Space Experiment Questions


#1

Answers to Logistic Questions about Space Experiments

Please post logistic questions about the space experiments here so that they can be answered by our engineering team and everyone can benefit from seeing the answers.


#2
  • Is there sample code available to show how to read and log sensor data?
    Yes. Please refer to https://github.com/ArduSat/ArdusatSDK/tree/master/examples for the latest examples for how to interact with the SDK & sensors. For sensors that are not currently supported by the SDK but are on the satellite (TSL2591 HDR Luminosity, MLX90621 IR array (not available on equatorial), TCS3472 Color Light Sensor , ISL29125 Digital RGB sensor, SI1132 UV Index & Ambient Light) , you can just put comments in the code where you would like to log them, and we will update it accordingly before we send it to the satellite. We’re working on getting full SDK support for all the sensors in the future.

  • Can our code run on both an equatorial orbit & a polar orbit satellite
    Unfortunately, no. Each individual experiment (running on a different satellite) costs us the same amount, so each individual satellite run counts as a different experiment.

  • Will latitude and longitude values be available? If so, how do we read these values?
    Yes, but the environment that the code runs in on the satellite does not have access to this information. We will backfill this data based on the timestamps associated with sensor readings and the telemetry database after the fact, and it will be included with your results data when it is delivered to you.

  • Will velocity and altitude values be available? If so, how do we read these values?
    Yes, but like lat/long data, the environment does not have access to them. We will backfill this data based on the telemetry database and include it with your results.

  • Is the satellite stabilized or tumbling?
    The satellites all have inertial control systems that stop the tumble and hold the sensor payload in a nadir (earth-facing) orientation. As long as this system is operating properly, there should be very little relative motion of the satellite. It is possible that some of the first experiments might have some rotation movement, since we are still in the process of fine-tuning this system.

  • Is ____ sensor pointing upwards or towards the Earth?
    At this time all sensors are pointing toward the Earth.

  • What sensor libraries should we use?
    You must use the ArdusatSDK (https://github.com/ArduSat/ArdusatSDK/) to read data from sensors. Other libraries will not work on the satellite. For the sensors that are on the satellite but currently unsupported by the SDK ( TSL2591 HDR Luminosity, MLX90621 IR array (not available on equatorial), TCS3472 Color Light Sensor , ISL29125 Digital RGB sensor, SI1132 UV Index & Ambient Light) , you can just put comments in the code where you would like to log them, and we will update it accordingly before we send it to the satellite. We’re working on getting full SDK support for all the sensors in the future.

  • Do we need to configure date/time on the satellite, or just read values?
    Just read values. The internal clock on the satellite is constantly synchronized with the GPS satellites.

  • Are we writing to an SD card, or Serial?
    Use the Logging SDK functions (https://github.com/ArduSat/ArdusatSDK-Logging) to save values. These will be saved to the satellites onboard computer and downloaded via the ground station network.

  • Are there specific variable name conventions we need to use (for local variables)?
    No. Feel free to use whatever convention you would like, although we suggest following the Arduino Style Guide: https://www.arduino.cc/en/Reference/StyleGuide.


#3

For one of our experiments (reading temperature of snowpack in Rocky Mountains) do we submit to you a upper left and lower right lat/long coordinates of the area we would like readings from? We would probably have several of these areas defined so we can compare the ground temperature in valleys (no snow) with those in the mountains.

While we understand it is a polar orbit, are those orbits from pole to pole straight lines from pole to pole over the curvature of the earth/orbit?

Cache Makers


#4

We wanted to know if we can choose the week it is in space because we are concerned that clouds would prevent data collection since it has been very rainy here in California. We also wanted to know if it is possible to get images from space and what the upper limit is for data collection. How often is too often to collect data? We are doing the polar orbit and wanted to collect every ten minutes for a week, is that too much?


#5

Hello Kevin,
Regarding submitting area of earth for experimentation: Yes, you may submit Lat/Long coordinate boundary corner to corner. We will then look at how we would task the satellite to best get readings from this region. At this early stage of space experimentation we want to learn how teams would like to design their experiments and we will then be building additional GUI and coding tools.
Regarding polar orbits: Most polar orbits (including our Satellites) do not have inclination of exactly 90 degrees to the equator. Here is an example of a Spire satellite Lemur-1 in polar orbit: http://www.wolframalpha.com/input/?i=lemur-1+satellite
As you can see it is near pole to pole but not exactly. As the satellite is traveling along the orbital plane earth is rotating beneath at the same time. When we trace the path of these polar orbiting satellites we see a curved line over earth. Note, curved path is pronounced when viewing this 3D world in 2D when looking at an orthographic projection of earth, the orbits appear like sine waves. Here is a sneak peak of an orbit tracking tool in development that shows 15 orbits and their paths.


#6

Good point regarding cloud coverage. We currently don’t have cloud cover integrated into our experiment planning tools, yet. We are researching integration of weather platforms like http://forecast.io/ that have realtime and predictive cloud cover percentage. Please do document your request regarding scheduling around cloud cover in your experiment. We will do our best to meet the teams needs and learn how to best design tools to support space experiments.

Regarding payload and data sizing I recommend checking out post: Sample Rate Confirmation

High level if you were taking a single sensor reading ((24*60)/10)*7 = 1,008 readings this would be within our current play load limit of 1,500 readings.


#7

How do I specify the latitude and longitude corners for polar orbit transit? I’d like to do a transit over the South Pole, and then have a second transit over East Tennessee. We have built a system that will face upward from our roof, want to correlate sensor readings with the satellite pass (sensors pointing downward). Haven’t found the place on the website that allows me to specify start\stop for data collection.
Thanks in advance


#8

Hi Joy,

We’re still working on building out a friendly user interface for specifying locations for satellite transits. For the time being, the process is fairly manual - we ask you to either specify coordinates for NW & SE corners that define a box on earth, or give us the coordinates of a specific location you are interested in collecting data for, and we will choose a transit that results in a high enough elevation pass to get good data for. At this time we are having groups write out these experiment parameters in the “Procedure” section of their experiment write-up on the Ardusat Experiment Platform (https://experiments.ardusat.com/).

Unfortunately, this next set of satellites won’t be in a true polar orbit; we just (mis-)used the term to differentiate the orbit from the equatorial ones that are available for the earlier experiments. They will be in orbit that is similar to that of the ISS, with an inclination of approximately 52 degrees. This means that the Tennessee transit will have no difficulties at all, but the South Pole transit won’t be possible - the furthest south these satellites will transit is about the southern tip of S. America.

Sorry for the confusion!


#9

I am having trouble uploading our code to the experiment platform. We have it in notepad and it will not copy and paste into the procedure section of the lab. Is there a way to copy it without having to retype the entire thing. We are still working on the citations and background research part so pardon our lateness in getting it done. If you can let me know what to do with our text file of our code that would be great. Besides the hypothesis, code, and background research is there anything else you need from us on our end?


#10

We also had some confusion on how we will only be able to look at California.Should we get all the data and then look at the locations after or is there a way you can filter out data points that are outside of California? Thank you!


#11

Thank you for message, you have uncovered an issue with pasting code that we can reproduce and have a bug report logged and will be fixing. For now you can just e-mail your code to kevin@ardusat.com.


#12

If you provide us with two lat/long coordinates of a bounding rectangle, we will set the mission to collect data within this area. We also append all the datasets from the satellites with Timedate, Latitude, Longitude, Altitude, Velocity. This appended data will allow you to further filter the data.


#13

The bug that prevented some code syntax from being posted in the experiment platform has been fixed.