Tuesday, February 28, 2012

Solar radio burst imaging from the lunar surface

Notional field array of 30-meter (short wave) antennae deployed on the lunar surface, beyond the effects of Earth's dynamic ionosphere, which is notoriously refractive of radio waves to HF wavelengths [NLSI].
Robert MacDowall, GSFC
NASA Lunar Science Institute
NLSI Director's Seminar

The lunar surface is often identified as a prime location for acquiring radio observations at frequencies below the terrestrial ionospheric cutoff or for lunar far-side observatories that would be shielded from terrestrial radio interference. We consider a candidate observatory for solar radio burst imaging below 10 MHz. 

The Radio Observatory on the Lunar Surface for Solar studies (ROLSS) consists of 3 arms of thin polyimide film, each 500 meters in length and radiating from a central hub, providing approximately 2 degrees angular resolution at 30-meters wavelength (10 MHz). Each arm includes 16 dipole antennas consisting of metal deposited on the film and transmission lines connecting to receivers at the central hub. These arms could be unrolled using a crewed or robotic rover. 

The data collected by the antennas are processed at the central hub and down-linked to Earth for final radio image synthesis. This antenna system is uniquely suited to the low mass and low volume requirements for delivery to the lunar surface. 

In an online presentation sponsored by the NASA Lunar Science Institute, Feb. 28, Robert MacDowell of NASA Goddard reviewed the scientific goals of ROLSS and their relationships to heliophysics, hardware components ROLSS requires, the current status and work to be completed and the role of a pathfinder mission to provide mission risk reduction at modest cost.

The ROLSS concept study was funded by the NASA Lunar Sortie Science Opportunities (LSSO) program. The LUNAR consortium (Jack Burns, P.I.) is funded by the NASA Lunar Science Institute to investigate concepts for astrophysical observatories on the Moon.

Robert MacDowall has worked at NASA Goddard Space Flight Center (GSFC) since 1979, originally as an employee of Computer Sciences Corporation and other contractors, and later as a civil servant. During his years at Goddard he has worked in the fields of solar and planetary radio astronomy, in analyses of the solar wind and interplanetary magnetic fields, and plasma wave physics. He is currently the Lab Chief for the Planetary Magnetosphere Laboratory. 

MacDowell's "other recent or ongoing responsibilities include" the Ulysses Unified Radio & Plasma Wave Investigation (as Principal Investigator.), Solar Probe Plus Magnetometers (Co-PI), Interstellar Boundary Explorer (Mission Scientist), NASA Lunar Science Institute/LUNAR team (Co-I), WIND/WAVES (Co-I), STEREO/WAVES (Co-I), Cassini/RPWS (Co-I) and Radiation Belt Storm Probes Magnetometers. His interests also include space-based radio aperture synthesis imaging from space by microsatellite clusters or from the surface of the moon.

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