The Gravity Recovery And Climate Experiment (GRACE), a joint mission of NASA and the German Space Agency, has been making detailed measurements of Earth's gravity field since its launch in March 2002.

Gravity is determined by mass. By measuring gravity, GRACE shows how mass is distributed around the planet and how it varies over time. GRACE data are important tools for studying Earth's ocean, geology, and climate.

GRACE is a collaborative endeavor involving the Center for Space Research at the University of Texas, Austin; NASA's Jet Propulsion Laboratory, Pasadena, Calif.; the German Space Agency and Germany's National Research Center for Geosciences, Potsdam. The Jet Propulsion Laboratory is responsible for the overall mission management under the NASA ESSP program.

The principal investigator is Dr. Byron Tapley of the University of Texas Center for Space Research, and the co-principal investigator is Dr. Christoph Reigber of the GeoForschungsZentrum (GFZ) Potsdam.

The GRACE satellites were launched from Plesetsk Cosmodrome, Russia on a Rockot (SS-19 + Breeze upper stage) launch vehicle, on March 17, 2002.

GRAIL =Gravity Recovery and Interior Laboratory 

The Gravity Recovery and Interior Laboratory (GRAIL) is an American lunar science mission in NASA's Discovery Program, which will use high-quality gravitational field mapping of the Moon to determine its interior structure. The two small spacecraft GRAIL A and GRAIL B were launched on 10 September 2011 aboard a single launch vehicle: the most-powerful configuration of a Delta II, the 7920H-10. GRAIL A separated from the rocket about nine minutes after launch, GRAIL B followed about eight minutes later. They will arrive at their orbits around the Moon 24 hours apart.

The science phase of the mission will last for 90 days. Following the science phase (or extended mission phase), a five-day decommissioning period is planned, after which the spacecraft will impact the lunar surface in about 40 days.^[6] The gravity mapping technique is similar to that used by Gravity Recovery and Climate Experiment (GRACE), and the spacecraft design is based on XSS-11.

Unlike the Apollo program missions, which took three days to reach the Moon, GRAIL will make use of a three- to four-month low-energy trans-lunar cruise via the Sun-Earth Lagrange point L1 to reduce fuel requirements, protect instruments and reduce the velocity of the two spacecraft at lunar arrival to help achieve the extremely low 50 km (31 mi) orbits with separation between the spacecraft (arriving 24 hours apart) of 175 to 225 km (109 to 140 mi). The very tight tolerances in the flight plan leaves little room for error correction leading to a launch window lasting one second and providing only two launch opportunities per day.

The planned orbital insertion dates are December 31, 2011 (for GRAIL-A) and January 1, 2012 (for GRAIL-B).

NASA's Jet Propulsion Laboratory manages the project. 

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.
Objectives
GRAIL's engineering objectives are to enable the science objectives of mapping lunar gravity and using that information to increase understanding of the Moon's interior and thermal history. Getting the two spacecraft where they need to be, when they need to be there, requires an extremely challenging set of maneuvers never before carried out in solar system exploration missions. Mission design
The two GRAIL spacecraft will be launched together and then will 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.
Spacecraft and payload
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.

The International Space Science Institute (ISSI) is an Institute of Advanced Studies based in Bern, Switzerland. The institute's work is interdisciplinary, focusing on the study of the solar system, and encompasses planetary sciences, astrophysics, cosmology, astrobiology, and the Earth sciences. A main activity is the interpretation of experimental data collected by space research missions.

ISSI is a non-profit organization and a foundation under Swiss law. ISSI operations are supported by grants from the European Space Agency, the University of Bern, the Swiss Confederation and the Swiss National Science Foundation (SNF).

It was established in 1995. Primary initial capital for the ISSI was provided by Oerlikon Space AG.

Mission

ISSI is an Institute of Advanced Studies where scientists from all over the world meet in a multi- and interdisciplinary setting to reach out for new scientific horizons. The main function is to contribute to the achievement of a deeper understanding of the results from different space missions, ground based observations and laboratory experiments, and adding value of those results through multidisciplinary research in the framework of International Teams, Workshops, Working Groups, Forums or as individual Visiting Scientists. The program of ISSI covers a widespread spectrum of disciplines from the physics of the solar system and planetary sciences to astrophysics and cosmology, and from Earth sciences to astrobiology.

The European Aeronautic Defence and Space Company N.V. (EADS) is a global pan-European aerospace and defence corporation and a leading defence and military contractor worldwide. The group includes Airbus as the leading manufacturer of commercial aircraft, with Airbus Military covering tanker, transport and mission aircraft; Eurocopter as the world's largest helicopter supplier; Astrium, the European leader in space programmes from Ariane to Galileo; and Cassidian as a provider of comprehensive and integral systems solutions for aerial, land, naval and civilian security applications. Through Cassidian, EADS is a major partner in the Eurofighter consortium as well as a key stakeholder in the missile systems provider MBDA.

In 2009, the EADS generated revenues of €42.82 billion and employed 119,500 personnel. EADS was formed on 10 July 2000 by the merger ofAérospatiale-Matra of France, DaimlerChrysler Aerospace AG (DASA) of Germany, and Construcciones Aeronáuticas SA (CASA) of Spain. Overall, the company develops and markets civil and military aircraft, as well as communications systems, missiles, space rockets, satellites, and related systems.

Subsidiaries:

• Airbus
• Astrium
• Cassidian
• Eurocopter

Intelsat Ltd. is a communications satellite services provider.

Originally formed as International Telecommunications Satellite Organization (INTELSAT), it was—from 1964 to 2001—an intergovernmental consortium owning and managing a constellation of communications satellites providing international broadcast services.

As of March 2011, Intelsat operates a fleet of 52 communications satellites, which is the world's largest fleet of commercial satellites.

The former PanAmSat Corporation founded in 1984 by Reynold (Rene) Anselmo, was a satellite service provider headquartered in Greenwich, Connecticut. It operated a fleet ofcommunications satellites used by the entertainment industry, news agencies, internet service providers, government agencies, and telecommunication companies. Anselmo got the idea for PanAmSat from Martine Rothblatt, an independent communications lawyer in Washington, D.C., to whom he had turned to for advice regarding difficulties he was encountering in getting reasonably priced satellite transmission of his UHF-TV based Spanish International Network (SIN), with studios on 42nd Street in New York City. Rothblatt had written a business plan entitled PanAmSat for her MBA thesis at UCLA's Graduate School of Management and was seeking a financial backer. Anselmo partnered with Rothblatt on the PanAmSat project, with Anselmo providing financing and Rothblatt filing for approval from the Federal Communications Commission and lining up an initial satellite from RCA Astro-Electronics and a heavily discounted launch from Arianespace.

PanAmSat effectively broke the monopoly on international satellite communications which was held by Intelsat, an international treaty-based organization founded and owned by several countries including the United States. PanAmSat, led by Anselmo, successfully lobbied the United States Congress to permit it to operate globally, competing against Intelsat. PanAmSat (and Anselmo) became famous for full-page advertisements in the Wall Street Journal depicting Spot, the PanAmSat mascot, urinating on politicians' legs. The company's motto was "Truth and Technology Will Triumph Over Bullshit and Bureaucracy."

Following the death of Rene Anselmo in 1995,^[1] his widow Mary Anselmo controlled the company for a time. PanAmSat was sold to Hughes Electronics, a division of General Motors, in a $3 billion cash and stock deal. The satellite operations continued to be under PanAmSat with Hughes being the majority shareholder. In May 1997, Hughes Communication Galaxy merged with PanAmSat, adding 9 more satellites to its fleet. In 2003, News Corporation purchased Hughes Electronic's PanAmSat division and on April 24, 2004 sold PanAmSat to a consortium ofprivate equity firms in an leveraged buyout including Kohlberg Kravis Roberts & Co. (KKR), Carlyle Group and Providence Equity Partners for $4.3 billion.

Stratolaunch Systems is a space transportation venture specializing in air launch to orbit, with its corporate headquarters located in Huntsville, Alabama, USA.

It was founded in 2011 by Microsoft co-founder Paul G. Allen and Scaled Composites founder Burt Rutan, who had previously collaborated on the creation of SpaceShipOne. The newly envisioned launch system will use similar components to that of Virgin Galactic though it will be made for orbital launch instead of sub-orbital.

The start up will build a mobile launch system with three primary components; a carrier aircraft to be build by Scaled Composites, A multi-stage launch vehicle built by Space Exploration Technologies (SpaceX), and a mating and integration system to be built by Dynetics.

Galileo is a joint initiative of the European Commission (EC) and the European Space Agency (ESA). Galileo will be Europe’s own global navigation satellite system, providing a highly accurate, guaranteed global positioning service under civilian control. It will be inter-operable with GPS and GLONASS, the two other GNSS (Global Navigation Satellite Systems). The complete system consists of:

• A space segment of 30 MEO satellites in 3 planes inclined at 56º

• A launch segment to place the satellites into their operational orbits

• A control ground segment for monitoring and control of the satellites

• A mission ground segment managing all mission specific data

• A user ground segment of equipment capable of receiving and using Galileo signals

The Galileo spacecraft was an unmanned spacecraft sent by NASA to study the planet Jupiter and its moons. Named after the astronomer and Renaissance pioneer Galileo Galilei, it was launched on October 18, 1989 by the Space Shuttle Atlantis on the STS-34 mission. It arrived at Jupiter on December 7, 1995, a little more than six years later, via gravitational assist flybys of Venus and Earth.

Despite suffering from antenna problems, Galileo conducted the first asteroid flyby near 951 Gaspra, discovered the first asteroid moon, Dactyl, around the asteroid 243 Ida, and was the first spacecraft to orbit Jupiter. It furthermore launched the first probe into Jupiter's atmosphere.

The spacecraft measured the atmospheric composition of Jupiter and directly observed ammonia clouds, which seem to be created by an outflow from the lower depths of Jupiter's atmosphere. Galileo also registered Io's volcanism and the plasma interactions between its and Jupiter's atmospheres. Other studies gave support for the popular theory of liquid oceans under the icy surface of Europa. There were also indications of similar liquid-saltwater layers under the surfaces of Ganymede and Callisto, while Ganymede was shown to possess a magnetic field. New evidence was also found for the existence of exospheres around Europa, Ganymede, and Callisto.

It was furthermore discovered that Jupiter's faint ring system is formed by dust from impacts on the four small inner moons. The extent and structure of Jupiter's magnetosphere was also mapped.

Galileo also provided the only direct observation of Comet Shoemaker-Levy 9's impact into the atmosphere of Jupiter in 1994.

On September 21, 2003, after 14 years in space and 8 years of service in the Jovian system, Galileo's mission was terminated by sending the orbiter into Jupiter's atmosphere at a speed of nearly 50 kilometres per second to avoid any chance of it contaminating local moons with bacteria from Earth. Of particular concern was the ice-crusted moon Europa, which, thanks to Galileo, scientists now suspect harbors a potentially life-supporting saltwater ocean beneath its surface.