The ice scanning satellite CryoSat-2 has had its initial data released to selected scientists around the world. The release, which takes the satellite data out of the exclusive hands of the team controlling it, is designed to allow these scientists to have a say in fine tuning the instruments. CryoSat-2 is still in its commissioning phase, meaning the data coming down need to be calibrated and validated against other sources of data. The satellite is due to be commissioned in the Autumn, when fully fledged science products will be sent back down to the Earth, but even in its current state, the instruments are outperforming expectations.
The Cassini satellite around Saturn has been sending back some nice images. The probe has been studying the F-ring, which contains strange fan-like features. The reason for this, it appears, is that the 148km potato-shaped shepherd moon Prometheus is in an orbit that allows it to approach the ring and then move away from it. As Prometheus orbits faster than the ring particles, each approach on the closest point of the 14.7 hour orbit is roughly 3.2 degrees apart from the previous one. This means the ring is kinked in a different place each time. The kinks allow for the formation of denser regions within the tenuous ring, which in turn can lead to particles coming together under self gravity and forming small moonlets, which may last a few months or so. Prometheus doesn’t just create moonlets, it can also destroy them as every 68 days it returns to approximately the same part of the ring and stirs up what might be a half-formed moonlet. However, there is a chance that one or two may get missed by this second process, leading to a longer lived formation. Serendipitously, while Cassini was watching the F-ring, a globular cluster passed by – image here. Animations of these things (including the globular cluster passing) can be found here.