MDRS Crew 122 (HI-SEAS)
Science Report #10
01/23/13
Thermal Analysis and Evaluation
By: Oleg Abramov
This report summarizes preliminary analysis results from the following thermographic datasets:
Exterior survey (evening) - taken 1/21/13 @ approx. 10 pm
Greenhab survey (evening) - taken 1/21/13 @ approx. 10 pm
The exterior survey was conducted in-sim from the Hab-to-Greenhab tunnel, and, as before, was limited to the northeastern quadrant of the Hab. Outside air temperature was -12 C at the time of the survey. Heat loss was noted along some joints between the Hab's exterior panels, as well as at the interface between the exterior panels and the roof. Maximum temperatures of 12 C were observed at the joints between the panels, and 14 C between the panels and the roof. Heat leaks in the top right and top left quadrants of the east window of the second-floor common room were noted along the seams, with a maximum temperature of 7 C.
North, east, and south sides of Greenhab were surveyed from the outside and compared to the results from the afternoon survey. Greenhab rear air vents had a maximum temperature of 16 C, down from 19 C recorded in the afternoon. The ~5 cm-wide gap between the antechamber and the main chamber of the Greenhab had a maximum temperature of 18 C, down from 19 C recorded in the afternoon.
Inside the Greenhab, steep nighttime vertical and horizontal temperature gradients were noted. The temperature of the ceiling was ~35 C, whereas floor temperature in the central aisle was 1 C. In general, the warmest temperatures were recorded in the central region of the main chamber, due in large part to the directed radiation from the heater. The coldest temperatures were recorded at the periphery near the floor, particularly at the corners, where temperatures as low as -9 C were recorded. Areas of missing insulation in the internal Greenhab layer showed temperatures of -8 C. Plant beds positioned perpendicularly to the central aisle exhibited a significant thermal gradient with temperatures ranging from 7 C to 16 C. The heat pad had a temperature of 27 C where it was exposed to air, and 38 C directly underneath a covered plant bed, which was at a constant temperature of 18 C.
Additional temperature data was collected using two Omega OMWT-TEMP15 wireless temperature sensors. After initial testing indicated consistent temperature readouts from both sensors, they were placed in the main chamber of the Greenhab and in my stateroom. The Greenhab sensor was placed immediately next to the AcuRite Digital Indoor / Outdoor Temperature & Humidity Monitor, which displays temperature but does not log it. Both sensors were positioned across two plant beds approx. 50 cm away from the central aisle. The temperatures recorded by the OMWT-TEMP15 unit were consistently lower than the AcuRite readouts by ~2 C. Infrared imaging revealed that the AcuRite sensor is indeed ~2 C warmer, possibly due to being slightly closer to the heater. The locations of the sensors were switched to test this hypothesis. Temperatures in the Greenhab decreases steadily through the night, reaching a minimum of 4 C shortly before 8 am. Between 8 and 9 am, temperature increased dramatically, from 4 C to 17 C. Today was partly cloudy and temperature waxed and waned throughout the day, reaching a maximum of 22 C at1 pm.
The stateroom temperature sensor recorded a constant temperature of 23 C throughout the day. At night, however, temperatures increased linearly between 11 pm and 4 am, and then at a decreasing rate between 4 am and 7 am, reaching a plateau maximum of 26 C between 7 am and 8 am, and dropping back to 23 C by 10 am. Several crewmembers, including myself, have noticed that the staterooms get uncomfortably hot in the early morning. This may be due to some crewmembers leaving the stateroom doors open during the day but closing them at night, disrupting ventilation and causing a heat accumulation in western part of the Hab.
Green Hab Activities
By: Angelo Vermeulen
Plant cultivation at the GreenHab is doing generally well. All cress seeds are sprouting except upland cress. Snow peas and broccoli are also sprouting. The containers with bush beans and mint also show sprouts, but these are probably seeds that were present in the garden soil. It seems garden soil with seeds was put back in its bag after usage, hence the contamination. One of the strawberry plants is currently flowering. The Deodar cedar and the Colorado blue spruce were moved into 12” pots. All plants were watered, and some yellow leaves of kale and collard plants were trimmed.
Soil temperature was measured in heated and non-heated 10” x 20” trays, and in a non-heated 23” long container using a mercury thermometer. Time of measurement was 3:00pm. Results can be found below.
The temperature in the 23” container with kale corresponded with the ambient temperature. However the temperature in the four non-heated trays was slightly higher. This can be attributed to the fact that these trays were in closer proximity to the propane heaters. As indicated by Oleg Abramov’s thermographic research there’s steep horizontal temperature gradients throughout the GreenHab. Interestingly, there’s also a gradient in the four non-heated trays ranging from 20°C to 24°C. Once again this can be explained in terms of proximity to the propane heater and was also confirmed in the thermographic analysis. The soil temperatures in the trays on the heat mat were obviously way higher, and reached as much as 34°C. The tray with a grid of small biodegradable containers displayed a higher temperature than the tray in which soil was distributed directly, without the any containers. Currently it is unclear why this is the case.
An ambient temperature profile of the GreenHab was established using Oleg Abramov’s wireless sensor equipment (graph below). Large temperature differences between day and night remain a core problem. Better insulation, more variable temperature control and thermal mass could all add to a more stable environment for the plants.
[See Attached PDF for graphic]
Oleg Abramov analyzed thermographic data sets of the GreenHab and disclosed very steep vertical and horizontal temperature gradients. The ceiling and center are significantly warmer than the lower and outer parts of the GreenHab. Better insulation combined with continuous air circulation could remediate this. Thermography also indicated a problematic gap of 5 cms between the two chambers where heat is leaking (photo below).
[See Attached PDF for graphic]
The pH of the water in the hydroponics system was measured and was within an acceptable range: 8.1 (at 17.8°C).
The herbs that are being grown inside the hab are not in good condition. Most of the potted herbs are entirely wilted, and only about half of the cuttings seem viable still. Transport of the potted herbs was probably too harsh with low temperatures. It might also be better to root herb cuttings in water and not in soil.