Exploration of Jupiter

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The exploration of Jupiter has consisted of a number of 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 has no 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 by the net change in velocity of the spacecraft, or delta-v. Reaching Jupiter from Earth requires a 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] Fortunately, gravity assists through planetary flybys can be used to reduce the energy required to reach Jupiter, albeit at the cost of a significantly longer flight duration.[1]

Contents

[edit] Fly-by missions

[edit] Pioneer flyby missions

Pioneer 10 flew past Jupiter in December of 1973, followed by Pioneer 11 exactly one year 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

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 performed a flyby of Jupiter at a distance of 409,000 km (6.3 Jovian radii). This critical maneuver was required for Ulysses to attain a polar orbit around the Sun. During this pass the probe conducted studies on 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. 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] It is thought that due to Jupiter's large mass and location near the inner solar system that 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. 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, while the information gained about the Jovian system from Galileo was extensive, its originally-designed capacity was limited by the failed deployment of its high-gain radio transmitting antenna.[11]

An atmospheric probe was released from the spacecraft in July, 1995, entering the planet's atmosphere on December 7. It parachuted through 150 km of the atmosphere, collecting data for 57.6 minutes, before being crushed by the pressure to which it was subjected by that time (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 possibly 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 2010.[12]

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.[13]

[edit] See also

[edit] References

  1. ^ a b Wong, Al (May 28, 1998). Galileo FAQ - Navigation. NASA. Retrieved on November 28, 2006.
  2. ^ Hirata, Chris. Delta-V in the Solar System. California Institute of Technology. Retrieved on November 28, 2006.
  3. ^ Lasher, Lawrence (August 1, 2006). Pioneer Project Home Page. NASA Space Projects Division. Retrieved on November 28, 2006.
  4. ^ Jupiter. NASA Jet Propulsion Laboratory (January 14, 2003). Retrieved on November 28, 2006.
  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 November 28, 2006.
  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 January 20, 2007.
  8. ^ Alexander, Amir (September 27, 2006). New Horizons Snaps First Picture of Jupiter. The Planetary Society. Retrieved on December 19, 2006.
  9. ^ Baalke, Ron. Comet Shoemaker-Levy Collision with Jupiter. NASA. Retrieved on January 2, 2007.
  10. ^ T. Nakamura, H. Kurahashi (1998). "Collisional Probability of Periodic Comets with the Terrestrial Planets: An Invalid Case of Analytic Formulation". Astronomical Journal 115 (1): 848–854. 
  11. ^ a b McConnell, Shannon (April 14, 2003). Galileo: Journey to Jupiter. NASA Jet Propulsion Laboratory. Retrieved on November 28, 2006.
  12. ^ New Frontiers - Missions - Juno. NASA. Retrieved on January 2, 2007.
  13. ^ "White House scales back space plans", MSNBC, February 7, 2005. Retrieved on January 2, 2007.
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