The first successful flight (the first was aborted) was test flight 1559P on
August 29, 1997 from Palestine, TX. It rode a Raven ZPV with a volume of
800,000 m
3
(28 million ft
3
). By using a telescope at an altitude of 38.5 km
(126,000 ft) it was possible to reduce the atmospheric absorption of microwaves to a minimum. This allowed massive cost reduction compared to a satellite probe, but only a tiny part of the sky could be scanned. The test flight
proved the robustness of the pointing and data acquisition systems, the feasibility of the scan strategy, and the utility of the cryogenic systems at float altitude… as well as obtaining important scientific data. For the two subsequent
flights in 1998 and 2003, the balloon was launched from McMurdo Station in
the Antarctic. It was carried by the polar vortex winds in a circle around the
South Pole and returned after two weeks. It was from this flight profile that the
telescope gained its name.
The BOOMERANG team was led by Andrew E. Lange of Caltech and Paolo
de Bernardis of the Universitá di Roma La Sapienza. The experiment made use
of bolometers, which measure the power of incident electromagnetic radiation
via the heating of a material with a temperature-dependent electrical resistance.
The bolometers were kept at a temperature of 0.27 K (–272.88°F or –459°F). At
this temperature the material has a very low heat capacity and incoming microwaves will cause a large temperature change that is proportional to the intensity
of the incoming waves, and the variations are measured using sensitive
thermometers.
An off-axis 1.3 m (4.26 ft) primary mirror focused the microwaves onto the
focal plane, which consisted of 16 horns. These horns operated at 145 GHz,
245 GHz, and 345 GHz, and were arranged into 8 pixels. It could view only a
tiny fraction of the sky, so the telescope had to be rotated to scan the entire field
of view.
Together with other experiments, the BOOMERANG data from 1997 and 1998
measured to a high precision “the angular diameter distance to the surface of last
scattering”. When combined with complementary data for the value of Hubble’s
Constant, which is a measure of how rapidly the universe is expanding, the data
showed that the geometry of the universe is close to being “flat”, supporting the
evidence from supernovas in the most distant galaxies for the existence of “dark
energy”.
Another flight was made on a Raven LDB of 1 million m
3
(35 million ft
3
) to an
altitude of 40 km (130,000 ft) in 2003. The payload weight was 1,656 kg (3,650
lb) and the overall weight was 2,156 kg (4,753 lb). Flight 516N gave extremely
high signal-to-noise ratio maps of the CMB temperature anisotropy along with a
measurement of the polarization of the CMB. See Chapter 8 for the award given
to the BOOMERANG team for its accomplishments.
154 Scientific Flight Types
August 29, 1997 from Palestine, TX. It rode a Raven ZPV with a volume of
800,000 m
3
(28 million ft
3
). By using a telescope at an altitude of 38.5 km
(126,000 ft) it was possible to reduce the atmospheric absorption of microwaves to a minimum. This allowed massive cost reduction compared to a satellite probe, but only a tiny part of the sky could be scanned. The test flight
proved the robustness of the pointing and data acquisition systems, the feasibility of the scan strategy, and the utility of the cryogenic systems at float altitude… as well as obtaining important scientific data. For the two subsequent
flights in 1998 and 2003, the balloon was launched from McMurdo Station in
the Antarctic. It was carried by the polar vortex winds in a circle around the
South Pole and returned after two weeks. It was from this flight profile that the
telescope gained its name.
The BOOMERANG team was led by Andrew E. Lange of Caltech and Paolo
de Bernardis of the Universitá di Roma La Sapienza. The experiment made use
of bolometers, which measure the power of incident electromagnetic radiation
via the heating of a material with a temperature-dependent electrical resistance.
The bolometers were kept at a temperature of 0.27 K (–272.88°F or –459°F). At
this temperature the material has a very low heat capacity and incoming microwaves will cause a large temperature change that is proportional to the intensity
of the incoming waves, and the variations are measured using sensitive
thermometers.
An off-axis 1.3 m (4.26 ft) primary mirror focused the microwaves onto the
focal plane, which consisted of 16 horns. These horns operated at 145 GHz,
245 GHz, and 345 GHz, and were arranged into 8 pixels. It could view only a
tiny fraction of the sky, so the telescope had to be rotated to scan the entire field
of view.
Together with other experiments, the BOOMERANG data from 1997 and 1998
measured to a high precision “the angular diameter distance to the surface of last
scattering”. When combined with complementary data for the value of Hubble’s
Constant, which is a measure of how rapidly the universe is expanding, the data
showed that the geometry of the universe is close to being “flat”, supporting the
evidence from supernovas in the most distant galaxies for the existence of “dark
energy”.
Another flight was made on a Raven LDB of 1 million m
3
(35 million ft
3
) to an
altitude of 40 km (130,000 ft) in 2003. The payload weight was 1,656 kg (3,650
lb) and the overall weight was 2,156 kg (4,753 lb). Flight 516N gave extremely
high signal-to-noise ratio maps of the CMB temperature anisotropy along with a
measurement of the polarization of the CMB. See Chapter 8 for the award given
to the BOOMERANG team for its accomplishments.
154 Scientific Flight Types