Where is the Galileo Spacecraft right now?

The app above shows the last resting place of the Galileo Spacecraft right now - which is within Jupiter where it was deliberately crashed in 2003. You can also wind the animation backwards in time to watch its launch and its flybys of Venus and the Earth, and insertion into orbit around Jupiter.

If you re-play the mission, you can see the Galileo's position as it orbits Jupiter. However the trails shown (which are with respect to the Sun) can be distracting so we recommend selecting Jupiter as the central object and fading out the orbit trails so that you can see Galileo’s orbits more clearly with respect to Jupiter.

Galileo Flight Path

Galileo was launched on 18th October 1989 and comprised the Galileo Orbiter and the Galileo Probe, both destined for the Jupiter system.

Problems

The spacecraft had suffered several delays and changes to its planned delivery system. It was designed to be launched on the space shuttle and accelerated on a direct trajectory to Jupiter using a Centaur-G booster rocket. Due to the Challenger disaster, the spacecraft launch was delayed and then due to a new safety regime, carrying the Centaur rocket aboard a space shuttle was no longer allowed. This meant that Galileo had to undertake a longer journey to Jupiter using Venus and Earth for gravity sling shots.

An unforeseen side effect of the period in storage was that the orbiters high gain antenna (which could transmit data at 130 kilobits per second) failed to deploy properly. The antenna was supposed to open like an umbrella, but due to lubricants drying out in storage several ribs failed to pop out. After many and varied attempts to get the antenna deployed it was abandoned in favour of the low gain antenna which could only send data at a much lower rate (16 bits a second). Improvements in data compression and the sensitivity of earth based receivers improved the data rate some what (1 kilobit per second) but meant that much more data had to be stored on the digital tape recorder and sent when time allowed - sometimes delaying data for months.

Unfortunately the tape recorders tape was also damaged when it got stuck in rewind for 15 hours. Also later in the mission radiation affected some of the DTR's components preventing it from working. However ingenious fixes meant that the mission could continue with only minor losses of data.

Mission Landmarks

951 Gaspra from Galileo

243 Ida from Galileo

The flight path involved 3 gravitational assists with 2 flybys of Earth and one of Venus. Asteroid 951 Gaspra (named after Gaspra, a Crimean town on the coast of the Black Sea) was encountered between earth sling shots and was the first asteroid to ever be visited by a spacecraft. Galileo passed within 1600km and sent back 57 images of this 12km diameter asteroid.

On its journey to Jupiter, Galileo used 34kg of fuel to adjust its trajectory to come within 2390km of asteroid 243 Ida (named after Ida who was a nymph of Crete who raised the Greek god Zeus) of size 54 x 24 x 15km. This resulted in another first - the detection of a moon orbiting about an asteroid - named Dactyl (after the mythological dactyls who inhabited Mount Ida on the island of Crete) at 1.4km radius.

Galileo Probe

Galileo Probe

The Galileo probe was a 1.3 metre across probe which was released from the Galileo Orbiter in July of 1995. It impacted Jupiter's atmosphere on the 7th December 1995 at a speed of 48 km/s. The probe then underwent a 250 g deceleration and reduced its speed to a subsonic velocity in 2 minutes, burning away 80kg of it 156kg heat shield. It then jettisoned its heat shield and deployed a parachute and began sending science data back to the Orbiter as it sampled the atmosphere on its descent.

It descended 156km and sent just under an hours worth of data before succumbing to the extreme pressures (23 atmospheres) and temperatures (153 degrees C) of the Jovian atmosphere.

The probe discovered that Jupiter had half the amount of helium expected and its data did not support the three-tiered cloud structure that most researchers at the time had postulated. It detected less lightning, less water, but more winds than expected; consistent 530 kilometres per hour winds during its descent. No solid surface was detected during its journey downward to 156 kilometres.

Galileo Orbiter

Galileo entered orbit on 8th December 1995 and spent 8 years and 35 orbits investigating the Jovian system. During that period it discovered a huge amount of new data including discovering ammonia clouds in Jupiter’s atmosphere, that plasma interactions on Io mean that it is electrically coupled to Jupiter's atmosphere. Europa, Ganymede and Callisto have a thin atmosphere and probably have a liquid salt-water sub-surface layer. Ganymede has a substantial magnetic field - a first found on a moon. It also mapped out the Jovian magnetosphere and provided evidence on how Jupiter’s faint ring system was created.

Galileo Mission End

At the end of the mission, Galileo was deliberately crashed into Jupiter to ensure that it did not accidentally hit and contaminate any of the Jovian moons that may support life. The spacecraft had not undergone sterilisation prior to launch and so could possibly be carrying bacterial life from earth. Galileo was de-orbited by passing close by the large inner moon Amalthea on the 5th November, 2002, at a distance of 163km. This allowed the mass of Amalthea to be measured (by determining how much it affected Galileo's trajectory) and also put Galileo into an extremely long thin orbit reaching 26 million km from the planet. It then fell into the planet and hit the atmosphere at a similar velocity to which the Galileo Probe did, e.g. 48 km/s.

More Information:

Galileo Mission - NASA

Image Credits:

"Galileo encounter with Io".
Licensed under Public Domain via Wikimedia Commons.