The approximately twenty space probes operational as of September 2014.
This is a list of active probes which have escaped Earth orbit. It includes lunar probes, but does not include probes orbiting at the Sun-Earth Lagrangian points (for these, see List of objects at Lagrangian points). A craft is deemed "active" if it is still able to transmit usable data to Earth (whether or not it can receive commands).
The craft are further grouped by mission status – "en route", "mission in progress" or "mission complete" – based on their primary mission. For example, though Voyager 1 is still contactable en route to the heliopause, it is listed as "mission complete" because its primary task of studying Jupiter and Saturn has been accomplished. Once a probe has reached its first primary target, it is no longer listed as "en route" whether or not further travel is involved.
Launched: 18 November 2013 | Destination: Mars| Arrival: September 2014 | Institution:NASA
MESSENGER is studying Mercury. It is only the second probe to do so and is the first to orbit the planet. Technologically, it is far superior to its 1975 predecessor, Mariner 10. Having previously passed Earth once, Venus twice and Mercury three times, it entered orbit in March 2011.
Launched: 4 August 2004 | Destination: Mercury| Arrival: 18 March 2011 | Institution: NASA
Lander: Opportunity Rover landed on Meridiani Planum. Expected to last 90 Martian days (sols), it continues to function effectively after 3946 sols. Its twin, Spirit Rover, explored an area on the other side of the planet, but became stuck in soft soil May 1, 2009, and communication was lost March 22, 2010 (sol 2210).
Launched: 10 June 2003 | Destination: Mars| Arrival: 25 January 2004 | Institution: NASA
Mars Reconnaissance Orbiter is the second NASA satellite orbiting Mars. It is specifically designed to analyze the landforms, stratigraphy, minerals, and ice of the red planet.
Launched: 12 August 2005 | Destination: Mars| Arrival: 10 March 2006 | Institution: NASA
Launched: 27 September 2007 | Destination: Vesta| Vesta arrival: 16 July 2011 |
Left Vesta: 5 September 2012 | Destination: Ceres| Arrival: 6 March 2015 | Institution:NASA
Lunar Reconnaissance Orbiter is engaged in lunar mapping intended to identify safe landing sites, locate potential resources on the Moon, characterize the radiation environment, and demonstrate new technology.
Launched: 18 June 2009 | Destination: Moon| Arrival: 23 June 2009 | Institution: NASA
ARTEMIS P1/P2 are studying the effect of the solar wind on the Moon. Originally launched as Earth satellites, they were later repurposed and moved to lunar orbit.
Launched: February 17, 2007 | Destination: Moon | Arrival: July 2011 | Institution: NASA
Lander: Curiosity rover is searching for evidence of organic material on Mars, monitoring methane levels in the atmosphere, and engaging in exploration of the landing site at Gale Crater.
Launched: 26 November 2011 | Destination: Mars| Arrival: 6 August 2012 | Institution: NASA
Lander: Chang'e 3 — first Chinese Moon lander and rover.
Launched: 1 December 2013 | Destination: Moon| Arrival: 14 December 2013 | Institution:CNSA
Voyager 1 is currently the farthest man-made object from Earth, as well as the first object to leave the Solar System, and cross into interstellar space. As of September 2014 it lies about 129 astronomical units (AU) from the sun (19.3 billion kilometers, or 0.002 light years), and it will not be overtaken by any other current craft. It was originally tasked with investigating Jupiter and Saturn, and the moons of these planets. Its continuing data feed offers the first direct measurements of the heliosheath and may eventually provide data on the heliopause. It is hoped that Voyager 1 will continue operating until at least 2020.
Launched: 5 September 1977 | Destination: Jupiter & Saturn| Arrival: January 1979 | Institution: NASA
Primary Mission Completion: November, 1980 | Current Trajectory: bound for heliopause
Voyager 2 has not yet left the solar system, but will become one of the first five probes to do so eventually. Its mission to study all four gas giants was one of NASA's most successful, yielding a wealth of new information. As of September 2014 it is some 106 AU from the sun (15.85 billion kilometers), and it is hoped that it will continue to operate until at least 2020. As with Voyager 1, scientists are now using Voyager 2 to learn what the solar system is like beyond the heliosphere.
Akatsuki would have been the first JapaneseVenusian probe. Also known as Planet-C and Venus Climate Orbiter, Akatsuki failed to enter Venusian orbit in December 2010. It is still functioning, and has a possible second chance to orbit Venus in 2015.
Pioneer 6, launched in 1965, is the oldest functioning probe (if still operating). Contact was last attempted 8 December 2000 to celebrate its thirty-fifth anniversary, and the attempt was successful. Like the three craft which superseded it, it took measurements of the solar wind, solar magnetic field and cosmic rays.
Giotto approached within 600 kilometers of Halley's Comet on its flyby mission, and survived some particulate impact on the inbound flight to capture scientific data and stunning images of the comet's nucleus. Its multicolor camera was subsequently destroyed, but the probe remained otherwise functional. Its mission completed, deactivation commands were transmitted on 15 March 1986. Awakened four years later on 2 July, it studied the comet Grigg-Skjellerup as it approached within 200 kilometers eight days later, and was again deactivated on the 23rd.
Launched: 2 July 1985 | Destination: Comet Halley| Arrival: 14 March 1986 | Institution: ESA