SOVIET SPACECRAFT HEADS FOR COMETBy John Noble Wilford Dec. 16, 1984 [NYT]
Leading off an international effort to greet the return of Halley's comet with a flotilla of spacecraft, the Soviet Union yesterday launched Vega 1 on an interplanetary voyage to reach the celebrated comet in March 1986.
The 8,800-pound Vega, carrying two television cameras and an array of scientific sensors, was reported to be functioning normally as it headed for the first close encounter with the comet, which has dazzled mankind with its spectacular visits every 76 years.
A Legend and an OmenOne of the more brilliant comets, Halley's is legendary as an omen of ill-fortune and irresistible as an object of scientific curiosity because so little is known about these wanderers from the fringes of the solar system.
Vega 1 is the first of four craft that are to visit the comet in the same month and conduct a comprehensive study of the comet's solid nucleus and surrounding cloud of gas, dust and other material. Vega's sensitive cameras could return the first images of the core of a comet.
Soviet scientists are expected to launch a companion craft, Vega 2, probably on Friday. The 11-nation European Space Agency plans to launch its craft, Giotto, next July. Japan expects to dispatch its craft, Planet A, next August.
The National Aeronautics and Space Administration, citing a lack of money, rejected proposals for a United States mission to rendezvous with Halley's comet but does plan observations with a telescope aboard the space shuttle. Scientists from all the nations, including the Soviet Union, have promised to share fully the results of the missions. Tracking data from the Vega craft, for example, are to be provided to the Europeans to help them plot the course of Giotto.
In an announcement of the launching, Tass, the Soviet press agency, said Vega 1 was boosted aloft by a Proton rocket fired from the Baikonur space center in the steppes of Kazakhstan. Tass said the craft appeared to be on course and functioning normally.
The announcement said scientists from Austria, France, West Germany, Bulgaria, Hungary, East Germany, Poland and Czechoslovakia were participating in the mission.
As planned, the two Vegas are to follow roughly the same course to their rendezvous with the comet, which was named for the British astronomer Edmund Halley, who first predicted the periodic return of the comet. They are also to fly by Venus next June to deploy capsules, developed with French scientists, containing an atmospheric balloon probe and a landing craft. Data on Venusian Atmosphere
The Soviet-French balloons should provide data on wind speeds and directions in the dense Venusian atmosphere. Tass called the atmospheric studies ''fundamentally new experiments.'' Antennas operated by the United States are to assist in tracking the drifting balloons. The landers will attempt the first nighttime descent to the surface of Venus and radio data on surface conditions to complement the findings of previous Soviet landings on the planet.
The name Vega is derived from the Russian names for Venus (Venera) and Halley (Gallei), reflecting the two targets of the missions.
In passing close to Venus, the craft will take advantage of the planet's gravitation to gain energy and change direction for the rest of the journey to the comet. American space experts said this would be the first mission by the Soviet Union using gravity in this way. American craft have used the gravity of Venus to proceed to Mercury and the gravity of Jupiter and Saturn to move on to the outer planets.
Vega 1 is scheduled to reach the vicinity of Halley's comet on March 6, 1986. Vega 2, if it is successfully launched, should arrive three days later. If all goes well, the European Giotto and Japan's Planet A are to arrive at about the same time on March 13. Disappears Behind Sun
By that time, the comet will have been observed for several months by ground-based telescopes. The comet, which last visited the inner solar system in 1910, should be clearly visible as it streaks in toward the Sun in the fall of 1985. Then it will disappear behind the Sun in January and February and re- emerge to begin its outbound journey. The comet in March should be resplendent as a ball of spreading gases and dust perhaps 60,000 miles wide. The solid nucleus is estimated to be about four miles wide.
Ray L. Newburn, an astronomer at the Jet Propulsion Laboratory in Pasadena, Calif., said Soviet scientists gave details about the Halley rendezvous at a meeting in Estonia two weeks ago. Dr. Newburn is the American leader of the International Halley Watch, an organization coordinating the efforts of professional and amateur astronomers in observing the comet.
Vega 1, Soviet leaders told the visiting scientists, will be directed to fly through the dust cloud, or coma, in front of the comet, coming within about 6,000 miles of the nucleus. Depending on the results of the first mission, Vega 2 may be directed to fly within 1,800 miles of the core.
Dr. Newburn described the Vega television cameras as very sophisticated. Developed by French, Soviet and Hungarian engineers, the black- and-white cameras have a short focal length for wide-angle photography and a long focal length for narrow-angle pictures. The wide-angle camera should provide clear pictures of the entire comet, the coma and the long tail. The narrow-angle camera will be focused to look through the coma to detect the nucleus, if the dust is not too thick. The camera may be able to detect features as small as 600 feet in width. Shield Against Comet Dust
The Vega spacecraft are built with thick metal shielding against the blizzard of potentially damaging dust particles they are expected to encounter at the comet.
With the assistance of the Soviet pathfinding missions, the European Space Agency's Giotto, named for the 14th-century Florentine painter who depicted Halley's comet in a fresco, will be aimed to fly within 300 miles of the Halley's nucleus for an even more detailed examination of the composition, physical processes and chemical reactions in the comet's immediate atmosphere and extended coma. Giotto also will be equipped to take pictures.
Going to Halley's comet represents the interplanetary flight debut for both the Europeans and Japan. Giotto will be launched by a European-built Ariane rocket from a launching base in Kourou, French Guiana. Japan's Planet A will be boosted by a Japanese- built rocket from the Kagoshima Space Center in Japan.
Because Planet A will not be capable of making extensive midcourse corrections, it will be aimed a safe distance away from the comet, about 60,000 miles. Even at that distance, however, the craft is expected to return data complementing the Soviet and European missions. Its goals are to observe the coma's growth and decay, the expanding hydrogen cloud around the nucleus and the shock front where the ''wind'' of solar particles meets the coma.https://www.nytimes.com/1984/12/16/world/soviet-spacecraft-heads-for-comet.htmlSPACECRAFT CONVERGE FOR FIRST LOOK AT COMETBy John Noble Wilford March 4, 1986 [NYT]
SCIENTISTS who study the solar system have waited years for this moment. Anyone who has looked in awe upon comets will now be seeing the most famous one revealed as never before.
Five spacecraft from earth are converging on Halley's comet, and in a week's time, beginning early Thursday morning, they are to fly near or through the luminous gases and dust for the first intensive close-up examination of this curious, dazzling vagabond from the fringes of the solar system.
Three of the craft, the two Vegas dispatched by the Soviet Union and the European Space Agency's Giotto, are carrying television cameras that should provide the first detailed pictures of a comet, including perhaps the first glimpses of a frozen cometary core. Giotto is targeted to sweep through the blizzard of dust to within 560 miles of Halley's nucleus for what could be the most revealing explorations.
Two spacecraft from Japan, named Suisei and Sakigake, will pass at safer distances with instruments for observing changes in the comet's atmosphere, the interaction of solar particles on the comet and the cloud of hydrogen that extends far out from the comet.
''It's the greatest week cometary science has ever had and is likely to have for quite some time,'' said Dr. John C. Brandt, an astronomer at the Goddard Space Flight Center in Greenbelt, Md.
Dr. Roger-Maurice Bonnet, director of scientific programs for the multinational European Space Agency, said, ''We are very confident these missions will end up with new discoveries on the origin of the solar system.''
Comets are assumed to be relatively unaltered icy bodies formed at about the same time the solar system was evolving 4.6 billion years ago. Most of them remain out beyond the planets, but occasionally the gravitational force of passing stars or other bodies presumably jostles some of the comets and sends them on trajectories past the inner planets and around the Sun.
The pictures and diverse observations of magnetic fields, energized particles and surrounding gases and dust are ''going to tell us more about comets than we have learned in all our past centuries of study,'' said Ray L. Newburn, co-leader of the 53-nation International Halley Watch organization at the Jet Propulsion Laboratory in Pasadena.
American scientists have a dust-collecting instrument aboard each of the Vegas. They are helping to track the international fleet and will participate in analyzing the spacecraft findings. Three American craft, Pioneer 12 orbiting Venus, the Solar Max spacecraft and the International Cometary Explorer, are focusing their instruments on Halley's comet this month.
The Explorer was redirected and renamed for its fly-by of the comet Giacobini-Zinner last September. This was the first close-up investigation of a comet, but the craft had no cameras and few instruments capable of conducting the kind of measurements that will be made of Halley's comet.
But no American craft expressly built for comet study is part of this international greeting party. The National Aeronautics and Space Administration cited budget restrictions in rejecting proposals for an ambitious American Halley mission. The space shuttle Challenger was carrying a comet-watching instrument when it exploded Jan. 28. And another shuttle was to have been launched this week with ultraviolet telescopes for making observations complementing the Soviet, European and Japanese expeditions.
Scientists at the Jet Propulsion Laboratory said Soviet officials had promised to share all the pictures and data from their Vega spacecraft. They were also expected to supply navigation information immediately to assist the Europeans in guiding Giotto on its possibly suicidal course close to Halley's nucleus. Depending on an assessment of the hazards from the Vega data, Giotto could be redirected to come as close as 300 miles to the comet's core. First Sighting in 240 B.C. This visit of Halley's comet, which returns to the inner solar system every 76 years, has been tracked by astronomers since 1982. Its first sightings, by Chinese astronomers, is believed to have been made in 240 B.C. Halley's rounded the sun during the current appearance Feb. 9 and is speeding to the outer limits again.
When the first Vega makes its close encounter, the comet will be 72 million miles from the sun, 109 million miles from earth and it will be traveling 106,000 miles an hour.
Vega 1 was reported to be on course and functioning properly for its scheduled rendezvous with Halley's Thursday at 2:20 A. M. Eastern standard time. The craft is to fly within 5,500 miles of the comet's nucleus, well within the gases and dust surrounding it, and rushing through at 174,000 miles an hour. The name Vega is a contraction of the Russian words for Venus (Venera) and Halley (Gallei). Launched in December 1984, the spacecraft flew by Venus, dropping off a landing probe there, on its way to the comet.
The Japanese craft, Suisei, which is the Japanese word for comet, is scheduled to come within 94,000 miles of the comet Saturday at 8:07 A. M. It will be studying the comet's atmosphere with an ultraviolet camera and a device to detect interactions between the solar ''wind'' of particles and the comet's surrounding gases.
The next day, at 2:21 A.M., Vega 1 is scheduled to pass within 5,000 miles of Halley's comet. It is outfitted with cameras and remote-sensors identical to its sister ship. An international team of scientists is gathering in Moscow to receive the data.
Next Monday, at 11:18 P.M., the second Japanese craft, Sakigake, will reach a point 4.3 million miles from the comet, not close enough for detailed examination of the comet itself but of the solar wind and magnetic fields in the vicinity. Sakigake, loosely translated, means pioneer.
Three days later, at 7:02 P.M. on March 13, Giotto is to make the closest approach to the comet, directed from a European Space Agency control center at Darmstadt, West Germany. Giotto is names after the Florentine painter Giotto di Bondone, who apparently used a sighting of Halley's comet in 1301 as the model for the Star of Bethlehem in his fresco ''Adoration of the Magi.''
Although the Giotto craft will be plunging through dense dust and gas, European mission officials said the craft had a protective shielding and was given a 90 percent chance of surviving its encounter with the celebrated comet.https://www.nytimes.com/1986/03/04/science/spacecraft-converge-for-first-look-at-comet.htmlCRAFT SWEEPS BY HALLEY'S COMETBy Felicity Barringer, Special To the New York Times March 7, 1986
An unmanned Soviet spacecraft plunged through the atmosphere of Halley's comet this morning and sent back the first pictures showing the icy core, formed as the Solar System was evolving 4.6 billion years ago.
The first view of the comet's nucleus was transmitted shortly before 10:20 A.M. (2:20 A.M., Eastern standard time) as the Vega 1 spacecraft closed to within 5,500 miles of the core. The image showed two small areas of concentrated brightness, raising the intriguing possibility that Halley's comet may have two nuclei.
The computer-enhanced television images, taken with a variety of filters, showed roughly oval areas of differing light intensities. The color coding showed the outer areas of least intensity in violet, then moved through yellow and into red, the area most closely surrounding the nucleus.
Size of Comet's Nucleus
After a pause, Albert A. Galeyev, a senior official at the Soviet Institute of Space Research, replied, ''Three or four kilometers,'' roughly the predicted size of the nucleus.
At this apparent confirmation that the previously invisible nucleus was on the screen, sudden, sharp applause filled the institute's main viewing room.
By that time the craft was already speeding away from the nucleus. The images took more than nine minutes to travel the 109 million miles back to Earth.
The television images were the chief jewel of a mission that sparkled with success. The Vega 1 spacecraft, operating in response to commands from the ground, was able to lock its cameras on the comet today and to generate more than 500 television images in three hours, while streaking by at 47 miles a second.
''This has been an unqualified success,'' said Tamas Gombosi, a physicist from Hungary. Seeing the cometary nucleus, he said, was as difficult as ''seeing the Eiffel Tower in a Sahara sandstorm.''
''This is indeed a watershed day for world science,'' said Thomas Donahue, chairman of the Space Science Board of the National Academy of Sciences in Washington, one of the many scientists from around the world who were invited to witness the encounter from the Moscow headquarters.
As the two screens in the viewing rooms went blank, Roald Z. Sagdeyev, head of the Institute for Space Research, who has overseen the project since its inception, was greeted with a burst of congratulations from more than 100 scientists representing 12 countries. Gorbachev Interrupts Meeting
Mr. Sagdeyev was informed by telephone shortly afterward that Mikhail S. Gorbachev, the Soviet leader, had interrupted the first meeting of the Communist Party's new Central Committee to announce Vega's accomplishment.
The Vega mission represented not just a technological success, but an exercise in scientific cooperation that brought scientists on both sides of the Iron Curtain together in a painstaking and complex collaboration.
The craft's cameras, for instance, are a blend of Hungarian electronic, French optics and Russian coupling devices. The rotating platform on which they were mounted was built in Czechoslovakia.
Preliminary data from more than a dozen experiments on board also indicated that the comet's icy nucleus, under constant buffeting by solar winds, may be transformed into gases at rates two or three times what was previously supposed.
At the same time, the microscopically-fine silicate dust that swirls around the nucleus may be more sparse than had been predicted, a potential boon to the European Space Agency's Giotto spacecraft. Giotto is set to take cameras and other monitors within 320 miles of the nucleus next Thursday, and there has been some fear that collision at great speed with the dust particles might destroy Giotto.
While many of the scientists present were sure that the final close-up images of the comet had shown the nucleus, Mr. Sagdeyev and a few others cautioned that data analysis might be necessary to determine that the images were of the comet.
There was no doubt in the mind of Fred Whipple, 79 years old, the director emeritus of the Smithsonian Institution's Astrophysical Observatory. In 1950, Mr. Whipple was the first scientist to suggest that comets contained a relatively tiny core that was largely made up of ice. 'A Complete Confirmation'
''I would say this was a complete confirmation,'' Mr. Whipple said. ''The fact the comet's image came out with a bright center shows we were seeing the nucleus. If that were simply dust, we wouldn't see the irregularities we saw.''
''The most interesting thing,'' Mr. Whipple added, ''was the question of whether there was a second nucleus or just a jet of dust. It looked to me like a second nucleus.''
Another surprise, according to A.K. Richter of the Max Planck Institute of West Germany, was the rate at which the icy outer skin of the nucleus was turning to gas.
While the molecular structure of the comet's atmosphere conformed to predictions, Mr. Richter said the cold layer of just-converted gases was traveling with greater velocity and stretching farther away from the nucleus than expected.
The spacecraft entered the comet's atmosphere shortly after 7:20 A.M. today, according to Mr. Galeyev. The last three commands to the craft's cameras were sent from Soviet ground stations about 30 minutes earlier, according to Mr. Gombosi.
For three hours after the high-speed telemetry devices on the craft began functioning, the main solar panels powering the craft were switched off in favor of chemical batteries. The mission planners had long feared that the high-velocity dust within the comet could damage the panels, causing a loss of power at the most crucial moments.
But Tass, the official Soviet press agency, reported that the spacecraft's systems ''remained workable and are functioning normally'' after the spacecraft emerged this afternoon from the atmosphere surrounding the comet.https://www.nytimes.com/1986/03/07/science/craft-sweeps-by-halley-s-comet.html
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