Surveyor 4

Spacecraft· NASA / JPLlost

Surveyor 4 — a lander lost in the final moments (launched 14 July 1967). Its descent looked flawless until radio contact ceased about two and a half minutes before touchdown, probably a retrorocket failure; it was never heard from again. (Intended site, Sinus Medii, shown.)

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Key facts

Distance from Sun

1.01 AU

Status

Lost

Launched

1967

Mission & specifications

Mission

Operator: NASA / JPL
Launched: July 14, 1967
Status: Lost

Trajectory

Distance from the Sun: 1.01 AU
Distance from Earth: 425,058 km
Distance from Venus: 0.603 AU

Mission

Surveyor 4 was lost in the last moments of what had looked like a perfect flight. Launched on 14 July 1967, it flew a flawless trajectory to the Moon and began its terminal descent toward Sinus Medii. Then, about two and a half minutes before touchdown — with the retrorocket firing — all radio contact abruptly ceased. Nothing was ever heard from it again. The most likely explanation is that the solid retrorocket failed, perhaps exploding, and destroyed the spacecraft in the final seconds of descent. After three successes it was a stark loss, and a reminder of how unforgiving those last moments above the surface were.

Images

A Surveyor lander (mock-up) — Surveyor 4 was lost seconds before touchdown, returning no surface imagery — NASA / JPL (public domain) · Wikimedia Commons

Images from open archives · credit shown per image