Lunes 21 de Enero de 2002, Ip nš 10

Antimatter could fuel rockets, heal patients
Por Fred Katayama

Astronauts have gone to the moon, but not other planets in large part because such a trip would require much more propulsion power and time. NASA researchers, however, are investigating antimatter for its propulsion potential.

Its explosive energy could someday enable journeys into deep space. A tiny amount would fuel the main engine of the space shuttle.

"We have an equivalent amount of energy in just one gram or about a raisin-size worth of antimatter," said George Schmidt, a scientist at NASA's Marshall Space Flight Center in Huntsville, Alabama.

Compared to conventional chemical propulsion systems, antimatter energy would slash the travel time to Mars and back from roughly two years to a few weeks.

Matter, the material that occupies space, consists of atoms and smaller subatomic structures such as protons, neutrons and electrons. For each fundamental particle in nature, there is a corresponding "antiparticle."

They have nearly identical properties, but some key characteristics are reversed. For example, protons and antiprotons have the same mass, but opposite electrical charges.

When a matter particle comes into contact with an antimatter particle, they annihilate each other and produce kinetic energy.

"The energy you get from the anti-particle particle annihilation is about ten billion times that of chemical combustion," Schmidt said.

But because no one knows where to find the antimatter, it has to be created. Scientists make it by colliding protons in particle accelerators at near light speed into targets made of nickel.

NASA built a portable trap to store antimatter. It hopes to use the device to someday transport the volatile material to a rocket launch site.

A space agency objective during the development phase is to collect one trillion particles in the trap. But that would just yield enough energy to light a 60 watt bulb for five seconds.

The production process is difficult and expensive. The world's largest maker of antimatter, the Fermi National Accelerator Laboratory in Batavia, Illinois, makes only one billionth of a gram a year at a cost of $80 million.

At that rate, it would take one million years and $80 quadrillion (80,000 trillion) to produce one gram. Unfortunately, a spacecraft would need several pounds, not grams, to travel to the nearest star. One pound is equal to 454 grams.

"It's in an extreme infancy right now. There are concepts for how things might work. It's not a technology that's going to come to jury in the next 20 or 30 years. It's a very futuristic technology," said Stephen Holmes, associate director for FermiLab.

Today, antimatter is being used in medical imaging systems for diagnoses. But it could hold bigger promise in treating diseases.

Chances are, antimatter will first be used as a medical treatment before it is used to travel to Mars. Scientists think it will be more effective than X-rays in killing cancerous tumors.

That application could happen within 10 or 15 years, according to medical researchers.

"Antimatter has definitely got potential in this area," said Dr. Timothy Akhurst, a nuclear medicine physician at the Memorial Sloan-Kettering Cancer Center in New York, New York.

"When a proton meets an antiproton, it will deliver a lot more energy to the local tissue because of the annihilation that's occurring. The question is, how well that can be focused and whether we can use that to be imaged."

As for celestial bodies, scientists hope to transform antimatter propulsion from science fiction to fact in 50 to 100 years.


  10/01/2002. CNN.