AFRL experiment will create artificial ionosphere

by Michael P. Kleiman
377th Air Base Wing Public Affairs

7/20/2012 - KIRTLAND AIR FORCE BASE, N.M. -- On successive days in September, a pair of two-stage sounding rockets will lift off from the U.S. Army's Ronald Reagan Ballistic Missile Defense Test Site, Kwajalein Atoll, Republic of the Marshall Islands, with each launch vehicle carrying a canister of samarium powder to its appointed trajectory over the Pacific Ocean.

Within minutes after departing the island, the dust payload will exit one rocket at 118 miles high and the other will be deposited 81 miles up.

After being jettisoned into the ionosphere, located in the upper atmosphere from 50 to 400 miles above the Earth's surface, the particles will form a plasma cloud, from which scientists of the Air Force Research Laboratory's Space Vehicles Directorate will obtain data from employing transmitters at two atolls and receivers at five separate isles.

"The two transmitters will send radio waves into the cloud, which will act like a miniature ionosphere. We should get a bounce of the signal off the cloud, depending on how dense it is. The cloud will create an artificial ionosphere and the signal will bounce off of both the real and artificial ionospheres," said Dr. Todd Pedersen, senior research physicist, AFRL's Space Vehicles Directorate. "During the Metal Oxide Space Cloud experiment, we will measure where the cloud is and how dense it is. We will also be studying the effects of naturally occurring disturbances in the ionosphere with multiple-directions looks (east-west and north-south passes). The ionosphere is not always a nice smooth line - there are often disturbances."

Ionospheric turbulence can cause scintillation, which disrupts ground and satellite communication. Information generated from the $3 million MOSC trial will be applied to models for scientists to study the possibility of remediating the detrimental impacts of disturbances in the ionosphere on radio wave propagation.

"Our primary goal of the MOSC mission is to diagnose the cloud, but the long-term ambition is to examine whether we can artificially induce such a cloud to potentially prevent these naturally occurring disturbances from developing. What happens is that in the equatorial region you have a seasonal effect on communication - disturbances that develop in the ionosphere in the nighttime hours that can cause scintillation," said Ron Caton, research physicist, and principle investigator on the MOSC experiment, AFRL's Space Vehicles Directorate. "For example, you have someone on the ground trying to communicate with a satellite and the signal is being disturbed as it passes through the ionosphere, similar to watching light scatter through water."

Although research for the MOSC experiment has spanned the past decade, on-site preparation for the mission began in earnest in June 2011, after a Mission Initiation Conference at NASA Wallops Flight Facility, Wallops Island, Va. With launch of both rockets tentatively scheduled for September 2012, the mission team is planning for placement of ground sensors, imagers and receivers, which has involved visits to four different atolls in the Marshall Islands. Caton recently traveled from Kwajalein to Rongelap, Likiep and Wotho Atolls on a 69-foot boat, with each leg of the trip taking approximately 18-20 hours.

"After being on the boat for so many hours, the team would get out to conduct the site survey in a short time, and then it was back on the water for the multi-hour trip to the next atoll," Caton said. "On the first night out, it got pretty rough, with 7- to 10-foot swells. I slept on the deck floor. It was definitely an interesting experience."

Mission partners include the Air Force Space and Missile Systems Center's Space Test Program and the NASA Wallops Flight Facility. The former is funding the two sounding rockets and the latter is providing them.

"If the MOSC experiment is successful, the next step would be to investigate our ability to introduce such a cloud in the proper location to short out the electric fields that lead to these disturbances that occur naturally," said Caton. "If we can artificially create this layer under the appropriate conditions, we have taken a huge step toward actively mitigating potential scintillation activity and ultimately enhancing warfighter communication."