Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission
Encyclopedia
Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE) is a program which utilizes balloon satellite
instrument package intended to measure the heating of the universe by the first stars and galaxies after the big bang and search for the signal of relic decay or annilhilation. In July 2006 a very strong radio source
has been found using the radiometer.
ARCADE has been funded by the NASA's Science Mission Directorate
under the Astronomy and Physics Research and Analysis Suborbital Investigation program. The program is composed of a team led by Alan Kogut of NASA's Goddard Space Flight Center
. ARCADE was launched from NASA's Columbia Scientific Balloon Facility
in Palestine, Texas
, conducted under the auspices of the Balloon Program Office at Wallops Flight Facility
. The balloon flew to an altitude of 120000 feet (36.6 km), viewing about 7% of the sky during its observations.
The craft contained 7 radiometers which were cooled to 2.7 K using liquid helium
, with the intent to measure temperature differences as small as 1/1000 of a degree against a background which is only 3 K. The optics in the instrument package were placed near the top of the dewar flask
which cooled them in order to prevent the instruments from seeing the walls of the container, thereby simplifying the processing of the observational data. This design choice necessitated the use of superfluid
pumps in order to drench the radiometers in liquid helium. The design also utilized heaters in order to create a cloud of helium gas, in place of using a (relatively warm) window, which also simplified processing of the observational data.
Balloon satellite
A balloon satellite is a satellite that is inflated with gas after it has been put into orbit.-List of Balloon Satellites:...
instrument package intended to measure the heating of the universe by the first stars and galaxies after the big bang and search for the signal of relic decay or annilhilation. In July 2006 a very strong radio source
Space roar
The space roar is a natural phenomenon picked up as a radio signal from outer space. A NASA team led by Alan Kogut discovered the roar. Described as a loud hiss, the team discovered the signal while trying to find traces of heat from first generation stars using an Absolute Radiometer for...
has been found using the radiometer.
ARCADE has been funded by the NASA's Science Mission Directorate
Science Mission Directorate
The Science Mission Directorate of the National Aeronautics and Space Administration engages the United States’ science community, sponsors scientific research, and develops and deploys satellites and probes in collaboration with NASA’s partners around the world to answer fundamental questions...
under the Astronomy and Physics Research and Analysis Suborbital Investigation program. The program is composed of a team led by Alan Kogut of NASA's Goddard Space Flight Center
Goddard Space Flight Center
The Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...
. ARCADE was launched from NASA's Columbia Scientific Balloon Facility
Columbia Scientific Balloon Facility
The Columbia Scientific Balloon Facility is a NASA facility responsible for providing launch, tracking and control, airspace coordination, telemetry and command systems, and recovery services for unmanned, high altitude balloons...
in Palestine, Texas
Palestine, Texas
Palestine is a city in Anderson County, Texas, in the United States. As of the 2000 census, the city population was 17,598, and 18,458 in the 2009 estimate. It is the county seat of Anderson County and is situated in East Texas...
, conducted under the auspices of the Balloon Program Office at Wallops Flight Facility
Wallops Flight Facility
Wallops Flight Facility , located on the Eastern Shore of Virginia, is operated by NASA’s Goddard Space Flight Center, primarily as a rocket launch site to support science and exploration missions for NASA and other U.S. government agencies...
. The balloon flew to an altitude of 120000 feet (36.6 km), viewing about 7% of the sky during its observations.
The craft contained 7 radiometers which were cooled to 2.7 K using liquid helium
Liquid helium
Helium exists in liquid form only at extremely low temperatures. The boiling point and critical point depend on the isotope of the helium; see the table below for values. The density of liquid helium-4 at its boiling point and 1 atmosphere is approximately 0.125 g/mL Helium-4 was first liquefied...
, with the intent to measure temperature differences as small as 1/1000 of a degree against a background which is only 3 K. The optics in the instrument package were placed near the top of the dewar flask
Dewar flask
A Dewar flask is a vessel designed to provide very good thermal insulation. For instance, when filled with a hot liquid, the vessel will not allow the heat to easily escape, and the liquid will stay hot for far longer than in a typical container...
which cooled them in order to prevent the instruments from seeing the walls of the container, thereby simplifying the processing of the observational data. This design choice necessitated the use of superfluid
Superfluid
Superfluidity is a state of matter in which the matter behaves like a fluid without viscosity and with extremely high thermal conductivity. The substance, which appears to be a normal liquid, will flow without friction past any surface, which allows it to continue to circulate over obstructions and...
pumps in order to drench the radiometers in liquid helium. The design also utilized heaters in order to create a cloud of helium gas, in place of using a (relatively warm) window, which also simplified processing of the observational data.
See also
- List of cosmic microwave background experiments
- Cosmic microwave background radiationCosmic microwave background radiationIn cosmology, cosmic microwave background radiation is thermal radiation filling the observable universe almost uniformly....