Pioneer 10
What is Pioneer 10?
Probes & telescopes· Launched 1972-03-02 – contact lost 2003-01-23 (drifting outward in silence). The NASA probe that first crossed the asteroid belt and first flew past Jupiter. Launched in 1972 and silent since 2003, it is still coasting in the direction of Aldebaran in Taurus.
Mission timeline
Spacecraft specs
| Launch | 1972-03-02 |
|---|---|
| Jupiter flyby | 1973-12-03 |
| Last contact | 2003-01-23 |
| Distance now | ~142 AU (as of Oct 2026), toward Aldebaran |
Figures are representative approximations. Distances that change over time are extrapolated from 2020-01-01. Source: compiled from NASA and IAU public data.
Why Pioneer 10 will never reach Aldebaran
Pioneer 10 is heading toward Aldebaran, the bright star in Taurus. Aldebaran is about 65 light-years away, so if the star stood still the trip would take roughly two million years at the probe's present speed. But Aldebaran is moving away from the Sun at 54 km/s, more than four times faster than the probe, so Pioneer 10 can never catch it. Toward Aldebaran simply describes the direction in which it left.
The space between stars is vast and nearly empty. The five spacecraft leaving the solar system (Pioneers 10 and 11, Voyagers 1 and 2, and New Horizons) are very unlikely ever to hit another star or pass deep into another planetary system. The chance that anyone will read Pioneer 10's plaque is tiny. Even so, the plaque remains a record of how humanity chose to introduce itself.
The mission in depth
Pioneer 10 was launched on 2 March 1972, and it lived up to its name. At the time there were fears that a spacecraft crossing the asteroid belt between Mars and Jupiter might be smashed by rocky debris. Pioneer 10 entered the belt that July and came through unharmed, the first proof that spacecraft could pass safely.
On 3 December 1973 it flew about 130,000 km above Jupiter's clouds. As the first probe to reach Jupiter, it took close-up pictures of the Great Red Spot and the moons. It also discovered that the radiation around Jupiter was far stronger than expected, a finding that helped later spacecraft prepare for it.
Jupiter's gravity boosted Pioneer 10 onto a path out of the solar system. It crossed Neptune's orbit in 1983 and remained the most distant human-made object until Voyager 1 overtook it in 1998. As its plutonium power source weakened, it sent its last signal on 23 January 2003, from about 80 AU.
Fixed to the spacecraft is a gold-anodised aluminium plaque. It shows a man and a woman and a diagram of where the Sun lies in the Galaxy. The probe is still coasting at about 12 km/s in the direction of Aldebaran. In the orbit view you can see its path straighten after the Jupiter flyby as it leaves the solar system.
Frequently asked
- When did Pioneer 10 launch?
- Pioneer 10 was launched on 1972-03-02.
- How far is Pioneer 10 from Earth?
- The distance now of Pioneer 10 is ~142 AU (as of Oct 2026), toward Aldebaran.
- In one line, what is Pioneer 10?
- Probes & telescopes — The NASA probe that first crossed the asteroid belt and first flew past Jupiter.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.