NASA, Universities Space Research Association (USRA) and the German Aerospace
Center, DLR, are working together to develop SOFIA, a 2.5-meter infrared telescope
mounted in a modified Boeing 747SP aircraft.
SOFIA – Stratospheric Observatory for Infrared Astronomy
The SOFIA Project
Built into a converted Boeing 747SP, SOFIA’s 2.5-meter (8.2-foot)-diameter telescope
will make it the world’s largest and most sensitive airborne observatory. Flying
at 39,000 to 45,000 feet, it will enable scientific observations that are impossible
for even the largest and highest of Earth-based telescopes. Peering out through
an open cavity in the side of the aircraft, the telescope will allow astronomers
to obtain sharper infrared images than ever before. The astronomers, technicians,
engineers, educators, and flight crew will work in a comfortable airliner environment
during a typical eight-to-nine-hour flight.
Based at NASA’s Ames Research Center near Mountain View, California, SOFIA is
scheduled to make scientific flights two to three times per week. Expected to
operate for at least 20 years, it will fly primarily from Ames’ Moffett Field
and for one or two months per year from a base in the southern hemisphere; it
will occasionally fly from other locations around the world, including Germany.
Image right: SOFIA- the world's largest airborne observatory.
The Universities Space Research Association (USRA), the SOFIA development prime
contractor, will also conduct scientific operations. L-3 Communications Integrated
Systems is making the extensive modifications to the aircraft’s structure and
control systems, and is also engineering the open cavity and the on-board computer
systems for communications and telescope operations. Scientists from NASA’s Ames
Research Center, the University of California, and other universities are working
with the USRA scientific and engineering team to develop SOFIA’s specialized instruments,
conduct observations, and support its scientific programs. SOFIA’s extensive education
and public outreach programs are being conducted by an alliance of two well-known
astronomy organizations, the SETI Institute and the Astronomical Society of the
Pacific. The project is managed by NASA’s Ames Research Center, which is also
providing design and fabrication of critical subsystems, along with engineering
SOFIA’s telescope was designed and built by a consortium of Germany’s leading
aerospace companies — Kayser-Threde GmbH and MAN Technologie. The telescope program
is being managed by DLR, the German Aerospace Center, which is supplying the telescope
and 20% operational support in return for that portion of SOFIA’s valuable observing
Airborne astronomy began in 1966, when Dr. Gerard Kuiper, a prominent planetary
scientist, flew a 30-cm (12-inch) telescope pointed out the window of a Convair
990. Having proven that airborne astronomy was feasible, scientists were soon
flying an infrared telescope aboard a Learjet.
From 1974 to 1995, NASA operated the Kuiper Airborne Observatory (KAO), named
after Dr. Kuiper, which carried a 91-cm (36-inch) reflecting telescope in a converted
C-141 military cargo plane. KAO science findings, focusing on solar system, galactic
and extragalactic astronomy, included discovery of the rings of Uranus, a ring
of dust around the center of the Milky Way, ultra-luminous infrared galaxies,
complex organic molecules in space and water in comets.
Featuring three times better image quality and greater than an order of magnitude
higher sensitivity than its predecessor the KAO, SOFIA is the world’s largest
mobile astronomical observatory, traveling to the right place at the right time
to observe celestial events.
Many of the most interesting objects in the universe emit much of their energy
in the infrared region of the electromagnetic spectrum. Yet ground-based telescopes
can detect only limited portions of the infrared spectrum since most of it is
absorbed by the water vapor in the Earth’s atmosphere. From its operating altitude
of about 41,000 feet and above, SOFIA will avoid more than 99% of the obscuring
water vapor, enabling it to make observations which are impossible for even the
largest and highest ground-based telescopes.
Furthermore, vast reaches of the universe contain huge dust clouds which block
visible light. However, they don’t block infrared radiation. As a result, infrared
detectors can, in effect, “see through” these dust clouds to observe otherwise
invisible objects inside and behind the clouds.
A key component of NASA’s Origins Program to explore fundamental questions about
the universe, SOFIA will help astronomers learn more about the birth of stars,
the formation of solar systems, the origin of complex molecules in space, the
nature and evolution of comets, how galaxies form and change, and even the nature
of the mysterious black holes lying at the centers of some galaxies, including
An early suite of instruments planned for SOFIA:
is a special-purpose science instrument for SOFIA designed to provide
simultaneous high-speed time resolved imaging photometry at two optical wavelengths.
It will be possible to mount HIPO and FLITECAM (see below) on the SOFIA telescope
simultaneously to allow observation at two optical wavelengths and one near-infrared
wavelength. HIPO will be used for the first critical tests of the completed SOFIA
Observatory. (P.I. Ted Dunham, Lowell Observatory)
is a facility-class multi-purpose near-infrared camera operating
from 1-5.5 µm. FLITECAM will also perform moderate resolution spectroscopy to
detect gas, dust, ices, and organic matter in space. FLITECAM is also designed
to provide a tool for testing the image quality of the SOFIA telescope in an optional
pupil-viewing mode. In its spectroscopic mode it can be used to study aircraft
exhaust plumes and provide a calibration of the SOFIA water vapor monitor. (P.I.
Ian MacLean, UCLA)
is a far-infrared camera designed to cover the 40-300 µm spectral
region at the highest possible angular resolution. HAWC's goal is to provide a
sensitive, versatile, and reliable far-infrared imaging capability for the astronomical
community during SOFIA's first years of operation (P.I. Al Harper, U. Chicago).
FORCAST is a facility-class, mid-infrared camera for SOFIA. FORCAST has
two channels with selectable filters for narrowband and broadband imaging in the
5-8, 17-25, and/or 25-40 µm regions. Simultaneous imaging in the two channels
(wavelengths less than and greater than 25µm, respectively) is possible (P.I.
Terry Herter, Cornell).
GREAT, a first-generation three-channel heterodyne instrument for high-resolution
spectroscopy aboard SOFIA, is being developed by a consortium of German research
institutes. High-spectral resolution is required to address a wide range of topics
of modern astrophysics, from questions about planetary atmospheres and the interstellar
medium in the Galaxy to investigations about the early Universe (P.I. Rolf Güsten,