X-37B OTV-4 (USA 261)

Spacecraft nº:

US spacecraft nº:

Launch data:

Spacecraft data:

The X-37B OTV-4 vehicle being encapsulated in its Atlas-V payload fairing for launch on the OTV-4 mission. Photo Credit: U.S. Air Force

The X-37B mounted in its ULA Atlas V protective fairing for mission OTV-4. Photo Credit: Boeing

Description:

• This is the fourth OTV (Orbital Test Vehicle) mission. The OTV 4 (X-37B) is a robotic spaceplane developed by the US Air Force Rapid Capabilities Office and carries secret test payloads.
• Built by Boeing´s Phantom Works division, the spaceplane is 29 feet long with a wing span of 15 feet, made of light-weight composite structures instead of aluminum and shielded with improved leading-edge ceramic insulation panels on its wings and tougher silica tiles affixed to its belly that are designed to be more durable than first-generation tiles used on the space shuttle. It can weigh up to 11,000 pounds fueled for launch.
• Unlike the space shuttles that used cryogenic liquid hydrogen and liquid oxygen reactants to generate electricity through onboard fuel cells, limiting the mission lengths by the amount of consumables that could be carried, the OTV is powered by a deployable solar array. The longest shuttle flight was 18 days.

Mission details:

• On May 20, 2015 an Atlas V orbited an X-37B Orbital Test Vehicle into an unknown orbit, probably around 400 km and 40 deg inclination like previous missions. There are two X-37Bs and for the first time the USAF has not announced which of them is flying the mission. In contrast there is somewhat more openness than before about the payload, which includes an AFRL ion engine test and a NASA materials exposure experiment. The launch had the codename Air Force Space Command 5, or AFSPC 5, and flew aboard the rocket with a tailnumber AV-054.
• After releasing the X-37B the Centaur AV-054 rocket stage reignited to reach a 355 x 700 km x 55-57 deg orbit and at around 17:00 UTC released a set of 10 cubesats. Centaur then made a third burn to deorbit itself over the Indian Ocean. Detailed orbital data for this mission are not yet available. The X-37B has been found by hobbyist observers in a 309 x 322 km x 38.0 deg orbit.
• A collection of 10 Cubesats also hitched a ride into low-Earth orbit aboard the Atlas 5 rocket and were to be deployed a few hours after the X-37B spaceplane. Together, the Cubesats are known as ULTRASat, or the Unique Lightweight Technology and Research Auxiliary Satellite.
• They rode inside eight Poly-Pico Orbital Deployers built by the California Polytechnic State University in San Luis Obispo and the P-PODs were packaged in the Naval Post-graduate School´s box-like CubeSat Launcher affixed to the Centaur upper stage next to the RL10 engine. The National Reconnaissance Office and NASA sponsored the ULTRASat launch.