... an X-ray telescope which will be lifted to an altitude of ~40 km with an enormous helium-filled balloon (one million cubic metres) in July 2013. Through PoGOLite's ability to determine the polarisation of X-rays, we aim to explore a new observational window on the Universe.
Contact: Mark Pearce (updated: July 13th 2013)
PoGOLite was lauched from the Esrange Space Centre on July
12th 2013 at 0818 UT.
Article at KTH (Swedish)
Article in Forskning och Framsteg (Swedish)
|Shortly after midsummer, an
enormous helium-filled balloon will be launched from the
Esrange Space Centre near Kiruna with the PoGOLite
(Polarised Gamma-ray Observer) telescope dangling under it.
The PoGOLite telescope will study the high energy light (known as X-rays) emitted by heavenly bodies such as neutron stars, pulsars and black hole systems. When fully inflated, the balloon has a volume of about 1 million cubic metres which is twice the volume of the Globen Arena in Stockholm. The balloon has to be so large because PoGOLite is not so light - it weighs about 2 Tonnes. It is important to lift PoGOLite as high as possible since X-rays are absorbed by the Earth's atmosphere.
After launch, PoGOLite will drift Westwards on stratospheric winds passing over Sweden, Norway, Iceland, Greenland and Canada. We are hoping to be able to continue the flight over Alaska and onwards over Russia, returning to Sweden some 20 days later.
X-ray emission from the Crab pulsar (artist's impression).
How polarised sunglasses help remove glare reflected from water.
|One of the observation
targets for PoGOLite are neutron stars. A neutron star is
formed when a star of a certain size has expended all its
fuel and collapses in on itself releasing huge amounts of
energy in a so-called supernova explosion. The conditions
during the collapse are so extreme that the atoms in the
star are pressed together converting protons and electrons
into neutrons. A neutron star is very small, only 15 km in
diameter, but weighs an astonishing one and a half times as
much as the Sun. A teaspoon of neutron star material would
weigh a billion tonnes!
A neutron star which rotates is called a pulsar. A pulsar in the constellation of Taurus called ‘The Crab’ rotates 30 times a second and sends out flashes of X-rays, like a cosmic lighthouse. The supernova explosion which gave rise to the Crab was recorded by Chinese and Arab astronomers in year 1054. We plan to intercept Crab X-rays with PoGOLite and measure their polarisation in order to learn more about how X-rays are produced in the pulsar.
X-rays are a form of electromagnetic radiation, just like visible light or radio waves. The polarisation of a wave describes how the oscillation of the wave is oriented with respect to the wave’s motion. Now that it’s summer, check your sunglasses - they may be polarised. If you’re near water on a sunny day you’ll notice a glare on the water as sunlight is reflected towards your eyes. You can remove much of this glare by putting on your polarised sunglasses. This is because the reflected light waves become polarised as they ‘bounce off’ the surface of the water and your sunglasses are designed to block these polarised waves. In a similar fashion X-rays can become polarised as they leave a pulsar.
PoGOLite is a Swedish-lead
project headed by the Particle
and Astroparticle Physics group within the Physics
Department of The Royal Institute of Technology (KTH). The Principal Investigator is
Mark Pearce. We
are one of the founding members of The Oskar Klein Centre for
Cosmoparticle Physics at AlbaNova University Centre in Stockholm.
At AlbaNova, we also work
members of the Astronomy Department at Stockholm University.
Internationally, we collaborate a Japanese consortium (Hiroshima
University, ISAS/JAXA, Waseda University, Tokyo Institute of
Technology), as well as SLAC/KiPAC and University of Hawaii. The
PoGOLite attitude control system was developed in conjunction with
DST Control in Linköping and SSC
Esrange developed the PoGOLite gondola, power and
communication systems and provide support during the campaign
phase of the project. An auroral monitor developed by the KTH Alfvén Laboratory is
included in the pathfinder flight.