A small and sturdy box weighing 25 pounds is packed with vital astronomical data gathered by one of the world's largest telescopes. Federal Express delivers it to a processing center where, once combined, the data will reveal details of the heavens so exquisite they'll be like seeing the dimples on a golf ball from across the United States.

There's just once catch: the telescope isn't exactly real. It's a virtual telescope, a cosmic eaves-dropper made up of the combined efforts of four very real radio telescopes scattered around the globe. The box holds a spool of magnetic tape more than three miles long. Encoded on it are some 36 miles of data collected by the four observatories.

Doeleman is part of an international group of astronomers who have linked radio telescopes in Arizona, Chile, Spain and Finland to create one of the largest, most powerful virtual telescopes ever. The spools of data are processed at two centers, one at MIT, the other at the Max Planck Institute for Radio Astronomy in Bonn, Germany. The boxes are seen as valuable, but they're not treated with any special care.

"They're very sturdy so we just throw them in the mail, FedEx, and they get to us just fine," Doeleman says.

Doeleman and his colleagues must have faith in the strength of the spools and, perhaps, in FedEx, because the data are hard to come by.

Using a technique known as Very Long Baseline Interferometry (VLBI), the scientists, in essence, created a radio telescope spanning the distance from Arizona to Spain, or about 5,280 miles (8,500 kilometers) wide. In comparison, the largest single radio dish, at Arecibo Observatory in Puerto Rico, is 1,000 feet (305 meters) across. The interferometry project with the longest baseline was the Japanese-led VLBI Space Observatory Program (VSOP), which launched a radio antenna into an elliptical orbit that created a telescope 13,000 miles (21,000 kilometers) across.

What is unique about the new project is the high angular resolution the team was able to achieve, which Doeleman has compared to "the equivalent of sitting in New York and being able to see the dimples on a golf ball in Los Angeles." In technical terms, the telescope can resolve 50 microarcseconds, or one hundred millionth of a degree of the sky.

Two factors determine angular resolution: the size of the telescope dish and the wavelength of light observed. The larger the dish and the shorter the wavelength, the more powerful the telescope. So even though they were not able to create a telescope as big as Earth, the astronomers observed at 2 millimeters, which had never been done before.

"We recorded at a frequency that is extremely high for VLBI standards," Doeleman said. "That was the key to this experiment."

(Radio stations use waves in the same band as those that radio astronomers observe, but they give their wavelength values in frequency. The two are inversely related.)

Coordinating radio telescopes on three continents to perform interferometry, especially at such a short wavelength, or high frequency, is not a trivial task.

"It's just very technically difficult to do," Doeleman said. "The atmosphere starts corrupting some of your data at those high frequencies."

The key to avoiding this problem is choosing telescopes at a high-altitude to minimize atmospheric distortions. Also, the telescopes must have comparable capabilities. "The telescope surfaces have to be extremely good; they have to be very, very smooth," Doeleman explained.

But these types of telescopes are usually not dedicated to VLBI and tend to be very much in demand, Doeleman said. So the astronomers apply for simultaneous observing time.

If the telescopes do not have the right equipment, it must be built. When all is ready, the observations are made, and the researchers cross their fingers and hope that the weather is clear at all the sites. Finally, when the data are taken and recorded onto the magnetic tape, they must be time-stamped so that during processing, radio signals taken at the same exact time can be identified.

The accuracy is so important that all of the telescopes were outfitted with hydrogen-maser clocks. (Masers are like lasers but use microwaves, not optical light.) The clocks are accurate to the 14^th order of magnitude, or to one-hundred-trillionth of a second. Bring down the precision to ten-trillionth or one-trillionth, and all the work is for naught.

"It was a lot of teamwork and everything had to be working at precisely the right time at these different places," said Lucy Ziurys, director of the Arizona Radio Observatory at the University of Arizona, which has jurisdiction over the two American telescopes used in this collaboration.

Ziurys was also a collaborator on the project, as was Thomas Krichbaum from the Max Planck Institute for Radio Astronomy, and Albert Greve from the Institut de Radio Astronomie Millimétrique.

According to Doeleman, initial discussions for this project started three to four years ago, "But things really started coming together and picking up speed about this time last year."

The high resolution achieved by this VLBI project enables astronomers to investigate phenomena not possible at lower resolutions.

One of the first objects the astronomers observed was Active Galactic Nuclei (AGN), which are located in the centers of galaxies that emit more energy than can be accounted for by the emission of stars alone. Instead, researchers believe that supermassive black holes lie at the galactic centers. These black holes, which can be billions of times the mass of the sun, often emit jets of high speed, high energy particles, up to millions of light years long. Using VLBI, the astronomers hope to zoom in on where the jets start to pin down the dynamics of the cosmic jets.

"If we can figure out how these jets start, then we'll be a long way to understanding what powers these central engines of galaxies," Doeleman says.

Similarly, astronomers believe that there is a black hole at the center of the Milky Way. Although it is of considerably smaller mass than those that power AGNs, it is "in our backyard," which could allow for amazing science as well. "If we could get this technique to work on an object that close, we would get such fine resolutions on it that we could start probing the size scales of the black hole itself," Doeleman says. "And in the future, if we can get enough sensitivity, we can actually start to see things that only theory has ever predicted, like the event horizon of the black hole."

There are also phenomena in the universe that are invisible at lower frequencies than those at which Doeleman and his colleagues observed, such as maser stars. Found around old and young stars alike, it appears that light from the stars creates masers by exciting the surrounding gas, also known as the circumstellar envelope. The masers create what appears to be a "ring of little points" of radio light around the star, Doeleman says. "This is crazy. When I first heard about this, it was very surprising to me."

Using VLBI, he hopes to investigate the maser stars to determine "how the atmosphere of a star is bubbling or broiling around the star itself."

The astronomers made observations of these phenomena back in April, but due to the complex nature of correlating the data, a few months passed before they were able to see their results. Preliminary findings were presented at a VLBI conference in Germany in June. While further observations using this technique will provide increased understanding of these phenomena, what may also help, of course, are further improvements in resolution.

Observations at 1 millimeter are tentatively planned for the spring, according to Ziurys.

"We’re just beginning to get this to work and there’s a lot of science that can be done provided we can keep the telescopes going and the whole project going," Ziurys says. "This was more of a proof of concept experiment."