Shortly after publishing the intriguing Mars Express VMC image showing the cloud over Arsia Mons on 2 July, we received an excellent analysis from one of our regular site visitors, Mike Malaska, of Chapel Hill, North Carolina, USA. He used the Mars Express VMC image together with NASA/JPL images and data from Google Mars in his analysis. We were impressed by Mike's in-depth report, and sent it on to several of the scientists working here at ESA for their comment (more details under 'Full story'). Herewith, and with Mike's kind permission, we'd like to republish his report in full - and with our sincere thanks for his hard work and well-argued results.

On 2 July 2009, Mars Express was orbiting over the Tharsis Montes volcano chain at around 6500 km when the VMC imaged what appears to be an extremely long, thin cloud trailing from near the peak of the southernmost volcano, Arsia Mons. VMC captured the pictures around 09:00 UTC and they were transmitted to Earth and then posted onto the blog on 8 July. The form, composition and overall profile of the cloud was unknown.

To our (pleasant) surprise, on 15 July, Mike Malaska, a keen amateur based in the USA who had previously shared several VMC images that he had processed, sent in an 18-page analytical paper providing an in-depth review of the cloud image. He argued persuasively that the cloud was consistent with an early morning radiation fog of water ice with a strong background westward flow.

His conclusions were very interesting: any suspected presence of water on Mars is, of course, important to extend scientists' understanding of the planet's physical history and current environment.

We sent copies of Mike's paper to Dr Michael Khan, Mission Analyst here at ESOC, the European Space Operations Centre, Germany, and Dr Olivier Witasse, Mars Express Project Scientist at ESTEC, the European Space Research and Technology Centre, the Netherlands. "This is excellent work, very thoroughly executed and well-presented," said Michael (Khan) in a reply email.

Olivier wrote:

"It's good work! It's a good idea to put it on the VMC blog. I have forwarded the document to SPICAM and OMEGA team members involved in cloud data analysis. Preliminary feedback from Anni Määttänen, cloud specialist and post-doctoral scientist at the LATMOS laboratory in France: It is a very interesting study."

By the way, SPICAM and OMEGA are two of the 'real' scientific instruments on Mars Express (the VMC camera was never intended to be used as a 'scientific' instrument).

SPICAM is the Ultraviolet and Infrared Atmospheric Spectrometer, which is used to study the composition of the Martian atmosphere from the wavelengths of light absorbed by the constituent gases; OMEGA is the Visible and Infrared Mineralogical Mapping Spectrometer, which is used to acquire images of the surface and atmosphere.

Olivier promised to let us know if he gets any more feedback from the any of the scientists, which we'll share right here in the blog.

We think Mike's paper is an excellent example of how solid amateur science can be done by, well, anyone. Mike took the time to examine the data, think about the facts and physical processes involved, and deduce significant conclusions that may lead to an increased understanding of our Mars history and evolution.

He's also taken very good advantage of the relatively low-resolution output from the VMC camera, 'mashed-up' with data from Google Mars and other NASA/JPL images of Mars.

Good work, Mike, and thanks! We're happy to see our 'Mars Webcam' blog being used for much more than casual enjoyment of cool Mars pics!

Mike's paper in full right here in the VMC blog: http://webservices.esa.int/blog/post/6/785

Mike's paper in SlideShare: 2 July 2009 Arsia Mons Cloud Observed by the MEX-VMC Instrument