ULA launches STP-3, carrying a laser communication demo for NASA and more

Early Tuesday morning United Launch Alliance launched its fourth and final Atlas V rocket of 2021. For STP-3, it was ULA’s largest variant with five solid rocket motors.

STP-3’s payloads

STP-3 contains both classified Department of Defense missions alongside scientific missions from NASA. The primary payload STPSat-6 and its ridesharing spacecraft include several experiments, most importantly NASA’s Laser Communication Relay Demonstration (LCRD). This demonstration will test if optical communications can be a viable replacement for radio communication, which has been used since the beginning of space travel.

Alongside LCRD will be the National Nuclear Security Administration’s Atmospheric Burst Reporting System 3 (SABRS-3). SABRS-3 is an operational mission to monitor and ensure other nation-states’ abide by nuclear test band treaties. STP-3’s payloads will be sent into a geostationary orbit, high above Earth, to continuously overlook the same part of Earth.

Photo Credit: ULA

Unique mission for ULA’s Atlas V

ULA attempted a direct to geostationary orbit (GEO) insertion for the first time with STP-3. This is not new for other rockets but a first for the Atlas’ Centaur upper-stage that had to coast for six adn a half hours to complete its mission. This differs from the more normal geostationary transfer orbit (GTO), an elliptical orbit that reaches out to GEO. In GTO, the responsibility to finish its orbit, costing precious station-keeping fuel, lands on the payload. Direct GEO insertions extend the payloads’ lifespan, allowing for their missions to continue longer.

Photo Credit: Daryl Sausse’ / Space Explored

STP-3 was the longest mission in ULA’s history, lasting seven hours from launch to final deployment of the rideshare payload. So far, everything has taken place without issue.

Featured Image: Jared Locke / Space Explored

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