Seeking an SOS from Mars

Cosmic sleuthing led Stanford scientist to find signal that could be from lost lander.

At first, Ivan Linscott just didn't think the odd signal amounted to much.

The scientist had been using Stanford University's 15-story-tall radio telescope to listen for messages from the wayward Mars Polar Lander. But the only data he had gotten back were one or two arcs that were all but obscured amid a Jackson Pollack tableau of multicolored specks.

He didn't know what to make of them - until he couldn't find a guest lecturer for a meeting of his Stanford radio-science group. Dr. Linscott decided to appoint himself speaker. He'd look over the computer image once more and take it to the meeting to see what his colleagues thought.

When he went back and tweaked his signal-filtering software, his computer suddenly produced a visual representation of the presumed transmission from the lost probe.

It went from, " 'Use your imagination' to 'Oh, I can see that,' " in a moment, Linscott says.

The discovery has set the astronomical world scrambling. To

be sure, the weak signal could be a million different things - but one possibility is a message from Mars.

Although the lander has been declared "Missing In Ether," NASA has held to one slim hope for communication. Days after the $165 million spacecraft plunged into the Martian atmosphere and radio oblivion Dec. 3, mission control at the Jet Propulsion Laboratory in Pasadena, Calif., sent a series of commands to the probe. JPL scientists told it to turn on its tiny UHF transmitter - a device with little more power than a cellular phone - and start "talking."

Based on Linscott's findings, NASA is now trying to start a conversation - from 200 million miles away. If the Stanford team and its massive dish can capture a signal and verify its authenticity, it could help determine what happened to the lander and possibly affect the future of what NASA has identified as one of its foremost missions: exploration of Mars. Even now, scientists say, crucial data could be salvaged.

Since he sent his information to NASA last month, Linscott says his phone has been "ringing off the hook." Word of the find spread quickly and NASA was soon coordinating assistance from astronomical institutions in England, the Netherlands, and Italy eager to help.

Late last week, JPL sent commands to the lander via NASA's Deep Space Network, but the "listening opportunity" returned no positive results. Scientists at the Pasadena facility altered the command protocols and tried again earlier this week. Researchers at the various cooperating radio telescopes around the world, including Stanford, are still analyzing the data from this week's listening opportunity. JPL could have results from this effort as early as today.

The Mars Polar Lander is equipped with a variety of antennas and communication devices, principally: the main system, a secondary one, and a very lower power UHF radio transmitter. Originally, the UHF transmitter was to be used only to relay scientific data from the planet's surface to the Mars Global Surveyor, a satellite that has been in orbit around the Red Planet since 1997. The Surveyor would then download the data to Earth.

Not quite 'Contact'

Unlike Jodie Foster in the film "Contact," Linscott and his crew do not don headsets and literally listen to signals from space. The radio signals are collected by computers that are housed in a plain cinder-block building at the base of their telescope, known universally as "the Dish."

Long a prominent landmark on the San Francisco peninsula, the Dish rests on the edge of the Stanford campus, atop the last grassy hillock of the Coast Range before the land flattens and runs to the bay. When the Dish was built in the 1960s, that flat land was covered with citrus groves. It is now known as Silicon Valley, and, in Linscott's words, has turned into "an ocean of RFI" (radio frequency interference).

Once the computer has collected the raw data, a different program provides an interpretation of the signal in the form of a spectra, "a waterfall display of noise at a particular frequency," says Linscott - a matrix of colored pixels.

Finding something that looked like a signal from Mars amid the clutter was as much art as science for Linscott. What first caught his eye was the signal with a slight arc. The timing of the transmission was important because it corresponded to the break of dawn on the Mar-tian south pole, when the temperature rose from an overnight low around minus 30 degrees F. to a balmy minus 10 degrees.

The rise would be enough to affect a temperature-sensitive crystal inside the lander's transmitter and, in essence, alter the frequency and - perhaps - produce the arc Linscott spotted.

Level of optimism

Unfortunately, Linscott's and JPL's initial enthusiasm for his discovery may turn out to be the high-water mark of their optimism. Neither Stanford nor any other facility has been able to duplicate the finding, and Linscott himself says he is "not overly optimistic at this point."

Adding to the pessimism is the coming Mar-tian winter. Soon, the warm season at the south pole will end, sending temperatures plunging to equipment-crippling lows. The lack of sunshine could also hobble the solar arrays that recharge the lander.

Nevertheless, scientists worldwide continue their effort to verify Linscott's tantalizing but elusive signal. It's just too important to ignore.

"There is a tremendous amount of information that could be gleaned just from establishing contact," says JPL's John Callas. "We probably couldn't get back any detailed science data, but we could get back very critical engineering data to tell us how it landed, what systems are healthy, where it might have had problems. That would be of tremendous value to future mission planning."

If JPL scientists determine this week's listening event came up empty, hope will further diminish, but yet another set of commands will be issued, Linscott will pay another visit to the Dish, and the search will go on.

(c) Copyright 2000. The Christian Science Publishing Society

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