KENNEDY SPACE CENTER, Fla — What began as an innovative radar communications project in the dry California desert is migrating to the swamplands of central Florida with a new focus on mapping nearby asteroids, orbital space debris, water on the Moon and even rover-trapping sand pits on Mars.
The Ka-Band Objects Observation and Monitoring Project, nicknamed KaBoom, is built around a collection of small radar dishes transmitting in the high-frequency Ka-band region of the electromagnetic spectrum. Ka-band transmissions allow for higher bandwidth, but unlike lower-frequency transmissions, the signals are far more susceptible to attenuation and the resulting loss of intensity due to water in the atmosphere, of which there is no short supply in rainy Florida.
“Nobody in their right mind would do a Ka-band kind of experiment at Kennedy. Ka-band is very sensitive to water. If you’ve been to Kennedy you know you’re surrounded by it and we’re into hurricane season now, so it’s even more of a challenge,” lead project scientist Barry Geldzahler, with NASA headquarters in Washington said in an interview with SpaceNews.
“If it works here, it’s going to work anywhere,” he added.
KaBoom started as a test to see if small radar dishes could be linked in a widely spaced array and used collectively to transmit and receive radio signals. The system, which entailed real-time compensation for atmospheric fluctuations, was successfully demonstrated at NASA’s Goldstone tracking complex in California in the 8-gigahertz X-band frequency.
The test will be repeated at Kennedy Space Center (KSC), where three 12-meter antennas spaced 60 meters apart have been set up at a site in the industrial area once used to process space shuttle payloads. That demonstration will be followed by a shift to Ka-band, transmitting at 33-37 gigahertz, which offers much higher resolution.
Whereas X-band radars at Goldstone, for example, can get to a maximum resolution of a little less then 4 meters, or about 400 centimeters, Ka-band can resolve down to about 5 centimeters — almost two orders of magnitude better, Geldzahler said.
The smaller dishes also require far less power for transmissions. Their signals are combined 100-200 kilometers above the planet, bypassing potential issues with aircraft and other environmental factors that come into play with high-powered transmissions from a single, large dish.
“The problem with sending up so much power, especially at Goldstone, is that we have to coordinate with roughly 30 different agencies out here and it takes about a month to get that done,” Geldzahler said.
The three dishes at KSC, for example, will transmit at a combined power level of 90 milliwatts. Goldstone’s 70-meter dish takes 450 kilowatts.
If the engineering test pans out, the next step would be to develop a more capable system that could map asteroids up to about 75 million kilometers away. The radar imagery is intended to supplement optical and infrared surveys that actually find and track the objects.
“You can determine the orbits [of asteroids] five orders of magnitude — 100,000 times — better in radar than in optical or infrared, which means you can project their orbits decades or sometimes centuries out and you can characterize the asteroid’s size, shape, spin and porosity,” Geldzahler said.
“If you’re going to go there, it’s nice to know what kind of tools to take; is it spinning too fast? How do I have to interact with it,” he added.
NASA’s current plan for human space exploration beyond the space station is to find a small asteroid, relocate it into an orbit around the Moon and send astronauts there to collect samples and conduct research.
The radar also would be key for assessing if an asteroid is discovered to be on a possible collision course with Earth, an area of interest since a small asteroid exploded over Chelyabinsk, Russia, in February, leaving more than 1,500 people injured by flying glass and debris. The same day, another larger but unrelated asteroid passed closer to Earth than the networks of communication satellites that ring the planet.
The radar system also could be used to identify small but potentially dangerous debris orbiting Earth, as well as for planetary science projects such as looking for water in lunar craters and scanning Mars for sand pits and other potential show-stoppers for surface rovers.
The KSC testbed, which is still being set up, is expected to run for up to three years at a cost of about $1 million per year.