The Remote Atmospheric and Ionospheric Detection System (RAIDS) is a suite of three photometers, three spectrometers, and two spectrographs which collectively span the wavelength range 50-874 nm and passively measures Earth's naturally-occurring airglow. RAIDS operates from the International Space Station (ISS) to remotely sense the Earth's thermosphere and ionosphere by scanning and imaging the atmospheric limb.
RAIDS was originally designed, built, delivered, and integrated onto the NOAA-J TIROS satellite in 1992, but was removed in 1994 when NOAA-J was reconfigured after the failure of NOAA-I. After a series of unfruitful flight opportunities, RAIDS was manifested in 2007 to fly on the new Japanese Experiment Module—Exposed Facility (JEM-EF) aboard the ISS. RAIDS and a companion NRL experiment named Hyperspectral Imager for the Coastal Ocean (HICO) are the first US payload on the JEM facility. The HICO-RAIDS Experiment Payload (HREP) was delivered to JAXA in May 2009 for launch on the inaugural flight of the Japanese H-II Transfer Vehicle (HTV) and the new H-IIB rocket.
The RAIDS mission objectives have been refocused since its original flight opportunity to accommodate the lower-altitude ISS orbit and to account for scientific advances. During 2008 RAIDS underwent a fast-paced hardware modification program to prepare for the ISS mission. The scientific objectives of the new RAIDS experiment are to study the temperature of the lower thermosphere (100–200 km), to measure composition and chemistry of the lower thermosphere and ionosphere, and to measure the initial excitation source of OII 83.4 nm emission. RAIDS will provide valuable data useful for exploring tidal effects in the thermosphere and ionosphere system, validating dayside ionospheric remote sensing methods, and studying local time variations in important chemical and thermal processes.
HREP was successfully launched on HTV-1 from Tanegashima Space Center in Japan on 17:01:46 UTC September 10, 2009. The unmanned HTV capsule includes a pressurized cargo area and an unpressurized bay in which payloads destined for the JEM-EF are stored. After several days of free flight and maneuvers the HTV rendezvoused with the ISS, and the Space Station Remote Manipulator System grappled the HTV and docked the pressurized portion to the Harmony module. After a time, astronauts employed the CanadArm2 and the JEM manipulator arm to extract the Experiment Pallet (EP) from the HTV, and attach the EP with the payloads to the External Facility. On September 24, the HREP payload was installed into its operating location at EFU#6 on the external facility.
One year of mission operations are provided by the Department of Defense Space Test Program, though the experiments could potentially operate aboard the ISS for a much longer period of time. During the period of RAIDS operations the NRL Atmospheric Neutral Density Experiment (ANDE) microsatellite experiment from NRL will measure atmospheric drag and density in the orbital plane of the space station over the course of approximately 12 months. The Special Sensor Ultraviolet Limb Imager (SSULI) aboard the Defense Meteorological Satellite Program (DMSP) satellite F18 was launched into a sun-synchronous orbit on October 18, 2009. These experiments and RAIDS remote sensing observations complement each other to provide mutual support for validation and multi-sensor studies.
After RAIDS science mission operations cease, the HREP payload will be decommissioned, and the manipulator arm will load it into an empty HTV for de-orbiting and disposal by atmospheric re-entry.
RAIDS is a collaborative experiment built jointly by the NRL Space Science Division and The Aerospace Corporation. RAIDS/HICO is integrated and ﬂown under the direction of DoD’s Space Test Program.