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One of Huygens' two data routes not working BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: January 14, 2005 Robert Mitchell, NASA's Cassini program manager at the Jet Propulsion Laboratory in Pasadena, Calif., says the loss of one telemetry stream from the Huygens Titan probe appears to be the result of an actual problem of some sort on board the spacecraft. "The evidence we have a problem on chain A is pretty clear," he said. "I don't think the continuing playback (of Huygens data from Cassini) is going to resolve that problem. We just need to sort out what happened with it." Engineers at the European Space Agency's Space Operations Center in Germany are receiving data from Huygens on chain, or channel, B but not from chain A. Both systems are identical and scientists should receive almost all of the desired data from chain B, Mitchell said. "The way the probe system works, there are two transmitters on the probe and there are two separate receivers on the orbiter so we have two separate, distinct data links between the probe and the orbiter," he said. "These data links were deigned to be largely redundant, not 100 percent, but nearly so. "The way we sit now, it's clear that the B channel is coming in loud and clear and up to this point, we haven't missed a single data packet. Now on the A channel, we do have a problem and we're still sorting out what happened thre. But this, I think, will be only a minor lien on the significance of the success that's been accomplished here just because of the redundancy between the two sides. "Of course, the reason you put redundancy in the design to begin with is to make yourself resilient to whatever may have happened here," Mitchell said. "So we're still sorting out exactly what happened to the A chain, but we've got at least most of the data we expected to get."
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After entering orbit around Saturn, the Cassini spacecraft will launch the European Huygens probe to make a parachute landing on the surface of the moon Titan. The scientific objectives of Huygens are explained by probe project manager Jean-Pierre Lebreton. (3min 14sec file)
Learn more about Saturn's moon Titan, which is believed to harbor a vast ocean, in this narrated movie. (4min 01sec file)
An Air Force Titan 4B rocket launches NASA's Cassini spacecraft at 4:43 a.m. October 15, 1997 from Cape Canaveral, Florida. (5min 15sec file)
Rick Grammier, NASA's Deep Impact project manager from the Jet Propulsion Laboratory, provides a detailed overview of the spacecraft and its mission. (4min 54sec file)
Deep Impact principal investigator Michael A'Hearn explains how the comet collision will occur and what scientists hope to learn. (7min 11sec file)
The pre-flight news conference is held at NASA Headquarters on December 14 to preview the Deep Impact mission to intercept a comet and blast a projectile into it. (54min 19sec file)
Steve Squyres of Cornell University, the rovers' principal investigator, discusses the latest discoveries from Spirit and Opportunity.