Ranger 7 impact

Ranger 7 · 1964 CE · The Moon

Televise the Moon's surface up to the moment of impact, at least ten times sharper than photographs from Earth.

Historical context

NASA wanted pictures of the lunar surface far sharper than any telescope could give, for science and for the manned landings to come. Six Rangers had fallen short, and Hall's history of the project records that another failure would have meant certain disaster for Ranger, with profound repercussions for the Jet Propulsion Laboratory and NASA.

The voyage, step by step

1. The seventh try

   28 July 1964

   At 16:50 UTC on 28 July 1964, 12:50 Eastern Daylight Time, an Atlas-Agena B lifts Ranger 7 off Launch Complex 12 at Cape Kennedy, a day after a scrubbed countdown.

2. Toward the Moon

   29 July 1964

   At 10:27 UTC on 29 July, 03:27 Pacific Daylight Time, a fifty-second burn slows Ranger 7 by about 30 metres per second and moves its aim from the Moon's far side to the northern rim of the Sea of Clouds.

3. Cameras on, eighteen minutes out

   31 July 1964

   At 13:07 UTC on 31 July, 06:07 Pacific Daylight Time, the two full-scan cameras begin to warm up, switched on by an onboard backup clock, by the mission report's account; the four partial-scan cameras follow about three minutes later, on a command from the spacecraft's sequencer.

4. Thousands of close-ups

   31 July 1964

   In its last seventeen minutes Ranger 7 sends 4,308 images, by NASA's archive count, the first from 2,110 kilometres up at 13:08:45 UTC and the last with a resolution of half a metre.

5. Silence at Pasadena

   31 July 1964

   At 13:25:49 UTC on 31 July, 06:25 Pacific Daylight Time, the signal stops as Ranger 7 strikes the Moon at 2.62 kilometres per second, over nine thousand kilometres an hour.

Outcome

Sent 4,308 pictures before striking Mare Cognitum on 31 July 1964; Kuiper put the gain in resolution at a thousandfold.

Ranger 7

NASA probe that televised the Moon's surface at close range in the last seventeen minutes before it struck, in July 1964.

Read on Wikipedia

Sources

• Lunar Impact: A History of Project Ranger (NASA SP-4210), chapters 17 and 18R. Cargill Hall · NASA · 1977
• Ranger 7 — NSSDCA Master CatalogNASA Space Science Data Coordinated Archive
• Ranger VII, Part I: Mission Description and Performance (JPL Technical Report 32-700)Jet Propulsion Laboratory (compiled under Gordon P. Kautz) · Jet Propulsion Laboratory, California Institute of Technology · 1964
• Ranger VII, Part II: Experimenters' Analyses and Interpretations (JPL Technical Report 32-700)R. L. Heacock, G. P. Kuiper, E. M. Shoemaker, H. C. Urey and E. A. Whitaker · Jet Propulsion Laboratory, California Institute of Technology · 1965
• Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016 (NASA SP-2018-4041)Asif A. Siddiqi · NASA History Division · 2018
• Making an Impact on History (Ranger 7 impact crater)Lunar Reconnaissance Orbiter Camera team, Arizona State University
• Ranger 7 — Wikipedia

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