Science Report – January 13th

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

Science Report – January 13th

Science Report (Microbiology)

13JAN2018

Author: Samuel Albert, Crew 186 Health & Safety Officer

Collaborators:

-Marshall Porterfield, Ph.D., Purdue University, West Lafayette, IN, United States

-Sarah Wallace, Ph.D., NASA JSC, Houston, TX, United States

-Sarah Stahl, M.S., NASA JSC, Houston, TX, United States

As part of my role as Health & Safety Officer of MDRS Crew 186, I have been conducting research on the microbial environment in the habitat and greenhouse at MDRS. To do this, I am using the sample-to-sequence method developed by spaceflight microbiologists at NASA including Dr. Sarah Wallace and Sarah Stahl, M.S. This method uses a combination of polymerase chain reaction (PCR) and DNA sequencing technology. Specifically, I am using the miniPCR and minION devices, as were used in the Genes in Space-3 experiment on the International Space Station (ISS).

The testing at MDRS is meant to survey the microbial environment in the habitat as an analog for operational monitoring that would be necessary on a Mars base. The ability to perform real-time DNA sequencing will help diagnose infectious diseases and monitor crew health on long-duration space missions. Thus, conducting this research at MDRS increases the fidelity of simulation while collecting useful data on the microbial environment in the habitat.

Four runs were planned originally. The first run encountered errors and yielded poor results, only about 350 reads. The second run, which sampled from crops growing in the GreenHab, yielded much better results, over 600,000 reads. This run was in collaboration with the ongoing experiments by GreenHab Officer Mark Gee. The third run, which sampled from locations on the upper deck of the habitat, yielded strong results as well, about 26,000 reads. The fourth run, which sampled from the bathroom and shower area on the lower deck of the habitat, unfortunately yielded the worst results, with a paltry 34 reads. In the case of the first and fourth runs, any one of the many steps could have gone wrong to produce such a low read count, but the most likely reason is that the flow cells were damaged at some point. The fourth flow cell had over 1000 active pores when a quality control test was performed early in the mission, but less than 600 active pores immediately prior to sequencing.

Following the mission, all results will be analyzed to assess which microbes were found in the various sampling locations. Return samples are also being sent to the Dr. Wallace at Wyle Laboratories at NASA JSC for post-mission sequencing, which will help validate results for runs 2 and 3 and help provide results for runs 1 and 4. These results will be compared with data from similar studies on the ISS (i.e. Genes In Space-3) as well as with data from other analog stations.

Samuel Albert, Crew 186 Health & Safety Officer

Science Report – January 10th

Science Report – Microbiology

10JAN2018

Author: Samuel Albert, Crew 186 Health & Safety Officer

Of the four DNA sequencing runs originally planned, three have been completed so far. The first run encountered errors and yielded poor results, only about 350 reads. The second run, which sampled from crops growing in the GreenHab, yielded much better results, over 600,000 reads. The third run, which sampled from locations on the upper deck of the habitat, yielded strong results as well, about 26,000 results. The fourth run, which will be completed in the last few days of the mission, is planned to sample from the bathroom and shower area on the lower deck of the habitat. Following the mission, all results will be analyzed to assess which microbes were found in the various sampling locations.

Science Report – January 8th

Science: Geology

No geology was performed on today’s EVA, except for collection of salts and clay samples in the region of the Moons. However, there was quite a bit of good lab work: thanks to troubleshooting with PANalytical, the TREK portable spectrometer is able again to communicate with the geologist’s laptop which will allow for quantitative analysis of the spectra.
In the meanwhile, work on the samples collected in sol 4 show the richness of the Moons region: Yellow Moon yielded sulfates (mainly gypsum, in the form of selenite), clays (montmorillonite/nontronite, and illite), hematite, and even some light volcanic ash (andesite). Beige Moon have similar composition, with an abundance of large layers of very pure gypsum.
Sulfates and clays are present on Mars, and constitute regions of high geological interest, since they can indicate hydrothermal
paleoenvironment. Human mission could make use of certain types of clays, analogous to those here on Earth, for construction. This makes the research on those materials even more interesting!

Science Report – January 7th

Science: Geology

EVA #6 was by far the most exhausting of our first 7 sols, but it was definitely worth it (more details in the EVA report). Our excursion into our little “Noctis Labyrinthus”, which we named “Boilermaker Canyon”, brought us into a quite different geological setting than the Morrison formation around the hab. The region is deeply eroded by Muddy creek and its seasonal tributaries, and forms deep canyons and high-walled mesas. The lowest strata belong to the Entrada Sandstone, dating to the middle Jurassic (180-159 million years ago). The location was slightly further away from the Sundance Sea, therefore it is characterized by an impressive sequence of thin layers of sandstone, at times interrupted by mudstone collars. Green colored layers are indicative of wet conditions that occurred in swampy, stagnant environment (reducing environment). The predominant feature that distinguishes this formation to the far Northeast of the habitat is the presence of layers of finely grained salts, indicators of a shift from wet to dry conditions, in which shallow water produced evaporites. In addition, the whole thickness of the formation is crossed by a large number of clastic dikes, most of which constituted by evaporites.
The EVA crew collected samples of the salts and the sandstone both on the way down and at the bottom of the canyon.
Though the route is rough, I hope many geologists will take advantage of the opportunity to study this breathtaking region, which was to date unexplored by any MDRS crew.

Cesare Guariniello
Crew Geologist – Boilers2Mars
Mars Desert Research Station

Science Report – January 5th

Science: Geology

EVA #5 revisited the location to the East of Greenstone Rd, in search of the elusive hematite-coated “blueberries”. Unfortunately, though spectra showed traces of hematite mixed with clay, no spherules were located. Nonetheless, the long EVA was satisfactory since it went through a variety of terrains, including stream beds, dunes, and various layers of sandstone and conglomerate formations. On the way back, the crew stopped at the Kissing Camel Ridge, where -among the sandstone and mudstone layers of the Morrison formation- the crew found boulders collapsed from the Dakota sandstone and conglomerates that top the Morrison formation.

Cesare Guariniello, PhD

 

Science Report – January 4th

Science: Geology

EVA #4 brought our crew to the Northwest of the habitat, in a region called “Yellow Moon”. The whole region sits between the top member of the Morrison formation (Brushy Basin) and the bottom of Mancos shale, and it is heavily weathered, with soft clay soil. The predominant geological feature of this region is the presence of salts, especially gypsum, from the region of Glistening Seas, through Beige Moon and Grey Moon, all the way to Yellow Moon. Besides samples of crystals, we collected some sandstones with traces of salts.
The different accretion of gypsum crystals, most often occurring in thin layers, and rarely in romboid shape, suggests different water and evaporation processes. The samples will be analyzed in the laboratory, since the short EVA time was just enough for in-situ selection and collection. The area presents outstanding views of the whole region, as described in the EVA report.

Thank you
Cesare

Science Report – January 3rd

Imagine that you are planning an expensive trip to a remote, amazing location that you always dreamed about. A couple of days before your trip, already with your enthusiasm through the roof, you pack your bags with clothing, some electronics and a few treats. Then, you call the agency to discuss the final details, and they tell you that you will be able to drive your vehicle there, and you are welcome to sleep in it. The location is so remote that they do not have any building available for you. In addition, they cannot provide any water. Ah, and there is no gas station anywhere near.

You think a little bit, and realize that this means that you will have to carry with you all the water you need to stay there, and all the gas you need to come back. Furthermore, if you want to sleep in anything better than your car or a tent, you will need to bring with you all the materials to build a better habitat. Obviously, this solution is going to be very expensive because your car will not be enough to transport all of that: you will need a large truck, or maybe multiple vehicles.

However, you have always been quite brilliant, and you think of a possible solution that will allow you to still take your trip, at the cost of a little extra effort: you could figure out if there are water sources at your destination, maybe with the help of your friends who know some geology and some chemistry. Likewise, you decide that you might modify your car and make it capable of using some fuel that you will be able to find or produce at your destination. And if you could also find some building material, then you would need to carry only a few extra tools, but your car would still be enough to reach that breathtaking place!!! The beauty of this place, and the awe you will feel once you are there, are totally worth the work required to make the trip feasible.

This is exactly what all of the people involved in the effort of Mars exploration are doing. It is called ISRU, which stands for In-Situ Resource Utilization. It means that we will not carry everything we need with us, but we will study our destination, figure out what we can find or produce there, and how to do it. The geology research performed by crew 186 is supporting the study of potentially useful materials for ISRU on Mars. In particular, the crew is studying minerals that have been detected on Mars and that are used on Earth for construction and other applications (kaolinite, gypsum), in addition to materials that have geological interest (hematite spherules, sulfates) and occur in the same location. This is suggesting what ISRU materials could be find in regions of potential interest for human landing on Mars, and it will guide the choice of tools for collection of such materials.

The Geology report on Sol 1 described the goal of the geology project of crew 186 in technical details. Future reports will combine technical results and descriptions with other non-technical explanations (similar to this report) of the reasons for the research we do towards our common objective, so stay tuned!!!

Cesare Guariniello, PhD

 

Geology Report – January 2nd

Crew 186 Geology Report 02JAN2018

The plan of today’s EVA included the two locations that were not visited yesterday: the area East of Greenstone Rd and the area between Robert’s Rock Garden and Zubrin’s Head, both in the Morrison formation. During the drive outbound, the crew geologist gave a short introduction to the other EVA members, who had not participated in the first EVA.
The crew spent a long time in the field, and the geologist was able to select, analyze, and collect various samples of clays in different strata of the Morrison formation. The search for hematite spherules was only partially successful, with two potential candidates found in the second site. The geologist also recorded temperature of the samples, for later analysis of thermal inertia of the material. The problem with the portable spectrometer is currently being addressed by personnel at Purdue.

😊

Cesare Guariniello, PhD

Science Report – January 1st

Science: Geology.

The goal of the geologic project of Crew 186 is testing the use of remote sensing to identify suitable minerals for In-Situ Resource Utilization (ISRU) and to analyze their physical properties for collection and use. Thus, several geology EVAs are scheduled, focusing on materials that are found on locations of geological interest on Mars.
The plan of today’s EVA included three locations, all within the Saltwash and Brushy Basin members of the Morrison formation, South and Southwest of the habitat: the area between URC South Site and Kissing Camel Ridge, the area between Robert’s Rock Garden and Zubrin’s Head, and the area East of Greenstone Rd. The crew geologist gave a short brief to the rest of the crew (a more in depth introduction to the geology of the area is scheduled for tomorrow), and instructed them on the type of samples to be collected during the EVA: different types of clays in the first two locations, and hematite inclusions (spherules, or “blueberries”) in the third one.

Due to delays in the first phases of simulation, the EVA started later than planned, and was consequently cut short. The EVA crew members reached only the first location, and upon directions by the geologist found appropriate samples. The samples were photographed and analyzed with the TREK portable spectrometer. Temperature of the samples was not recorded, due to the reduced duration of the EVA. The samples collected today were a chlorite sandstone, illite/hematite soil, a montmorillonite mudstone, and a clays conglomerate. Once back from the EVA, we reviewed the spectra of the samples, comparing them visually with the USGS library spectra; however, it was not possible to download the data from the portable spectrometer to a laptop, due to a software error which has not been yet been solved. We will work on the connection problem tomorrow, or failing that, all the analysis can be performed after we return to Earth.

HAPPY NEW YEAR
Cesare