S-55 (Explorer)

Explorer-13 (S-55a)

The S-55 series satellites were NASA's research satellites as part of the Explorer program . The aim of the satellites was to study the frequency of micrometeorites in near-earth space. As soon as the S-55 satellites had successfully entered orbit, they were given an Explorer designation with a sequential number from the Explorer program.

The four largely identical satellites were all launched from the Wallops Flight Facility with the help of Scout missiles.

construction

Each of the satellites was cylindrical in shape, 61 cm in diameter and 192 cm in length, and remained firmly attached to the final stage of the Scout rocket. The upper part of the satellite contained solar cells for power supply and electronics. Several types of micrometeorite sensors were mounted on the satellite:

• Penetration detectors consisting of a series of gas-filled stainless steel tubes that were attached around the fourth stage of the launcher (five rows with 32 cells each)
• Piezoelectric impact detectors
• Foil capacitor detectors
• Cadmium sulfide cell detectors
• Wireframe detectors

With the help of these detectors, information about the size, number, distribution and speed of the dust particles in the low orbit could be obtained.

Results

The measurements showed that the micrometeorite density was significantly lower than initially assumed. This information was important for the Mercury program to be able to assess the dangers for manned space flights. Later, advanced measurements were made from the three Pegasus satellites and Explorer 46 .

Missions

Explorer	Surname	date	Launch rocket	Starting place	Orbit (apogee, perigee, inclination)	Dimensions	Remarks
---	S-55	June 30, 1961	Scout-X1	WI	---	84 kg	False start, failure of the launcher
Explorer 13	S-55a	August 25, 1961	Scout-X1	WI	125 km 1,164 km 37.70 °	86 kg	Orbit reached too low, burned up after only two days without delivering measurement results
Explorer 16	S-55b	December 16, 1962	Scout-X3	WI	750 km 1,181 km 52.01 °	101 kg	Worked for seven months
Explorer 23	S-55c	November 6, 1964	Scout-X4	WI	466 km 977 km 51.95 °	134 kg

swell

• Explorer-13 in the NSSDCA Master Catalog (English)
• Explorer-16 in the NSSDCA Master Catalog (English)
• Explorer-23 in the NSSDCA Master Catalog (English)
• Explorer: S-55, a, b on Gunter's Space Page