TECHNOLOGY FOR CHANGE

Nanotube Memories Enable Smarter Electronics in Space

R. Colin Johnson | Date: 11-30-09 | Comments

NASA demonstrates that nanotube memory chips are impervious to the extreme environment and lethal hazards of space during a recent shuttle mission.

NASA demonstrates that nanotube memory chips--NRAMS--are impervious to the extreme environment and lethal hazards of space during a recent shuttle mission. Lockheed Martin and NASA reported this month that they successfully tested Nantero's nanotube-based memory chips on the Space Shuttle Atlantis while it serviced the Hubble Space Telescope earlier this year. Nanotube memory chips--NRAMs--store information by virtue of tiny mechanical switches that are immune to the heat, cold, cosmic rays, hard radiation and every other hazard from which conventional semiconductors must be protected in space, according to their inventors, Nantero.

"This demonstration of carbon-nanotube-based semiconductor devices in the rigorous conditions of space is an important step towards a whole new suite of future applications," said Jim Ryder, vice president and general manager of the Lockheed Martin Advanced Technology Center.

Nantero's nanotube-based devices hold great promise as terabit-per-chip mechanical memories that squeeze bit cells down to as small as five-nanometers square. The devices are fabricated as a planar thin films, representing zeros, but bit cells can be selectively deformed to touch buried electrodes to mark ones.

Nantero's chip fabrication process uses conventional semiconductor manufacturing equipment to deposit, mask and etch monolayers of carbon nanotube thin films, forming bits cells suspended over air cavities with a metal electrode at the bottom of each. The metal electrode can attract the film downward using electrostatic force to represent a one. Once deformed, the memories remain held there indefinitely by van der Waal forces, even when the power is removed, making the memories nonvolatile. A reverse electrostatic force can subsequently force the deformed nanotube film back up, disconnecting it from the electrode to again make the bit cell a zero. Nantero claims the deformations do not damage its films, allowing for unlimited re-writes.

Conventional memory chips must be kept inside a heated and heavily shielded "warm box," making the electronics one of the most expensive elements of a space mission. NASA's Goddard Space Flight Center (GSFC) worked with Nantero and Lockheed Martin to adapt NRAMs to space applications because of their potential to greatly reduce the space and power requirements for space-based electronics.

"Carbon nanotubes have tremendous potential for a wide range of future space-based applications," said Dan Powell of GSFC.

For the test, Nantero's NRAMs were incorporated into a special autonomous testing rig installed in the Shuttle's payload bay, which is directly exposed to the harsh vacuum, extreme temperatures and unrelenting cosmic radiation of space, as well as the violent acceleration and vibrations during launch and re-entry.

The functionality of Nantero's NRAMs was tested throughout the mission and found to perform equally well before, during and after completion. This successful proof-of-concept demonstration is currently being followed up by NASA and Lockheed Martin Nanosystems for future testing aimed at eventual deployment as high-density, non-volatile, carbon-nanotube-based electronics for space.

"Nantero has a development partner that is now willing to explore the potential rad-hard applications of nanotube memories," said Dean Freeman, research vice president at Gartner. "But any commercialization is still a ways off."