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Earth Invaders

by Perry Pezzolanella

A new Golden Age of planetary exploration began with the landing of Mars Pathfinder and its Sojourner Rover on July 4, 1997 and continues to this very day. The good news is that it will continue for the rest of this decade and into the next. Bold new missions are following on the heels of the successful ones that are currently under way. Spacecraft will orbit, land, rove, and return samples. New vistas will be explored and old theories will be disproven while new ones will be created. The following is a list of all missions, current and planned, for the planets, Pluto, asteroids, and comets. Launch and arrival dates for missions not yet flown are subject to change.

Mercury: MESSENGER continues to orbit Mercury since its arrival on March 17, 2011 and will do so until March 2015 when it will run out of attitude control fuel and crash into the surface. The European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) are building a dual spacecraft, BepiColombo, which is set to launch on July 9, 2016 and go into orbit around Mercury on January 1, 2024. The spacecraft will separate with the ESA spacecraft exploring Mercury's geology and the JAXA spacecraft exploring the magnetic field. The Russian Federal Space Agency (Roscosmos) has been studying a lander mission, but nothing is firm at this time.

Venus: ESA's Venus Express is still orbiting Venus since arriving on April 11, 2006 and continues to monitor the atmosphere for lightning and the heat flow on the surface for volcanic activity. JAXA will make a second attempt to insert Akatsuki into orbit around Venus on November 22, 2015. It hopes to study the lightning and volcanic activity in even finer detail than Venus Express along with the weather patterns. Roscosmos is planning to land Venera D on the ancient tesserae region of Venus around 2024 and NASA is still considering a mission to land a probe on the flanks of a potentially active volcano around 2021, although not yet approved.

Mars: Three orbiters, Odyssey, Mars Reconnaissance Orbiter (NASA) and Mars Express (ESA), and two NASA rovers, Opportunity and Curiosity, continue to send a wealth of data and images back to Earth. NASA's MAVEN orbiter will arrive in a few months on September 22 to study the upper atmosphere of Mars. India's Mars Orbiter Mission will arrive two days later on September 24 to orbit Mars. Another NASA mission, InSight, will launch on March 8, 2016 and land September 20 the same year to study the internal workings of Mars. The ExoMars orbiter known as the Trace Gas Orbiter (ESA/Roscosmos) will launch on January 7, 2016 and arrive later that year on October 19 to study the atmosphere for the origins and evolution of rare gases, especially methane. The ExoMars rover (ESA/Roscosmos) is scheduled for launch during April 2018 with touchdown on Mars during January 2019. NASA is planning to launch another Curiosity-class rover for about $1 billion less than the original using existing and proven components in 2020. It will have the added capability of being able to collect rocks that could be returned to Earth by another rover in the future. The intense exploration and focus on Mars will eventually lead up to the return of samples to Earth and the ultimate goal of manned landings and colonization.

Jupiter: NASA's Juno spacecraft was launched on August 5, 2011 and is well on its way to going into orbit around Jupiter on July 4, 2016. It will orbit Jupiter 33 times and study its clouds and wind as close as 2700 miles from the cloud tops until the mission ends on October 16, 2017. ESA is developing JUICE (JUpiter ICy moons Explorer) that is planned to launch in June 2022 and enter into Jupiter's orbit during January 2030. It will eventually go into orbit around Ganymede, its primary goal of study, in September 2032, and continue until at least June 2033. A dedicated Europa mission by NASA is being considered with the recent discovery of possible geysers. Initial funding has been approved for what may eventually become the Europa Clipper mission. A Ganymede lander by Roscosmos is under preliminary review.

Saturn: Cassini is the crown jewel of planetary exploration since its arrival at Saturn ten years ago on June 30, 2004 with huge discoveries such as methane lakes on Titan and water-ice geyser on Enceladus. It will continue to explore Saturn and its moons until the mission ends on September 15, 2017. The loss of Cassini will mark a sad end to Saturn exploration with no firm follow-up missions approved. Pressure is mounting to launch a probe to explore the methane seas of Titan and the geysers of Enceladus. There are also plans for another orbiter that would drop a probe into Saturn's atmosphere, which has yet to be probed. These missions will be up for consideration in the years ahead.

Uranus: No missions are approved and nothing has flown past Uranus since the Voyager 2 flyby on January 24, 1986. Plans for an orbiter/probe mission have been drafted but flight times of 10-15 years and other more interesting worlds during a tight budget continue to keep Uranus on the back burner.

Neptune: No missions are approved and nothing has flown past Neptune since the Voyager 2 flyby on August 25, 1989. Plans for an orbiter/probe mission with a possible Triton lander are drafted. If approved it probably would not launch until around 2030 with little hope of seeing any data or photos until around 2045. Triton, with its active nitrogen geysers, may actually motivate a Neptune mission to fly before one is flown to Uranus.

Pluto: New Horizons was launched on January 19, 2006 and will fly past Pluto and its five moons on July 14, 2015. This encounter with Pluto will reveal it for the first time and there should be plenty of surprises. No other missions to Pluto are planned. ESA has blueprints for an orbiter but it is not likely to fly in our lifetime due to the tight budget, long flight time of nearly 20 years, and commitments to BepiColombo, JUICE, ExoMars, and Rosetta.

Comets: ESA's Rosetta mission to Comet 67P/Churyumov-Gerasimenko was launched on March 2, 2004 and is just now beginning to explore the comet as it goes into orbit this August and will deploy a small lander in November. It will be the first spacecraft to both orbit and land on a comet, and it will study the comet as it grows more active as it nears the Sun.

Asteroids: NASA's Dawn spacecraft was launched on September 27, 2007 and successfully orbited Vesta during 2011-12. It is now on its way to dwarf planet Ceres and will arrive on March 28, 2015 and go into permanent orbit. OSIRIS-REx is a NASA mission to asteroid Bennu that will launch in September 2016 and land on the asteroid in 2019 to collect a sample and return it to Earth by 2023.

The invasion of spacecraft from planet Earth to the worlds throughout the Solar System continues. These are exciting times for planetary exploration with the bizarre and unexpected being discovered. A wealth of beautiful, awe-inspiring vistas and rich data will continue to quench the thirst of the imagination and of the scientific-minded for decades to come.