Exploration of Jupiter

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The exploration of Jupiter has consisted of a few automated spacecraft visiting the planet since 1973. A large majority of the missions have been "flybys", in which detailed observations are taken without the probe landing or entering orbit; the Galileo spacecraft is only one to have orbited the planet. As Jupiter is projected to have only a small rocky core and no real solid surface, a landing mission is impossible.

Flights to other planets within the Solar System are accomplished at a cost in energy, which is described in astrodynamics by the net change in velocity of the spacecraft, or delta-V. Reaching Jupiter from Earth orbit requires an additional delta-V of 9.2 km/s,[1] which is comparable to the 9.7 km/s delta-V needed to reach low Earth orbit.[2] However, gravity assists through planetary flybys can sometimes be used to reduce the energy required at launch to reach Jupiter, albeit at the cost of a significantly longer flight duration.[1]

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[edit] Flyby missions

[edit] Pioneer flyby missions

Pioneer 10 flew past Jupiter in December of 1973, the first space craft to ever explore Jupiter, followed by Pioneer 11 thirteen months later. Pioneer 10 obtained the first-ever close up images of Jupiter and the Galilean moons, studied its atmosphere, detected its magnetic field, observed its radiation belts and found that Jupiter is mainly liquid.[3]

[edit] Voyager flyby missions

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Voyager 1 took this photo of the planet Jupiter on January 24, 1979 while still more than 25 million miles (40 million kilometres) away. Click image for full caption.
Voyager 1 took this photo of the planet Jupiter on January 24, 1979 while still more than 25 million miles (40 million kilometres) away. Click image for full caption.

Voyager 1 flew by in March 1979 followed by Voyager 2 in July of the same year. The Voyagers vastly improved the understanding of the Galilean moons and discovered Jupiter's rings. They also took the first close up images of the planet's atmosphere.[4] -

[edit] Ulysses flyby mission

In February 1992, Ulysses solar probe flew past the north pole of Jupiter at a distance of 409,000 km (6.3 Jovian radii). This important maneuver was required for Ulysses to attain a very high-inclination orbit around the Sun. Ulysses drew gravitational energy from Jupiter to cast it into the desired orbit where it could make observations over the poles of the Sun.

During this pass the probe made measurements of Jupiter's magnetosphere. However, since there are no cameras onboard the probe, no images were taken. In February 2004, the probe came again to the vicinity of Jupiter. This time the distance was much greater—about 240 million km. - [5]

[edit] Cassini flyby mission

The most detailed map of Jupiter ever produced. Taken by Cassini.
The most detailed map of Jupiter ever produced. Taken by Cassini.

In 2000, the Cassini probe, en route to Saturn, flew by Jupiter and provided some of the highest-resolution images ever made of the planet. On December 19, 2000, the Cassini spacecraft, captured a very low resolution image of the moon Himalia, but it was too distant to show any surface details.[6]

[edit] New Horizons flyby mission

Jupiter by New Horizons probe.
Jupiter by New Horizons probe.

The New Horizons probe, en route to Pluto, flew by Jupiter for a gravity assist. Its closest approach was on February 28, 2007. While at Jupiter, New Horizon's instruments refined the orbits of Jupiter's inner moons, specifically Amalthea. The probe's cameras measured plasma output from volcanoes on Io and studied all four Galilean moons in detail.[7] Imaging of the Jovian system began September 4, 2006.[8]

[edit] Shoemaker-Levy comet

Main article: Comet Shoemaker-Levy 9

During the period July 16 to July 22, 1994, over twenty fragments from the comet Shoemaker-Levy 9 hit Jupiter's southern hemisphere, providing the first direct observation of a collision between two solar system objects. Although not a probe from Earth, the impact did provide data on the composition of Jupiter's atmosphere.[9] Due to Jupiter's large mass and location near the inner solar system, the planet receives the most frequent comet impacts of the solar system's planets.[10]

[edit] Galileo mission

Jupiter as seen by the space probe Cassini. This is the most detailed global color portrait of Jupiter ever assembled.
Jupiter as seen by the space probe Cassini. This is the most detailed global color portrait of Jupiter ever assembled.

So far the only spacecraft to orbit Jupiter is the Galileo orbiter, which went into orbit around Jupiter on December 7, 1995. It orbited the planet for over seven years, conducting multiple flybys of all of the Galilean moons and Amalthea. It was the first probe to encounter Jupiters 4 major moons Io, Europa, Ganymede and Calisto. The spacecraft also witnessed the impact of Comet Shoemaker-Levy 9 as it approached Jupiter in 1994, giving a unique vantage point for the event. However, although the information it gained about the Jovian system was extensive, it was not as great as intended because the deployment of its high-gain radio transmitting antenna failed.[11]

An atmospheric probe was released from the spacecraft in July, 1995, entering the planet's atmosphere on 7 December 1995. After a high-g descent into the jovian atmosphere, the probe discarded the remains of its heat shield, and it parachuted through 150 km of the atmosphere, collecting data for 57.6 minutes, before being crushed by the pressure & temperature to which it was subjected (about 22 times Earth normal, at a temperature of 153 oC). [1] It would have melted thereafter, and possibly vaporized. The Galileo orbiter itself experienced a more rapid version of the same fate when it was deliberately steered into the planet on September 21, 2003 at a speed of over 50 km/s, in order to avoid any possibility of it crashing into and contaminating Europa.[11]

[edit] Future probes

NASA is planning a mission to study Jupiter in detail from a polar orbit. Named Juno, the spacecraft is planned to launch by 2011.[11]

Because of the possibility of a liquid ocean on Jupiter's moon Europa, there has been great interest to study the icy moons in detail. A mission proposed by NASA was dedicated to study them. The JIMO (Jupiter Icy Moons Orbiter) was expected to be launched sometime after 2012. However, the mission was deemed too ambitious and its funding was cancelled.[12]


[edit] References

  1. ^ a b Wong, Al (May 28, 1998). Galileo FAQ - Navigation. NASA. Retrieved on 2006-11-28.
  2. ^ Hirata, Chris. Delta-V in the Solar System. California Institute of Technology. Retrieved on 2006-11-28.
  3. ^ Lasher, Lawrence (August 1, 2006). Pioneer Project Home Page. NASA Space Projects Division. Retrieved on 2006-11-28.
  4. ^ Jupiter. NASA Jet Propulsion Laboratory (January 14, 2003). Retrieved on 2006-11-28.
  5. ^ K. Chan, E. S. Paredes, M. S. Ryne (2004). Ulysses Attitude and Orbit Operations: 13+ Years of International Cooperation (PDF). American Institute of Aeronautics and Astronautics. Retrieved on 2006-11-28.
  6. ^ C. J. Hansen, S. J. Bolton, D. L. Matson, L. J. Spilker, J.-P. Lebreton (2004). "The Cassini-Huygens flyby of Jupiter". Icarus 172 (1): 1-8. doi:10.1016/j.icarus.2004.06.018. 
  7. ^ New Horizons targets Jupiter kick. BBC News Online (January 19, 2007). Retrieved on 2007-01-20.
  8. ^ Alexander, Amir (September 27, 2006). New Horizons Snaps First Picture of Jupiter. The Planetary Society. Retrieved on 2006-12-19.
  9. ^ Baalke, Ron. Comet Shoemaker-Levy Collision with Jupiter. NASA. Retrieved on 2007-01-02.
  10. ^ T. Nakamura, H. Kurahashi (1998). "Collisional Probability of Periodic Comets with the Terrestrial Planets: An Invalid Case of Analytic Formulation" ([dead link] – Scholar search). Astronomical Journal 115 (1): 848–854. doi:10.1086/300206. 
  11. ^ a b McConnell, Shannon (April 14, 2003). Galileo: Journey to Jupiter. NASA Jet Propulsion Laboratory. Retrieved on 2006-11-28.


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