|Mission type||Lunar lander|
|Mission duration||62 hrs. 9 min. 1 sec. (launch to last contact)|
|Launch mass||1,039 kg|
|Dry mass||283 kilograms (624 lb)|
|Start of mission|
|Launch date||July 14, 1967, 11:53:29UTC|
|Rocket||Atlas LV-3C Centaur-D|
|Launch site||Cape Canaveral LC-36A|
|End of mission|
|Last contact||July 17, 1967, 02:02:30UTC (approx)|
|Lunar impact (failed landing)|
|Impact date||July 17, 1967, 02:05:00 UTC|
Surveyor 4 was the fourth lunar lander in the American uncrewed Surveyor program sent to explore the surface of the Moon. This spacecraft crashed after an otherwise flawless mission; telemetry contact was lost 2.5 minutes before touchdown. The planned landing target was Sinus Medii (Central Bay) at 0.4° north latitude and 1.33° west longitude.
Surveyor 6 successfully landed near the crash site of Surveyor 4 a few months later in November 1967.
This spacecraft was the fourth in a series designed to achieve a soft landing on the Moon and to return photography of the lunar surface for determining characteristics of the lunar terrain for Apollo lunar landing missions. Equipment on board included a television camera and auxiliary mirrors, a soil mechanics surface sampler, strain gauges on the spacecraft landing legs, and numerous engineering sensors. Like Surveyor 3, Surveyor 4 was also equipped with a surface claw (with a magnet in the claw) to detect and measure ferrous elements in the lunar surface.
After a flawless flight to the Moon, radio signals from the spacecraft ceased during the terminal-descent phase at 02:03 UT on July 17, 1967, approximately 2.5 minutes before touchdown. Contact with the spacecraft was never reestablished, and the mission was unsuccessful. The solid-fuel retrorocket may have exploded near the end of its scheduled burn.