I am really sorry for the lack of information in the last weeks but things outside spacEurope’s realm have been quite time consuming.
As I have made mention in the last post, the AFM was something to keep an eye on for the following days, that was because I have requested our dear Daniel Parrat for an update.
If you are remembered, Daniel works as an Instrument Sequence Engineer on the microscopy station of MECA, i.e. the Optical Microscope (OM) and the FAMARS instrument at the Phoenix Science Operations Center.
With no more delays neither fancy headers, but with a lot of excuses for this long silence here is Parrat’s report.
……………………………………………………………………………………………………
The fourth day (or sol) after the landing, we did a check up of the instrument, the first one since pre-launch. Our silicon chip was in great shape, the eight cantilevers having survived the launch, the journey in space and the landing. This first result was very encouraging, but unfortunately we could only enjoy it for a few minutes: the same day, the first measurement of a calibration substrate failed. The stage was stopped before reaching the first sensor tip, thinking that it was already in contact with it. In terms of Phoenix operations, that meant that AFM imaging was “out of the table” for a while. Fortunately, we were still allowed to initialize it during OM experiments (as a self-defense mechanism against a possible bad motion of the stage).
Looking at the results of those initializations, we soon realized that the AFM was more sensitive than what we thought to thermal changes. This was confirmed by experiments in our lab, and we found that reinitializating it every half-hour, in combination with a few changes in the approach procedure, was sufficient to solve the problem. However, it took still about five weeks – the longest of my life – to get the approval for those changes in the commanding sequences. The reason is that each instrument team had to do some changes at that time, the AFM being at low priority (well, it had the lowest one).
On sol 44, we were back on track. We were very nervous about trying again to bring the calibration substrate towards the AFM. It had been on Mars for more than seven weeks, without further testing than a basic initialization.
A couple of hours before the downlink of the results, I was at home with my family. I received a phone call from Urs Staufer: “Are you not coming? The first image is there!!!”. That’s how I missed the downlink of the first AFM image from Mars. However, I was so happy that this detail did not ruin this wonderful day. When I came to the operations center, everybody was celebrating and busy analyzing the image (it is probably not yet over…). It looked very nice, showing three lines of the calibration substrate. This first image was taken in static mode, also called contact mode (see “Famars-Part I” in Rui’s blog for explanations).
However, once again, the happiness was not total (I would say 81%, the ISEs of the mission will understand). During the same day, we also tried to take another image, this time in dynamic mode. However, this one was not successful, only showing a sad blank image. So the lab was calling us again…
After a series of tests (both in the lab and on Mars!), we found that the heat generated by the SWTS motors was transmitted to the AFM scanner in a very short time, causing the signal to drift a lot (even more than in static mode). John Michael Morookian, who knows the whole MECA payload better than anybody else, found a convenient way to reduce the heat generated by the stage. His proposition seemed the best for me, even if there was a risk of going two or three microns too far because of the higher speed of the stage.
Using this new approach and having adjusted the feedback parameters of the AFM, we were finally able to take a good image in dynamic mode, on Sol 64. The sample was another calibration substrate with “chess-like” structure (TGX1 for the experts). I was perhaps even happier with this image. First because it showed that the scanner that I built produced only a few distortions in the image, and secondly because the AFM tip was still sharp, even after a few scans in static mode. From an engineering point of view, we were at the Nirvana. From a science point of view, we had not yet started…
Dynamic mode being usable, the chase for Martian particles could finally start. On sol 68, we targeted a substrate with possible scientific interest. This substrate, designed and fabricated at Imperial College by Tom Pike, Sanjay Vijendran and Hanna Sykulska, was composed of small pits (5 microns wide and deep), which could have trapped some particles delivered previously by the robotic arm. And it did! One of the AFM images of that substrate showed a tiny particle, quietly nested in one of the pits. Its diameter was about one micron, a size much smaller than any other object measured in space (at my knowledge). If you think to the powers of 10, it’s a 10-6m object “seen” at a distance of about 1011m from the viewer…
Now the MECA microscopy team continues its experiments, both with the OM and the AFM. A few other good AFM images were taken, and we hope that the extended mission will allow discovering other interesting particles. Today we have just started the transition to Earth time operations, which is a relief after having spent the last three months at Mars time. We will soon reach the end of the initial 90 days, which makes me both happy and sad. Happy because the Phoenix instruments are all still doing well, and sad because the Phoenix team will soon no longer exist, after all these years of work together...
As I have made mention in the last post, the AFM was something to keep an eye on for the following days, that was because I have requested our dear Daniel Parrat for an update.
If you are remembered, Daniel works as an Instrument Sequence Engineer on the microscopy station of MECA, i.e. the Optical Microscope (OM) and the FAMARS instrument at the Phoenix Science Operations Center.
With no more delays neither fancy headers, but with a lot of excuses for this long silence here is Parrat’s report.
……………………………………………………………………………………………………
The fourth day (or sol) after the landing, we did a check up of the instrument, the first one since pre-launch. Our silicon chip was in great shape, the eight cantilevers having survived the launch, the journey in space and the landing. This first result was very encouraging, but unfortunately we could only enjoy it for a few minutes: the same day, the first measurement of a calibration substrate failed. The stage was stopped before reaching the first sensor tip, thinking that it was already in contact with it. In terms of Phoenix operations, that meant that AFM imaging was “out of the table” for a while. Fortunately, we were still allowed to initialize it during OM experiments (as a self-defense mechanism against a possible bad motion of the stage).
Looking at the results of those initializations, we soon realized that the AFM was more sensitive than what we thought to thermal changes. This was confirmed by experiments in our lab, and we found that reinitializating it every half-hour, in combination with a few changes in the approach procedure, was sufficient to solve the problem. However, it took still about five weeks – the longest of my life – to get the approval for those changes in the commanding sequences. The reason is that each instrument team had to do some changes at that time, the AFM being at low priority (well, it had the lowest one).
On sol 44, we were back on track. We were very nervous about trying again to bring the calibration substrate towards the AFM. It had been on Mars for more than seven weeks, without further testing than a basic initialization.
A couple of hours before the downlink of the results, I was at home with my family. I received a phone call from Urs Staufer: “Are you not coming? The first image is there!!!”. That’s how I missed the downlink of the first AFM image from Mars. However, I was so happy that this detail did not ruin this wonderful day. When I came to the operations center, everybody was celebrating and busy analyzing the image (it is probably not yet over…). It looked very nice, showing three lines of the calibration substrate. This first image was taken in static mode, also called contact mode (see “Famars-Part I” in Rui’s blog for explanations).
However, once again, the happiness was not total (I would say 81%, the ISEs of the mission will understand). During the same day, we also tried to take another image, this time in dynamic mode. However, this one was not successful, only showing a sad blank image. So the lab was calling us again…
After a series of tests (both in the lab and on Mars!), we found that the heat generated by the SWTS motors was transmitted to the AFM scanner in a very short time, causing the signal to drift a lot (even more than in static mode). John Michael Morookian, who knows the whole MECA payload better than anybody else, found a convenient way to reduce the heat generated by the stage. His proposition seemed the best for me, even if there was a risk of going two or three microns too far because of the higher speed of the stage.
Using this new approach and having adjusted the feedback parameters of the AFM, we were finally able to take a good image in dynamic mode, on Sol 64. The sample was another calibration substrate with “chess-like” structure (TGX1 for the experts). I was perhaps even happier with this image. First because it showed that the scanner that I built produced only a few distortions in the image, and secondly because the AFM tip was still sharp, even after a few scans in static mode. From an engineering point of view, we were at the Nirvana. From a science point of view, we had not yet started…
Dynamic mode being usable, the chase for Martian particles could finally start. On sol 68, we targeted a substrate with possible scientific interest. This substrate, designed and fabricated at Imperial College by Tom Pike, Sanjay Vijendran and Hanna Sykulska, was composed of small pits (5 microns wide and deep), which could have trapped some particles delivered previously by the robotic arm. And it did! One of the AFM images of that substrate showed a tiny particle, quietly nested in one of the pits. Its diameter was about one micron, a size much smaller than any other object measured in space (at my knowledge). If you think to the powers of 10, it’s a 10-6m object “seen” at a distance of about 1011m from the viewer…
Now the MECA microscopy team continues its experiments, both with the OM and the AFM. A few other good AFM images were taken, and we hope that the extended mission will allow discovering other interesting particles. Today we have just started the transition to Earth time operations, which is a relief after having spent the last three months at Mars time. We will soon reach the end of the initial 90 days, which makes me both happy and sad. Happy because the Phoenix instruments are all still doing well, and sad because the Phoenix team will soon no longer exist, after all these years of work together...
