PRE2019 3 Group3

General information

Information about the groupmembers and the logbooks each week can be found here.

A full list of all the references used can be found here.

Problem statement

Setting

For years now, new initiatives to colonize Mars kept popping up all over the world. Examples include Mars One [1] and SpaceX [2]. It still seems far away, but when these plans eventually become reality, Mars will likely be covered with multiple colonies within the near future. While some companies and/or countries might try to work together to build one colony, others might end up establishing their own. This behaviour can also be seen in the construction of space stations right now. While the ISS is a collaboration between multiple space agencies, China is building their own space station in the form of the Tiangong program [3]. Because of political distrust, China is not allowed to collaborate on the ISS [4]. This distrust will probably continue when the time of Mars colonies is here. Some companies also might choose to build their own colony, like Bigelow Aerospace is doing with the Genesis program [5] when looking at space stations.

When these colonies are established, they will need resources to continue and expand. Delivering these resources from earth through rockets is time consuming and very expensive, so gathering as much of these materials as possible on Mars would be a better option. Ideally, these colonies would be build on locations that offer one or more of these resources, like water, building materials or minerals like copper and iron, at their site. However, these resources will eventually run out at the colony site and there is a possibility that not every resource is available at one location. This also could be a reason for having multiple colonies or a separate mining site. In this situation, trading or transporting resources between other colonies or mining sites becomes a solution. Just like countries here on earth trade with other countries to get their hands on things they can’t get in their own country, like for example oil, colonies on Mars could trade with each other to get easy access to the resources they need.

In order to build a colony, different factors to choose a certain spot for a colony have to be examined. To look at the different factors that determine what a good place to build a colony is, two different situations will be looked at. Firstly, there should be a good landing spot for the crew to arrive on Mars. Secondly, there should be a good location to actually start the colony. Ideally, these two locations should be on the same sport or really close to each other. For now, let’s assume the colony will be build on or around the landing spot, since too great a distance between them will create problems for travel. For a good landing spot, the landing area should be as flat as possible. According to [6] It also needs to be clear of rocks and boulders, since this would make landing dangerous and the landing area should not be too soft. It states that Mars has areas where the dust is several meters high, which is unfitted for landing. For building a colony, this also seems important. Building will be hard on areas that are too soft, since this would require better foundations. Non-flat and rocky areas can be not ideal for building, but can be worked around. [7] States that a good landing spot should be as close as possible to the equator, because this ensures that the solar arrays of the lander can deliver enough power at all times of the year and the temperature is high enough for the lander to stay warm. This factor is situational but can be really helpful when the colony will rely on solar power for generating energy. This will also decrease the power needs for warming the colony. Both previously mentioned articles say that the altitude of the area is also an important aspect. According to these articles, a lower altitude is better for landing. This means that there is more atmosphere above the land to slow down and steer for a good landing. [8] talks about food production which is another important aspect. At first the colonizers can live from provisions sent with them, but in order for them to live on mars indefinitely they have to grow crops. In order to grow crops there needs to be usable soil at the landing site and there needs to be enough water. Water is not only important for food production, but also for drinking or even as a fuel by turning it into hydrogen. Currently, the best way to get water on Mars is by gathering ice that is located underneath the surface on Mars. Ideally, this ice will be located as close to the surface as possible, since this makes it as easy as possible to mine. The image [9] below shows the depth of the ice on the surface of Mars.

As shown on the map, the ideal location for digging up ice according to NASA is noted with the white box. This is fairly close to the north pole however, which contradicts with the earlier mentioned preference of building the colony as close as possible to the equator. This already shows that there is not one ideal location to build a colony. Different countries/companies might choose a different location for their colony. Now, let’s assume some choose to build their colony close to the north pole, in the white boxed area, because they think water is more important than other factors. Now, other countries or companies choose to build their colony close to the equator, because they know other colonies can already easily mine water. They now value the better temperatures and sunlight more because they know they can buy and/or trade with the other colonies for water. This means that the citizens of the colony need a way of transporting water from colony to colony. Another possible option could be that a company chooses to build a colony close to the equator and a separate mining site for water. This way, they have the better temperatures and sunlight for solar power at their living area, the colony, and have a way to gather water on Mars. However, this again, brings the need for a transportation system between the colony and the mining site.

Problem

In order to trade or transport water from colony to and from another colony/mining site a way of transportation between the colonies is needed. Going out themselves is dangerous for the colony citizens. Radiation, low temperatures, dust storms and a toxic atmosphere [10] [11] [12] are all reasons to search for another solution than letting humans drive from colony to colony in person. Because of this, the colonies are in need of a transport system that does not require the citizens to go out themselves.

Solutions

There are a few solutions for this:

Option 1: Building a transportation conveyor tube.

Option 2: Building a protected manned transportation vehicle. This vehicle must be protecting the people inside from radiation and temperatures.

Option 3: Building a remote-controlled unmanned transport vehicle with cameras attached which will be controlled by someone in the colony. There must be someone controlling the vehicle.

Option 4: Building a transport robot that would be able to autonomously deliver water from the one colony to the other.

Comparing solutions

We are going to dismiss options by comparing the most important properties needed to solve the problem:

Option 1 can only transport from two static locations, while option 2, 3 & 4 are more dynamic in this aspect. Because of uncertainty of the location of the colonies in the current development it might be best to leave this one out. Also, with the big distance between colonies this could be an extremely big project that is way too expensive and would still need human help in the dangerous environment to build.

The difference between option 2 versus 3 & 4 is that if we are sending a human on the transportation vehicle or not. As stated before sending a human on the vehicle would be dangerous and would require the vehicle to be of much higher quality to ensure safety of the human inside, which is most likely much more expensive solution than option 3 & 4. Also the added weight of the drivers and extra materials in order to protect the drivers will increase energy consumption of the vehicle.

Now we are left with a remote-controlled transportation vehicle versus an autonomous transportation vehicle. The remote-controlled vehicle will be controlled by a human. This means that the human is always aware of its position and situation allowing to help with overcoming obstacles. This means that decision making will be in human hands which the users might prefer over handing the driving over to an AI. However, the remote-controlled vehicle requires a driver. Since distances could be pretty far in between the colonies/mining sites it would be a better option for the users since they don’t have to spend that much time driving and/or routing.

Because the user will most likely prefer a transportation system that does not require a driver, we have decided to go for solution option 4: Building a transport robot that would be able to autonomously deliver water from the one colony to the other. This robot will autonomously drive to a colony or mining site and will bring back water for the colony.

Alternative

There is one simple alternative namely, using no transport at all. This is the case if every colony can obtain enough water, such that no transport is needed. We in this case assume that only water transport is debated, not mineral. Though the robot in question will most likely be able to transport minerals as well. The 2 most likely ways any colonies will have enough water will be whether it is near a water source or not. There are 2 methods that do not rely on location based water obtaining techniques namely recycling and obtaining water from the air.

Water can almost perfectly be recycled. However, this is only possible when recycling human waste, like urine, not when the water is used for growing crops or industrial usage.[13]

Water can also be obtained from the air using humidifiers. One example is the Water Vapor Adsorption Reactor(WAVAR), an industrial-level dehumidifier, that could extract water from the atmosphere. This should be able to obtain some amount of water a day but this would not be enough when also water is needed for crops and such. This is also the reason it is not the first choice between getting water from the glaciers or soil. However, the WAVAR is a very energy efficient method, so it might still be useful under certain conditions.[14]

Using both techniques a colony would be able to sustain humans, but would not have enough water to also sustain water for growing crops and industrial use. Industrial use includes creating rocket fuel and usage for fabricating, processing, washing, diluting, cooling, or transporting a product. Large amounts of water are used mostly to produce food, paper, and chemicals.[15]

Objective questions

- What kind of transportation method will the transportation robot use?

- How will the robot obtain energy for transportation?

- What relevant information from the environment does the transportation robot need to percept to drive successfully from one colony to another?

- What kind of protection do the goods need while being transported?

- How will the robot determine its location?

- How is the robot going to define a path?

- How will the robot deal with complex situations? (Think of getting stuck, etc)

- What kind of distance does the robot have to travel? How long will this take the robot?

RPC list

Requirements	Preferences	Constraints
The robot has to be able to percept the environment accurately.	The robot has to be able to move around the martian surface efficiently.	The angle on which the robot can drive uphill
The robot must have the capacity to carry enough water	The robot must be able to go as fast as possible.	The maximum mass
The robot must be resistant to radiation, low temperatures, dust storms and a toxic atmosphere and needs to be able to protect the water from this as well
The robot has to be able to find a path across a known Martian surface with the possibility of alterations.

What does the robot already know?

The robot already knows the location of the colonies/mining sites and already knows the terrain of Mars in between. Unexpected obstacles such as boulders, duststorms or cave-ins are not known however.

Users

Technological Difficulties

Aside from the financial aspect, there are some other difficulties in conducting a journey to Mars. The most prominent ones will be elaborated here.

Distance

Mars is the planet that is closest to earth in our solar system. However, the distance that would have to be covered if we launch a manned vessel to Mars is still significantly large. On average Mars is around 225 million km from earth, with 55 million km at its closest, occurring every 26 months. This journey would take around 150-300 days, according to [16]. This is a reasonable amount of time, but the trouble lies in fuel consumption, as a manned vessel would be larger than a unmanned vessel, due to supplies that a manned mission needs. This would lead to a large fuel consumption. However, technologies are present to cover this distance in space with a manned vessel [17].

Housing

Three other factors to take in consideration are the atmosphere, the temperatures and the storms on Mars. As for the atmosphere, oxygen could be produced using the carbon-dioxide that is present in the Martian atmosphere [18]. For example, greenhouses could be built with plants that convert CO2 into O2 or a device for converting carbon-dioxide into oxygen could be developed. The temperatures range anywhere from -125°C to +20°C [19]. These kinds of temperatures are acceptable in the building of a space colony, with good isolation and air-conditioning systems. There are also severe dust storms on Mars from time to time. This means that a rigid structure needs to be built to withstand such storms, building underground or in caves.

Supplies

Once a group of people is settled on Mars, a huge challenge will be to supply them in their needs. First of all, food is needed to keep the population alive. This could be realized by both transportation of food from earth and, ultimately, growing food on Mars. Also building materials must be transported through space. This requires new rockets that can carry heavy loads. NASA is developing these spacecrafts [20]. This means that this issue, although very cost-intensive, can be technologically overcome.

In conclusion, we can say that a colony on Mars is possible in the future, because all the technologies to realize it is there. It is only a matter of further development and major investments to make this happen. This means that there will be a need for Mars-exploring robot technologies in the future.

The main users of the robots will be a Martian space colony. This colony is non-existent today. However, the idea of a Mars-colony is widely researched right now. NASA, for example, has launched several Mars-exploration-robots in the past [21] and still does extensive research on the planet today. There is also an organization that focuses solely on the development of a human colony on Mars. This organization is called Mars One and it focuses on the selection of astronauts and the raise of funding [22]. Mars One claims that all technologies to get to Mars and to begin a colony there, are already present. Only a return mission is impossible right now, but that will not be needed if the crew of the mission will settle on Mars. This means that, in theory, a Mars colony is feasible within the coming 50 years [23]. This means that the navigation technology, that we will design, is certainly of use for this yet to be founded colony.

Other parties of interest for this technology would be organizations like NASA, ESA, Space-X, Mars One, and other space-oriented companies, as they will be the organizations that will put people on Mars.

Stakeholders

The primary users of a device that can navigate itself across a planet, in this case Mars, are the people that live on Mars. At the moment, there are no people living on Mars yet. This means we should look at the probability for a Mars-colony to be formed in the near future. Most likely the first people that are send to mars will have certain skills. This includes engineers that are in charge of repairs. They are also secondary users since they are the ones that have to repair and perform maintenance on the robot. People have always dreamed about relocating the human race to another planet, in case something would happen to planet earth. This idea generates even more interest nowadays, than it did, say, 50 years ago, with the current problem of climate change affecting the earth. Now, more than ever, people are looking for another place to live in the galaxy. One of the most prominent candidates for this migration would be Mars, because it is ‘close’ to earth in comparison to other planets. Furthermore, it is believed to have water, which is a major life source, in its soil. But are we ready to move there in the near future?

The most recent commitments to researching permanent settlement include those by public space agencies NASA, ESA, Roscosmos, ISRO and the CNSA, and those by private organizations such as SpaceX, Lockheed Martin, and Boeing.[24]

Mars One

Mars One is an organization, that certainly believes that the colonization of Mars is possible. Mars One handles the selection procedure for astronauts that want to settle on Mars in the yet to be formed space colony. It is also responsible for raising funds in order to make the mission happen. In [25] they state that the formation of a space colony, instead of a visiting mission that has to return to earth, excludes most technological and cost-intensive problems. Namely, if people want to settle on mars, no return vehicle, return propellant or the systems to produce the propellant locally are required. This decreases technological challenges and reduces costs dramatically. Furthermore, they mention that all the technologies to send people to Mars and make them survive there are already present. This means that a Mars colony is certainly feasible within the next 50 years. However, in [26] they mention that the funds to actually develop a Mars settlement mission are not present right now (1 million USD of the 1 billion USD required). On the other hand, donations and investments might rapidly increase when more research is conducted in this field, and people would get convinced that a Mars colony is feasible. Also, if the situation on earth gets worse, people might have no choice but to invest in these kinds of missions.

SpaceX

SpaceX is another organization that has made plans to colonize mars.

NASA

NASA: Moon to Mars

Space Launch System

Manufacturers

The robot will most likely be manufactured on Earth and send to Mars via spacecraft. The company in charge of manufacturing can be part of the organization colonizing Mars or different private organization that is looking to make a profit. This will most likely affect certain decisions based on what their goals are.

Plan

Milestones

- Create a coordinate system for Mars that can be used by the robot.

- Relevant specifics of Mars environment that influences the navigation are known.

- Being able to create a virtual ground environment in a simulation that is similar to Mars.

- Determining the optimal specifics of the robot and it's sensors.

Deliverables

- Research on all relevant topics/objectives.

- Suggestions for a (best) solution for each objective.

- Presentation

State of the art

Preliminary version about navigation on Mars

State of the art

In the area of navigation on mars, there are several things that have already been tried. In order to understand what has already been done in the field of navigation on Mars, we need to have a look at the most recent, still working devices that have landed on Mars. In the past there have been a lot of rovers and other devices that have landed on Mars in order to explore the planet and its surface. However, the only two landers that are still active and in contact with earth are Insight (2018) and Curiosity (2012)[27]. All the other spacecrafts that have ever been on Mars are either broken, or have lost contact with earth in another way. There is also a future rover, scheduled to launch in 2020, which is called Mars 2020. Next, Insight, Curiosity and Mars 2020 will be elaborated.

Insight

The Insight Mars lander was launched in 2018 and landed successfully on Mars. Its primary goal is to investigate the ‘inside’ of the planet. More specifically its "pulse" (seismology), "temperature" (heat flow), and "reflexes" (precision tracking) [28]. It is a stationary device, as it does not navigate itself across the surface of the planet. Instead, it measures the key characteristics of Mars from one place on the surface, with the goal to determine how small, rocky planets in our solar system have been formed. Therefore, this mars lander does not contribute to the state of the art of our project, as we will focus on the navigation across the surface. However it might still have some value, as it maps the seismological activity of Mars. This could be of importance when navigating across the surface.

Curiosity

The Curiosity Mars lander was launched in 2011 and reached Mars in 2012. It is a car-sized Mars rover that will explore the Gale crater on Mars. The rover navigates itself across the surface of Mars by itself, which makes it an interesting device to look at for our project. Furthermore, its primary goal is to investigate whether or not life was ever possible. This means that it also looks for essential life conditions like water, oxygen, sulfur, phosphor and other minerals [29]. It uses very sophisticated techniques in order to collect samples from the Mars surface and to analyze them. To navigate itself across the surface, Curiosity uses so called ‘Hazcams’ and ‘Navcams’. These are hazard avoidance cameras and navigation cameras. These will be further elaborated.

Hazcams

The four hazard avoidance cameras are located on the lower front and back of the vehicle. They operate in black and white, using visible light to create a 3D-image of its surrounding environment [30]. It also works in tandem with software that allows the rover make its own safety choices and to "think on its own", which makes it autonomous. The cameras each have a wide field of view of about 120 degrees. The rover uses pairs of Hazcam images to map out the shape of the terrain as far as 3 meters in front of it, in a "wedge" shape that is over 4 meters wide at the farthest distance. The cameras need to see far to either side because unlike human eyes, the Hazcam cameras cannot move independently; they are mounted directly to the rover body.

Navcams

Mounted on the mast (the rover "neck and head"), these black-and-white cameras use visible light to gather panoramic, three-dimensional imagery. The navigation camera unit is a stereo pair of cameras, each with a 45-degree field of view that supports ground navigation planning by scientists and engineers. They work in cooperation with the hazard avoidance cameras by providing a complementary view of the terrain. [31]

Mars 2020

The Mars 2020 rover is basically a more advanced version of the Curiosity rover. It has as a goal to not only investigate if life was ever possible on Mars, but also to look for signs of microbiological life in the past. It will collect promising rock samples and store them for future investigation with equipment that is too large to take to Mars. Furthermore it will also look for ways to produce oxygen from the Mars atmosphere and for ways to collect water from the Martian soil [32]. It will use the same navigation instruments as the Curiosity rover, only a bit more advanced.

Navigation

[33] This paper describes multi createria dicision making methods for autonomous navigation for ground robots. According to the paper, this method should be able to let the robot make more precise alternative evaluations and minimize the probability the robot will be stuck or collide with objects.

[34] This paper is focused on underground mining. Uses four-wheel vehicles that minimizes curvature variation in the path it takes and stays in a certain safety margin from the mine walls. It presents a study that uses a B-spline for path determination. A B-spline (or basis spline) is a spline function. This means that the function can be reconstructed by connecting different polynomials. All possible spline functions can be reconstructed by connecting different B-spline functions.

[35] The focus of this paper lies on aerial robots in an underground mine. These aerial drones use both visual and thermal cameras to ensure a good understanding of the surroundings in order to map in these dark, dust-filled areas.

[36] This paper describes a framework for terrain characterization and indentification. This framework is composed of vision-based classification of upcoming terrain, terrain parameter identification via wheel-terrain interaction analysis and acoustic wheel-terrain contact signatures based terrain classification.

[37] This paper provides a new solution to the simultaneous localization and mapping problem with six degrees of freedom. he additional three degrees of freedom are yaw, pitch and roll angles. A robot on a natural surface has to cope with all of these degrees of freedom. With this solution an autonomous mobile robot can create a 3D map of a scene such as a mine or a cave.

[38] This article shows the parts of planet Mars that the robot is most likely to be on in case of harvesting missions.

[39] Mars orbital data explorer

Mars Terrain

[40] This paper investigates the slope distribution in the northern hemisphere of Mars from topographic profiles collected by the Mars Orbiter Laser Altimeter.

[41] This paper describes the calculation of slopes and the characterization of surface roughness using profiles obtained by the Mars Orbiter Laser Altimete.

OLD STATE OF THE ART:

General

[42] NASA plans to use multiple mining robots together in order to supply a colony with materials. These robots should work together in a "swarm". They will work individual first, but when one robot finds something interesting it will call the other robots in order to help it with extraction.

[43] Competition for students to build mining robots. Maybe a good place for inspiration.

[44] Maybe interesting. Not looked at yet.

[45] NASA page including all kinds of information sources about space colonies.

[46] Space Settlements: A Design Study. Includes information about all aspects of a space settlement including resources needed to maintain and expand.

[47] What do we need to know to mine an asteroid? States that science is nearly able to develop a space mining technology, only further knowledge of asteroid contents is needed.

Locating and mining materials

[48] While not about robots, this paper presents the method of using a detailed world model of the geological structure of the ground in order to locate different ores in the ground. It uses different sensors across the mining area, which could be placed on a robot which moves around, in combination with a supervised learning algorithm to build this world model. ~Might be interesting. No access to full paper yet however.

[49] This paper describes methods to build the spectral library to map geology on minefaces. The library includes multiple environmental conditions such as the inclusion of shade and moisture. Such a spectral library can be used by autonomous mining robots to identify different materials.

[50] In this paper an automated technique that allows a robot to classify the shape and other geological characterics of material from a 2D photographic images and stereographic data. This technique first seperates the material from the background after which various metrics are used to classify the materials sphericity, roundness, and other geometric properties.

[51] In this paper a new automated geological perception system is presented. It detects and classifies geological structures by using hyperspectral imaging sensors and a learning algorithm. Ultimately the system builds a rich model of the operating environment which can be used in autonomous mining.

[52] This paper gives information about an economically favourable mining technique called Optical mining. This method of mining will provide affordable mission consumables and radiation shielding.

[53] Asteroid Mining. Explores possibilities for space mining on asteroids. This paper comes to the conclusion that a solar powered mining vehicle, that runs on water and that mines water and platinum group metals, would be potentially feasible in the near future.

[54] Asteroid Mining. States how far we are on developing space mining technology. This might happen within a decade, once a cost-effective method is found. Also addresses financial, environmental and legal issues.

Transporting materials

[55] June 26, 1951 R. w. GAUSMANN APPARATUS FOR TRANSPORTING MATERIALS 5 Sheets-Sheet 1. Is about a technique for for transporting materials without changing the compounds temperature which may be necessary to prevent chemical changes in the material being transported, or to prevent it from solidifying within the car whereupon it would have to be heated to be removed therefrom.

[56] Describes a bag with means for vacuuming an internal space of the bag. This can extend the lifetime of organic matter.

[57] Extraterrestrial construction materials by M.Z.Naser. This review explores the suitability of construction materials derived from lunar and Martian regolith along with concrete derivatives, space-native metals and composites, as well as advanced and non-traditional materials for interplanetary construction.

[58] Space-native construction materials for earth-independent and sustainable infrastructure. This review covers feasibility of exploiting in-situ lunar and Martian resources as well as harvesting of elements and compounds, from near Earth objects (NEOs), to produce extraterrestrial materials suitable for construction of space-based infrastructure.

[59] Materials and design concepts for space-resilient structures. This paper presents a state-of-the-art literature review on recent developments of “space-native” construction materials, and highlights evolutionary design concepts for “space-resilient” structures.

Society

[60] Societal challenges in sustainable space mining. This article focuses on sustainable space mining and the issues it brings up. Potential issues are: 1) Legal issues 2) Issues in investment 3) International disputes 4) Environmental protection.

[61] Space Law in Asteroid Mining. In order to ensure legitimate space mining, countries need to update their own legislation and cooperate internationally in this area.

Research

Relevant information about Mars

General

Mars is a relatively small planet in the Solar system with a surface area of 144.798.500 squared kilometres. The highest point on Mars, the summit of Olympus Mons, is at 21.229 meters above the Mars areoid, and the lowest point on Mars, the bottom of the Hellas impact basin, is at 8,200 meters below the Mars areoid. This makes the topographic range of Mars 29.43 km while Earth has a topographic range of 19.7 km, meaning Mars is much 'rougher' in comparison with Earth. The Mars areoid is defined at a radius of 3.396.000 metres from the centre of mass. It is an useful measurement to define elevation. Mars has a equatorial radius of 3.396km and a polar radius of 3.376km.

An easy way to map coordinates is by using longitude and latitude coordinates.

On this map you see we can divide positions in x & y coordinates using a Cartesian coordinate system. 1 degree longitude = 59.27 km (x-axis), 1 degree latitude = 58.923 km (y-axis) The difference between the two numbers is caused between the difference in polar radius and equatorial radius.

Slope distribution

Median Slope

The median slope differs based on the based on the baseline length, the length over which the height difference is measured, which is used while calculating the median slope. The graph shown below shows the median slope of different geological formations based on the baseline length which ranges from 0.1 to 100 km [62]. The graph shows that the median slope decreases the higher the baseline length.

Steep Slopes

For kilometer-scale baselines, slopes steeper than the angle of repose, the steepest angle of descent relative to the horizontal plane to which a material can be piled without slumping, are scarce. In the complete MOLA (Mars Orbiter Laser Altimeter) data set there are a total of 105 point-to-point segments have slopes steeper than 35 degrees. 9 of these are probably data errors. The slopes of steep segments are sorted according to some feature classes in the table shown below [63].