Volume 10, Number 4 • July/August 2002 • Small Business/SBIR

NICMOS Cryocooler–Reactivating a Hubble Instrument

This image was possible because of the installation of the NICMOS Cryocooler, a high-tech cooling system, on the Hubble Telescope.

The Near-Infrared Camera and Multi-Object Spectrometer (NICMOS), dormant since January of 1999, has been reactivated by a high-tech cooling system, the NICMOS Cryocooler.

Installed on Hubble in February of 1997, NICMOS used infrared vision to probe dark, dusty, never-before-seen regions of space with the optical clarity that only Hubble can provide. Its infrared detectors operated at a very cold temperature (minus 352 degrees Fahrenheit, which is minus 272 degrees Celsius, or 60 degrees Kelvin). To keep the detectors cold, NICMOS was encased in a thermos-like container filled with solid nitrogen ice. Unfortunately, the nitrogen ice was consumed more quickly than planned, due to a very small heat leak. In anticipation of this shortened lifespan, NICMOS’s subscribed observations were tripled in order to get the most usage of this instrument before it ran out of coolant. In 1999, with its supply of ice exhausted, NICMOS became dormant.

Scientists and engineers coordinated by NASA Goddard Space Flight Center, in Greenbelt, MD, devised a way of adding a new high-tech refrigeration device to NICMOS to re-cool its detectors and other components. The Hubble team developed the NICMOS Cryocooler–a state-of-the-art, mechanical, cryogenic cooler that has returned NICMOS to active duty.

Using nonexpendable neon gas as a coolant, this closed system delivers high cooling capacity, extremely low vibration and high reliability. It employs a miniature cryogenic circulator to remove heat from NICMOS and transport it to the Cryocooler. The system uses a tiny turbine turning at up to 400,000 rpm (over 100 times the maximum speed of a typical car engine). The NICMOS Cryocooler is virtually vibration-free–which is very important for Hubble. Vibrations could affect image quality in much the same way that a shaky camera produces blurred pictures.

The new cryogenic system cools the NICMOS infrared detectors to about minus 334 degrees Fahrenheit (minus 203 degrees Celsius or 70 degrees Kelvin). This is an ideal temperature for the detectors and will make NICMOS more sensitive than ever to incoming light, enabling discoveries not previously possible. Engineers expect it to increase the life span of NICMOS to more than five years, with hopes that it will last as long as Hubble itself.

The unique technologies required for the NICMOS Cryocooler were only made possible by a series of SBIR contracts beginning in the 1980s, developing the miniature rotor fabrication techniques, high-speed motors, heat exchangers and cold bearings. Creare, Inc., a small R&D lab in New Hampshire, had applied its talented staff to needs identified by NASA and had slowly assembled the required building blocks for a very sophisticated cooling system. When Hubble called, these components were already able to provide the low-vibration, high-efficiency, and instrument-cooling characteristics that NICMOS needed.

In 1998, the Hubble team successfully demonstrated this new technology as a complete system aboard the space shuttle Discovery on STS-95. The test took place less than 18 months after system development began–an extremely short time for successfully developing a new space technology. The demonstration system was then refurbished and installed on Hubble during Servicing Mission 3B in March 2002. With a command to turn on the Cryocooler, the NICMOS was finally brought back to life! Starting with a new idea for a tiny turbine, this revolutionary technology now paves the way for exciting advances in infrared astronomy on Hubble and beyond.

“It is fantastic that we have restored Hubble’s infrared eyesight. NICMOS has taken us to the very fringes of the universe and to a time when the first galaxies were formed. We can’t wait to get back out there,” said Dr. Rodger Thompson, NICMOS principle investigator, University of Arizona, Tucson.

In the case of NICMOS, the Cryocooler is replacing the solid nitrogen cooler that originally encased the instrument. But this advanced type of Cryocooler can replace both liquid and solid nitrogen-based cooling systems on Earth, as well as in space.

The Cyrocooler offers earthly benefits in electronics manufacturing, medical imaging and magnetic field detection. One particularly important application is in brain imaging. Magnetic encephalograms, which measure brain waves, allow doctors to determine if the various parts of the brain are functioning properly. This new cooler technology may someday make such brain-imaging equipment more user-friendly, compact and affordable. Q

For more information, contact Rob Boyle at NASA Goddard Space Flight Center, AETD Code 552, Greenbelt, MD 20771, phone: 301/286-7185, fax: 301/286-0389. Please mention you read about it in Innovation.

NASA Official: Jonathan Root • Web Design: Printing & Design Office, NASA Headquarters • Credits