PRE2018 3 Group1

Group members

Name	Student ID
Max van Mulken	1006576
Mart Hagedoorn	1
Niels Verstappen	0999624
Rani van Hoof	1026024
Kees Voorintholt	1005136

Introduction

This wiki is an information page about a study on a huge problem that is known as the Kessler Syndrome. This Kessler Syndrome is basically a form of cascade failure. It starts with for example two satellites colliding, this collision will cause a lot of debris to fly around in orbital space. This debris will then again collide with other debris, space stations or satellites, which can eventually lead to a shield of debris around the planet earth.

The importance of this problem will be further explained and several solutions will be considered and discussed.

The study is done for a TU Eindhoven course: Robots Everywhere (0LAUK0). While studying this problem and its possible solutions, it is made sure that the 3 USE aspects: User, Society and Enterprise, are central.

Problem definition

As mentioned in the introduction the problem that will be studied is the Kessler Syndrome. In the long term this shield of debris around the earth can have disastrous consequences. Starting with the consequence of not being able to send any new satellites into orbital space as they would get smashed by orbital debris immediately. At the speed of which these objects travel they will just shatter in tons of smaller objects and travel straight ahead. This means that now all these smaller pieces make a cloud of debris of which the total area is bigger than it was before it crashed. This cloud will destroy everything it encounters, only making the cloud of debris bigger and bigger.

But why would this affect the ordinary human being living his life on planet earth, the orbital debris is in space right why would we care? Well at the point where we have no more satellites in orbital space there will be quite some changes to our way of life. How would we make the important business call to a CEO on the other side of the world? How would we know what the weather will be for the coming weeks? All these things will become impossible without satellites.

Also it might seem like a future problem that we could maybe still prevent, however that is not true, in fact it has already started a long time ago. There are numerous reports of orbital debris colliding with satellites or space stations, the US government logged 308.984 close calls and 665 emergency alerts in 2017 alone ^[1]. Furthermore, on average a satellite crashes to the earth once every week which causes a rain of space junk that will burn up on the way to the earth. However some of this space junk may stay in orbit, which means the amount of orbital debris keeps increasing.

To have some kind of visualization of how much orbital debris is already out there, there are about 650.000 objects between the size of a softball and a fingernail. Next to that there exist approximately 170 million pieces of space junk that are smaller than the tip of a pencil ^[1]. All of this together with the roughly 23.000 satellites, rocket bodies and other human made objects, make a huge amount of objects flying around in orbit.

So if you had the impression that this problem was not very relevant, think again because it will change our ways of living drastically

Objectives

While studying the subject we have set several objectives for ourselves:

• We want to find as many solutions as we can to clean the orbital debris by using a robot.
• For every possible solution that is considered we want to assess the feasibility, the effectivity and the financial cost. This way we can get a clear image on which of the solutions might be the best.
  • We want to show that the best solution is a significant improvement for the Kessler Syndrome by running simulations.
• To support the feasibility of the best solution we will also use visual representations of several simulations.
• The robot has to be autonomous, such that it can operate without a human controlling the robot.

USE aspects

While the problem described above is a very ambitious one to solve entirely, we believe the work we can do in 8 weeks is more than enough to impact multiple stakeholders. We will identify stakeholder groups and look at what our project can do for these groups.

Users

The users of this project are hard to define. Since the project aims to do research at the development of an autonomous robot which cleans up orbital debris, there are no real direct everyday users who will directly be influenced by the success of the project. The real users of the product are most likely going to be enterprises that specialise in “space infrastructure”: enterprises like NASA that launch satellites and other space crafts. Since these enterprises have direct access to the resources to launch objects into space, and have the experience of doing so as well, they are most suited to apply the product if it were ever to be finished.

Society

The product aims to prevent or even solve the problem that the Kessler Syndrome poses, in the extent to which that is still possible. If prevention of or a solution to this problem is no longer possible, it will at least attempt to reduce the consequences and growth of the problem. The Kessler Syndrome poses multiple complications that will influence society in a major way.

Since the Kessler Syndrome will cause everything in orbit to be in danger of being damaged and/or destroyed, it will be very hard for humans to launch and maintain satellites into orbit. This has a number of consequences, since satellites are very important for society today. First of all, they allow us to do a lot of research of the entire solar system and even beyond the solar system, expanding our knowledge of our place between the stars. Perhaps even more important to some people, satellites have allowed us to be way more accurate when predicting weather forecasts and potential storms, which is not only nice when you are planning a camping trip but can also be a lifesaver when it concerns a hurricane prediction. Also, since communication over large distances works in straight lines, satellites have greatly increased the distance over which communication can work correctly, along with increasing quality of communication. Instead of having a direct communication channel between two points which can be blocked by a large building or a mountain, communication via a satellites allow the communication to avoid large obstacles. Society has prospered and greatly benefitted from these communication channels, delivering the Internet, modern television and even radio stations to millions of people around the world. Finally, satellites play a key role in navigation. The GPS (Global Positioning System), which is used by every piece of modern navigation technology, has not only allowed individuals to find their way around but is also used by giant infrastructures like air traffic control, and is used by corporations like Google to provide society with an all-inclusive map of the entire world. It is safe to say that satellites are key to modern society, meaning development of the Kessler Syndrome to disallow satellites would be disastrous.

Later stages of the Kessler Syndrome could form a cloud of space debris in orbit that would make it too dangerous to send any spacecraft either into or past orbit. This not only limits satellites, but we would no longer be able to send out missions to other planets or moons because of a fear of the spacecraft getting destroyed. We as a society would be forever stuck on Earth, unable to accomplish the dreams science-fiction has set out for us.

Enterprise

Enterprises that would suffer from this problem, were it not to be addressed, would be both enterprises that focus on space exploration and any enterprise that benefits from sending satellites into orbit. As discussed above, there are a lot of enterprises which would suffer from a lack of satellites since communication methods would suffer severely. Next to these indirect consequences, more direct consequences are suffered by enterprises like NASA and SpaceX. These enterprises focus on space exploration and flight research to bring multiple benefits and large chunks of knowledge to the general public. Both of these tasks, especially space exploration, will become a lot harder were the close Earth orbit to be home to huge amounts of debris. It would greatly increase the risk of crafts being damaged when send into or beyond orbit. Thus, it is in these enterprise’s best interest that the Kessler Syndrome’s effect is reduced.

State of the Art

One of the most important things to do at the start of this project is to understand the state of the art of the current technology. The literature study is divided in two relevant topics: How to track space debris? How to remove space debris?

The first will cover the state of the art in finding and tracking debris in space. Where the second will focus on the methods on how to remove pieces of debris from space. We will divide the topic on how to remove space debris in several parts, such that all parts focus on the state of the art of one method.

Literature study on tracking space debris:

There is already a lot of information available on debris that is in orbit around the earth. The sources of this debris are normal launch operations, certain operations in space, fragmentations as a result of explosions and collisions in space, firings of satellite solidrocket motors, material ageing effects, and leaking thermal-control systems. To track those pieces of debris several techniques are developed. At this moment the pieces of debris that are bigger than 10 cm can be tracked. Nowadays, space-object tracking is done with radar technology. To track debris, a radar beam is aimed to a predetermined position in space. When a piece of debris is observed, this piece will be tracked and the motion of the debris is saved. With the motion data of the debris the orbit can be calculated. With this technology we can track pieces of at least 10 cm, but pieces of debris greater than 1 cm can seriously damage satellites. At this moment tracking of debris that is smaller than 1 cm is extremely hard because of the size, but also the reduced orbital stability. Also the total number of objects we have to track when we reduce the size threshold exponentially increase.

In July/August and April/May 2013 a new technique for space debris tracking was tested. Here a laser was fired and the reflected signal was received. Then the time between the laser that was fired and the received signal can be used to calculate the distance. These techniques of tracking space debris can be used for tracking satellites with reflectors, but not yet to track smaller pieces of debris. To be able to track smaller pieces of debris, we need to upgrade the laser power, laser irradiance and efficiency.

Literature study on removing space debris:

• Net

One of the techniques to remove space debris is to capture space junk with a net. A satellite has to identify pieces of space debris and capture with a net that is tethered to the satellite. Once such an object is captured small rockets can be used to drag the satellite and object back in the atmosphere. This technique is being tested today and a first experiment has been successful. A satellite has been successful in capturing a dummy satellite with a net in low orbit. The research group says: “Our small team of engineers and technicians have done an amazing job moving us one step closer to clearing up low Earth orbit”.

• Harpoon

The same experimental satellite RemoveDebris that was successful in capturing a piece of space debris earlier in 2018 has also been equipped with a harpoon and a drag sail. Soon, in early 2019 as stated by the development group RemoveDebris will shoot a pen-sized harpoon at a composite target that will be deployed by the International Space Station. The idea is that RemoveDebris could afterwards deploy a drag sail that would speed up the deorbiting process of the satellite. This will also be tested by the satellite but separately from the harpoon experiment. A drag sail will be deployed so the satellite can re-enter the atmosphere and this will be the final experiment of RemoveDebris.

• Laser

The idea is simple, take a laser and gradually evaporate space debris till it doesn’t exist anymore or it changes of orbit. A lot of research has been done into this solution, it has been estimated that with a ground based laser it would be possible that under the right circumstances an object could be slowed down by 1 millimeter a second. For most objects it would still take a long time before they are slowed down enough for them to break up in the atmosphere, but with this technique it would be possible to avoid major collisions.

• Gecko-inspired robot

Another technique on removing space debris is inspired from a gecko, the gripper that is used can be compared with the fingers and toes of the gecko. A gecko can hang upside down by their toes, since the toes are covered in a kind of bristles that stick when moved in one way and can easily be removed when moved in the other way. The grabber used the same adhesion technique, when the grabber is moved in the right direction, the debris will stick to it. The robot was tested in a zero gravity environment and could grab debris in a shape of a cube or an beach ball. This technique is not yet fully developed, next steps could be to develop sensors that could help monitor adhesion and the robot still needs to be tested outside the space station in a more extreme environment.

• Magnets

The last technique we will cover is using magnets to deorbit pieces of debris. This solution does not require contact with the debris, because magnetic fields can influence each other without contact. Therefore it is safer for the robot to use magnets, since no contact is required. The technique is based on magnetic field, these fields can attract or repel pieces of debris, to change the orbit or to completely deorbit it. To create a magnetic field, superconducting wires are used that are cooled to extreme low temperatures. These field can then influence the orbit of multiple pieces of debris at once. A disadvantage of using magnets, is that they will not influence pieces of glass or aluminium and therefore the robots using magnets are only useful for debris that is made from elements that react to magnetic fields.

Approach

Planning and division of work

Date finished	Concern	Responsible member(s)
09-02-2019	Introduction, Problem Definition and Objectives	Niels
10-02-2019	Planning, Approach and Milestones	Rani & Max
09-02-2019	State of the Art analysis	Kees & Mart
08-02-2019	USE aspects	Max

Milestones

Date	Milestone	Remarks
04/02/2019	Determine subject for the project	Subject chosen: Cleaning up orbital debris
10/02/2019	Finish State of the Art analysis	-
17/02/2019	List of possible solutions to the problem	-
	Comparison of the solutions and conclusion on best fit(s)	-
	Concept design on chosen solutions	-
	Simulations of chosen solutions	-
	Comparison of simulated solutions and final conclusion	-

Deliverables

The deliverables are as follows:

• Wiki page

This wiki page will describe the project progress in detail and will be updated weekly. It will contain all relevant information about the project and links to the end products.

• Robot designs

The wiki will contain a list of possible robot ideas that might aid in a solution to the Kessler Syndrome. These ideas will be compared, and the most promising ideas will be developed further into a concept design of an autonomous robot capable of cleaning orbital debris.

• Simulations

The designs of the robots will be put to the test in simulations that sketch the practical workings of these robots.

• Presentation

This presentation will be held during week 8 of the project and includes an introduction of the problem followed by possible solutions and a comparison of these solutions by using the above mentioned simulations. This ultimately leads to a recommendation of the best solution.

References

[1] Mosher, D. (2018, april 15). The US government logged 308,984 potential space-junk collisions in 2017 — and the problem could get much worse. Retrieved february 7, 2019, from https://www.businessinsider.com/space-junk-collision-statistics-government-tracking-2017-2018-4?international=true&r=US&IR=T