Author: Eleftherios Kosmas

Global Management Network – Intro and UX

SatNOGS as a project has been concieved as many Satellite Ground Station implementations (like the v0.1 which is ready) coupled together under a global Network that would enable anyone to utilize SatNOGS as a single platform for observations.

The UX idea is simple. An observer/astronomer/maker/hacker accesses our global Network via a web interface. Then she provides details about the observation that she would like to schedule like, which satellite, which band, what timeframe, which encoding etc. Then, having all the info , the system calculates the possible observation windows, on the available Ground Stations connected to the Network for the given timeframe (taking into account any tool, location and time constrains). Once the observer confirms the proposed “observation job” then it gets sent as a job to each Ground Station (GS) job queue to be executed when it has to.

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GSs are gathering observations, decoding/recording them and sending them back to the Network, making them available to the observer (and the world!).

Here is a glimpse into the initial DB Schema of the Network (not all attributes are populated in the tables)

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The general design of the Network part of SatNOGS constitutes a typical many-to-many scheduling problem (many observers to many ground stations) Interestingly enough projects have been developed for observations planning and scheduling on satellites like Hubble (HST) Projects like SPIKE [1] and ASPEN [2]. Those are examples of many-to-one scheduling system s and we have been looking around for implementations that would be similar to our proposed one. Unfortunately we haven’t found anything closely related, thus we are building the Network part from scratch.

Given the expertise of our software people, we are building the application part on Django (python), and relying on rest APIs for communication with our ground stations. The first iteration of the network will be focused on a client-pull approach (versus a server-push) to eliminate any network restrictions.

Our challenges towards the global network are interesting. Given the data-heavy approach of the network (imagine all observations from all stations stored and indexed) we expect data storage to be a serious challenge. We are evaluating deep-storage as an approach to this, and we welcome any feedback or ideas around that.

[1] http://www.stsci.edu/institute/software_hardware/spike/

[2] http://aspen.jpl.nasa.gov/

New Electronics Shield

For v0.2 of our ground station we have been working on consolidation of our electronics trying to minimize size and upgrade the components. Combined with the current minimized approach for the gear assemblies, this will enable us to deliver a smaller more rigid and reliable ground station.

The electronics that needed to be fitted in are the following:

* An Arduino. We selected Pico for the size advantage

* Two stepper drivers. We are using Pololu compatible A4983 based stepper drivers.

Agis (our electronics expert) designed an integrated board to fit everything in. Here is the result

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And the schematic:

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We are printing the PCB as we speak and will be posting a new log with the construction and testing.

New design and NEMA17 motors

Despite the fact that NEMA 17 stepper motors were considered our best choice, at the time of our first design some old NEMA 14, spare parts from an old Rep-Rap, where available so we stuck with them. Last week, we received our new motors and did some tests. The first test was to find the optimal torque without overheating the (also new) drivers. Although we have some results, tests will be continued and we will come up with some numbers probably by next week.

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Additionally we are working on the new rotator design. We placed the motors on top. This way we managed to decrease the profile of the design a bit and also now the device is a lot more serviceable. Now you don’t need to remove everything if you want to access the motors or the worm gear. We are also trying different designs in order to improve the connection between the stepper shaft and the worm gear.

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