The world’s smallest high-performance mass spectrometer,
newly delivered to the International Space Station, may play a
critical role in detecting leaks outside the orbiting

Delivered last week to the space station by Space Shuttle
Atlantis, the instrument will be available in the airlock for
use by astronauts during their spacewalks. The device was
specifically designed for use outside the space station. It
can detect ammonia, rocket propellant, oxygen, nitrogen and
water leaks.

“The instrument will promote spaceflight safety for the
International Space Station,” said Dr. Ara Chutjian of NASA’s
Jet Propulsion Laboratory, Pasadena, Calif. Chutjian is the
principal investigator on the instrument, called the
quadrupole mass spectrometer array.

The mass spectrometer, about 5 centimeters long (about 2
inches), is part of a shoebox-sized system with software and
visual readout called the trace gas analyzer, developed in
collaboration with NASA’s Johnson Space Center and
subcontractor Oceaneering Space Systems, both in Houston. The
whole unit weighs about 2.3 kilograms (5 pounds) and can be
placed on an astronaut’s chest pack, where it can easily point
toward the areas under inspection. A small screen displays a
graph that reports the detection of specific gases and their
amounts, indicating to the astronauts a potential safety risk.

“JPL has developed the smallest mass spectrometer ever
produced for either manned or robotic spaceflight,” said
Chutjian. “On missions to Mars and beyond, where commodities
will be at a premium, miniaturizing devices while maintaining
their performance is crucial to mission success. We feel the
device is very versatile and envision it being used in a cabin
or airlock both for long-duration human flight missions and
for planetary on-site life detection.”

The instrument can detect ammonia coolant leaks that may
arise from the many quick-disconnect fittings on the U.S.
laboratory module Destiny. Cooling is required to maintain a
uniform temperature as the space station travels through the
temperature extremes of direct sunlight and shadow. On
Saturday, February 10, during the first spacewalk, an obvious
leak occurred while astronauts installed the coolant ammonia
lines to the Destiny module. The trace gas analyzer was not
used because the leak was obvious, but the instrument will
remain on the space station for future use. JPL scientists
were on standby for consulting with NASA during all three

The present generation of quadrupole mass spectrometers
being flown on the Galileo mission to Jupiter and the Cassini
mission to Saturn are based on 1970s technology. They weigh
approximately 9 to 12 kilograms (20 to 24 pounds) and consume
about 25 watts of power. The mass spectrometer in the trace
gas analyzer that is currently flying on the space station is
smaller and consumes less power.

Three years ago, JPL scientists were given the challenge
to create a small, hand-held mass spectrometer for use by
astronauts in flight during their spacewalks. JPL had to
reduce the sensor size while maintaining as nearly as possible
the performance of the large commercial units the size of a
five-drawer cabinet. They did just that. The new system
maintains a mass range, resolution, precision and stability
comparable to larger units.

“We envision using this device in the future for other
applications like studying planetary geology, doing isotopic
analysis, detecting surface-evolved gases on Jupiter’s moon
Europa, comets and asteroids and testing air and water quality
on Earth,” said Dr. Murray Darrach, cognizant scientist who
also worked on the device at JPL.

A paper and photos on the trace gas analyzer are
available at

NASA’s Office of Space Science and Office of Biological
and Physical Research funded work on the device. Under
contract from JPL, Johnson Space Center contracted Oceaneering
Space Systems to develop a package or casing for the mass
spectrometer and to conduct the final tests on the instrument
before flight. Managed for NASA by the California Institute of
Technology in Pasadena, JPL is the lead U.S. center for
robotic exploration of the solar system.