UC Berkeley Assembles Upcoming COSI Mission

  • Released Monday, August 31, 2026
View full credits
Engineers Bradley Pafchek and Matt Rubly examine the COSI (Compton Spectrometer and Imager) detector assembly at Space Sciences Laboratory on July 15, 2026. COSI is an upcoming spacecraft that will measure gamma rays, the highest-energy form of light, to help scientists study energetic phenomena in the Milky Way and beyond. Credit: UC Berkeley/Alan Toth Alt text: Two people examine the COSI detector assembly.Image description: Two people stand on yellow step ladders and lean over to examine a small gold box. The box is centered inside the top of a hexagonal white frame. A larger hexagonal silver and black box extends from the bottom of the frame. The person on the left wears a blue cleanroom suit, and the one on the left wears a white one. They both wear hairnets, masks, gloves, and shoe covers. A floor-to-ceiling plastic sheet separates the back of the room, which is full of metal shelving and boxes.

Engineers Bradley Pafchek and Matt Rubly examine the COSI (Compton Spectrometer and Imager) detector assembly at Space Sciences Laboratory on July 15, 2026. COSI is an upcoming spacecraft that will measure gamma rays, the highest-energy form of light, to help scientists study energetic phenomena in the Milky Way and beyond.

Credit: UC Berkeley/Alan Toth

Alt text: Two people examine the COSI detector assembly.

Image description: Two people stand on yellow step ladders and lean over to examine a small gold box. The box is centered inside the top of a hexagonal white frame. A larger hexagonal silver and black box extends from the bottom of the frame. The person on the left wears a blue cleanroom suit, and the one on the left wears a white one. They both wear hairnets, masks, gloves, and shoe covers. A floor-to-ceiling plastic sheet separates the back of the room, which is full of metal shelving and boxes.

The upcoming COSI spacecraft is a wide-field gamma-ray telescope that will study energetic phenomena in the Milky Way and beyond, including the creation and destruction of matter and antimatter and the final stages of the lives of stars.

The images here show engineers at the University of California, Berkeley assembling flight instrumentation at the Space Sciences Laboratory during summer 2026.

The mission, part of NASA’s Astrophysics Explorers program, is a collaboration between UC Berkeley’s Space Sciences Laboratory; the Naval Research Laboratory; NASA's Goddard Space Flight Center; the University of California, San Diego; Northrop Grumman; the University of Utah’s Space Dynamics Laboratory; the Italian Space Agency; and many other research institutions.

UC Berkeley engineer Christopher Smith checks the spacing between the layers of the COSI germanium gamma-ray detectors on June 12, 2026. The layers will allow COSI to track the paths of a gamma ray as it enters the detector assembly and collides with a particle, like an electron, and transfers some of its energy to it, an interaction called Compton scattering. Credit: UC Berkeley/Alan Toth Alt text: A person works on the COSI detector. Image description: A person works on a box of electrical equipment on a gold base. The person is crouched out of frame, so only their hands and head are visible in the bottom right corner. They wear gloves, a mask, glasses, and a hairnet. The box is made of four stacks of four white and silver squares. The assembly rests on top of a blue and silver frame. The person uses a long thin rod to check the spaces between the white and silver squares.

UC Berkeley engineer Christopher Smith checks the spacing between the layers of the COSI germanium gamma-ray detectors on June 12, 2026. The layers will allow COSI to track the paths of a gamma ray as it enters the detector assembly and collides with a particle, like an electron, and transfers some of its energy to it, an interaction called Compton scattering.

Credit: UC Berkeley/Alan Toth

Alt text: A person works on the COSI detector.

Image description: A person works on a box of electrical equipment on a gold base. The person is crouched out of frame, so only their hands and head are visible in the bottom right corner. They wear gloves, a mask, glasses, and a hairnet. The box is made of four stacks of four white and silver squares. The assembly rests on top of a blue and silver frame. The person uses a long thin rod to check the spaces between the white and silver squares.

Rubly uses a laser to check the alignment of the COSI detectors on June 15, 2026. Credit: UC Berkeley/Alan Toth Alt text: A person works on the COSI detector. Image description: A person in a blue cleanroom suit, gloves, mask, and hairnet adjusts a laser pointed at a stack of white and silver squares in a laboratory. The stack sits on a gold base on top of a blue and white frame.

Rubly uses a laser to check the alignment of the COSI detectors on June 15, 2026.

Credit: UC Berkeley/Alan Toth

Alt text: A person works on the COSI detector.

Image description: A person in a blue cleanroom suit, gloves, mask, and hairnet adjusts a laser pointed at a stack of white and silver squares in a laboratory. The stack sits on a gold base on top of a blue and white frame.

UC Berkeley engineers Pafchek and Rubly watch as the COSI detector assembly is slowly raised from a table on July 8, 2026, alongside Smith, Hannah Goldberg (payload manager), and John Grinold (mission assurance manager). The four pieces of silver material on the top of the detector box cover the flex circuits, which carry signals from the detectors to the readout electronics. John Tomisck, COSI’s principal investigator, and project systems engineer Ellen Taylor watch from the window. Credit: UC Berkeley/Alan Toth Alt text: A group of people watch the COSI detector. Image description: A group of five people wearing cleanroom suits, hairnets, and masks watch a small gold and silver box suspended by a small crane in a laboratory. In the background, slightly out of focus, two more people watch through a window. Next to the window is a large decal of the COSI mission patch.

UC Berkeley engineers Pafchek and Rubly watch as the COSI detector assembly is slowly raised from a table on July 8, 2026, alongside Smith, Hannah Goldberg (payload manager), and John Grinold (mission assurance manager). The four pieces of silver material on the top of the detector box cover the flex circuits, which carry signals from the detectors to the readout electronics. John Tomisck, COSI’s principal investigator, and project systems engineer Ellen Taylor watch from the window.

Credit: UC Berkeley/Alan Toth

Alt text: A group of people watch the COSI detector.

Image description: A group of five people wearing cleanroom suits, hairnets, and masks watch a small gold and silver box suspended by a small crane in a laboratory. In the background, slightly out of focus, two more people watch through a window. Next to the window is a large decal of the COSI mission patch.

Tomsick and Taylor watch Smith and Pafchek guide the COSI detector assembly toward its baseplate on July 8, 2026. Credit: UC Berkeley/Alan Toth Alt text: People watch work on the COSI detector. Image description: Out of focus in the foreground, two people in cleanroom suits, masks, and hair nets help guide a suspended gold and silver box towards a gold square gold base in a laboratory. In focus in the background, two more people watch through a window. The COSI mission patch is on the wall to the right of the window but is cut off in the middle.

Tomsick and Taylor watch Smith and Pafchek guide the COSI detector assembly toward its baseplate on July 8, 2026.

Credit: UC Berkeley/Alan Toth

Alt text: People watch work on the COSI detector.

Image description: Out of focus in the foreground, two people in cleanroom suits, masks, and hair nets help guide a suspended gold and silver box towards a gold square gold base in a laboratory. In focus in the background, two more people watch through a window. The COSI mission patch is on the wall to the right of the window but is cut off in the middle.

The COSI detector assembly rests on its baseplate on July 8, 2026. The gold part of the box is one of two thermal shields the mission will use to keep the detectors cold. Credit: UC Berkeley/Alan Toth Alt text: The COSI gamma-ray detector assembly Image description: A gold box with silver flaps on the top sits on a gold base plate in a laboratory. The plate rests on a brass square attached to a black box via several wires. The assembly sits on a larger hexagonal base inside a hexagonal frame. In the background, the lab is full of equipment, and a window shows another room.

The COSI detector assembly rests on its baseplate on July 8, 2026. The gold part of the box is one of two thermal shields the mission will use to keep the detectors cold.

Credit: UC Berkeley/Alan Toth

Alt text: The COSI gamma-ray detector assembly

Image description: A gold box with silver flaps on the top sits on a gold base plate in a laboratory. The plate rests on a brass square attached to a black box via several wires. The assembly sits on a larger hexagonal base inside a hexagonal frame. In the background, the lab is full of equipment, and a window shows another room.

Pafchek uses epoxy to seal off screw heads on the COSI detector assembly on July 15, 2026. The flex circuits are folded along the top of the box. Credit: UC Berkeley/Alan Toth Alt text: A person works on the COSI detector. Image description: A person in a blue cleanroom suit, gloves, mask, and a hairnet uses a syringe on a gold box. The box has rectangles of brown and silver material on the sides, and flaps of brown and silver material folded on the top. The assembly rests on a gold base plate.

Pafchek uses epoxy to seal off screw heads on the COSI detector assembly on July 15, 2026. The flex circuits are folded along the top of the box.

Credit: UC Berkeley/Alan Toth

Alt text: A person works on the COSI detector.

Image description: A person in a blue cleanroom suit, gloves, mask, and a hairnet uses a syringe on a gold box. The box has rectangles of brown and silver material on the sides, and flaps of brown and silver material folded on the top. The assembly rests on a gold base plate.

Engineers attach a second thermal shield to the outside of the COSI detector assembly on July 15, 2026. The detector must be kept below minus 205 degrees Fahrenheit (minus 183 degrees Celsius). That way, when a gamma ray strikes it, the thermal noise in the detectors is low enough for COSI to detect the signal. Credit: UC Berkeley/Alan Toth Alt text: The COSI gamma-ray detector assembly Image description: Two pairs of white-gloved hands work on a gold box on a gold base plate. The side of the box facing the camera has two rectangular silver panels. Silver and brown material is folded on the top of the box.

Engineers attach a second thermal shield to the outside of the COSI detector assembly on July 15, 2026. The detector must be kept below minus 205 degrees Fahrenheit (minus 183 degrees Celsius). That way, when a gamma ray strikes it, the thermal noise in the detectors is low enough for COSI to detect the signal.

Credit: UC Berkeley/Alan Toth

Alt text: The COSI gamma-ray detector assembly

Image description: Two pairs of white-gloved hands work on a gold box on a gold base plate. The side of the box facing the camera has two rectangular silver panels. Silver and brown material is folded on the top of the box.

Pafchek and Rubly adjust the flex circuits underneath the COSI detector assembly on July 16, 2026. The honeycombed box is the cryostat, which keeps the detector assembly cold. Credit: UC Berkeley/Hannah Goldberg Alt text: Two people work on the COSI detector assembly. Image description: Two people in cleanroom suits, gloves, masks, and hairnets work beneath a piece of scientific instrumentation. Between them is a gold honeycombed box attached to the underside of a platform. Brown strips of circuitry hang from the bottom of the box and pass through a rectangle of gold material.

Pafchek and Rubly adjust the flex circuits underneath the COSI detector assembly on July 16, 2026. The honeycombed box is the cryostat, which keeps the detector assembly cold.

Credit: UC Berkeley/Hannah Goldberg

Alt text: Two people work on the COSI detector assembly.

Image description: Two people in cleanroom suits, gloves, masks, and hairnets work beneath a piece of scientific instrumentation. Between them is a gold honeycombed box attached to the underside of a platform. Brown strips of circuitry hang from the bottom of the box and pass through a rectangle of gold material.

Smith and Rubly perform assessments on the spacing and alignment of COSI’s germanium gamma-ray detectors on June 12 and 15, 2026, at Space Sciences Laboratory.

Credit: UC Berkeley/Alan Toth

0:00 Smith adjusts the detector.

0:06 Rubly examines and rotates the detectors.

0:28 Rubly inserts screws into the corners of the detector.

1:04 Smith adjusts the spacing of the detector layers.

1:26 Rubly adjusts the spacing of the detector layers.

1:36 Rubly uses a laser to test the alignment of the detector layers.

Engineers at Space Sciences Laboratory move the COSI detector assembly to the frame that will house it inside the spacecraft on July 8 and July 15, 2026.

Credit: UC Berkeley/Alan Toth

0:00 Pafchek and Rubly prepare the COSI detector assembly.

0:07 Pafchek, Rubly, and Smith work on the detector assembly.

0:21 Pafchek, Rubly, and Smith use a small crane to lift the detector assembly.

0:38 Pafchek, Rubly, Smith, and Goldberg examine the raised detector assembly.

0:45 Smith adjusts wiring while Pafchek holds the detector assembly steady above the baseplate.

1:09 The detector assembly lowers toward the baseplate while Smith and Pafchek hold it steady.

1:24 Shot of the detector assembly on its baseplate

1:32 Smith and Rubly adjust the detector assembly.

1:42 Grinold looks on as Pafchek and Rubly adjust the detector assembly.

1:51 Shot of the detector assembly with the COSI mission patch in the background

1:57 Rubly and Pafchek adjust the detector assembly.

2:10 Pafchek performs an electrical test on the detector assembly.

2:18 Rubly screws the detector assembly onto the baseplate.

2:42 Pafchek applies epoxy to the screwheads on the detector assembly.

2:46 Different shots of Pafchek and Rubly adding the secondary thermal shield to the detector assembly.

3:47 Shot of the COSI mission patch on the lab wall

Credits

Please give credit for this item to:
NASA's Goddard Space Flight Center

This page was originally published on Monday, August 31, 2026.
This page was last updated on Monday, September 7, 2026 at 11:57 AM EDT.