2022-2023 Field Season (#22)

MDRS – Crew 186 – Final Geology Report

Research Project and Goals

The need to reduce payload mass for future space exploration is imperative, especially for long-term missions. Experts in the field or space exploration have been working for years on concepts of In-Situ Resource Utilization (ISRU). The idea of finding, collecting, processing, and using materials found at the destination requires various steps: we need to determine what materials are present and what is their abundance, accessibility, and usability; we also need to figure out what are the best ways to collect them; finally, based on the materials and their properties, we can decide how to process and use them. The simplest ISRU designs propose production of water, oxygen, and propellant [Sanders and Duke,
2005; Cuadros and Michalski, 2013]. However, establishment of bases on Mars will probably require the use of in-situ construction materials and metals, which must be easily accessible [Cooper, 2002; Curreri and Criswell, 1999;
Muscatello and Santiago-Maldonado, 2012; Sacksteder and Sanders, 2007; Wan et
al., 2015]. Identifying appropriate locations, with an adequate amount of resources will be a major factor for the selection of human landing sites, together with the scientific importance of the site [Horgan et al., 2013].

The goal of this project has been to test the use of remote sensing (performed in various locations) to support In-Situ Resource Utilization. Assessment of mineralogy and temperature readings – via remote sensing – has been performed to provide information about material abundance, water content and thermal inertia. The latter will be correlated to particle size and cohesiveness of the material, which in turn suggests the most appropriate tools to effectively collect the material for processing. Simple collection tools including rock hammers, spoons, and trowels have been evaluated in terms of ease of use, and efficacy of collection of the material, based on the physical properties of the material.

The MDRS region, in the Colorado Plateaus, is a good Mars analog, especially in the areas pertinent to the middle Jurassic Entrada Sandstone, the middle and and late Jurassic Morrison Formation, and the Dakota Sandstone. These areas exhibit mudstones and sandstones mainly composed of clays (montmorillonite, illite, and kaolinite, often coated with hematite), strata of paleo-gypsum and other sulfates, and recent evaporites. Most of those minerals are present close to regions of geological interest on Mars, and are dug on Earth for construction and other purposes.

Figure 1. Geology of the MDRS area

EVAs, samples, and results

Six geologic EVAs have been performed by the crew, visiting the following regions: URC North Site, area East of Greenstone Road, and The Moons (Morrison Formation and Dakota Sandstone); “Boilermaker Canyon”, previously unexplored by MDRS crews (Entrada Sandstone and lower Morrison Formation); Skyline Rim (Mancos Shale). The crew geologist and the rest of the crew collected a variety of samples in these location, and analyzed them with a “PANalytical QualitySpec TREK” portable spectrometer. The 86 Visible and Near Infrared (VNIR) spectra gave information about the mineralogy of the samples, and will be used to assess water content in the various locations. The geologist also measured temperature of rocks and soil at different depths and in different conditions, in replacement of measurements that were supposed to be taken with a thermal camera, which was not received in time for the mission. These measurements will be used after the end of the mission to determine the correlation between thermal inertia and physical properties of the material, such as cohesiveness and bulk size. The geologist used a rock hammer and a trowel to simulate collection of different material, under simulated Martian conditions for what concerns EVA suits and bulky gloves.

The EVAs brought the analog astronauts through diverse fields, ranging from plains covered in clays and characterized by salt deposits to deep canyons where million of years of strata are exposed. All the types of terrains are found on Mars, though the presence of large angular boulders is more prominent in most Martian landscapes. Analysis with the portable spectrometer confirmed the presence of mudstone and sandstone, with a few layers of conglomerates, mainly composed of illite and montmorillonite, with some samples of chlorite shales. The iron is almost all present in the form of hematite, thus reducing the occurrence of nontronite. Receding water from the Jurassic Sundance Sea left behind strata of salts in period of dryness. The salt is mainly sulfates, which (together with perchlorates) is present on Mars in various locations of geologic interest. White layers of gypsum, in the form of transparent selenite and white satin spar in the Morrison Formation, are accompanied by pink dikes of manganese sulfate in the lowest strata. Spectra will be further analyzed for water content and impurities. The results were extremely satisfactory, both in terms of Mars analog mineralogy and for what concerns collection of the samples with the various tools, and yielded useful outcomes for ISRU on Mars, described in the last section.

Difficulties and lessons learned: towards Mars

The experience in this project at MDRS was twofold informative, on the geology aspect and on the exploration aspect. The crew geologist, as an analog astronaut, had to face various difficulties in this mission: unexpected situations require a certain amount of flexibility. For example, the absence of the thermal camera, which can be considered analogous to an instrument malfunction, required a last-minute change in the details of the research project. Contingent situations, such as weather or communication failures cut short some of the EVAs, thus reducing the amount of time spent in the field, which of course is much less than what would be spent on a field expedition on Earth. Instruments which are very simple to use on Earth, such as the portable spectrometer or a marker to write on the clipboard, are much harder to use when the analog astronaut is incumbered by a space suit and bulky gloves. With much pride, our crew geologist managed to never break simulation, though at times he had to find ingenious solutions to be able to operate his instruments or to reach certain locations. On the other side, all these occurrences suggested ideas for better design of astronaut tools for use on planetary surfaces, where the presence of gravity needs to be added to the bulkiness of the garments (in orbit, astronauts experience the problem of large gloves, but can have a variety of tools just attached to their belts without their movements being made harder by gravity). Areas that require long walks because not accessible by vehicles suggest that surface EVAs will be probably shorter than in-orbit EVA: the crew geologist performed four EVAs in five days without particular overexertion, but a single EVA to Boilermaker Canyon was harder than multiple EVAs, because of the configuration of the terrain and the longer hiking distance. From a geologic perspective, the site also provided valuable lessons: besides the analogies with Martian mineralogy, the MDRS site gave information on how to use remote sensing to evaluate the abundance of the material, and some of the physical properties to facilitate collection. The mission also showed how much variety of material can be found within short distances, which suggests that more detailed surveys of interesting locations on Mars will be necessary to determine optimal places for human exploration and activities.

In conclusion, despites all the limitations to the fidelity of the simulation (gravity and atmospheric conditions, not-airtightness of the habitat and the space suits), the crew managed to achieve an adequate level of Mars analogy in the geologic EVAs. The landscape, the colors, the cumbersomeness of the suits, and the attention given by the crew to simulation details gave the impression of being exploring Mars and added to the challenges of the experience, producing outstanding results.

Bibliography

Clarke, J. (2003), The regolith geology of the MDRS study area, report.

Cooper, J. (2002), Mining Mars, CMA Management, September 2002, pp. 38-41.

Cuadros, J., and J. R. Michalski (2013), Investigation of Al-rich clays on Mars: evidence for kaolinite-smectite mixed-layer versus mixture of end-member phases, Icarus, vol. 222, pp. 296-306.

Curreri, P. A., and D. R. Criswell (1999), In situ production of solar power systems for exploration: potential for in situ rectenna production on Mars, AIP Conference proceedings, vol. 458, pp. 1623-1628.

Gundlach, B., and J. Blum (2013), A new method to determine the grain size of planetary regolith, Icarus, vol. 223, pp. 479-492.

Hargitai, E., ed. (2008), MDRS unofficial expedition guide, technical report by MDRS crews 42 and 71.

Horgan, B., J. A. Kahmann-Robinson, J. L. Bishop, and P. R. Christensen (2013), Climate change and a sequence of habitable ancient surface environments preserved in pedogenically altered sediments at Mawrth vallis, Mars, 44th Lunar and Planetary Science Conference.

Jones, E., G. Caprarelli, F. P. Mills, B. Doran, and J. Clarke (2014), An alternative approach to mapping thermophysical units from Martian termal inertia and albedo data using a combination of unsupervised classification techniques, Remote Sensing, vol. 6, pp. 5184-5237.

Muscatello, A. C., and E. Santiago-Maldonado (2012), Mars in-situ resource utilization technology evaluation, 50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition.

Presley, M. A., and P. R. Christensen (2010), Thermal conductivity measurements of particulate materials, 4. Effect of bulk density for granular particles, Journal of Geophysical Research, vol. 115 no. E07003.

Sacksteder, K. R., and G. B. Sanders (2007), In-situ resource utilization for Lunar and Mars exploration, 45th AIAA Aerospace Sciences Meeting and Exhibit.

Sanders, G. B., and M. Duke (2005), In-situ resource utilization (ISRU) capability roadmap executive summary, NASA report.

Sanders, G. B., and W. E. Larson (2015), Final review of analog field campaigns for in situ resource utilization technology and capability maturation, Advances in Space Research, vol. 55, pp. 2381-2404.

Wan, L., R. Wendner, and G. Cusatis (2015), A novel material for in situ construction on Mars: experiments and numerical simulations, Northwestern University Center for Sustainable Engineering of Geological and Infrastructure Materials (SEGIM) internal report.

MDRS_Final_Geology_Report.docx

The Effectiveness of Radio Direction Finding for EVA Navigation in Situations of Low Visibility

Justin Mansell

MDRS Crew 186 Journalist

Motivation

Determining one’s position is a fundamental problem encountered in engineering. On Earth it is possible to use the constellation of GPS satellites to accurately pinpoint your position relative to a location where you would like to go. This capability does not currently exist on Mars, nor will it be likely to exist when humans first set foot on the planet. The difficulty of localizing an astronaut’s position relative to a location of interest is amplified in conditions of low visibility such as night or an unexpected dust storm. The resulting disorientation could greatly imperil any astronaut caught unprepared in such circumstances.

The purpose of this research was to explore how a disoriented astronaut might use radio signals to guide them to a target while on EVA. The core concept is to have the astronaut carry a radio antenna whose sensitivity is directional. Meanwhile, a navigation beacon at the target broadcasts a radio signal in all directions. If the astronaut is unable to locate their query by traditional means they can use the directional radio to determine the direction of the transmitting beacon, and therefore the direction they must walk to reach it.

Figure 1: Searching for the direction of maximum signal.

Experiment Setup

Prior to the mission I assembled a 3-element handheld Yagi antenna from schematics researched on the Internet. The particular design uses foldable elements made from steel tape measure and originated with Joe Leggio for use in amateur radio foxhunts [Leggio, 1993]. This design is lightweight and easy to stow due to the foldable elements. A coaxial cable with an SMA adapter allows the antenna to be plugged into virtually any portable ham radio.

The transmitter beacon is a commercial handheld ham radio with no special modifications. I created an audio file of a Morse signal toning the phrase, “This is the MDRS amateur navigation beacon crew 186”, and broadcast this signal from the beacon by connecting an iPod playing the audio file to the radio with an aux cable. In each test of the navigation experiment the radio beacon was located at the habitat and the Morse signal was broadcast at regular intervals by having a crewmember simply hold down the transmit button. A crewmember on EVA would then attempt to use the Yagi antenna to locate the direction of maximum signal and thereby the bearing to the habitat. The beacon was transmitted on the low power setting of the beacon radio (approximately 2.5 Watts) at a frequency of 146.565 MHz.

The Yagi antenna was used to aid EVA navigation on a total of four EVA’s, two of which were dedicated exclusively to testing its effectiveness. On the first two tests I followed a road on the outward trek and then attempted to follow the navigation signal along a straight line back to the habitat. This took me through unfamiliar terrain but did not adequately represent conditions of low visibility. On the later two tests I gave the antenna to a crewmember unfamiliar with amateur radio and covered the upper two thirds of their helmet with a cardboard visor. This restricted their vision to approximately 5 meters and prevented them from using landmarks to help them locate the habitat. Supporting members of the EVA then led the “lost astronaut” volunteer at least 2 kilometers from the habitat and monitored their safety as they attempted to return to the habitat using the radio alone.

Figure 2: Preparing the lost astronaut before EVA.

Results

The first two tests of the navigation antenna were useful for understanding its performance. The accuracy of the antenna in locating the direction to the beacon generally improves with distance. This is because close to the beacon the signal is strong enough to saturate the receiver even along its insensitive axis. The beacon signal therefore appears to originate from all directions. At greater distances the beacon signal is weak and careful pointing of the antenna may be required to receive it at all. At a distance of 4 kilometers the accuracy of the antenna in determining the bearing to the habitat appeared to be better than 10 degrees. This was reduced to over 90 degrees when within a kilometer of the habitat and worse still when even nearer.

During the tests I found that the poor accuracy of the antenna near the transmitter could be mitigated in the following way. The antenna is least sensitive to incoming signal along a direction parallel to the receiving elements. By searching instead for the direction of minimum signal I could deduce that the beacon was located at a right angle to my current pointing direction. This provided acceptable accuracy at sub-kilometer distances.

On the tests with the cardboard visor limiting the astronaut’s vision the difficulty of navigating by natural senses alone was professed by the arcing paths participants took prior to and in between broadcasts of the navigation beacon. In fact, on the final test the mock “lost astronaut” walked a complete circle with a radius less than 100 m in between two broadcasts of the beacon. To limit the drift of the astronaut’s path it was necessary to decrease the intervals between the beacon transmissions to a nearly continuous broadcast. In both tests with the cardboard visor the astronaut was able successfully navigate to within 500 meters of the habitat despite limited knowledge of their initial position and orientation.

I also note that the surrounding terrain did not appear to have a significant detrimental affect of the performance of the antenna, but this has been difficult to quantify.

Figure 3: Scanning to find the bearing to the hab.

Recommendations

The navigation experiments of MDRS Crew 186 suggest that a handheld directional antenna is a simple and effective means of EVA navigation in low visibility conditions. However, the current set up has several limitations which are noted below.

The current means of searching for the direction of maximum signal provides only the direct bearing to the transmitter beacon. As was found in several of the tests, following a direct path to the beacon is not always possible due to intervening terrain. The user is then on their own to determine an appropriate detour and this may act to further their disorientation. Additional information may be required beyond that provided by a directional antenna in order to navigate successfully.

At distances close to the transmitter the technique of searching for a direction at right angles to the directions of minimum signal proved satisfactory in our experiments. However, because there are always two such directions the astronaut is at risk of following a path directly away from the beacon instead of towards it. This is possible when receiving along the sensitive axis of the antenna as well, but is less likely because the signal strength received by the back lobe of the antenna is generally much weaker compared to the front. Instead of searching for the direction of minimum signal, a better solution would be to attach an attenuator between the antenna and receiver so that the astronaut can reduce the received signal when close to the beacon.

Finally, the rapid drift of participants from their initial heading in between broadcasts of the beacon suggests that either the navigation beacon should be broadcast continuously or astronauts should have some way of preserving their orientation while walking. The later option is desirable because terrain, weather, or the need to handle equipment may temporarily prevent the signal from being received. On Earth an obvious solution is to mark the desired bearing on a compass and follow it accordingly, but this will not work on Mars due to the lack of a global magnetic field.

Figure 4: Finding the habitat using its radio beacon.

Bibliography

Leggios, J. (1993), Tape Measure Beam Optimized for Radio Direction Finding, http://theleggios.net/wb2hol/projects/rdf/tape_bm.htm.

Acknowledgements

I would like to thank Geoffrey Andrews, Jennifer Pouplin, and Cesare Guariniello at Purdue University for their assistance fabricating and testing the Yagi antenna prior to the mission.

Nav Experiment 13Jan2018.docx