TAGSAM or Touch-and-Go Sample Acquisition Mechanism is a robotic arm on the OSIRIS-REx space probe for collecting a sample from asteroid 101955 Bennu. OSIRIS-REx was launched in 2016. It arrived at asteroid Bennu in December 2018, and began scientific studies. It collected a sample of the material making up the surface of Bennu in 2020, and returned that sample to Earth in 2023.
Overview
TAGSAM is a robotic arm attached to the main body of the spacecraft that collects a sample from the asteroid, and puts the samples into the Earth return vehicle. Bennu is about 500 meters in diameter and has very low gravity, so the arm must perform the collection in near zero gravity, yet still contend with some gravitational forces from the asteroid. One issue with small asteroids is their unique gravitational environment, and Bennu became the smallest body orbited by a spacecraft.
TAGSAM was designed to take up to three samples from the asteroid, although in the event the first sample was so large no other samples were attempted. The collection head was filled using a nitrogen gas injection that stired up the regolith. The arm is about long, and has three joints for articulation on it. SamCam will acquire images of the collection head. Two major parts of TAGSAM are the robotic arm and the sample collection head.
The arm was used in conjunction with several instruments on the spacecraft including three cameras, three spectrometers, and a laser altimeter.
Two identical TAGSAM units were made, one for use on the spacecraft called the flight unit and another for testing on Earth called the qualification unit.
Timeline
17 October 2018 — TAGSAM head cover jettisoned
25 October 2018 — Frangibolts fired, releasing the TAGSAM arm
14 November 2018 — TAGSAM arm fully extended for the first time
15 April 2020 — rehearsal manouvre performed by OSIRIS-REx
20 October 2020 — successful TAGSAM deployment and sample collection
24 September 2023 — safe touchdown on Earth of the OSIRIS-REx sample return capsule