Anyone without a degree in astronomy, physics or general sciences can safely conclude that space exploration is astronomically expensive. This is why NASA initiated its Small Explorer Program (SMEX) that would fund space exploration missions that cost a maximum of $120 million – each mission so far has cost an estimated $35 million for operations, design and creation for the first 30 days in orbit.

It provides frequent flight opportunities for inexpensive space science missions. The SMEX space craft weigh between 180 kg and 250 kg that maintain a power consumption of approximately 50 to 200 watts. SMEX was operated and managed by the SMEX Project Office at the Goddard Space Flight Center (GSCF) in Greenbelt, Maryland.

The space initiative within NASA was established in 1989. The first set of three SMEX missions was launched between 1992 and 1998:

–          Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX); launched July 3, 1992 to investigate local stellar matter and solar material.

–          Fast Auroral Snapshot Explorer (FAST); launched Aug. 21, 1996 to probe the physical process that produces aurorae.

–          Submillimeter Wave Astronomy Satellite (SWAS); launched May 12, 1998 to study chemical constitution, energy stability and composition of interstellar clouds and how planets and stars form.

After the first set of missions, NASA announced a second set of missions that were launched in 1997 and 1998:

–          Transition Region and Coronal Explorer (TRACE); launched Apr. 2, 1998 to study the connection between the sun’s heating of the corona and its magnetic fields.

–          Wide-Field Infrared Explorer (WIRE); launched May 5, 1999 to study our galaxy’s evolution.

Following the first two sets of missions, NASA shut down its SMEX office and converted the program so that it would be managed by its Principal Investigator and receive supervision from the GSCF Explorers Project.

The final set of three missions is currently underway. The first launch occurred in 2007 and the third is expected sometime this year.

–          Aeronomy of Ice in the Mesosphere (AIM); launched Apr. 25, 2007 to study the noctilucent clouds (NLCS), which are also known as polar mesospheric clouds, that transpire in our atmosphere.

–          Interstellar Boundary Explorer (IBEX); launched Oct. 19, 2008 to map the boundary between our solar system and interstellar space.

–          Nuclear Spectroscopic Telescope Array (NuSTAR); to be launched in 2012 (originally scheduled for Mar. 21, 2012) to project high energy X-rays by using a Wolter telescope, which utilizes grazing incidence optics.

In 2008, NASA announced a series of candidates for mission proposals, such as a mission to measure the polarization of cosmic X-ray sources, a mission to survey transiting extrasolar planets and a mission to observe the sun, especially its chromospheres.

One year later, the space agency announced that Gravity and Extreme Magnetism SMEX (GEMS) and Interface Region Imaging Spectrograph (IRIS) were the winning candidates.