This is a one-year effort to refurbish and deliver a scientific grade optical instrument, Limb-imaging Ionospheric and Thermospheric EUV Spactrograph (LITES), which will be flown as a hosted payload onboard a commercial satellite as part of a US Air Force (USAF) program. LITES is a compact, high-sensitivity extreme and far ultraviolet spectral imager designed to measure key ion and neutral species in the ionosphere-thermosphere system. It will be constructed by modifying an existing, flight-proven high-sensitivity imaging spectrograph developed by the proposer. Specifically, the instrument will be upgraded by replacing the existing detector with a larger, more capable detector, providing an extended spectral range for the instrument as well as lower noise. To meet the current schedule for the payload, the upgraded instrument must be ready by mid 2012, which leaves less than 12 months for its construction and testing.
The project will provide valuable opportunities for graduate and undergraduate students to experience a real life space project in collaboration with the USAF and aerospace industry. The upgrade to the instrument will expand the scope of this USAF project from purely technology demonstration to a science investigation and the NSF participation in the project will help ensure that the science data is made freely available to the scientific community. Finally, the project will advance the technological development and demonstration of miniaturized instruments that may benefit the realization of future small satellite missions.
The Limb-imaging Ionospheric and Thermospheric Extreme-ultraviolet Spectrograph (LITES) is an instrument that will fly aboard the International Space Station (ISS) and study the upper layers of Earth’s atmosphere. LITES is an integral part of a suite of three instruments and together they will provide new data to help us understand the effect of the Sun on the Earth’s atmosphere, or space weather. Space weather is an important area of research, as it has implications for satellites and communications. Earth’s upper atmosphere is a complex and dynamic region of the space environment. While space scientists have learned much about the climatology of Earth's space environment, we still have only sparse data from which to understand the details of what drives specific space weather events and their potential impact. In order to fully understand the many different phenomena that occur, we need new measurements from new instruments to allow us to better discern the role that the Sun, disturbances in the lower atmosphere, electric and magnetic fields, and the interaction of ionized and neutral particles all play in determining how Earth's upper atmosphere responds. These phenomena create scintillations on radio waves propagating through the affected region, causing interference and outages of radio navigation and communication links. Because of this impact on operational navigation and communication systems, understanding and forecasting irregularity formation, development, and evolution is a vital and vibrant area of research for the space weather community. The LITES instrument has been built and tested by our team and is now undergoing final calibration and integration to prepare it for flight to the ISS. It consists of an imaging slit, a grating, and a detector. LITES is an imaging spectrometer, so when light hits the instrument it is dispersed into different wavelengths. By separating different wavelengths, we can study specific molecules in the atmosphere such as ionized oxygen and nitrogen. LITES will detect extreme ultraviolet (EUV) light which cannot be seen through the atmosphere; putting LITES on the ISS provides unique measurements unobtainable from the ground. In addition, the ISS covers all latitudes within ±51.6° and all longitudes. This enables us to make measurements over huge portions of the Earth where ground-based instruments cannot be located (such as oceans). LITES will measure the intensity of naturally-occurring ultraviolet airglow from the region of Earth's atmosphere called the thermosphere and ionosphere between 150 and 400 kilometers (about 90 to 250 miles) in altitude. By measuring the intensity of these emissions versus altitude, we are able to determine the density of the corresponding particles over this altitude range. The information is used to observe, model, and better forecast space weather. The results from the LITES experiment will improve our ability to measure, model, and forecast space weather events that can affect the accuracy of GPS systems, force airlines to alter transpolar routes, impact the availability of satellites that provide signals for communication and entertainment, and have the potential to create current surges in electrical lines that would blow out transformers and power stations. The LITES experiment is also serving as a proof-of-concept for a smaller, simpler, yet more sensitive instrument that could be easily duplicated to serve as a networked observatory on a fleet of tiny CubeSat-styled satellites or as payloads attached to larger satellites to observe space weather over the entire globe.
