By Dr. Gary L. Deel, Ph.D., J.D.
Faculty Director, School of Business, American Military University
This is the fourth article in a seven-part series reviewing the extraterrestrial planets and other bodies of the solar system, as well as exploratory missions to study them.
Jupiter plays an extremely important role in our solar system. The giant planet is approximately 2.5 times more massive than all of the other planets in the solar system combined. It is a giant mass of gas mainly composed of hydrogen, but it has a solid core of ice, rock, and metals.
Experts believe that Jupiter’s intense gravitational field has had a protective effect on the inner solar system planets (including Earth). For hundreds of millions of years Jupiter’s gravity has flung rogue comets and asteroids out and away from the inner planets. In this sense, it is possible that life on Earth might not have arisen and evolved but for Jupiter’s presence.
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Since the dawn of the space age, several missions have been directed at Jupiter in order to learn more about our largest planetary neighbor. Yet, despite its massive influence, there is much we still don’t know about Jupiter.
In 1972, NASA sent Pioneer 10 into deep space, the first probe to make flybys of the outer gas giant planets. In late 1973, Pioneer 10 flew within about 200,000 km (12,427 miles) of Jupiter and measured the radiation levels in its vicinity, which were surprisingly high due to the intense gravity and magnetic field at work. Mission operators were able to communicate with the probe until contact was lost in 2001.
In 1974, Pioneer 11 followed its predecessor into the Jovian system. Pioneer 11 flew much closer to Jupiter’s atmosphere — within about 34,000 km (21,127 miles). The probe measured Jupiter’s magnetic field and atmospheric dynamics. It also took a number of pictures of Jupiter and its moons before ultimately moving on to Saturn. Pioneer 11 continued its mission until 1995 when it was shut down due to lack of power.
In 1979, the Voyager 1 and 2 mission probes performed detailed flybys of Jupiter on their way out of the solar system. Voyager 2 was launched a few days before Voyager 1, but due to differing speeds and trajectories, Voyager 1 actually arrived at Jupiter first. Each Voyager probe took around 18,000 photographs of Jupiter and its moons during their flybys. Together, they were responsible for the discovery of three new Jovian moons and the ring structure that exists around Jupiter.
Voyager 1 and Voyager 2 are technically still both active missions, as NASA is still able to communicate with them. Now almost 40 years later, the two probes recently reported data which indicate that they are just now exiting the heliosphere and entering deep space.
In 1989, NASA launched the Galileo probe, and in 1995 it became the first mission probe to successfully achieve orbit around Jupiter. Galileo had a troubled start because its high gain antenna failed to deploy, but it still carried out an overwhelmingly successful mission.
The Galileo spacecraft included an atmospheric probe that it deployed toward Jupiter’s surface after reaching orbit. The probe sent back a wealth of useful data about the temperatures, wind speeds, and pressures within the Jovian cloud cover before it was eventually crushed about an hour into its descent by the enormous weight of the gas above it.
The Galileo orbiter took detailed measurements of the magnetosphere and also studied the origin and composition of Jupiter’s ring system. Galileo’s mission was extended three different times so that it could study some of the more interesting Jovian moons. In 2003, at the end of its useful life, it ultimately was sent plunging into Jupiter itself.
In 1990, NASA launched the Ulysses space probe. The primary mission of the Ulysses spacecraft was to study the Sun. But before it reached its destination, it needed a gravitational assist from Jupiter, which it navigated in 1992. During this maneuver, Ulysses took measurements of Jupiter’s magnetic field and radiation levels.
In 1997, NASA launched the Cassini-Huygens probe toward Saturn. This probe also required a gravity assist from Jupiter, which it performed in 2000. During the flyby, it conducted some synchronized observations and measurements with the Galileo probe that was actively researching the Jovian system at the time.
In 2006, NASA launched the New Horizons probe on a nine-year journey to Pluto. On its way, it too utilized a gravity assist from Jupiter and spent about five months observing the planet and its moons. It was the first probe to photograph the newly formed “Little Red Spot” on Jupiter, as well as live volcanic activity on the Jovian moon Io. New Horizons made it to Pluto on schedule in 2015 and is still active, studying other objects in the Kuiper Belt.
In 2011, NASA launched the Juno spacecraft for Jupiter. After a 2013 flyby, Juno achieved orbit in 2016. Juno has several science instruments onboard that it will use to study the characteristics of Jupiter’s solid core, atmosphere, and magnetic field. Juno is still healthy and active.
In 2021, NASA plans to send the Lucy probe to study several Trojans in Jupiter’s orbit. Trojans are asteroids that orbit the Sun in the same orbital path as Jupiter, either ahead of or behind the planet itself. If Lucy is launched on schedule, it should arrive in the Jovian system sometime in the late 2020s.
In 2022, NASA intends to launch the Europa Multiple-Flyby Mission, which will consist of a spacecraft that — as the name suggests — will study Jupiter’s moon Europa through flybys. It will also include a lander that will make contact with the moon’s surface and collect data. If this mission launches as scheduled, the probe would arrive at Europa around 2030.
The European Space Agency (ESA) plans to launch the JUICE mission in 2022. JUICE is an acronym for Jupiter Icy Moon Explorer. It will consist of a space probe that will study the surfaces, interiors, and subsurface oceans of several Jovian moons. If it launches on schedule, JUICE should also arrive around 2030.
The missions that have explored Jupiter so far have made some intriguing discoveries. We can only hope that future missions will follow suit.
About the Author
Dr. Gary Deel is a Faculty Director with the School of Business at American Military University. He holds a J.D. in Law and a Ph.D. in Hospitality/Business Management. Gary teaches human resources and employment law classes for American Military University, the University of Central Florida, Colorado State University and others.