury, Britain's minister for science and innovation, said in a statement today that his country remains committed to the long-term exploration of Mars.
"We've always recognized that Beagle 2 was a high-risk project, and we must avoid the temptation in [the] future to only do low-risk projects," he said.
NASA currently has two twin rovers en route to Mars, Spirit and Opportunity. Spirit is scheduled to land on January 3. Opportunity will arrive January 24.
The NASA and ESA spacecraft are on complementary but unrelated missions to Mars to search signs of past or present life, including water and chemical compounds in soils and rocks.
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