Few things are as thrilling and scary for a New Space company as launching a new satellite into orbit. And there are few things as frustrating as sorting out the first few niggles that a new mission inevitably has.
FarEarth for SmallSats can help with the first significant milestone of a new Earth Observation mission: the commissioning phase.
The first light image of a satellite is often celebrated, and rightly so, as a significant milestone for new EO missions. What is not always shown is that the image acquired is often far from the intended target and sometimes heavily “photoshopped” to look good for the press.
To help with this, FarEarth for SmallSats can provide a Level 0 quality report that helps visualize what the satellite is doing and why you might be struggling to get the perfect acquisition.
You can look at an example report here.
The map
The report starts with a preview of the raw data and a map. This map has a red line indicating where the satellite was flying when the image was taken, according to its GPS location. If this line is far from what you were expecting, chances are that the image was not acquired at the intended time (an onboard clock issue), or there might be something wrong with the GPS telemetry.
Next, a green line shows the location on Earth where the satellite was pointing. Often, the assumption is that this line stems directly from the “bottom” of the satellite, but future calibration campaigns will dial in the deviation from this ideal scenario. If the green line is, for example, towards the east of the satellite, while you were expecting it towards the west, it might indicate that you are flying backwards! And yes, this happens more often than you might expect. There are other potential reasons for this mismatch, but this will give you a clue where to start looking.
Then, there is an outline of where the image would be, assuming some basic geometry of the sensor relative to the direct line of sight. This outline can reveal quite a lot as well. Together with the preview image at the top of the report, it might indicate a problem with orientation, vibrations, or settings that might be wrong on the camera.
The map view also indicates the start and end of the acquisition window—when the camera was switched on and off—relative to the ancillary data received. This is to give you an idea of how much lead-in and lead-out time there is on the ancillary data before and after the imaging acquisition. Having a couple position and orientation points before and after an image acquisition improves the accuracy of the models.
The ancillary data
The next couple of pages show the position and orientation of the satellite, again with a red section indicating where the camera was turned on and off.
These graphs help determine how noisy the attitude data of the satellite might be. It will also show if the satellite achieved a stable orientation before the camera was switched on, and if it might have done some manoeuvring during the acquisition. Together with the preview image, this will also help distinguish whether there is a control problem or a measurement/determination problem (the ‘C’ and ‘D’ in ADCS, respectively).
If everything goes well, you should expect straight lines for the roll, pitch and yaw graphs, with a bit of blue line before and after the red line that is not too noisy (though some noise is normal and can be dealt with). And if you employ techniques such as forward motion compensation, you should see a stable rotation on the pitch.
Likewise, there are two sets of graphs for the position and velocity information of the satellite in both ECI and ECR reference frames. Satellites don’t often jump around in their orbit—physics takes care of that—but if you see sudden changes in these graphs, you have a problem measuring the location of your satellite.
Basic metadata
The report also contains some statistics for the number of ancillary points before, during, and after the acquisition and other fields that might help resolve any timing issues.
The L0 quality report is available on the FarEarth for SmallSats portal. It is a valuable tool in your arsenal to troubleshoot acquisition issues during commissioning and throughout the satellite’s life.