Huygens science data received; one channel out
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: January 14, 2005
NASA's Cassini Saturn orbiter began downlinking science data from the European Space Agency's Huygens probe at 11:19 a.m. EST (1619 GMT), confirming the spacecraft not only survived its high-speed plunge into the atmosphere of Saturn's moon, Titan, but that its instruments worked to remotely explore one of the strangest worlds in the solar system.
"Cassini has just started to deliver the data collected during the descent," said Jean-Jacques Dordain, director general of the Eruopean Space Agency. "This is a fantastic success for Europe!"
Cassini and Huygens mission managers, scientists and engineers erupted in cheers and applause when the first data packets began showing up on computers screens at the European Space Agency's Space Operations Center in Germany. Successful reception of science data capped a morning of high drama and ended any uncertainty that Europe had achieved one of its most impressive engineering and scientific triumphs.
"All instruments are on," a flight controller told the Huygens team.
Mission managers already knew Cassini had survived its hellish plunge into Titan's atmosphere and had made it to the moon's surface because of an unimaginably faint carrier signal that was detected by a network of Earth-based radio telescopes. The signal, some 50 quadrillion times weaker than a typical FM radio signal in a car radio, proved Huygens had survived entry, deployed its main parachute and activated critical subsystems. The signal lasted more than two hours after the predicted landing, but it did not carry any scientific data. It was merely a tone and while it showed the craft was alive, it didn't prove whether it had accomplished its scientific objectives.
But the European spacecraft apparently worked as advertised and right on schedule, after Cassini dropped below Titan's horizon, the NASA mothership turned back toward Earth and began transmitting data from Huygens' suite of six instruments.
"So the morning was good. The afternoon is better," Dordain said at a news conference. "This morning, we had an engineering success and we can say this afternoon that we also have a scientific success. We are the first visitors to Titan and the scientific data we are collecting now shall unveil the secrets of this new world."
It will take several hours for mission scientists and engineers to extract and stitch together pictures from the data stream, but the first panoramic views showing the surface of Titan as Huygens descended through its hazy atmosphere may be available between 5 p.m. and 6 p.m.
"The torch has been handed off from the engineers ... who've done their job of delivering the probe and delivering the data back," said David Southwood, European Space Agency science director. "Now the scientists start work. We're going to be working, I think, very hard in the next hours and days but in fact, this data is data for posterity.
"This is a historic event. I don't think it's likely in the lifetime of anyone in this room that we will repeat a landing on Titan. so this is the data, it's for posterity, it's for mankind. But it's got to be unraveled, it's got to be put together and then scientists, being scientists, are going to argue about what it means as we piece together our place in the universe and how we came to be. I think this is a very major step forward. But it's only the beginning for our science teams."
NASA science chief Al Diaz choked back tears as he called the probe mission "a tremendous success."
"This really is another first," he said. "There will only be a first successful landing on Titan and this was it. The European Space Agency deserves a tremendous amount of credit. We're glad we could have been a partner."
Claudio Sollazzo, ESA's Huygens operations manager, said engineers were investigating the apparent loss of data from one of two channels, or chains, of telemetry from Huygens. But he said the spacecraft was fully redundant and that "we can ensure that so far, on chain B, we see everything went well."
"The probe went through the entry phase and the (main) parachute was deployed essentially at the time we predicted," he said. "We are anxious to see what we call the history data, the telemetry that was recorded on board the probe before even the back cover came off so we can reconstruct how the probe entered the atmosphere. This is very important information for the scientists to know how the higher atmospheric layers are. it is also very important for the engineering community."
Data on chain B showed "the batteries are OK, the computers worked as expected, the software shows healthy status and instrument status as far as we could receive ... were nominal," Sollazzo said. "The internal temperature of the probe was about 25 degrees centigrade. So ... our instruments are working at a very comfortable temperature."
One of Huygens' six experiments, the Doppler Wind Experiment, relied in part on chain A of the probe's communications system. It was designed to measure wind speeds by detecting subtle changes in the frequency of radio transmissions as th craft is blown this way or that. If chain A did not work, scientists will lose measurements of that shift between Huygens and Cassini. But Sollazzo said similar measurements from Earth-based radio telescopes will allow scientists to collect similar data to make up the shortfall, assuming the data on chain A is, in fact, lost.
"We have a wonderful mission on Titan," he said, "and we are eager to deliver the data to our scientists on time and then they will go on and analyze the data and we should get some interesting results later tonight."