The goal of the Firefly cubesat is to unambiguously determine if Terrestrial Gamma Ray Flashes (TGFs) are produced by lightning, and to determine the characteristics of lightning that produce the fluxes of gamma rays observed at high altitude. This information will strongly constrain the processes that accelerate electrons to ~35 million electron volts (MeV) above thunderstorms, since these electrons are thought to be the source of TGFs. Firefly will detect a minimum of 50 TGFs, with a goal of more than 200, to definitively determine the types of lightning that produce gamma rays. TGFs are of inherent interest, as they result from the most powerful natural particle acceleration process on Earth, in which thermal electrons are energized to tens of MeV in less than 1 millisecond. These energized electrons create copious bremsstrahlung gamma and X-rays that can be observed from orbiting platforms, and the electrons themselves may escape to magnetospheric altitudes and populate the inner electron radiation belt. By studying the TGF phenomena and the acceleration processes responsible for them on Earth, the investigators will improve understanding of other regimes of electron acceleration, including the radiation belts, solar flares, cosmic shocks, and other planets, including Venus, the outer planets, and dust devils and dust storms on Mars. Firefly CubeSat satellite will be designed, built, tested, and operated on-orbit as part of this project. Firefly consists of two instruments: a gamma-ray detector (GRD) and a very low frequency receiver/ photometer experiment (VP). GRD will measure photons between 10 keV - 10 MeV, and up-going energetic electrons over an energy range of 10 keV to a few MeV. The Firefly team is a collaboration between the NASA Goddard Space Flight Center and Siena College, with the Hawk Institute for Space Sciences serving as the spacecraft bus provider, and the systems engineering, education, and public outreach lead. Students will be involved in all aspects of the project, from design and development, through fabrication and test, to mission operations and data analysis. Firefly will help to train undergraduate students at Siena College and the University of Maryland Eastern Shore (UMES), as they get hands-on experience designing, building, testing, and operating the spacecraft, as well as analyzing the data. Local high school students and interns will also have access to the Firefly data, educational materials, and website. Finally, the Firefly project includes the installation of two World Wide Lightning Location Network ground stations at Siena and UMES, giving the students access to a tool that can be used for many data analysis projects, and that will be a permanent addition to the educational infrastructure at these institutions. Firefly will support the development of a website, with continuous updates on the development of the instrument and spacecraft, and on-orbit mission status, open access to the data and science results, a "data users' manual", and a Firefly manual, including lessons.
Firefly and FireStation: Missions to Study Terrestrial Gamma-Ray Flashes Lightning discharges represent the release of enormous amounts of energy and are associated with familiar and powerful manifestations near the Earth's surface: thunder, a bright flash, and a powerful current that can shatter trees and turn sand to glass. Lightning may also give rise to x-ray and gamma-ray bursts, and unlike the well-known flashes of light and claps of thunder, these energetic rays are channeled upward and can be detected only from space. A new small satellite mission, called Firefly and sponsored in part by the National Science Foundation, will explore the relationship between lightning and these bursts of radiation called Terrestrial Gamma Ray Flashes (TGFs). Firefly will be the first dedicated mission launched to study TGFs, their link to lightning, and their effect in producing energetic electrons that may become stably trapped in the inner radiation belt. Firefly demonstrates the capability of small missions such as CubeSats to do important, focused science, with abundant student involvement, and with a minimal budget and available resources. A launch date of October 2013 is planned. TGFs are of inherent interest, as they result from the most powerful natural particle acceleration process on Earth, in which thermal electrons are energized to tens of millions of volts in less than 1 millisecond. By studying TGFs, we can learn fundamental physics critical in understanding not only lightning, but also solar flares, cosmic shocks, black holes, and even dust storms on Mars. Firefly is a small satellite (4.0 kg, 10x10x34 cm), that was designed, built, and tested as part of this NSF grant. The Firefly team is collaboration between Siena College and NASA. Students at all levels (grade-school to college) are involved in all aspects of the project, from design and development to mission operations and data analysis. Inside the body of the CubeSat is the Gamma-Ray Detector (GRD). On the nadir side of the satellite are four photometers to optically detect lightning. Each photometer is angled slightly to obtain a general direction vector. The CubeSat is also equipped with a Very-Low Frequency (VLF) detector. Previous studies have shown correlation between ground-based VLF-detectors and TGFs. Firefly represents a new pairing of a gamma-ray detector and a VLF-detector on the same platform. In addition, a related mission called FireStation will be part of the STP-H4 platform on the International Space Station. FireStation relies heavily on existing flight experience from the NSF-funded Firefly CubeSat mission, with some modifications to interface and sensors.
