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X-ray Scintillation Counters

NSSDCA ID: 1961-032A-08

Mission Name: Ranger 2
Principal Investigator:Dr. Theodore G. Northrop


The X-Ray Scintillation Counters on Ranger 2 were designed to detect extremely short-term variations of bursts of low-energy solar X-rays, both for scientific studies of the Sun and to help enable future instruments to distinguish between nuclear events and solar bursts. The instrument consisted of a pair of scintillation counters / photomultipliers mounted about a foot apart with the sensitive surfaces facing the Sun. Six opaque windows in the front of each counter protect against cosmic ray dust puncture while allowing X-rays to pass through. They could detect low-energy solar X-rays in the range from 1 to 20 keV. The instrument had a mass of 5.4 kg and included its own 2 W battery power supply, logic, and data handling system. Timers turned the high-voltage supply to the photomultipliers on 8 hours after launch to avoid possible damage during passage through the Earth's radiation belts.

The X-ray experiment was built and supplied by Los Alamos Scientific Laboratories in cooperation with Sandia Corp. as part of the Air Force and Atomic Energy Commission Vela Hotel Project, to aid in their ability to identify nuclear tests. The instrument was added to Ranger 1 and 2 at the request of ARPA and the behest of NASA Headquarters after the science package had been confirmed, hence the self-contained nature of the instrument. The instrument was accomodated on the spacecraft after some reshuffling of the spacecraft components.

Because the last data obtained from Ranger 2 were from approximately 6 hr, 49 min. after launch, and the instrument timer was set for 8 hours, no data were returned from this experiment.

Alternate Names

  • Ranger2/ScintillationCounter

Facts in Brief

Mass: 5.4 kg
Power (avg): 2 W


  • Space Physics: Heliospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Theodore G. NorthropPrincipal InvestigatorNASA Goddard Space Flight
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