A probe launched by the European Space Agency in 1985, to obtain the first close-up pictures of Halley's Comet.

Using Ariane 1, Giotto was launched from Kourou, French Guiana at 2nd of July 1985 11:23 UT. The Giotto-mission was ESAs first deep-space mission. The project was supposed to be a joint U.S. - European mission, but due to financial problems, NASA pulled out. ESA decided to go on alone, since it would be 75 years until the next opportunity. Giotto was named after the famous Italian artist with the same name who lived 1266-1337.

After a successful launch, Giotto waited, and at March 13, 1986, at a distance of 0.89 AU from the sun, Halley's Comet went by, and Giotto got some great pictures. Giotto was never meant to survive the meeting with the comet, due to the massive amount of dust and particles. Although some of the instruments on board giotto were damaged, Giotto itself was still operational. After the mission was successful, Giotto was remotely switched off.

In 1992 ESA came up with a new mission for Giotto: Grigg-Skjellerup.
The problem was that ESA did not know if Giotto still worked after being exposed to the harsh environment of space. Neither did they know which direction the antenna was facing. The only thing they could do was to send the wakeup-signal, and hope that the low-range omni-directional antenna received it. It took two hours after the wake-up signal had been sent, before signals from Giotto was received at the NASA Deep Space Network ground station near Madrid, Spain. After a week Giotto was fully operational again (well, apart from the damaged instruments). To be able to get close to Grigg-Skjellerup, the orbit of Giotto had to be altered. This was done by using the earth's gravitational field. Giotto flew 22730 Km above earth, and successfully got into the right orbit*.

*Giotto was the first probe to use earth's gravity to alter its orbit

On 10th of July, 1992, It was time for Giotto to prove that he was still alive and kicking: Grigg-Skjellerup was close. Grigg-Skjellerup flew past Giotto at 17000 Km, but unfortunately, Giotto's camera missed by a mere 100 to 200 km, due to differences in the fly-by conditions between Halley's and Grigg-Skjellerup.

After some minor orbit-adjustments, Giotto was once again switched off. There are still no plans to revive it, but there is reason to believe that Giotto still is operational, and can be re-activated.

Giotto's mission:
  • Obtain the first close-up images of a comet nucleus (from a distance less than 500km).
  • Determine the elemental and isotopic composition of ices in the cometary coma.
  • Study the physical and chemical processes that occur in the comet's atmosphere.
  • Determine the elemental and isotopic composition of cometary dust particles.
  • Measure the comet's total gas-production rate.
  • Measure the amount of dust around the comet and its size/mass distribution.
  • Determine the relative amounts of dust and gas in the near-comet environment.
  • Investigate the interaction between the comet and the electrically charged particles of the solar wind.

Giotto's Achievements:
  • The first probe to pass by two asteroids.
  • First probe to photograph a comet nucleus.
  • Europe's first deep space mission.
  • First deep space mission to change orbit by returning to Earth for a gravity assist.
  • Discovered the size and shape of Comet Halley 's nucleus.
  • Made the closest comet flyby to date by any spacecraft (200 km from Comet Grigg-Skjellerup).
  • Discovered a black crust and bright jets of gas on the nucleus of Comet Halley.
  • Measured the size, composition and velocity of dust particles near two comets.
  • Measured the composition of gas produced by two comets.
  • Discovered unusual magnetic waves near Comet Grigg-Skjellerup.

Technical Specifications:
Weight: 960 kg (including fuel)
Launch Vehicle: Ariane 1

Equipment on board:
  • A narrow-angle, multicolour camera to obtain pictures of the nucleus.
  • Three mass spectrometers to measure gas and dust composition.
  • A dust impact detector to measure the mass of dust particles striking the shield.
  • Two plasma experiments to study the solar wind and charged particles.
  • An energetic particles analyser to study electrons, protons and alpha-particles.
  • A magnetometer to study changes in the magnetic field.
  • An optical probe to study brightness of the coma.
  • A radio science experiment to investigate the electron environment was also carried out by comparing signals sent at different frequencies from the spacecraft.

  • NASA web-site
  • ESA web-site
  • My local library