A "hot" topic in space exploration circles these days is transient activity, which is one of 12 topics discussed in the May special issue on the subject of Solar System Radar and Radio Science of Proceedings of the IEEE, the world's most highly-cited general interest journal in electrical engineering and computer science since 1913.

The paper entitled "A Prototype Radio Transient Survey Instrument for Piggyback Deep Space Network Tracking" defines NASA's Deep Space Network (DSN) as a tool for making radio transient observations.

The authors discuss invigorated interest in using radio transient phenomena to observe short-lived and impulsive space events and detail how it could be deployed to acquire data for extended periods and substantially improve statistics of rare radio transient events, heretofore not considered tractable.

"Traditional astronomy focuses on properties of the steady-state universe," explains Faramaz Davarian, Manager, DSN Advanced Engineering, JPL/NASA and guest editor of this special issue. "Recent discoveries of strong, isolated radio pulses have opened the door to the potential for greater examination of the bursting and transient universe and one of the major areas of unexplored deep space."

The special issue discusses recent advances in solar system radar and radio science with an eye on tools, methodology, system design, algorithms and results. Both ground-based and space-based systems as well as hybrid systems are reviewed. Solar system radar has travelled light years since 1961 when W. Victor and R. Stevens made the first pioneering strides in this field at the Jet Propulsion Laboratory.

And progress using Radio Science for scientific exploration now provides scientists with the opportunity to observe and investigate gaseous planets, the atmosphere of Titan, the rings of Saturn, the solar corona and more.

For those who stay awake at night worrying that an asteroid might hit the earth, this special issue has an article that may help improve their chances for peaceful sleep.

According to the article "Goldstone Solar System Radar Observatory: Earth-Based Planetary Mission Support and Unique Science Results," all near-Earth objects which have been monitored with the Goldstone Radar have had their orbits extended for hundreds of years. What this means is that, if an asteroid's orbit is "secure" in this way, any chance of this particular asteroid impacting the Earth is ruled out.

This meticulous monitoring is being performed at Goldstone Solar System Radar (GSSR), which is the only fully steerable radar in the world for high-resolution ranging and imaging of planetary and small body targets.

Located in California's Mojave Desert, the precise level of detection has recently been improved by use of a chirp waveform signal to reach never-before-achieved levels of range resolution precision. To learn more about the monitoring of asteroids and other outer space activities at the Goldstone Observatory, log on here.

The presence of ice in lunar craters is a significant finding in the paper, "The Lunar Mini-RF Radars: Hybrid Polarimetric Architecture and Initial Results."

The authors chronicle the use of mini radio frequency (RF) lunar radars on board the Chandrayaan-1 spacecraft of ISRO and NASA's Lunar Reconnaissance Orbiter that can peer into many craters whose interiors are known to be in solar shadow throughout the lunar year. Results from the Mini-RF observations show that the polarimetric signatures from approximately 100 such craters are consistent with the response that would be expected from substantial volumetric ice deposits.

Among the other topics covered in this special issue of Proceedings of the IEEE are using antenna array as a radar transmitter; NASA's Mars Reconnaissance Orbiter MRO to identify traces of water ice on or below the Martian surface, an experiment for obtaining bistatic and polarimetric radar scattering signatures of the Martian surface and a processing approach for the open-loop reception of radio science signals.