Cassini images of Saturn, Hyperion, and Rhea

More great images photos of the Saturn system from Cassini:

*Titan in front of Saturn – Val Klavans

This is an approximate true color view of Saturn and its moon Titan. Titan is seen here hovering near Saturn’s rings.

This composite is made of images that were taken by Cassini’s camera system, the Imaging Science Subsystem (ISS) on May 22, 2015 and received on Earth May 24, 2015. The camera was pointing toward Titan and Saturn, and the images were taken using the green, violet, and infrared filters.

Credit: NASA / JPL / SSI / Val Klavans

Cassini Solstice Mission: Cassini Prepares for Last Up-close Look at Hyperion –

NASA’s Cassini spacecraft will make its final close approach to Saturn’s large, irregularly shaped moon Hyperion on Sunday, May 31.

The Saturn-orbiting spacecraft will pass Hyperion at a distance of about 21,000 miles (34,000 kilometers) at approximately 6:36 a.m. PDT (9:36 a.m. EDT). Mission controllers expect images from the encounter to arrive on Earth within 24 to 48 hours.

Mission scientists have hopes of seeing different terrain on Hyperion than the mission has previously explored in detail during the encounter, but this is not guaranteed. Hyperion (168 miles, 270 kilometers across) rotates chaotically, essentially tumbling unpredictably through space as it orbits Saturn. Because of this, it’s challenging to target a specific region of the moon’s surface, and most of Cassini’s previous close approaches have encountered more or less the same familiar side of the craggy moon.

Cassini scientists attribute Hyperion’s unusual, sponge-like appearance to the fact that it has an unusually low density for such a large object — about half that of water. Its low density makes Hyperion quite porous, with weak surface gravity. These characteristics mean impactors tend to compress the surface, rather than excavating it, and most material that is blown off the surface never returns.

PIA07740-br500[1]Here’s a view of Hyperion when Cassini made a close pass in 2005.

Cassini Solstice Mission: Rhea’s Horizon

Gazing off toward the horizon is thought-provoking no matter what body’s horizon it is. Rhea’s horizon is slightly irregular and battered by craters, so thoughts inevitably turn towards the forces that shape these icy worlds.

The surface of Rhea (949 miles or 1527 kilometers across) has been sculpted largely by impact cratering, each crater a reminder of a collision sometime in the moon’s history. On more geologically active worlds like Earth, the craters would be erased by erosion, volcanoes or tectonics. But on quieter worlds like Rhea, the craters remain until they are disrupted or covered up by the ejecta of a subsequent impact.

Lit terrain seen here is on the trailing hemisphere of Rhea. North on Rhea is up and rotated 12 degrees to the right. In this view, Cassini was at a subspacecraft latitude of 9 degrees North. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 10, 2015.

PIA18316-br500[1]Rhea’s horizon


New batch of Rosetta images of Comet 67P/Churyumov-Gerasimenko

Lots more images have been released by the ESA Rosetta team: NAVCAM image bonanza: close orbits and comet landing –  Rosetta/ESA’s comet chaser

The 1776 images cover the period between 23 September and 21 November 2014, corresponding to Rosetta’s close study of the comet down to distances of just 10 km from the comet centre – 8 km from the surface – and the images taken during and immediately following the landing of Philae on the comet.


The Hatmehit region on the small lobe of Comet 67P/Churyumov-Gerasimenko as seen by Rosetta’s navigation camera around the time of Philae’s first touchdown, flight over the comet and final touchdown at 15:35, 16:35 and 17:35 GMT (onboard spacecraft time) on 12 November 2014. The distance between the spacecraft and comet centre over this period was between 17.4 and 17.8 km; apparent changes in the image scale are due to projection effects as the comet rotated underneath the spacecraft. The first landing site can be found in the first image, in the bottom left corner of the frame. The images have been contrast enhanced.

The images are part of today’s NavCam data release: NAVCAM image bonanza: close orbits and comet landing

This animation shows the trajectory of the probe during this period:

MarsPolar aims for colony + Mars One update + Mars Society annual conference in DC in Aug

A new international group called MarsPolar seeks to overtake Mars One and put a base on Mars by 2029: New Project Aims to Establish a Human Colony on Mars – Science 2.0.

The name comes from the goal of establishing a  colony in a polar area of the Red Planet where there is sub-surface water ice available.

The group’s plans depend on SpaceX lowering the cost of space travel: Mission Description – MarsPolar.

The funding plan involves “donations, investments and future business income opportunities”.

Meanwhile, Mars One marches on despite lots of criticism and funding shortfalls. Here is the latest update: Mars One Newsletter May 2015. Topics include:

  • The Science of Screening Astronauts
  • Food for Mars
  • Brand Engagement
  • Candidate Interviews
  • Support our Mars Mission

To answer some of the critics, the group has initiated a series of articles they call Inside 360Introducing Inside 360: looking behind the scenes of Mars One’s mission processes – Mars One

Mars One is proud to introduce Inside 360; a series of in-depth articles that present an inside look into the details and feasibility of the Mars One mission. The first article can be found on Mars Exchange. Subsequent articles will be added periodically.

Mars One has taken the first crucial steps in the process of establishing the first human settlement on Mars. In order to address the questions and concerns that have been raised, Inside 360 will foremost provide an in-depth explanation of the individual phases of the mission. Mars One is continuously improving their mission plans based on advice from advisers and suppliers, and Inside 360 will offer the rationale behind decisions made. The ongoing series will additionally feature interviews with Mars One team members and external experts about the different aspects of the mission.

In the first entry in the series, Norbert Kraft, an expert on the effects of long-duration spaceflight, describes the process used to select candidates for Mars expeditions: The Science of Screening Astronauts – Blog/Mars One Community Platform,


The Mars Society will hold its annual conference this year at Catholic University in Washington, D.C., Aug. 13-16, 2015.

Some recent announcements about the meeting:

Here’s the full Speaker List.

Planetary Society waits to hear from the LightSail

The Planetary Society‘s first LightSail, a prototype solar sail, went to orbit last week (see post here). For several days communications with the spacecraft went well. The plan was to wait until mid-June to unfurl the sail. However, late in the week a software flaw caused the system to shut down and now the control team waits for it to reboot and call home again: Software Glitch Pauses LightSail Test Mission – The Planetary Society.

This sort of problem often happens with these small satellite projects. Usually the satellites do wake up but there’s is no guarantee. So the LightSail team could be in for an anxious few days.

If the LightSail does re-connect, it appears it will be commanded to unfurl the sail very soon rather than risk another shutdown.

The latest episode of Planetary Radio reviews the launch and the subsequent software problem : The Launch of LightSail – The Planetary Society. Listen to the audio (mp3).

Find the latest updates at the Mission Control Center – The Planetary Society.