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STEP 4 (Space Test Experimental Program 4) was a US military satellite launched from Wallops Island aboard a Pegasus XL rocket released from a plane. The solar panels failed to deploy properly, and there has been little or no uplink or downlink contact with the spacecraft. The failure is similar to those of the previously launched STEP 1, 2, and 3.

Alternate Names

  • Space Test Experimental Program 4
  • 25013
  • STEP4

Facts in Brief

Launch Date: 1997-10-22
Launch Vehicle: Pegasus XL
Launch Site: Wallops Island, United States

Funding Agency

  • Department of Defense (United States)


  • Surveillance and Other Military

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office

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