OTV-7

Orbital Test Vehicle 7 (OTV-7), also referred to as United States Space Force-52 (USSF-52) or USA-349, is the fourth flight of the second Boeing X-37B, an American unmanned vertical-takeoff, horizontal-landing spaceplane. It was launched to a highly elliptical high Earth orbit aboard a Falcon Heavy rocket (for the first time) from LC-39A on 28 December 2023.

The spaceplane is operated by the Department of the Air Force Rapid Capabilities Office and United States Space Force, which considers the mission classified and as such has not revealed the objectives. The spaceplane will be sent to orbit with a wide range of test and experimentation objectives. These tests include operating in new orbital regimes, experimenting with space domain awareness technologies and investigating the radiation effects to materials provided by NASA.

Background and mission
OTV-7 is the fourth mission for the second X-37B built, and the seventh X-37B mission overall. It was flown on a Falcon Heavy in the expendable center core-recoverable side cores configuration, and launched from Kennedy Space Center Launch Complex 39A. It is the second classified flight of Falcon Heavy, awarded in June 2018. It is valued at US$130 million, increased to $149.2 million in August 2021, due to "a change in the contract requirements" and expected to be completed by 14 April 2022. Draft solicitation said the launch was 6350 kg to GTO. A month before launch, the Air Force announced that the mission will fly an X-37B spaceplane.

OTV-7 was deployed into a Highly elliptical HEO orbit of 323 km x 38838 km x 59.1° orbit.

Payloads and experiments
Onboard experiments include NASA's Seeds-2 experiment investigating the effects of space-based radiation on plant seeds during a long-duration spaceflight.