Institut d'Astrophysique Spatiale

The stratospheric balloon carrying the PILOT instrument was launched from Timmins in Canada at 9 pm (local time) on Sunday, September 20th. The gondola, weighting more than a ton, the heaviest the CNES took in the last 25 years, was lifted by a stratospheric balloon of 800.000 m3 and reached the altitude of 39.500 m after 3 hours of ascent. After a last transfer of helium carried out just before take-off, the detectors reached nominally their operating temperature of 320 mK when the balloon reached its flight ceiling, and the scientific observations could then start.

The CLASP instrument (Chromospheric Lyman Alpha Spectropolarimeter) was successfully launched by a sounding rocket on September 3, 2015 at 17H UT from White Sands Missile Range in New Mexico. The suborbital flight was nominal. The instrument went nominally through its observing program and the data quality is superb.

To reconcile the standard cosmological model with the X-ray measured number of galaxy clusters, a team of French scientists has shown that the cluster masses should be increased by 70% compared to current estimates. These results follow the conclusions obtained by the Planck mission in 2013 from observations of galaxy clusters in the microwave domain. This huge difference is intriguing: either our understanding of the physics of galaxy clusters needs to be revised, or the standard cosmological model is incomplete.