Colour and Stereo Surface Imaging System - CaSSIS

Titleimage: CaSSIS

Welcome to the web site of the Colour and Stereo Surface Imaging System (CaSSIS) built at the University of Bern.

If you are looking for information about the ExoMars Trace Gas Orbiter mission to Mars or want to learn more about CaSSIS please visit the instrument page.

Should you be interested in the scientific research underway with CaSSIS, or want to download data for scientific purposes please visit the science page. You can use the images released here under the Creative Commons Licence  (CC BY-SA 3.0 IGO). CaSSIS images should be credited to ESA/Roscosmos/CaSSIS and other images on the site are Credit: Uni Bern.

Media information can be found on the press page. Contact us to learn more about our team.


News & Events


CaSSIS book

The stunning colour images of CaSSIS have been compiled in the book titled 'Bilder von Mars' and published recently by Weber Verlag press!

CaSSIS at the double

CaSSIS at the double

CaSSIS has been working hard over the past months. With Mars being close to the Earth, the data rates from the spacecraft have been high allowing the acquisition of close to 300 images per week in some cases. Many of these images provide excellent colour information. In this example the CaSSIS team targeted colourful bedrock exposures on the floor of Ganges Chasma in Vallis Marineris. This false colour image reveals a variety of mineral types: Tan represents dusty surfaces, cyan represents mafic rocks, purple is characteristic of the basaltic materials & orange may be hydrated minerals, perhaps clay containing bound water. Image ID: MY35_012770_351_0. ESA/Roscosmos/CaSSIS.


CaSSIS at Fantasy Basel

The CaSSIS team presented the ExoMars programme at Fantasy Basel on 3 May 2019. Lots of Cosplayers around and we all had a fun time mixing science fact with fantasy.


CaSSIS and Mars 9

Thanks to the committee of the Ninth International Mars Conference in Pasadena for choosing a CaSSIS image to advertise their meeting. Uni Bern and the CaSSIS team will be in attendance!


CaSSIS Anaglyphs

Jason Perry of the University of Arizona has been producing anaglyphs from CaSSIS geometrically rectified data. Here is a lovely example from the Hellaspontes region. Use red-blue stereo glasses to view it. This is a colour anaglyph. The ratios of the colours support assessment of the surface composition.


CaSSIS Science Team Meeting in London

The team had a science team meeting in London. The social event was held at the London Eye.


Latest CaSSIS images

We have released some example images through ESA's gallery today. Here is an example of a colour composite from Ius Chasma. Looking good here but the dust storm is very evident. Currently more than 80% of our images are being affected by the dust storm. We may have to wait until mid-August before things clear.


Mars South Polar Layered Deposits

The poles of Mars have huge ice caps that are similar to Earth's polar caps in Greenland and Antarctica. These caps are composed primarily of water ice and were deposited in layers that contained differing amounts of dust depending on the Martian climate during deposition. We therefore refer to them as the Martian Polar Layered Deposits (PLD). Thanks to massive canyons that dissect the PLD, we are able to use orbital imagers to view the layered internal structure. CaSSIS is able to view the margin of the South PLD, which extend as far north as 70ºS. Here, CaSSIS has captured remnant SPLD deposits within a crater close to this margin. The beautiful variations in colour and brightness of the layers are visible through CaSSIS colour filters, which highlight the bright ice and the redder sandy deposits toward the top of the image.


CaSSIS sends first colour images from primary science orbit

This image is from the rim of Koralev crater (165.9 E, 73.3 N) at 5.08 m/px with a ground-track velocity of 2.90 km/s. The solar incidence angle was 76.6 deg at a local solar time of 07:14:11.

The CaSSIS test images have looked pretty good so far - even at low Sun. We do have a problem with an Error Detection and Correction (EDAC) software in the instrument which we are trying to solve. CaSSIS detects this and re-boots itself when that happens. The spacecraft doesn't like that!! We are working with ESOC in Darmstadt to find better ways of dealing with the issue. Should be manageable in the short term with a fix due to be ready in a couple of weeks.


CaSSIS FSW So far so good

The upload of the new flight software version - FSW V1.0.3 - went OK today. We are running on the new software and later tonight we will perform some tests.


Victoria Roloff

Our close friend and colleague, Vicky Roloff, unexpectedly passed away last week. Vicky was a key member of the CaSSIS team in Bern and worked tirelessly for the project on instrument testing and calibration. She will be deeply missed by us all.


CaSSIS Science Team Meeting in Padova

We held a team meeting in Padova (hosted by co-PI Gabriele Cremonese) where we discussed operations planning for the coming few months. Most of the attendees are here in the picture.


Science image of the week

CaSSIS took an image of the flanks of Arsia Mons in November 2016. We have now corrected this data for full colour and some misalignments in the data. The result is quite spectacular and also shows evidence of cloud above the surface. This image was used as one of the Science Images of the Week by ESA in October celebrating the first anniversary of orbit insertion.


Ground Reference Model ready for prime mission

We try to verify our commands with a system that is similar to the CaSSIS instrument. We do that with our Ground Reference Model. It doesn't really look like CaSSIS but from an electrical and software perspective it is very similar. We can issue commands to it to check that we are not breaking the instrument when we send the commands to the spacecraft.


Upcoming operations

We have just been informed that there is likely to be a further operation for CaSSIS from 5-7 March 2017. Until then we'll be cleaning up data and improving the calibration for release to the public in a few months time.

Getting stuff into archives for a public release is a time-consuming job and neither ESA nor we have too much manpower to handle that but we had a meeting last week to try to define timetables that we can meet without killing ourselves.It's coming.


CaSSIS nails Phobos

CaSSIS managed to get a stereo pair with colour coverage of Phobos during the operation on 26 November. Antoine Pommerol (UBE) and Ramy El Maarry (former UBE Post-Doc. and now LASP in Boulder) made colour views and anaglyphs. Here is the colour image which shows that Phobos is relatively blue close to the crater Stickney (which is just over the limb to the left). Be aware that this is false colour indicating relative colour. CaSSIS's filters are tuned for science - not human eye response.


Hebes Chasma - Improvements in Calibration

We have been working on improving the calibration of the first data. The so-called flat-field (the non-uniformity of the system and detector across the field of view) has been improved. The image here shows a composite of Hebes Chasma (seen in the movie we made on the first weekend after data acquisition) after the improvements made. It is really hard to see where the individual images are and the dust particle on the filter has been almost completely taken out.


More results from the first periapsis pass - Stereo!

A pair of framelets from the first periapsis pass over Noctis Labyrinthus have been put together by our colleagues from the Astronomical Observatory in Padova (INAF) to produce a first 3D model of a surface. The images were acquired at about 7 m/px. After combination the vertical resolution should be better than 20 m and is probably a bit better than that. Thanks to Emanuele and Christina for their work over the weekend.

Credit: ESA/Roscosmos/CaSSIS


CaSSIS First Results from Mars

Image of a crater rim to the north of da Vinci crater taken on 22 November 2016. Taken at around 7 m/px during the first periapsis pass when was CaSSIS was active (orbit 9 of the Mars Capture Orbit phase). The image is made up of a lot framelets put together. If you zoom in closely you can see that it is not yet perfect. But ...... Credit: ESA/Roscosmos/CaSSIS


Getting ready to orbit

The control room at ESOC in Darmstadt where they will be watching over the Mars Orbit Insertion. Many of the guys in the picture are well-known to us through our regular meetings. Big responsibility for them coming. Good luck, everyone.

Follow it live on

(text updates)




Programming our first in orbit observations

We are just programming up our first observations for the Mars Capture Orbit phase. Just for fun, this is what one of the image acquisition commands looks like in our interface to ESA.

ACSF023A ( \ # CaSSIS ECSZ0027 / Prepare Image
XF023A01 = 06011004 \ #Unique Identifier
XF023A02 = 00000000 \ #Coarse_Time
XF023A03 = 000000 \ #Fine_Time
XF023A04 = 04 \ #Parameter Table REF
XF023A05 = 50d3 ) #CRC


Successful Flight Software Update

CaSSIS was successfully upgraded to version 16 of the flight software. This sounds very boring but is actually pretty important. The previous version contained issues connected to the housekeeping telemetry. This telemetry was not being returned properly. Having fixed it, not merely does the CaSSIS team get better visibility of the instrument behaviour but ESOC in Darmstadt can see our housekeeping allowing them to alert us much more quickly if something is wrong. The image shows the output produced in real-time by ESOC's support computer. The TM was automatically calibrated to give real values.

Why wasn't this correct in the first place? Misunderstanding of the protocols.


SPIE Proceedings about CaSSIS

Two new technical papers about CaSSIS and its calibration have been put online. These papers were presented at the SPIE conference in Edinburgh.

De Sio, A., V. Da Deppo, L. Gambicorti, M. Gerber, R. Ziethe, G. Cremonese, and N. Thomas, (2016), Alignment procedure for detector integration and characterization of the CaSSIS instrument onboard the TGO mission, Proc. SPIE 9904, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 990452 (July 29, 2016); doi:10.1117/12.2232080

Gambicorti, L., D. Piazza , A. Pommerol , V. Roloff, M. Gerber, R. Ziethe, M. R. El-Maarry, T. Weigel, M. Johnson, D. Vernani, E. Pelo, V. Da Deppo, G. Cremonese, I. Ficai Veltroni, and N. Thomas, (2016), The CaSSIS imaging system: optical performance overview, Proc. SPIE 9904, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 99041E (July 29, 2016); doi:10.1117/12.2233255


The Bundesrat visits Bern and CaSSIS

The Federal Council of Switzerland visited the Space Research Division of the University to view progress on Rosetta/ROSINA, CHEOPS, and ExoMars/CaSSIS. The picture shows the CaSSIS PI explaining aspects of CaSSIS and the CaST targetting tool to (left to right) Federal Chancellor Walter Thurnherr, Bundesrat members Simonetta Sommaruga and Doris Leuthard, and new Rector of the University, Christian Leumann.


First image of Mars

CaSSIS obtained its first image of Mars on 13 June 2016. This image was taken from 41 million kilometres and shows the Elysium side of Mars (Tharsis is towards the right limb). At the time, Mars was roughly 15 pixels in diameter and one can see clearly the different reflectivity of the surface on this hemisphere.


The rotation motor moves!

The rotation motor was tested on 13 April 2016 and it appeared to work. The plot shows the position angle of the rotation motor and it seemed to be OK. Homing was successful. Images were also acquired that confirmed the motor had moved. We are continuing to analyse this.


Stars identified

During the first switch-on, we were able to see stars down to about visual magnitude 11 with CaSSIS in 2 second exposures. We were able to identify the starfield and name the stars using standard databases (SIMBAD). The plot shows the identified stars. The size of the diamonds is roughly proportional to the brightness of the star. The coordinates (x and y) give the detector positions for the stars.


First Switch-On of CaSSIS

CaSSIS successfully switched on. Data were acquired. More to come in the next few days.


We are on our way :-)

Receiving a signal from the spacecraft at 21:29 GMT showed that all stages of the launch were successful and the ExoMars TGO with CaSSIS is on its way to Mars now! Image © ESA–Stephane Corvaja, 2016


PM in Darmstadt

Our Project Manager Ruth Ziethe explains CaSSIS to the world @ESOC in Darmstadt, Germany.


ExoMars Liftoff

ExoMars with CaSSIS on board lifted off from Baikonur in Kazakhstan as planned at 09:31 GMT on 14 March 2016. Confirmation of spacecraft separation, solar array deployment and first acquisition of signal will follow in about 10 hours.
Image © ESA


CaSSIS on ESA's ExoMars Trace Gas Orbiter will be launched with a Proton rocket from the Baikonur cosmodrome in Kazakhstan. Launch of the ExoMars TGO

The Rocket is Standing

The Proton rocket is now on the pad and raised to the vertical position. Image © ESA


Encapsulation of the TGO

CaSSIS and TGO are now inside the rocket fairing ready for launch.


12 Days to Launch

The covers are off.


Electrical Interface Model

Electrical Interface Model (test bed for the spacecraft/instrument interface) updated with the latest version of the Flight Software.


Test in Baikonur

Commands delivered for the next System Verification Test in Baikonur.


Setting Default Window Sizes and Positions on the Detector

We are just setting the default window sizes and positions on the detector. We need to specify the rows that will be returned to give us the four filtered images. The filters are fixed above the detector. Antoine has looked at this and provided the numbers. They will be 354-633 PAN; 712-967 RED;1048-1303 NIR; 1409-1664 BLU


CaSSIS switched on

CaSSIS switched on in Baikonur. Seems OK but we need to check in detail.


TGO now in Baikonur

TGO has been transported to Baikonur.


System Verification Test

The System Verification Test (SVT) has been completed. CaSSIS commanded from Darmstadt by ESOC. Instrument in Cannes on the spacecraft. We acquired 44 images and 1 incomplete image. Couple of bugs were found but it looks pretty good. Example image is below. Yes. It is dark. The aperture cover was on!


Press Conference

Press conference to show spacecraft is ready to ship to Baikonur.

..... and a quote or two ......


CaSSIS on the spacecraft

CaSSIS is now on the spacecraft!!
No pictures ... not allowed ..... CaSSIS is on the spacecraft.


Arrival in Cannes

The cans are in Cannes .... I feel a tune coming on.


Ready to go

Packed and in the truck!


Delivery Review

ESA are just leaving after the Delivery Review Board meeting. The meeting closed with us being given permission to ship to Cannes!!! This is not acceptance to fly. That has to go through the flight acceptance review and we still have to justify some waivers and ..... stuff. But the truck leaves on Monday morning as planned.



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