... 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)


Current status

PoGOLite was lauched from the Esrange Space Centre on July 12th 2013 at 0818 UT.
Balloon trajectory

Follow our progress here:
Rymdkanalen / OKC Blog

Background articles:
Article at KTH (Swedish)
Article in Forskning och Framsteg (Swedish)

PoGOLite: a brief introduction

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.
Crab pulsar
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.

The stamps

(c) Posten Frimärken. Designer: Einar Åkerlind.

PoGOLite was featured on two stamps issued by the Swedish post office in January 2009 to mark the International Year of Astronomy. A number of first-day covers featuring the stamps will be flown on-board the maiden flight.

Who's involved?

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.


Swedish participation in PoGOLite was made possible through a grant awarded in 2005 by The Knut and Alice Wallenberg Foundation. Now-a-days, PoGOLite is classified as a National Project by the Swedish National Space Board and as such enjoys programmatic support, including support from SSC Esrange. The Swedish Research Council (Committee for research infrastructure) has funded our work on the attitude control system. Several PoGOLite team members receive salary support from The Swedish Research Council or The Swedish National Space Board. The Göran Gustafsson Foundation has funded work on the star tracker systems. Support has been recevied from KTH in the form of faculty research funding.