U.S. participation in Planck was established through an open solicitation and review of proposals by NASA's Office of Space Science in early 1997. The U.S. provided the following hardware:

Sorption Cooler - The U.S. LFI team is responsible for the design, development, fabrication and characterization of the hydrogen sorption cooler system, excluding control electronics, that cools the LFI to 20 K and provides pre-cooling to the HFI at 18K.

Bolometers - The U.S. HFI team is responsible for: the design, development, fabrication, and characterization of all bolometers for the HFI; and support for the design of the feed horns, readout electronics, thermal design and sub-kelvin thermometry.

Radiometers - The U.S. LFI team is responsible for: the design, fabrication and testing of the prototype 100 GHz radiometer; support for the design of the radiometers at other frequencies; design and testing support of the 4 K reference loads; detailed design and test requirements for TRW for the 100 GHz modules (built by TRW under a direct contract with the Italian Space Agency); support of TRW in testing and assembling the qualification and flight models of the 100 GHz modules.

IPAC's role - Data Reduction and Analysis Support:

The U.S. team at IPAC is responsible for the generation of the Early Release Compact Source Catalog (ERCSC), which is the first public data product from the mission.

They also serve as the U.S. Data Center, which is hosted at NASA's Infrared Science Archive (IRSA) at IPAC.

IPAC engineers and scientists are responsible for retrieving mission data from the Planck Data Processing Centers (in Paris, France and Trieste, Italy), staging data for usage by Planck team members, and ultimately for archival research by the astronomical community. U.S. team members are also closely involved with LFI and HFI instrument characterization, with the science working groups such as those dealing with Galactic and extragalactic foregrounds to the CMB, and with data processing steps which are crucial for the cosmological data analysis.

U.S. Based Scientific Groups Contributing to Planck:

• Caltech Observational Cosmology
• Haverford Cosmology
• IPAC - The Infrared Processing and Analysis Center
• JPL - The Jet Propulsion Laboratory
• National Energy Research Scientific Computing Center
• Santa Barbara Experiment Astrophysics and Cosmology Group
• Stanford Observational Cosmology at Millimeter Wavelengths Group
• UC Berkeley CMB
• UC Davis Cosmology