The first closeup temperature measurements of Saturn's mysterious moon Titan apparently were lost in space today, victims of the storms that have been raging for the last month on the surface of the sun.
"There's a chance the Titan measurements are hidden in a tape recorder at our receiving station outside Madrid," Pioneer program manager Charles F. Hall said today at the National Aeronautics and Space Administration's Ames Research Center, where Pioneer 11's fly-by of Saturn is being directed. "But the chance is slim and it appears we've lost the data."
Scientists were eagerly awaiting Pioneer's temperature measurements of Titan, the largest moon in the solar system and thought to be the only one possessing an atmosphere rich enough to support a primitive form of life. Crucial to the question of life on Titan is its temperature, estimates of which range from 310 degrees below zero Fahrenheit to just below zero.
Pioneer scanned the surface of Titan with its infrared radiometer late Sunday night as the spacecraft moved away from Saturn on the beginning of its long voyage out of the solar system. The way Pioneer and Titan were positioned meant the spacecraft had only that one chance to take the moon's temperature.
Early this morning, Pioneer sent its temperature measurements of Titan back toward Earth, but they apparently never got here. Not only had solar storms caused a rise in space noise this morning, but Pioneer itself was facing almost directly into the sun while it was transmitting, meaning it sent Titan's temperature measurements right into the teeth of the storm of electrons and protons pouring off the sun.
"If that wasn't enough, there was a rain squall at our station in Madrid that was in position to receive the data," Hall said. "For all we know, this combination of events was too much for the data and drowned it all out."
Unless a miracle occurs and the temperature measurements are dug out of the tape recorder in Spain, the first closeup temperature readings of Titan will have to wait until November 1980 and August 1981, when Voyagers 1 and 2 arrive at Saturn.
Both Voyager spacecraft are equipped with better infrared devices and will fly much closer to Titan than Pioneer did, which never got closer to the big moon than 220,000 miles. The strength of Voyager's radio signal is 30 times that of Pioneer's, which means the question of radio noise in space drowning out its signal will be eliminated. But until the Voyagers arrive, the temperatures on the surface of Titan apparently will remain a mystery.
Not all the news of Pioneer 11 was bad today. As the 570-pound spacecraft flew behind Saturn and looked back at its dazzling rings, it took a picture of the rings lit by the sun behind it that was so spectacular it showed details in the rings essentially hidden from earthbound telescopes for 300 years.
The picture showed the three brightest rings around Saturn in vivid colors that ranged from brown to orange to yellow. It showed a striking brown-and-white shadow cast on the globe of Satury as the sun shone against the rings.
The picture revealed a division or gap between the two innermost bright rings that had never been confirmed before from Earth. French astronomers had said they had seen this division from Earth, but no other astronomers had seen it and most doubted that it was there.
"I don't know what to call this division, but possibly we ought to call it the French Division," Dr. Thomas Gehrels of the University of Arizona said today. "But for the time being it will have to go unnamed."
So clear and precise was the picture taken of the rings today that the dim division that separates the outermost large ring known as the Encke Division was clearly visible. Structures could be seen in the Cassini Division, the large gap between the two outer rings known as the A ring and B ring.
Despite its clarity, the photograph did not reveal the innermost ring known as the D ring, a faint ring outside the A ring called the E ring and the newly discovered ring beyond the E ring known as the F ring. Saturn's bright surface apparently washed out the innermost ring, while the E and F rings were too faint to show up in the photograph.