Editing Pioneer 10 (section)

===Launch and trajectory===
[[File:Launch of Pioneer 10-2.jpg|thumb|The launch of ''Pioneer 10'']]

''Pioneer 10'' was launched on March 3, 1972, at 01:49:00&nbsp;UTC (8:49&nbsp;p.m. Eastern Standard Time on March&nbsp;2) by the [[National Aeronautics and Space Administration]] from [[Cape Canaveral Air Force Station Space Launch Complex 36|Space Launch Complex 36A]] in Florida, aboard an [[Atlas-Centaur]]. The third stage of the [[expendable launch system |expendable vehicle]] consisted of a solid fuel [[Star-37E]] stage (TE-M-364-4) developed specifically for the Pioneer missions. This stage provided about {{Convert|67|kN|lbf}} of thrust and spun up the spacecraft.<ref name=glenn_2003/> The spacecraft had an initial spin rate of 30&nbsp;rpm. Twenty minutes following the launch, the vehicle's three booms were extended, which slowed the rotation rate to 4.8&nbsp;rpm. This rate was maintained throughout the voyage. The launch vehicle accelerated the probe for a net interval of 17&nbsp;minutes, reaching a velocity of {{Convert|51682|km/h|mph|abbr=unit}}.{{sfn|Rogers|1995|p=23}}

After the high-gain antenna was contacted, several of the instruments were activated for testing while the spacecraft was moving through the Earth's radiation belts. Ninety minutes after launch, the spacecraft reached interplanetary space.{{sfn|Rogers|1995|p=23}} ''Pioneer 10'' passed by the Moon in 11 hours,{{sfn|Fimmel|van_Allen|Burgess|1980|p=73}} and became the fastest human-made object at that time.{{sfn|Burrows|1990|pp=17}} Two days after launch, the scientific instruments were turned on, beginning with the cosmic ray telescope. After ten days, all of the instruments were active.{{sfn|Fimmel|van_Allen|Burgess|1980|p=73}}

During the first seven months of the journey, the spacecraft made three course corrections. The on-board instruments underwent checkouts, with the [[photometer]]s examining Jupiter and the [[Zodiacal light]], and experiment packages being used to measure cosmic rays, magnetic fields and the solar wind. The only anomaly during this interval was the failure of the Canopus sensor, which instead required the spacecraft to maintain its orientation using the two Sun sensors.{{sfn|Rogers|1995|p=23}}

While passing through [[interplanetary medium]], ''Pioneer 10'' became the first mission to detect interplanetary atoms of helium. It also observed high-energy ions of aluminum and sodium in the [[solar wind]]. The spacecraft recorded important [[heliophysics]] data in early August 1972 by registering a [[Solar storm of August 1972|solar shock wave]] when it was at a distance of {{Convert|2.2|AU|e6km e6mi|abbr=unit}}.<ref name=Knipp/> On July 15, 1972, ''Pioneer 10'' was the first spacecraft to enter the asteroid belt,<ref name=beyond/> located between the orbits of Mars and Jupiter. The project planners expected a safe passage through the belt, and the closest the trajectory would take the spacecraft to any of the known asteroids was {{convert|8.8|e6km|e6mi|abbr=off|sp=us}}. One of the nearest approaches was to the asteroid [[307 Nike]] on December 2, 1972.{{sfn|Fimmel|van_Allen|Burgess|1980|p=75}}

The on-board experiments demonstrated a deficiency of particles below a [[micrometre|micrometer]] (μm) in the belt, as compared to the vicinity of the Earth. The density of dust particles between 10 and 100&nbsp;μm did not vary significantly during the trip from the Earth to the outer edge of the belt. Only for particles with a diameter of 100&nbsp;μm to 1.0&nbsp;mm did the density show an increase, by a factor of three in the region of the belt. No fragments larger than a millimeter were observed in the belt, indicating these are likely rare; certainly much less common than anticipated. As the spacecraft did not collide with any particles of substantial size, it passed safely through the belt, emerging on the other side about February 15, 1973.<ref name=ns57_835_470/>{{sfn|Burgess|1982|p=32}}

<gallery mode="packed" heights="180">
File:72413main_ACD97-0036-3.jpg|alt=Official NASA map of the ''Pioneer 10'', ''Pioneer 11'', ''Voyager 1'', and ''Voyager 2'' spacecraft's trajectories through the Solar System.|NASA map showing trajectories of the ''Pioneer 10'', ''[[Pioneer 11]]'', ''[[Voyager 1]]'', and ''Voyager 2'' spacecraft.
Pioneer 10 December 4 1973 Jupiter.png|''Pioneer 10's'' trajectory through the Jovian system
File:Animation of Pioneer 10 trajectory.gif|Animation of ''Pioneer 10''{{'s}} trajectory from March 3, 1972, to December 31, 1975<br>{{legend2|magenta| ''Pioneer 10'' }}{{·}}{{legend2|Royalblue|[[Earth]]}}{{·}}{{legend2| Lime |[[Jupiter]]}}
File:Animation of Pioneer 10 trajectory around Jupiter.gif|Animation of Pioneer 10's trajectory around Jupiter<br>{{legend2|magenta| ''Pioneer 10'' }}{{·}}{{legend2|Lime|Jupiter}}{{·}}{{legend2|OrangeRed|Io}}{{·}}{{legend2|RoyalBlue|Europa}}{{·}}{{legend2|Gold|Ganymede}}{{·}}{{legend2|Cyan|Callisto}}
</gallery>