PoGOLite
The unfavorable weather conditions this summer has made it very difficult to launch large balloons. At the end of July, the stratospheric winds start to change direction and turn from a westerly into an easterly direction. After 25 July it was no longer possible to achieve a circumpolar or transatlantic flight and it was decided to postpone the launch of PoGo Lite until 2013.
The light-weight Polarized Gamma-ray Observer (PoGOLite) experiment is designed to measure the polarization of soft gamma rays in the 25 keV – 80 keV energy range. The PoGOLite mission is scheduled to fly from Esrange Space Center in July, with full circumpolar navigation and recovery in Scandinavia. PI is Mark Pearce from KTH, Sweden. An Aerostar 1.12 Mm3ballon will be used. The scientific gondola has a mass of approximately 1900 kg.
Maiden flight
PoGOLite balloon-borne telescope will be SSC “maiden” circumpolar flight studying the polarisation of gamma-rays from pulsars. Due to the specific conditions during the Arctic summer with continuous daylight and nearly constant solar heating keeping the balloon at a constant altitude with a minimum of ballast. This balloon will be recovered in Scandinavia after 12-15 days.
The PoGoLite project is a collaborative project between Swedish, Russian, Japanese and US scientific teams.
SSC will build the outer structure of the payload with solar panels and will also be in charge of the power system, data communication, and the security system. SSC will be in charge of the launch facilities at Esrange Space Center.
Description of the instrument and the mission
Polarized gamma rays are expected from a wide variety of sources including rotation-powered pulsars, accreting black holes and neutron stars, and jet-dominated active galaxies. Polarization has never been measured at soft gamma-ray energies where non-thermal processes are likely to produce high degrees of polarization.
The polarization is derived from the azimuthal distribution of Compton scattering angles in the sensitive volume of the instrument. The scattering angle will be measured by detecting coincident Compton scattering and photo-absorption sites in an array of 217 phoswich detectors.
Polarization measurement requires high purity coincident signal detection. PoGOLite applies a well-type Phoswich Detector technology for this purpose. The technology has proven to be very effective in reducing source-confusion and cosmic-ray-induced backgrounds.
The PoGOLite experiment is being developed by groups in Japan, Sweden, USA and France.
Mark Pearce from KTH (The Royal Institute of Technology) is the spokesman for the international PoGOLite Collaboration and is leading the Swedish Consortium.
General information
| Launch site | Esrange Space Center |
| Launch date | Launch postponed to 2013 |
| Mass/kg | ~2 tons |
| Balloon size | 1,2 Mm³ |
| Height | ~39 km |
Contact persons
Mr. Torbjörn Eld, Project manager SSC, torbjorn.eld@sscspace.com
