NASA’s Small Explorer Satellite Program (SMEX) is a project created to substantially reduce the costs of spacecraft missions through the introduction of advanced design tools and advanced technology. Since 1988, SMEX has provided frequent flight opportunities for highly focused and inexpensive space science missions in a variety of disciplines. Through the use of small spacecraft, SMEX program controls focused investigations, proves new scientific concepts and helps make significant contributions in space science.
Overview of NASA’s Small Explorer Satellite Program (SMEX)
The SMEX program is oriented at providing flight opportunities and relatively inexpensive and highly focused space science missions. SMEX is a multi-mission flight operations team which involves that each member of the team be knowledgeable of not just one, but multiple missions. The program consists of a number of unmanned spacecraft which are operated by a team situated at the Goddard Space Flight Center (GSFC) whose operations consist of primarily monitoring spacecraft during real-time contacts and sending commands in order to retrieve science data to insure continued operation of the spacecraft.
The Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX), which was the first SMEX mission, was designed for a three year nominal mission and was sent into space on July 3, 1992. SAMPEX instruments include a set of high resolution detectors, three sensor assemblies, an 8-bit instrument microprocessor, and a tank of isobutane to be used by one of the sensors. Its main objective is to investigate the origin and transport of galactic cosmic rays; observe precipitating magnetospheric charged particles interacting with the Earth’s atmosphere; investigate the isotropic composition of particles originating from energetic solar flares shortly after a solar maximum.
Fast Aural Snapshot Explorer (FAST), the second mission, was launched on August 21, 1996. FAST instruments consist of sixteen electrostatic analyzers, four electric field Langmuir probes on 30 m wire booms. Two electric field Langmuir probes on 3 m extendible booms, a time of flight mass spectrometer, and one search coil and one fluxgate magnetometer. FAST is examining the physical processes involved in the production of aurora (luminous displays of light) in the upper atmosphere´s high altitudes.
The Submillimeter Wave Astronomy Satellite (SWAS), the third mission, was scheduled to be launched on June 1995, but its launch was postponed until 1999. SWAS is a submillimeter wave telescope that includes dual heterodyne radiometers and an acousto-optical spectrometer which will allow the investigation of dense interstellar clouds. SWAS will observe and measure the amount of water and molecular oxygen within interstellar clouds, and will also measure the composition of atomic carbon and carbon monoxide within these clouds.
The Transition Region and Coronal Explorer (TRACE), the fourth mission, was launched in 1997. TRACE instruments include a telescope with an image compensation mechanism, an Attitude Control System (ACS) which uses three magnetic-torque coils, one digital Sun sensor, six coarse Sun sensors, one three-axis magnetometer, four reaction wheels, and three two-axis inertial gyros. TRACE is observing the Sun to study the relation between its magnetic field and the high temperatures in the Sun´s corona.
The Wide-Field Infrared Explorer (WIRE), the fifth mission, was launched in 1998. WIRE uses a cryogenically-cooled telescope and arrays of highly sensitive infrared detectors to study the evolution of the galaxy. WIRE will observe principally galaxies with unusual rates of star formation which emit most of their energy in the infra-red wavelength. WIRE will help discover the role of starburst galaxies in the evolution of other galaxies.
SMEX program is an attempt of NASA to fund space exploration missions with an ultra-low-cost small spacecraft. In 1999, NASA released the next Small Explorer and Missions of opportunity. There are three missions currently funded for their primary objectives: Aeronomy of Ice in the Mesosphere (AIM); Interstellar Boundary Explorer (IBEX); and the Nuclear Spectroscopic Telescope Array (NuSTAR). AIM was launched in 2007, IBEX in 2008, and NuSTAR is projected to be launched in 2012.
