After yesterday’s unscheduled release of images of 67P/C-G, our next release will be tomorrow at 15:00 CEST as planned, containing new images and a movie, coordinated with all partners involved in the Rosetta mission. In the meantime, in response to a number of requests made to us and our partners about the general availability of images from Rosetta, Fred Jansen (Rosetta mission manager), Matt Taylor (Rosetta project scientist), and Mark McCaughrean (Senior Scientific Advisor) have prepared this post to explain the way this works.

As Rosetta gets closer to its destination, comet 67P/Churyumov-Gerasimenko, it’s exciting to see the comet grow larger, revealing ever more details of this previously unseen icy world.

From the reaction we’re seeing on the web and in media, many people are enjoying this amazing journey along with us.

Indeed, some of you are keen to see much more, asking for access to as many images as possible on a near-continuous basis, citing NASA’s Mars rovers and the Cassini-Huygens mission, where images are available soon after they’ve reached the Earth. Similarly, images from the NASA-ESA SOHO and ESA’s PROBA-2 solar missions are also available to the public immediately.

However, it is important to know that such an “open data” policy is not the norm for most ESA and NASA missions. Data from the Hubble Space Telescope, the Chandra X-Ray observatory, the MESSENGER mission to Mercury, or for that matter, some NASA Mars orbiters, are all subject to a so-called “proprietary period”, as are the data from ESA’s Mars Express, XMM-Newton, and Rosetta, for example.

This period, typically 6-12 months, gives exclusive access to the data to the scientists who built the instruments or to scientists who made a winning proposal to make certain observations. In ESA’s case, the length of the period is decided by our Member States when a mission is selected, although in some cases, the period is made shorter when a mission has been in operation for some time.

The aim of a proprietary period is to ensure that the academic teams who spent decades developing and running the sophisticated scientific instruments on-board the spacecraft are able to calibrate and verify the data, as well as reap the rewards of their efforts: their scientific careers depend on it. Otherwise, it would be very hard to engage people in this long and difficult process. Similarly, it’s reasonable that those who won observing time, typically against stiff competition with over-subscription factors of three to ten, have the first chance to exploit the data.

That said, the proprietary period is finite and usually rather short, to ensure that the instrument teams and winning proposers don’t sit on the data: at the end of the period, the norm in space science is that all of the data become freely available to all scientists and the general public, world-wide. For example, all of the data from ESA’s Herschel mission are now open to all via our archives, as are many of the data from Mars Express and our other missions.

With Rosetta, all data from its 21 instruments (11 on the orbiter, 10 on the Philae lander) are subject to a 6 month proprietary period. Thus any release of images and scientific results that we are making now, as we approach rendezvous with 67P/C-G on 6 August, is being done with direct involvement of the instrument science teams, who are agreeing to waive the proprietary period for those items.

Because no-one has ever been to 67P/C-G before, each new piece of data from Rosetta has the potential for a scientific discovery. It’s only fair that the instrument science teams have the first chance to make and assess those discoveries. At the same time, it’s exactly because 67P/C-G is unknown territory and because there is an exciting journey underway that some are clamouring to see everything as soon as possible, in near “real-time”. We understand that, but a balance must be struck, which is why only some of the data are being released now.

Finally, many people know that in addition to the main scientific imaging system, OSIRIS, developed and run by a consortium of institutes under the leadership of the Max-Planck-Institut for Solar System Research in Göttingen, there are a pair of navigation cameras (NAVCAMs) on-board under ESA’s responsibility. “Why don’t we release those NAVCAM images freely?”, we’re asked.

As mentioned in a previous blog post, the reason we’re not doing so is to avoid undermining the priority of the OSIRIS team, as there is some scientific overlap between the two camera systems. Some NAVCAM data are however being put out in coordination with the regular OSIRIS releases.

We know that this won’t satisfy all demands for full, open access, with people making the argument that “the public funded all of this”. That’s true, of course, but it has to be remembered that the national agencies responsible for funding Rosetta and its instruments approved the proprietary period for the data returned from the mission, and we are operating according to those rules.

At the same time, everyone at ESA and on the science teams is keen to let the public know what’s going on, to share in this adventure. In particular, we have made extensive social media efforts on Facebook, Twitter, and other channels to communicate with as wide an audience as possible and to keep everyone up-to-date, including a variety of competitions to engage people directly.

Beyond that, when it comes to the big “events” like the comet rendezvous on 6 August, the landing in November, and the perihelion passage in August next year, we aim to put out the very best images taken right on those days as quickly as possible, much as we did for Rosetta’s fly-bys of asteroids Steins and Lutetia. And plenty of other results will be made available along the way.

Posted on behalf of Fred Jansen (Rosetta mission manager), Matt Taylor (Rosetta project scientist), and Mark McCaughrean (Senior Scientific Advisor)