When: Thursday, April 03, 4:00 p.m.

Where: 7500Wean Hall

Jeff Peterson, Professor
Physics Department, Carnegie Mellon

Joint SCS/RI/Physics Seminar

Abstract:
I will describe a program to use robotic systems to construct a radio telescope on the Moon.

When the universe was less than 100 million years old, before the first stars formed, it was filled with hydrogen gas. This gas can be detected and mapped via its absorption at the wavelength 21 cm. Because of the Hubble expansion these wavelengths get stretched to several meters before arriving at our solar system. This means that by mapping the sky using a meter-wave radio-telescope astronomers can study the dark ages of the cosmic expansion.

If successful such a program could be revolutionary. The data set would span several octaves of cosmic expansion and would be rich with detail. The data set would be huge and three dimensional, since frequency encodes radial distance. In addition to addressing the innate human desire to understand our origins, such data can be used to test Einstein's theory of General Relativity, and place limits on a possible earlier episode of exponential inflation.

Meter-wave astronomy suffers from two limitations: Radio Frequency Interference and Ionspheric Distortion. Both problems can be solved by using a lunar site for the telescope. A telescope for these wavelengths can consist of an array of very light-weight pop-up dipole antennas, powered by solar cells and communicating via wireless internet. Since thousands of such dipoles are needed, spread across a several square kilometers, it may make sense to place and maintain these antennas using robotic vehicles.

Jeff Peterson got his BS at University of Illinois, and PhD at the University of California at Berkeley. He has served on the faculty of the Department of Physics at Princeton and at Carnegie Mellon. His research group has built telescopes at the South Pole, in China and in India. These radio-telescopes have been used to weigh the Universe, and to study Dark Energy, the anti-gravity agent that seems to be accelerating the expansion of the Universe.

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