Postcards from Mars

by Grant Hawkins, lead developer for SIMOC B2 at Over the Sun, LLC

In mid-2022, our team took on the challenge of modeling Biosphere 2 (B2) in SIMOC. Beyond simply describing the outcomes and making sure that they match the published data, we also had to make sure that — The system and sub-systems responded correctly to changes in the configuration. When a user changes the area of sweet potatoes or the CO2 scrubber activation threshold, other agents are responding appropriately to those changes.

The sub-systems remain accurate on the original SIMOC validation data, the NASA CELSS growth-chamber experiments. There, plants were grown in highly-controlled environments in order to maximize their food productivity. For certain plants, the production rate in kg/m2-day was as much as 10x greater at CELSS than in Biosphere 2.

Light was found to be the biggest contributing factor to the differences in plant productivity. At CELSS, plants received constant-output electric lighting at an optimal level for an optimal number of hours per day. These ranged from 1.4 Mol/m2-h for 12 hours/day for rice, to 3.53 Mol/m2-h for 20 hours/day for wheat. At B2, the plants received whatever sunlight passed through the B2 windows and structural frame. Our approach was to use the CELSS data as the baseline for SIMOC plant consumption and production, and

The first step toward implementing SIMOC-B2 was to add a ‘light-response’ mechanism to the SIMOC plant agent. We added a new variable, ‘par_factor’, which scales the rate of biomass accumulation to the species-specific, hourly light requirement. The other functions of the plant (photosynthesis) are scaled to its total accumulated biomass, so the light response will be applied to those exchanges as well.

So this was a big step forward for the accuracy and flexibility of our plant growth model, but that wasn’t all. Some of the deeper changes to how exchange values are calculated led to a major reduction in memory footprint – more than 80% for simulations with more than one plant – which is great news for our cloud computing budget 🙂

The SIMOC development team has for the past six months been hard at work in developing two new versions of SIMOC: SIMOC B2 and SIMOC Live. SIMOC B2 is a new kind of simulation, a model of the first and second missions at Biosphere 2 in order to present citizen scientists with the tools to understand the challenges faced by the world’s largest and longest running human-in-the-loop bioregenerative experiment. SIMOC Live enables the real-time monitoring and capture of data from sensor arrays, such as those used to monitor carbon dioxide or oxygen levels, and other air quality measures.

We apologize for the lack of updates to this forum, but promise to catch-up (and back date) several stories soon!

This month brings new features and performance improvements. The migration to Vite is now complete, which has decreased startup time from around a minute to less than a second. A basic Kiosk mode is also now functional, and is being fine tuned.

Progress has been made on the Biosphere 2 simulation mode too, with new menus being developed such that a user can choose between whether they want to run a Mars simulation or a Biosphere 2 simulation, with corresponding visuals for each mode. New features are also being integrated into SIMOC’s model in order to account for factors that made the two Biosphere 2 experiments challenging, such as low light levels due to shadows cast by space frame and a year of heavy cloud cover in southern Arizona. The effect of pests and their role in the actual Biosphere 2 experiment are included, as well as a new agent to represent the concrete and associated carbon dioxide uptake.

Exciting new developments for SIMOC are underway. Research has started on implementing the agent based model to simulate Biosphere 2 itself, to replicate the original (1991-93) and second (1994) Biosphere 2 missions within SIMOC. A thorough literature review is being conducted by project lead Grant Hawkins with interviews being conducted with original Biosphere 2 crew members. Graphics are being designed in anticipation of the revised user interface.

Also, development is underway for a specially tailored SIMOC interface for use at exhibit kiosks. This streamlined version will have supplemental information, and automatically reset after periods of inactivity to make it more friendly for use at an exhibit where a person might interact with it briefly and then walk away without exiting the simulation.

Some new developments have been made for SIMOC Live. For example, a new configuration file facilitates major improvements in sensor behavior. Now sensors are automatically recognized when they are attached, and if disconnected the data capture will resume automatically when the connection is restored. There are also new options for exporting sensor data via the educational web dashboard.

SIMOC developers have also taken additional steps to improve performance. Data transmission from back-end to front-end has again been made more efficient. The frameworks and libraries used in the codebase have also been updated. For instance, ChartJS, SocketIO, and Vue have all been changed to the latest versions, and the developers have begun to migrate from Vuex to Pinia which should yield a performance increase.

The SIMOC development team has been hard at work improving the performance of SIMOC. Bugs that occurred when saving the game have been fixed in the latest code update, with a great many changes in the works to improve overall performance. In particular, performance due to many simultaneous instances of SIMOC are being addressed, for both cloud and local computing.

Core SIMOC developer Grant experimented with new ways to send batches of data and was able to achieve a 10x performance increase in performance. Lead SIMOC developer Ezio also found a way to cut load times in half. Ian has developed a test suite to stress test local and cloud servers, with an eye toward a return to locally managed servers for higher quality services. The development team also updated the Docker images on the backend to the latest version, and data logging has been improved.

Over the last few months, SIMOC developers have created features and interface improvements, with thorough tests in process. The SIMOC developer team is also working on the automation of startup scripts, and improving the appearance of charts as well as the variety of data that can be displayed on them.