Cassini mission hit by camera fault

Cassini will orbit Saturn studying the planet, its rings and moons

By BBC News Online science editor Dr David Whitehouse

The Cassini spacecraft, currently traversing the space between Jupiter and Saturn, has a major problem with one of its two cameras.

Engineers noticed that the narrow angle camera was showing some haze around its images, due to some form of deposit in the camera.

The camera has been warmed by heaters to drive-off the contamination - with some success.

Cassini mission director Bob Mitchell told BBC News Online that he was very optimistic that the problem would be fixed well before the probe got to Saturn in 2004.

Unknown contamination

Cassini was launched in 1997 on a mission to Saturn. It passed Jupiter at the end of 2000, making many measurements and taking some fantastic images.

Cassini mission control: Engineers and scientists are confident

It is only recently that the camera problem has arisen.

After investigation, it was believed that some form of contamination had accumulated either on the camera's optics or on its light-sensitive charged-coupled-device (CCD) detector. Worryingly, the origin of the contamination is unknown.

At first, the suspicion was that something had happened to the camera during Cassini's trip past Jupiter and the ambitious observing campaign it carried out in the Jovian system. But a close check on the state of the camera showed that nothing done during the Jupiter fly-by was to blame.

Space engineers say that very cold optics and sensors in space are vulnerable to accumulating contamination and are, as a consequence, built with heaters that hopefully can correct such problems.

Similar case

Cassini's mission director Bob Mitchell told BBC News Online: "We are beginning a series of decontamination cycles to see if we can correct the problem. So far, one warming cycle has been completed and the situation improved. But it was not entirely corrected.

"In January, we will conduct another such cycle that will go to a higher temperature than last time. I'm very optimistic that we will be able to correct the problem."

Cassini's engineers have been in touch with engineers from the Stardust project, which had a similar problem that was much worse. In that case, Stardust's team were able to completely remove the contamination.

"Obviously we don't yet know how this will work out, but I'm highly confident that in the two and a half years before we get to Saturn, we will be able to fix it," Bob Mitchell said.