航天飞机挑战者号执行唯一在轨放弃应急程序

1985年7月29日，NASA航天飞机挑战者号从肯尼迪航天中心升空执行STS-51-F任务1。升空后3分31秒，上升中心引擎因温度传感器失效而自动关闭1，触发了航天飞机计划历史上首次也是唯一一次在轨放弃（Abort-to-Orbit）应急程序1。这次发动机故障迫使航天飞机进入较低轨道，高度为265公里×262公里，低于原定的385公里×382公里计划轨道1。

尽管轨道高度下降，挑战者号仍顺利完成了STS-51-F任务的科学实验目标1。任务搭载的Spacelab 2实验室模块及多项科学载荷继续运行，其中红外望远镜观测了银河系平面60%的红外辐射1。航天飞机于8月6日太平洋时间中午12时45分26秒在加州爱德华兹空军基地安全着陆1，滑行距离为2612米1。事后，助推系统工程师詹妮·M·霍华德建议禁用自动RS-25发动机关闭功能，以防止可能的航天器和机组人员损失1。

NASA's Space Shuttle Challenger experienced an unprecedented in-flight emergency on July 29, 1985, when a center engine shut down during ascent due to a faulty temperature sensor, forcing the orbiter to execute an abort-to-orbit procedure—the only such occurrence in the Space Shuttle program's history 1. The shutdown occurred at three minutes and thirty-one seconds into the launch, requiring the crew to complete the STS-51-F mission at a lower orbital altitude than originally planned 1.

The mission had been designed to reach an orbital altitude of 385 by 382 kilometers, but the emergency maneuver resulted in Challenger achieving a lower orbit of 265 by 262 kilometers instead 1. Despite this unplanned trajectory, the flight successfully deployed its primary payload, the Spacelab 2 experimental module, which carried multiple scientific instruments including an infrared telescope that observed sixty percent of the galactic plane in infrared wavelengths 1. The mission also included various experiments such as a cola dispenser test 1. The orbiter safely landed at Edwards Air Force Base in California on August 6, 1985, at 12:45:26 p.m. Pacific Daylight Time, covering a rollout distance of 2,612 meters 1.

Following the incident, Booster Systems Engineer Jenny M. Howard recommended inhibiting automatic RS-25 engine shutdowns in future flights to prevent potential loss of crew and vehicle, marking a significant policy shift in response to this first failed in-flight shutdown of an RS-25 engine in the Space Shuttle program 1.