The Fermi Gamma-ray Space Telescope (FGST), formerly referred to as the “Gamma-ray Large Area Space Telescope (GLAST),” is a space observatory being used to perform gamma-ray astronomy observations from space in a low earth orbit.

Its main instrument is the Large Area Telescope (LAT), with which astronomers mostly intend to perform an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, pulsars, other high-energy sources and dark matter. Another instrument aboard Fermi, the Gamma-ray Burst Monitor (GBM; formerly GLAST Burst Monitor), is being used to study gamma- ray bursts.

It was launched in June 2008. The mission is a joint venture of NASA, the United States Department of Energy, and government agencies in France, Germany, Italy, Japan, and Sweden.


Glory was to be a remote-sensing Earth-orbiting observatory designed to achieve two primary mission objectives:

  • Collect data on the properties of aerosols, including black carbon, in the Earth’s atmosphere and climate system. It was to enable a greater understanding of the seasonal variability of aerosol properties.
  • Collect data on solar irradiance for the long-term effects on the Earth climate record. Understanding whether the temperature increase and climate changes are by-products of natural events or whether the changes are caused by man-made sources was of primary importance.


  1. The determination of the global distribution, microphysical properties, and chemical composition of natural and man-made aerosols as well as clouds with accuracy and coverage sufficient for a reliable quantification of the aerosol direct and indirect effects on climate;
  2. The continued measurement of the total solar irradiance to determine the Sun’s short-term and long-term effects on the Earth’s climate.


The Glory spacecraft is equipped with the following scientific instrumentation:

  • The Total Irradiance Monitor (TIM): The instrument measures the amount of solar energy that enters the Earth’s atmosphere. This information will help researchers understand any long-term changes in the amount of energy coming from the Sun and how those changes affect Earth’s climate.
  • The Aerosol Polarimetry Sensor (APS) with its two supporting Cloud Cameras: This instrument will measure the size, quantity, refractive index, and shape of aerosols. This is the first space-based instrument to be able to identify different aerosol types, which will help researchers distinguish the relative influence of natural and human-caused aerosols on our global climate.


The Glory mission was intended to respond to the U.S. Climate Change Science Program (CCSP) by continuing and improving upon NASA’s research of the forcings influencing climate change in the atmosphere. The mission ended March 4, 2011, when the spacecraft failed to reach orbit following its launch from Vandenberg Air Force Base in California.


The Gravity Recovery and Climate Experiment (GRACE) is a space-based mission whose objective is to make detailed measurements of Earth’s gravity field to show how mass is distributed around the planet and how it varies over time. The mission consists of two identical spacecrafts – named Nicole and Melissa – flying in a polar orbit about 220 km apart and 500 km above Earth. As the twin GRACE satellites circle the globe 16 times a day, they sense minute variations in Earth’s gravitational pull. GRACE data are important tools for studying Earth’s ocean, geology, and climate. The GRACE satellites were launched in 2002. It is a joint mission of NASA and the German Space Agency.



The GRAIL mission will place two spacecraft into the same orbit around the Moon. As they fly over areas of greater and lesser gravity, caused both by visible features such as mountains and craters and by masses hidden beneath the lunar surface, they will move slightly toward and away from each other. An instrument aboard each spacecraft will measure the changes in their relative velocity very precisely, and scientists will translate this information into a high-resolution map of the Moon’s gravitational field. This gravity-measuring technique is essentially the same as that of the Gravity Recovery And Climate Experiment (GRACE), which has been mapping Earth’s gravity since 2002.


Primary objectives:

  • Determine the structure of the lunar interior, from crust to core.
  • ¬†Advance understanding of the thermal evolution of the Moon.

Secondary Objectives:

Extend knowledge gained from the Moon to other terrestrial planets.


  • Map the structure of the lunar crust and lithosphere
  • Understand the asymmetric thermal evolution of the Moon
  • Determine the subsurface structure of impact basins and the origin of lunar mascons
  • Ascertain the temporal evolution of crustal brecciation and magmatism
  • Constrain the deep interior structure of the Moon
  • Place limits on the size of the Moon’s inner core


The two GRAIL spacecraft have to be launched together and then would fly similar but separate trajectories to the Moon after separation from the launch vehicle, taking about 3 to 4 months to get there. They will spend about 2 months reshaping and merging their orbits until one spacecraft is following the other in the same low-altitude, near-circular, near-polar orbit, and they begin formation- flying. The next 82 days will constitute the science phase, during which the spacecraft will map the Moon’s gravitational field.


The two GRAIL spacecraft are near-twins, each about the size of a washing machine, with minor differences resulting from the need for one specific spacecraft (GRAIL-A) to follow the other (GRAIL-B) as they circle the Moon.

The science payload on each spacecraft is the Lunar Gravity Ranging System, which will measure changes in the distance between the two spacecraft down to a few microns — about the diameter of a red blood cell. Each spacecraft will also carry a set of cameras for MoonKAM, marking the first time a NASA planetary mission has carried instruments expressly for an education and public outreach project.

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