Brazilian Experiment Will Investigate Solar Radiation
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reader!
It
follows an article published day (05/01) in the english website of the Agência
FAPESP reporting that a Brazilian Experiment will
investigate mysterious Solar Radiation.
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Falcão
Article
Brazilian Experiment Will Investigate Mysterious
Solar Radiation
By José Tadeu Arantes
May 1, 2013
Equipment focused on detecting
emissions with frequencies
over 1
trillion Hertz will be
placed 40 kilometers from the
Earth’s surface using
stratospheric balloons
|
Agência FAPESP – Brazilian equipment to measure solar
radiation in the range of 1 terahertz ( 1 trillion Hertz, or 1012 Hz),
corresponding to wavelengths below 1 millimeter, will soon be sent to altitudes
of 40 kilometers from the Earth’s surface in long flights on stratospheric
balloons.
The experiment, named Solar-T, is focused on exploring one of the lesser
known and more enigmatic aspects of the Sun’s activity. In the study of solar
emissions, the terahertz (THz) range of the electromagnetic spectrum, between
microwaves and near-infrared waves, has been almost ignored until recently.
“It was thought to be of little importance, including only radiation
from thermal phenomena. But relatively recent discoveries at the frequencies of
0.2 THz and 0.4 THz changed this concept,” said the coordinator of the
experiment, Pierre Kaufmann, of the Center for Radioastronomy and Astrophysics
(Craam) at Universidade Presbiteriana Mackenzie, in an interview with
Agência FAPESP.
Terahertz emissions associated with solar explosions were detected by
solar radiotelescopy for sub-millimeter waves by an instrument located at El
Leoncito, in the Argentinean Andes. This landmark discovery left researchers
perplexed and excited.
“It began a decade of enormous theoretical and experimental efforts
focused on understanding the phenomenon. That’s why we dedicated eight to nine
years to conceiving and building the Solar-T in collaboration with the Center
for Semiconductor Components at Universidade Estadual de Campinas (Unicamp) and
the Bernard Lyot Solar Observatory in Campinas, São Paulo,” commented Kaufmann.
Terahertz emissions, sometimes called “T-rays”, are thought to result
from (previously unsuspected) particle acceleration mechanisms at high energy
levels.
One of the hypotheses is that the emissions are produced by
ultrarelativistic electrons (accelerated by electromagnetic fields at speeds
close to that of light). “Others relate the origin to the decay of pions,
producing high-energy positrons,” said Kaufmann.
The Solar-T, which could help to clarify this mystery, is basically a
system of photometers, instruments used to gauge the intensity of photons.
Specifically, the device includes two photometers; collectors; filters to block
undesirable radiation levels (near-infrared and visible light) that could mask
the phenomenon; a source feed; and a telemetry system to submit information to
Earth by radiowaves, using the Iridium satellite network.
“The Solar-T is a quasi-radio, quasi-optical telescope. It does not form
images like optical telescopes do but detects and measures radiation between
the frequencies of the upper limit of radio (microwaves) and the lower limit of
visible light (infrared),” explained Kaufmann.
The equipment had to be launched in the stratosphere because the
atmosphere blocks almost all terahertz radiation and prevents it from reaching
the Earth’s surface. “The interpretation of the production mechanism of
T-radiation is dependent on obtaining more information about this range of the
spectrum. And the Earth’s atmosphere is highly opaque,” he said.
“At El Leoncito, we managed to explore two small windows at the
frequencies of 0.2 THz and 0.4 THz. But we need to investigate higher
frequencies. The Solar-T will operate at 3 THz and THz and observe the entire
solar disk, detecting any small variations resulting from explosions at specific
points,” explained Kaufmann. The study coordinated by Kaufmann is funded
by FAPESP through its Thematic Project and Regular Research grant program.
Transportation Via Balloons
One alternative to using stratospheric balloons is to place the Solar-T
onboard satellites. If this happened, however, what would be stratospheric is
the cost of the experiment.
A second option is to transport another version of the Solar-T to very
dry and cold high-altitude areas, such as the High Plains of Atacama, to
observe radiation in atmospheric windows of terahertz frequencies. This option
has not been excluded, but it would require major infrastructure.
According to Kaufmann, transportation by balloon will have a cost of
practically zero for the Brazilian experiment. Because of the high impact of
articles that have been published in scientific journals and the success of
presentations at conferences, the Brazilian researchers have received the cost
of transportation as part of a collaboration offer.
“We have accepted two invitations: one for a 7- to 10-day flight over
Russia, in collaboration with the Lebedev Physics Institute in Moscow, and
another for a two-week flight over Antarctica, in cooperation with the
University of California at Berkeley,” he said.
Because these gigantic balloons carry several types of equipment on
board, with a total cargo of around 8 to 12 tonnne, and the Brazilian apparatus
weighs only 60 kilograms, the dates of the launch may change so that they are
compatible with the two different experiments. The mission over Russia is
slated for July or August 2014. The mission over Antarctica is scheduled for
the summer of 2015-2016 in the Southern Hemisphere, preceded by a 1 day test
flight over Texas during the previous year.
In the flight over Antarctica, the Solar-T will be installed along with
a gamma-ray experiment, GRIPS, from the University of California at Berkeley,
which has its own automatic detection and tracking system. The balloon will be
launched and recovered at the McMurdo base on Ross Island, near the Antarctic
Coast.
According to Kaufmann, the flight over Russia, to be launched from
Kamchatka, on the extreme eastern edge of Siberia, and recovered in Volgograd,
will require an automatic tracking cabin, developed and constructed in
collaboration with the University of California at Santa Barbara.
“The mission of the Solar-T in stratospheric balloons will be conducted
in the short-term to take advantage of the cyclical phase of intensification of
solar activity over the next few years, when explosions will become more
frequent,” said Kaufmann.
Source: English
WebSite of the Agência FAPESP
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