Iridium satellite

SAN FRANCISCO — A team led by the Johns Hopkins University Applied Physics Laboratory (APL) plans to ask the U.S. National Science Foundation to support an ambitious campaign to equip the constellation of Iridium Next mobile communications satellites with sophisticated sensors designed to gather data on the Earth’s atmosphere, climate, oceans, gravity and space weather.

The proposed project, known as GEOScan, would cost roughly $200 million and create the world’s most dense concentration of small satellites featuring instruments designed to provide continuous, global observations for students, scientists and researchers around the world, said Lars Dyrud, senior scientist at APL in Laurel, Md.

A consortium led by APL also is seeking NASA funding for a related effort to place Earth observation sensors in the Iridium Next constellation, which is slated to include 66 operational satellites and seven spares in low Earth orbit to provide mobile communications coverage worldwide. In October, APL proposed the Earth’s Radiation Imbalance System, or ERIS, an effort to gather data on incoming solar energy and the Earth’s thermal energy reflected back into space, as a candidate for NASA’s Earth Venture program of science-driven missions that can be launched within five years and completed for $150 million or less. NASA plans to announce its selection of one or more Earth Venture projects to receive funding in April 2012.

“The time to take advantage of this Iridium Next opportunity is so short, we didn’t want to leave any stone unturned,” Dyrud said. In addition to seeking NASA funding through the Earth Ventures program, APL team members have briefed U.S. National Oceanic and Atmospheric Agency officials on the ERIS plan in the hopes of obtaining support from that agency if the mission does not win NASA funding, he added.

Dulles, Va.-based Orbital Sciences Corp., the satellite integrator for the Iridium Next constellation, announced plans in February to market space for hosted payloads on each satellite in the constellation. Iridium Communications of McLean, Va., is scheduled to begin launching Iridium Next spacecraft in 2015.

ERIS is an offshoot of GEOScan, a project that APL officials have been discussing for more than a year with partners including the Charles Stark Draper Laboratory, L-1 Standards and Technology, the Massachusetts Institute of Technology and Utah State University’s Space Dynamics Laboratory, Dyrud said.

GEOScan represents a radically new approach to Earth science missions, said Seamus Tuohy, Draper Laboratory’s space systems director. Instead of identifying an important area of scientific research and then designing Earth-observing instruments, spacecraft and missions to gather the data, the GEOScan team analyzed plans for the Iridium Next constellation to determine the maximum amount of Earth science data that could be obtained given the planned orbit, timeline, data links, power and space available for instruments.

“We think this may be a path to the future,” Tuohy said. “When you look at the challenging budget environment, hosted payloads offer a way to get maximum utility at a far lower price than targeted Earth science missions.”

Under the proposed plan, each GEOScan sensor would fit in a pod measuring 20 centimeters by 20 centimeters by 14 centimeters and include instruments to gather Earth imagery and space data. Additional room in GEOScan sensor pods would be set aside for payloads proposed by researchers, students and small businesses to further scientific research or perform instrument testing, Dyrud said.

“As an idea, GEOScan is really exciting and I certainly can see the good science that would come out of it,” said Therese Moretto Jorgensen, a National Science Foundation program director. “So far it’s just an idea being proposed to us. Whether there is any path for us to even accept a proposal of this magnitude is unclear.” The National Science Foundation has provided funding to enable researchers to study the feasibility of the GEOScan concept, she added.

Dyrud said the National Science Foundation is the appropriate source of funding for the GEOScan program because the agency supports high-risk, high-payoff projects and unique research facilities. GEOScan would be an orbiting global observation facility capable of providing vast quantities of data for many different types of scientific research, he added.

Each GEOScan pod would include: a bolometer to measure Earth’s outgoing electromagnetic radiation; a miniature GPS occultation sensor to measure changes in Earth’s gravity and atmospheric water vapor; an imager to provide global snapshots and pictures of clouds, vegetation and land use; a dosimeter to detect energetic particles; and a compact Earth observation spectrometer to measure the composition of the atmosphere.

Due to the global distribution of the Iridium Next satellites, GEOScan would be able to provide certain types of data that would be impossible to obtain with a smaller constellation, Dyrud said. GEOScan could, for example, gather detailed information on moisture concentration in the atmosphere to detect atmospheric rivers, a meteorological phenomenon that can produce rainstorms and flooding in areas of the U.S. West Coast, he added.

Debra Werner is a correspondent for SpaceNews based in San Francisco. Debra earned a bachelor’s degree in communications from the University of California, Berkeley, and a master’s degree in Journalism from Northwestern University. She...