Pioneer 2Also referred to as “Pioneer 0”, the Pioneer space probe is launched by the US Air Force, with the intention of sending it to the moon. Just over a minute after Pioneer’s Thor-Able booster lifts off, the first stage explodes, and Pioneer’s short flight ends in the Atlantic Ocean. The next Pioneer space probe will be handled by the newly formed National Aeronautics and Space Administration later in 1958.

Pioneer 1

Pioneer 1The newly-formed National Aeronautics and Space Administration launches its first space probe, Pioneer 1, atop a Thor-Able booster. Intended to image the moon at the infrared end of the spectrum from close range, Pioneer 1 is the victim of a technical error which instead sends it into an 80,000 mile arc which eventually brings it back into Earth’s atmosphere. Its flight lasts just 43 hours, but it does yield some information about the radiation belts surrounding Earth, as well as the first experiment to measure the density of micrometeor impacts registered by an onboard sensor.

Pioneer 2

Pioneer 2NASA launches Pioneer 2, a near-identical twin to the failed lunar probe Pioneer 1 it launched a month earlier. Again, technical errors prevent the probe from entering lunar orbit or, for that matter, even reaching the moon – Pioneer 2 limps into a looping arc, barely a thousand miles from Earth, and returns home to burn up in the atmosphere.

Pioneer 3

Pioneer 3NASA launches the Pioneer 3 space probe, intended – like its predecessors – to visit the vicinity of the moon. Designed to activate a television camera to get the first look at the moon’s far side, Pioneer 3 never reaches its target, only covering a third of the distance between Earth and the moon before it loops back toward Earth and burns up in the atmosphere a day later. Its near-identical twin, Pioneer 4, will be launched in 1959.

Pioneer 4

Pioneer 4NASA’s Pioneer 4 space probe is launched toward the moon atop a Juno II booster. For the first time in the Pioneer program, the target is reached, with Pioneer 4 passing the moon at a distance of 37,000 miles. The television camera designed to activate just in time to catch the first glimpse of the lunar far side fails to deploy, thanks to a light sensor that isn’t tripped by the light reflected from the moon. Measurements of radiation near the moon are taken and transmitted back to Earth before Pioneer 4 slides into an orbit around the sun.

Pioneer 10 launched

Pioneer 10NASA launches Pioneer 10, the first spacecraft sent to study the huge planet Jupiter at close range. Its Atlas-Centaur booster gives it a good head start, propelling it to over 32,000 miles per hour en route to Jupiter, the fastest man-made object in history at this point. Pioneer 10 is also the first man-made vehicle to traverse the asteroid belt, with instruments detecting fewer large particles than anticipated. It will reach Jupiter in late 1973.

Pioneer 10 plunges into the asteroid belt

Pioneer 10En route to becoming the first human-made spacecraft to visit Jupiter, NASA’s Pioneer 10 also becomes the first human-made spacecraft to enter the asteroid belt between the orbits of Mars and Jupiter. Whether or not the spacecraft will survive this crossing is indeed one of the mission’s major experiments, and is a topic of active debate between scientists with differing views of how densely populated the asteroid belt may be. The spacecraft will survive the crossing without incident.

Pioneer 11 launched

Pioneer 11The unmanned space probe Pioneer 11 is launched on a course that will be one of the first real tests of the theory of gravity assist. Reaching Jupiter in 1975, it will use the giant planet’s gravity to throw it across the solar system to rendezvous with Saturn, the first human-made vehicle to visit that planet. The experience gained with Pioneer 11’s groundbreaking trajectory through the solar system will prove instrumental in the upcoming Mariner Jupter/Saturn ’77 mission, which is later be renamed Voyager.

Pioneer 10: Jupiter’s first visitor from Earth

JupiterNASA’s Pioneer 10 space probe, launched in 1972 and boosted to unprecedented speeds by a three-stage rocket, makes its closest pass to the planet Jupiter, the first human-made vehicle to do so. Zooming past Jupiter’s equator at a distance of less than 100,000 miles, Pioneer 10’s electronics are nearly fried by the giant planet’s intense radiation. Pioneer 10 presses on toward the edge of the solar system, continuing to report back through the 1990s.

Pioneer 11 visits Jupiter

Pioneer 11 at JupiterNASA’s Pioneer 11 space probe passes close to Jupiter, barely 27,000 miles above the giant planet’s cloudtops, again encountering radiation capable of frying spacecraft electronics. Pioneer 11 captures the first images of Jupiter’s polar cloud structure and pulls off a daring gravity assist maneuver: the planet’s gravity flings Pioneer 11 up and over the north polar region and across the solar system for a 1979 rendezvous with Saturn, the first spacecraft to visit that planet.

Pioneer Venus Orbiter launched

Pioneer VenusNASA launches the 1,100 pound Pioneer Venus Orbiter, designed to orbit Venus for a year to study the planet’s atmosphere and its interaction with other space phenomena. Though launched separately, the two Pioneer Venus spacecraft will arrive at Venus within days of one another in December 1978. The Orbiter takes radar observations of the cloud-shrouded planet, from which the first surface map of Venus is derived. As with many other unmanned NASA spacecraft designed for relatively short-duration missions, the Pioneer Venus Orbiter outlives its design lifespan, staying fully functional into the 1990s and eventually becoming the only American spacecraft to view Halley’s Comet in 1986.

Pioneer Venus Multiprobe launched

Pioneer VenusTrailing its supporting orbiter by several months, the Pioneer Venus Multiprobe – also known as Pioneer 13 – lifts off en route to deposit its payload of four atmospheric entry probes designed to measure the planet’s inhospitable, poisonous atmosphere. Following the launch of those probes, the Multiprobe carrier vehicle will then enter the atmosphere of Venus itself and take measurements, burning up before it ever reaches the surface.

Pioneer Venus: visit to a hot planet

Pioneer VenusJust five days after the arrival of the Pioneer Venus Orbiter, the Pioneer Venus Multiprobe arrives at Venus, having already deployed its payload of four atmospheric penetration probes on their own trajectories to plunge through the planet’s dense atmosphere at different latitudes. Only one of these probes survives impact, transmitting for an hour afterward. The Multiprobe “bus” spacecraft, having relayed the smaller probes’ readings to Earth, then follows suit, plunging into the atmosphere and disintegrating before it can hit the surface. The Pioneer Venus Orbiter remains at Venus into the 1990s.

Pioneer 11: first visitor to Saturn

SaturnThe unmanned space probe Pioneer 11 makes its closest approach to the planet Saturn, the first man-made object to visit the ringed planet. Scientists pay careful attention to Pioneer’s transmissions as it passes between Saturn’s clouds and its rings, watching for signs of damage (or worse) resulting from collision with the tiny particles that are predicted to exist there; Pioneer 11 slides past Saturn at a distance of only 12,800 miles from the planet’s cloudtops. This is Pioneer 11’s last planetary stop.

Pioneer Venus completes its map… for now

VenusNASA’s unmanned Pioneer Venus Orbiter completes its radar mapping survey of the planet Venus, having used radar to create the first-ever topographical map of that world, which is usually hidden behind a thick, toxic cloud deck. Launched in 1978, Pioneer Venus Orbiter is the only surviving component of the two-vehicle Pioneer Venus mission, but with its solar arrays still gathering adequate power and all of its instruments still functioning well, the orbiter is not deactivated or deorbited at this time; future tasks will be found for it in the years ahead.

Pioneer 10 past Pluto

Pioneer 10NASA’s Pioneer 10 unmanned spacecraft becomes the first human-made spacecraft to pass beyond the orbit of Pluto, the outermost known planet in the solar system. (Pioneer 10 merely crosses the planet’s orbital path; Pluto itself is in a different part of its orbit, nowhere near Pioneer at the time.) Launched in 1972, Pioneer 10 was the first spacecraft to cross the asteroid belt and observe the giant planet Jupiter at close range, blazing a trial for other outer solar system robotic exploration missions.

New assignment for Pioneer Venus

Pioneer VenusHaving received new orders from NASA, the still-functional Pioneer Venus Orbiter – launched in 1978 and in a high, looping orbit over Venus since it ceased active observations of the planet in 1981 – turns its instruments in the direction of Comet Encke, which is currently passing through the inner solar system. Rather than its cameras, the orbiter’s ultraviolet spectrometer is trained on the comet as Earth-based researchers try to determine the composition and rotational speed of Encke’s nucleus. The Pioneer Venus Orbiter will continue to observe other comets through the late 1980s.

Pioneer Venus captures Halley’s Comet

Halley's CometHaving already conducted measuresment of Comets Encke and Giacobini-Zinner, the still-functioning Pioneer Venus Orbiter, launched in 1978, becomes the centerpiece of the American effort to gather close-up data on Halley’s Comet. Imaging the comet in ultraviolet light, Pioneer Venus captures Halley from a unique vantage point: both the comet and the planet being orbited by Pioneer are on the opposite side of the sun from Earth, when Halley is at its closest approach to the sun – an event that no other spacecraft is in a position to witness. The Pioneer Venus data will become the most critical data gathered on Halley by an American spacecraft after a planned March 1986 Space Shuttle mission to image the comet from Earth orbit is scrapped in the wake of the Challenger disaster in January.

Pioneer Venus eyes Comet Wilson

Comet WilsonA victory lap after its successful study of Halley’s Comet in 1985 and 1986, the Pioneer Venus Orbiter uses its unique position at the solar system’s second planet to observe another comet, the recently-discovered Comet Wilson. Spotted for the first time only the year before, little is known about Comet Wilson, a lack of data that Pioneer Venus helps to correct by imaging the comet in the ultraviolet portion of the spectrum. Pioneer Venus will also study two other comets later in 1987.

Farewell to Pioneer Venus

VenusThe Pioneer Venus Orbiter, launched into orbit around Venus in 1978 and now the only surviving component of the Pioneer Venus mission, enters the cloudy planet’s dense, toxic atmosphere and disintegrates, its fuel supply too exhausted to keep it in orbit any longer. Originally intended to orbit Venus for only a year, Pioneer Venus has survived, fully functional, for nearly 14 years in Venusian orbit, continuing to study the planet and taking readings not only Venus but such objects as Halley’s Comet.

Voyager 1: furthest robot out

Voyager 1Unmanned space prove Voyager 1, launched in 1977, surpasses its forerunner Pioneer 10 as the furthest man-made object in space. Due to a sharp increase in its speed imparted by a very close pass by Saturn’s large moon Titan in 1980, Voyager 1 has outrun Pioneer 10, which was launched in 1972. Both vehicles are still returning science data, and Voyager 1 is now 6.5 billion miles from the sun, 70 times further out from the sun than Earth. Voyager’s on-board nuclear power source is expected to keep it active through 2020.