Sky's Limit for Telescope Tech

Sky's Limit for Telescope Tech

Sky's Limit for Telescope Tech

It seems impossible to turn around without tripping over some major telescope project of one kind or another.

NASA is developing the infrared Next Generation Space Telescope (NGST), while the Atacama Large Millimeter Array (ALMA), an international collaboration between Europe and North America, intends to build a synthesis radio telescope for small wavelengths. Meanwhile, the Pierre Auger Project has installed the first of a planned series of 3,200 particle detectors, half of which will eventually be strewn across 3,000 square kilometers of the Pampas in Argentina, and the other half in Utah. The project will study the elusive high-energy cosmic rays.

The Europeans are planning to follow up their Very Large Telescope (VLT) with a concept telescope called the Overwhelmingly Large Optical Telescope (OWL) and are studying the potential of the Astrophysical Virtual Observatory. A virtual observatory is a collection of data archives and software tools that utilize the Internet to create an environment in which astronomical research programs can be conducted.

"Governments have a big problem with this. They say, 'We just paid for a big telescope. What do you want another one for?'" says Harvey Butcher, spokesman for the Square Kilometer Array (SKA).

"In astronomy what we're dealing with is remote sensing. We can't send a satellite out to the next galaxy and study it. We have to take what nature offers us in the way of signals from various phenomena. What you find is that in every band of frequency different physics occurs."

Astronomers must use the full spectrum of electromagnetic radiation including, in order of decreasing wavelength, radio waves, millimeter and submillimeter waves, infrared radiation, visible light, ultraviolet radiation, X-radiation and gamma radiation. Infrared, which is used in the NGST, is good for looking into dark clouds. It's not sensitive to space dust and is excellent for objects with a thermal signal. Millimeter telescopy is great for studying molecules and thus is essential for astro-chemistry.

Radio waves, on the other hand, have many general applications and are very good with cold objects and hydrogen, which makes up 90 percent of all matter in the universe.

Meanwhile, optical projects like the European OWL concept are great for spectroscopy, or breaking down light sources to extract information from them. The Auger will use surface arrays and fluorescence detectors to study high-energy cosmic particles that hit our upper atmosphere. Theoretically they shouldn't exist.

Finally, X-rays are ideal for studying black holes.

Hence the need for different instruments: Each tool studies a particular phenomenon or studies general phenomena in a particular way.

"My point is the different telescopes are used for different things. You just need to know what's there," Butcher says.

Radio telescopes discovered dark matter, for example, and no other device could have done it. Each instrument studies a particular part of the spectrum and offers its piece of the puzzle.

"I think what's coming in the future is astro-particle physics where neutrinos and extremely high-energy cosmic rays and things impinge upon the earth, and that's a different kind of radiation that will teach us something different," Butcher says.

"For example, there's a very small number of extremely high-energy particles, not light particles but elementary particles – probably protons, but no one knows for sure. These particles have been detected with the energy as a launching golf ball. It would knock you flat if it could hit you. No one knows where it comes from. In theory it can't exist, so there's something going (on) out there. I think it's one of the exciting discoveries waiting to be made."