WASHINGTON — A balloon-lofted X-ray observatory is blazing a trail for the satellite constellation NASA wants to launch in the decade ahead to study black holes, galaxy clusters and dark matter.
Dubbed InFocus, the airborne observatory has flown twice since 2000 and is slated to fly again in September. Equipped with advanced focusing optics and detectors, InFocus is a capable X-ray observatory in and of itself.
But the primary motivation behind InFocus is proving out some of the technologies needed for Constellation X, a roughly $1 billion X-ray astronomy mission NASA has penciled in for early in the next decade.
At the heart of the InFocus observatory is a multi-layered conical mirror nearly identical to the optical assembly built for Astro-E, a $200 million U.S.-Japanese X-ray astronomy satellite that was lost to a launch failure in February 2000.
The mirror, a joint effort between NASA’s Goddard Space Flight Center, Greenbelt, Md., and Nagoya University in Japan, is a complicated assembly consisting of hundreds of concentric layers of thin, reflective foil.
Measuring less than a half-meter across, the mirror assembly sits atop an 8-meter length of truss. Midway down the truss are the observatory’s electronics and pointing control system. Anchoring the so-called gondola at the bottom are the telescope’s detectors.
Hans Krimm, a Universities Space Research Association scientist running the project for NASA, said the InFocus telescope incorporates breakthroughs in focusing optics and detectors to open a window on such high-energy targets as active galactic nuclei, that is, galaxies that are being swallowed by a black hole.
"One of the things InFocus can do because we have very good angular resolution is map out regions of supernovae remnants where we think new elements are being made," Krimm said.
To find pockets of nucelosynthesis, InFocus looks for a Titanium-44 signature, an isotope that tends to be present at the creation of new elements.
The InFocus observatory has gone aloft twice suspended from the bottom of a 120 meters in diameter research balloon launched from NASA’s National Scientific Balloon Facility in Palestine, Texas.
After a successful test flight in 2000, InFocus returned to the skies over rural Texas in July 2001 for three days of observation of a relatively easy to detect black hole known as Cygnus X-1.
Krimm and his associates are making some adjustments to the observatory’s pointing system — there was more atmospheric turbulence at 36,000 meters than expected — and plan to return to the skies in September.
In addition to a new pointing system, the third InFocus mission will feature a new mirror and detector. An arctic flight, launching from either Sweden or Northern Canada, is in the works for 2005, Krimm said.
NASA has budgeted about $2 million for the InFocus project through 2005, not including the cost of balloon launch. Japan’s Institute of Space and Astronautical Science also contributes to the project.
Assuming funding is extended beyond 2005, Krimm and his colleagues would like to beef up InFocus for much longer missions enabled by long duration balloons currently in the works. Krimm said the new breed of long duration balloons would make it possible to keep InFocus aloft for 100 days or more — enough time to observe dozens of targets.
Rob Petre, head of the X-ray astrophysics branch at Goddard, said the telescope powering InFocus is a forerunner to the Hard X-ray Telescope envisioned for Constellation X.
