An Etymological Dictionary of Astronomy and Astrophysics
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A machine capable of flying by means of → buoyancy or → aerodynamic forces, such as an airplane, helicopter, glider, or balloon.

→ air; → craft.

A ship or other vessel.

M.E., from O.E. cræft "strength, skill;" cf. Ger. Kraft, D. kracht, O.N. kraptr. The "ship" meaning comes from the expression "vessel of small craft (trade)."

Nâv "ship;" O.Pers./Av. *nāv-, O.Pers. nāviyā- "fleet;" cf. Skt. nau-, nava- "ship, boat;" Gk. naus.

NASA's mission to explore the two largest objects in the → asteroid belt, the asteroid Vesta and the → dawarf planet Ceres, gathering data relating to their composition, internal structure, density and shape. Launched in September 2007, Dawn entered the orbit of → Vesta in July 2011 and spent 16 months there before leaving for → Ceres. It entered Ceres orbit on March 6, 2015. The Dawn spacecraft is made of aluminium and graphite composite, it has a dry mass of 747.1 kg and a mass of 1217.7 kg when fully fuelled prior to launch. The spacecraft is a box-shaped design measuring 1.64m × 1.27m × 1.77m. Dawn ran out of fuel on Nov. 1, 2018, but the spacecraft will continue to orbit Ceres for several decades.

→ dawn; → spacecraft.

A space mission whose main goal was to explore → Jupiter and its moons and rings. The spacecraft was launched on October 19, 1989, arrived at Jupiter in December 1995. It disappeared on September 21, 2003, after eight years orbiting Jupiter, when mission controllers crashed it into → Jupiter's atmosphere. On December 7, 1995, Galileo's probe dived into Jupiter's atmosphere, and measured atmospheric pressure, density, and composition, and explored the planet's → radiation belts. Galileo had two parts: an orbiter and a descent probe that parachuted into Jupiter's atmosphere. The orbiter sent back hundreds of pictures of the four large → Galilean satellites of Jupiter (→ Io, → Europa, → Ganymede, and → Callisto). It made many discoveries during its eight years looping around Jupiter. It found evidence for layers of salt water below the surface on Europa, Ganymede, and Callisto, and measured high levels of volcanic activity on Io. When → Shoemaker-Levy slammed into Jupiter in 1994, Galileo had the only direct view of the → comet striking Jupiter's atmosphere. Galileo determined that → Jupiter's rings are formed from dust hurled up by → meteorite impacts on planet's inner moons. Measurements by the orbiter's → magnetometer revealed that Io, Europa, and Ganymede have metallic cores, while Callisto does not. Also, Galileo discovered that Ganymede possesses its own → magnetic field; it is the first moon known to do so. The orbiter also found that the Galilean satellites all have thin atmospheres. During it's trip from Earth to Jupiter, Galileo passed by and studied two asteroids: → Gaspra in 1991 and → Ida in 1993, around which it discovered → Dactyl, the first moon orbiting an asteroid (windows2universe.org).

→ Galileo; → mission.

A vehicle capable of travelling over land or water on a cushion of air.

→ space; → craft.

A → NASA space telescope launched in March 2009 to discover Earth-size planets using the → transit method. The telescope has a diameter of 0.95 m and its only instrument is a → photometer that continuously monitors the brightness of over 145,000 → main sequence stars in a fixed field of view of 115 deg² (about 12° diameter). The expected mission lifetime is 3.5 years extendible to at least 6 years.

In honor of Johannes → Kepler; → spacecraft.

A NASA robotic spacecraft that orbited the planet → Mercury for more than four years, between 2011 and 2015. Among its accomplishments, the mission determined Mercury's surface composition, revealed its geological history, discovered details about its internal magnetic field, and verified its polar deposits are dominantly water-ice. → Mercury's tail.

Messenger, short for "MErcury Surface, Space ENvironment, GEochemistry, and Ranging", a reference to the → messenger god Mercury from Roman mythology; → spacecraft.

A vehicle designed to travel or operate, with or without a → crew, in a controlled → flight pattern in space beyond the Earth's atmosphere or in → orbit around the Earth. Also called spaceship.

→ space; → craft.