SHERPA (space tug)

SHERPA is a three-axis stabilized platform capable of on-orbit maneuvering meant to deploy small satellites carried as secondary payloads on rideshare orbital launches. SHERPA is integrated to the rocket as a standard adapter that is designed to fit on the SpaceX Falcon 9, Orbital Sciences Corp.'s Antares, and United Launch Alliance's Atlas V and Delta rockets. since 2010 and was unveiled in May 2012. Spaceflight Industries fabricates SHERPA, and the SSPS, at its facility in Tukwila, Washington. SHERPA's first mission was to deploy 90 small payloads, during a 2015 launch on a Falcon 9 rocket, then it was rescheduled for 2017, but delays caused in part by a Falcon 9 rocket explosion on a launch pad in 2016, prompted Spaceflight to cancel the mission. SpaceX appears to have severed ties with Spaceflight Inc., but has continued to fly manifested missions with the last launch on 25 May 2022. == Variants ==

Standard SHERPA There are at least five SHERPA variants: SHERPA (non-propelled), SHERPA 400, 1000, 2200 and FX. Each SHERPA is able to be launched in a stacked configuration with other SHERPA modules for later separation and independent free-flying. ;SHERPA The basic SHERPA is based on a commonly used secondary payload adapter known as an ESPA ring and it is not propelled. It is used for low Earth orbit deployments, and can unfurl a dragsail to lower its orbit before payload deployment. SHERPA-NG SHERPA-FX The FX variant, intended to be flown on board a SpaceX Falcon 9 Block 5 is an optional third stage for delivery of deployable and hosted payloads in low earth orbit (LEO) and polar orbit (SSO). SHERPA-AC Augmented version of the free-flying SHERPA-FX equipped with attitude knowledge & control capabilities and a flight computer, optimized for hosted payloads. SHERPA-LTC SHERPA LTC builds on SHERPA-AC by adding a bi-propellant propulsion system to deliver satellites and hosted payloads to low earth orbit (LEO) and polar orbit (SSO). Propulsion system by Benchmark Space Systems uses high test peroxide and isopropanol as propellants, with four pressure-fed 22 N thrusters. SHERPA-LTE SHERPA LTE builds on SHERPA-AC by adding a Hall effect electric propulsion system to deliver satellites and hosted payloads to Geostationary orbit (GEO), Cislunar, or Earth-escape orbits. SHERPA-ES SHERPA-ES (SHERPA EScape) is a high-energy SHERPA-NG variant that will utilize the same bi-propellant propulsion system as SHERPA-LTC with 6 times more propellant to deliver satellites and hosted payloads to geostationary and cislunar orbits. == Flight history ==