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Thursday, 3 February, 2000, 14:28 GMT
Quiet please, we're listening to Mars

Trained on Mars, listening very hard Trained on Mars and listening very hard


By BBC News Online science editor Dr David Whitehouse

The mighty Jodrell Bank radio telescope will make a sensitive search for signals from the crippled Mars Polar Lander (MPL) on Friday - but scientists hope that journalists will keep their distance.

"They may wreck the whole thing," astronomer Ian Morison told BBC News Online.

Last week, an array of radio telescopes in Holland tried to listen for the errant Mars craft, but the posse of journalists who descended upon the Westerbork observatory to cover the story rendered the astronomers' efforts useless because of the interference from their mobile phones and satellite uplinks.


Jodrell's observing room Jodrell's observing room
Now Jodrell Bank astronomers have asked the media to stay away from their 76-metre Lovell dish, which is sited in the Cheshire countryside.

If MPL is trying to call Earth, Jodrell could be the place to intercept the signal.

"If it is there, then we have a good chance of picking it up," said Ian Morison.

 Ian Morison: Mobile phones could ruin the search

The lander signal, if that is what it is, is extremely weak. Radio astronomers in the United States only saw it after processing the data from Mars for many days. It may be coming from MPL's secondary transmitter which is short-range.

"It is not really meant to be picked up on Earth. It is a weak signal, meant for the Mars Global Surveyor in Martian orbit. It is just a few Watts - mobile phone power," said Mr Morison.

Right frequency

American scientists using a radio telescope at Stanford believe that they may have twice, possibly three times, picked up a very weak signal from MPL. It was at the right frequency, 400 MHz, and the correct polarisation.

Its frequency also drifted slightly in a way that would be expected from the transmitter on the Polar Lander.


Dish The Stanford dish picked up what could have been MPL signals on two, possibly three, occasions
Jodrell Bank is a more sensitive electronic ear with which to listen. "Our Lovell telescope is about three times the size of the Stanford telescope. We also have one of the world's best receivers at the right frequency that has been connected to the telescope this week," said Ian Morison. "So we are probably about four times more sensitive than anything else."

Jodrell Bank will be observing for two half-hour periods on Friday afternoon, between 15.30 - 16.00 GMT and 18.30 - 19.00 GMT. However, the signal is so weak that it will take Jodrell scientists a day or so to sift it out from the data received by the telescope.

One help will be that MPL has been commanded to turn the signal off during the time that Jodrell will be listening. This should help distinguish the signal from terrestrial interference - that is if MPL received and obeyed the commands.

The weak bleeps that American scientists may have detected are all that has been heard from MPL since it was on its way down to the surface of Mars on 3 December. It has been suggested that it crash landed, rolled over, and was unable to point its main antenna towards the Earth.

It is also possible that MPL's solar panels are facing the Martian dirt or are covered in soil and are unable to provide any power.

Either way, MPL's science mission is over. All that can be hoped for now is that a few bits of information can be got back from Mars so that what really happened can be determined.

And Jodrell Bank may be the one facility capable of getting that information. "So I am rather hoping it will be quiet on Friday night," said Ian Morison hopefully.

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See also:
06 Dec 99 |  Sci/Tech
Mars 2 - Earth 0
02 Feb 00 |  Sci/Tech
Earth turns its ears to Mars
26 Jan 00 |  Sci/Tech
Nasa investigates 'Mars peep'

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