INVITED: STUDYING FIRST LIGHT AND THE COSMIC DARK AGES FROM BEYOND THE EARTH

I will first briefly review the major space-based missions and ground-based telescope projects that explore our universe, including the ones planned for the next decade. These telescopes are designed to observe our universe, which has expanded by a factor of more than 10^50 since the Planck time. The first observable epoch is that of the Cosmic Background Radiation, released when the universe was 378,000 years old and 1100x smaller than it is today.

One of the new missions is the 6.5 meter James Webb Space Telescope (JWST), slated for launch into an halo L2 orbit past the Moon's orbit in 2012. Its main science themes are to measure First Light, Reionization, Galaxy Assembly, as well as the process of Star-formation and the origin of Planetary Systems. The First Light epoch occurred when the universe was about 200 Myrs old and 20--30x smaller than it is today. Because this light is redshifted by a similar factor, JWST is an optimized infrared telescope that will deploy automatically.

Finally, I will discuss what is required to observe the cosmic "Dark Ages'', which occurred before the first stars starting shining. During this epoch, the universe was less than 200 Myrs old and between 30--1000x smaller than today. It consisted purely of neutral Hydrogen and Helium, and is best observed through the 21 cm neutral HI-line. Redshifted by 30--1000x, observing HI in the Dark Ages requires a low-frequency radio interferometer that operates at frequencies of 10's of MHz with baselines of 100's of km. Ionospheric absorption and human-made interference pose serious limitations in this frequency range. The long baselines required and the need to rotate the sparsely filled aperture then require that we build this Dark Ages array on the far-side of the Moon. I will outline how this low-frequency radio interferometer may be built with long-duration science rovers on the Moon's far-side.