"Diamonds May Not Be Forever." 1979. Time 134:59.
If a physicist says he is being sent off to a salt mine these days, he may not be joking. He could be heading 40 km (25 miles) east of Cleveland where an 81-ton digging machine is carving a huge cavity in a salt mine 600 meters (2000 ft.) below the ground. When excavation is completed, the cavern will be lined with synthetic rubber and filled with 10,000 tons of exceptionally pure, filtered water. Then, about two years from now, physicists will begin looking in the pool for flashes of light that could signal the decay of protons, confirm a unifying theory of nature, and end the cherished notion that matter is permanent.
Protons, which along with neutrons form the nuclei of atoms--and hence the bulk of the matter in the universe--have long been regarded as permanent fixtures on the subatomic scene, members of a family of heavy particles known as baryons. If they happened to collide with still other subatomic particles, one thing was certain: the number of baryons coming out of such interactions was always the same as the number going in. To put it in the language of physics, there was conservation of baryon number.
Now that idea is being challenged by, among others, Physicists Steven Weinberg and Sheldon Glashow of Harvard and Pakistani Abdus Salam, winners of this year's Nobel Prize in physics, for showing an underlying unity of two of nature's four basic forces: Electromagnetism and the so-called weak force, which governs some forms of radioactive decay within the atomic nucleus. In carrying their work further to relate these two forces to a third--the strong force (which binds the atomic nucleus together)--they and other researchers determined that such unity requires a net loss of baryons when certain particles collide. In other words, the proton must decay into lighter subatomic fragments. By most physicists' reckoning, protons have a mean life of around 10,000 billion billion billion (1031) years (more than half of them will disintegrate in that time). Thus out of 1031 protons, only one is likely to decay each year. The problem: how to detect that rare disintegration.
Enter the subterranean reservoir, as well as similar experiments at a South Dakota gold mine, a Utah silver mine, and a Minnesota iron mine. Based on the number of protons in the cavity's water (more than 1033), Physicists John Wander Velde of the University of Michigan, Frederick Reines of the University of California at Irvine, and their colleagues figure that there should be about 200 decay "events" per year.
Each dying proton would shoot off two decay products; most likely a positron (or positively charged antielectron) in one direction, a neutral pion in the opposite. Hurtling through the clear water faster than light travels through it, the fleeting particles will leave distinctive cone-shaped wakes of light, which should be detected by one or more of the 2,000 photomultiplier tubes lining the reservoir walls. Cosmic rays can produce similar flashes, but most of them are blocked by the thick layer of earth above the chamber. An occasional will-o'-the-wisp particle called a neutrino also may cause flashes. But its light pattern is different, and the detecting system should be able to distinguish it from those produced by disintegrating protons.
If proton decay is indeed detected, it will help establish a unity among the strong force, electromagnetism and the weak force. That would leave only nature's fourth force, gravity, outside the unified field theory sought in vain by Einstein in his later years. Perhaps most startling of all, it will set an absolute limit on the life of all matter. Says Physicist Larry Sulak: "If proton decay is true, then dust doesn't go to dust and diamonds are indeed not forever."
"Diamonds May Not Be Forever." 1979. Time 134:59.
The decay of protons, signaled by flashes of light in a large, underground pool of filtered water near Cleveland, could confirm a theory that would show the unity of three of nature's four basic forces and at the same time destroy the cherished notion that matter is permanent. The long-held belief that the same number of baryons (heavy subatomic particles including protons and neutrons) come out of collisions as go into them is being challenged by a number of physicists who are attempting to show an underlying unity of electromagnetism, the "weak force" which governs some forms of radioactive decay, and the "strong force" which binds the atomic nucleus together. This unity would be shown by the decay of protons into lighter fragments, probably positrons (positively charged anti-electrons), and neutral pions.
In order to detect this decay, several reservoirs containing thousands of tons of pure water have been constructed underground (to negate the effects of cosmic rays) around the country. Based on the number of protons in the Cleveland reservoir, physicists calculate that there will be some 200 decay "events" per year. These events will leave distinctive cone-shaped wakes of light in the water which will be detected by the photomultiplier tubes lining the walls of the reservoir. If proton decay is detected, the unity of the three forces will have been established, leaving only the fourth, gravity, outside the unified field theory so long sought by Einstein.
Doerner, William R. 1987. "Revving Up for New Voyages." Time 14 December: 65.
The explosion of the shuttle Challenger nearly two years ago threw the U.S. space program into such staggering disarray that officials have shied away from predicting when the program would get back on track, much less undertake new ventures. Though the shuttle's return to service is still at least six months away, NASA officials last week managed to look beyond that crippling disaster and announced plans for two ambitious programs for the next decade. In 1989, the space agency declared, it will finally launch its long-delayed unmanned Galileo project to Jupiter, a 23 billion-mile mission that is expected to last eight years. NASA also awarded four contracts for the construction of the long-planned space station that will serve as the nation's first permanent outpost in space.
While the projects each offer exciting prospects, they amount to something less than the fully rethought agenda that many space experts have urged on NASA. For one thing, both depend on the restored health of the shuttle program, which will be used to launch the Galileo mission to Jupiter and provide transport for the components of the space station. For another, both the space station and the shuttle program confront major budget uncertainties.
The timing of last week's announcements reflected mounting external pressure on the beleaguered agency. The Galileo mission has an approaching launch "window" that will last only six weeks in the fall of 1989. As for the space station, NASA Administrator James Fletcher faced the growing impatience of firms competing for contracts that had each spent about $75 million for preliminary design proposals.
The most striking new feature of the long-planned Galileo mission, first scheduled for 1982, is a looping itinerary that will provide momentum for the spacecraft by using the gravitational fields of Venus and the earth. This "sling-shot" routing became necessary when NASA officials decided that the rocket originally scheduled to boost the craft from a shuttle cargo bay could pose a hazard; it was replaced with a safer solid-fuel booster. Another change in plans involved putting extra gold sheeting on the Galileo spacecraft because of the scheduled pass close to the superhot atmosphere of Venus.
On its long voyage toward Jupiter, the spacecraft is scheduled to pass within 620 miles of the asteroids Gaspra and Ida, the first such close encounter in the annals of interplanetary travel. Then, five months before reaching Jupiter near the end of 1995, Galileo is to release a 730-lb. probe that will become the first man-made object to penetrate the gaseous atmosphere of the planet. Its instruments are expected to transmit data on the Jovian atmosphere for about 75 minutes before being silenced by the planet's intense atmospheric pressure. Galileo is next scheduled to settle into a two-year-long orbit of Jupiter that will enable it to make detailed studies of the planet and four of its moons.
The space station, which could eventually cost up to $30 billion, would serve as a laboratory for scientific, commercial and possible military research, as well as a base for planetary exploration. Last week contracts for its construction went to Boeing ($750 million), McDonnell Douglas ($1.9 billion), Rockwell International ($1.6 billion), and General Electric ($800 million). Nineteen shuttle missions--only six fewer than have been flown since the program began in 1981--would be required to carry the station's 200 tons of hardware into orbit.
That daunting prospect is one reason why practically no one takes seriously NASA's contention that the space station could become operational as early as 1995. Says former Astronaut Donald ("Deke") Slayton, head of a private launch firm based in Houston: "The law of averages says it won't happen." Moreover, many scientists remain opposed to the concept of a manned station, contending that most of the experiments NASA has in mind can be conducted on unmanned missions.
But the pressures to get an American laboratory of some kind into space are strong. By a sobering coincidence, on the day after Fletcher made his contract announcement, the Soviet crew commander marked his 300th consecutive day aboard Mir, the world's only space station.
I. Two new ambitious projects announced by NASAA. Galileo project to Jupiter
B. Space station
II. Problems that must be solved in order to realize goals
A. Both depend on the health of the Shuttle Program
B. Both face major budget problems.
III. Outside Pressures on the programs
A. A very limited launch window for Galileo (6 weeks in the fall of 1989).
B. Firms, having spent 75 million on proposals, are pushing for contracts on the station.
IV. Galileo Mission
A. Changes already made because of cost and mechanical problems.
1. Sling-shot routing--caused by change to solid fuel booster
2. Extra gold-sheeting--caused by close approach to super-hot Venus
B. Three Important goals
1. First close pass to asteroids Gaspra and Ida
2. Will release a 730 lb. probe to penetrate the atmosphere of Jupiter
3. Two-year-long orbit of Jupiter will give detailed studies of it and 4 moons
V. Space Station
A. Expense
1. 30 billion total, plus several multi-million dollar contracts already let
2. 19 shuttle missions will be required to carry the station's 200 tons into orbit
B. Major Problems
1. Law of averages against a 1995 operational date--"Deke" Slayton
2. Its work could be done by unmanned missions--thus many are opposed to it
VI. Irony--Plan announced on day a Soviet had spent a record 300 days on Mir
Doerner, William R. 1987. "Revving Up for New Voyages." Time 14 December: 65.
Two years after the shuttle explosion, NASA has announced two new ambitious projects: the delayed, unmanned Galileo project to Jupiter, and the construction of a space station. Both, however, face major problems and outside pressures. Both depend on the renewed health of the shuttle program and both confront major budget battles. In addition, the Galileo project has a very limited launch window (6 weeks in the fall of 1989), while NASA is being pressured by contractors, who have already spent 75 million on proposals, to speed up work on the station.
The Galileo mission's goals are to collect data on the asteroids Gaspra and Ida, to release a 730 lb. probe to penetrate the atmosphere of Jupiter, and to provide detailed studies of Jupiter and four of its moons during a two-year orbit. Yet changes have already been made in the project because of mechanical problems. The shift from a potentially dangerous liquid-fuel rocket to a solid-fuel booster caused a change in the routing of Galileo. It will use the gravitational fields of the earth and Venus to give it the momentum to reach Jupiter. Since it will pass close to super-hot Venus, extra gold sheeting had to be applied to the spacecraft.
The space station project also faces formidable problems. One is cost. Several multi-million dollar contracts have already been let, and the total could reach 30 billion. In addition, 19 shuttle missions will be required to carry the station's 200 tons into orbit. Former astronaut "Deke" Slayton believes the law of averages to be against NASA's 1995 operational date, while many scientists oppose the station because they believe its work could be done by less-expensive unmanned stations. A final irony is that on the very day these projects were announced, a Soviet cosmonaut had just completed a record 300 days aboard the in-place Soviet space station, Mir.