Tinkerbell On OrbitThe Tiny Canadian Spaceship 

by Eric D. Tarkington (Back to Home Page) 

Why We Fly 

Some of us have the strong impression that, at some point in the not-too-distant future, the success of the human outreach to space will decide some crucial issues for the planet. 

With the biosphere now irretrievably in human hands, we have no choice but to become skilled in managing the Earth, and the view from space offers too many learning opportunities to be ignored. At the least, it will deepen our understanding of the Earth, and at the most, it may provide solutions that will save life, or greatly enhance life, among humanity's billions. 

Space exploration and research started as a competition between global superpowers, financed by governments, and driven by military and strategic considerations, but commercial uses of space developed quickly in the form of communications satellites. From the beginning, the world's people and their governments have always expressed their hopes for non-military applications of space technology for the benefit of humanity. 
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On Orbit, the Road Ahead 

Today, space is no longer an arena for military or governmental competition -- space must become a field for free and independent research and commercial development. Although governments have an indispensable role to play, NASA now talks in terms of going from a "space mission" to a "space movement", and new areas of space development must follow the path of communications satellites into private hands. 

With the International Space Station, the world is setting out to colonize space, nothing less. For all of its size, cost, and complexity, the Space Station is only a small beginning, but it will provide a secure, long-term, human environment in space, where we can learn the skills that we need to thrive and prosper outside the nurturing envelope of the Earth. 

We don't know exactly how to do it yet, but what we're talking about is an academic and industrial park in the neighborhood of the space station. 
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The Canadian Role 

In this enterprise, Canada is perfectly able to play an important role. With its heritage of achievements in communications and robotics, and its ongoing role in providing the main robotic arms for the Space Shuttle and the Space Station, Canada is already in this game. What we must do now is choose development targets in areas where we foresee needs emerging in the new space arena. This article is about a pilot project for just such a development area. 
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Development Opportunities 

It's easy to get the impression that we are experienced in space operations. People from this planet have been to the Moon, put large living quarters in Earth orbit, spent periods measured in months doing laboratory work on orbit, and done subtle repairs on several complex pieces of space hardware without bothering to bring them back to the terrestrial factory. 

These are all solid achievements, and they say a lot about human capability in space, but the fact is that we still don't know exactly what we're doing, and that is the reason why we will continue to need humans in space. We will continue to take on things that we don't know exactly how to do. Humans are incredibly slow, clumsy, and inefficient on many tasks, but they can make novel adjustments to unpredictable conditions in seconds or minutes -- things that machines or systems will not be able to do for a very long time. 

For all that automation can do (and your author is a software pro who works in automation), human hands-on intervention is indispensable in creating the kind of environment that we need for an intellectual and industrial revolution in space. 

The problem is, putting humans in space is very expensive, and will continue to be so (barring some very aggressive new initiatives) for at least another decade. At one point, for example, the projected cost of Extravehicular Activity (EVA), was a very serious problem for the Space Station budget. 

The International Space Industrial Park will need to avoid EVAs, and any other risky or labor-intensive human activity on orbit, to the fullest possible extent. The humans will always have too much to do, and their time is precious. 
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The Tiny Spaceship Rationale 

Canada is very well positioned to help maximize the benefit of human time in the Space Park. One thing that we are well-prepared to do is an initiative that I have informally called "Tinkerbell" (a little light that flies around) for the past several years. Tinkerbell is a small, teleoperated, free-flying inspection robot for use in the Space Park or with the Space Shuttle. It's the Tiny Canadian Spaceship, and it is entirely feasible from the technical point of view. 

The savings in Space Station EVAs for inspection alone could easily pay for the Tinkerbell development many times over, but the overall plan does not stop there. 

The Space Park will be a line in orbit, centered on the Space Station, and at most a few kilometers in length, in which various free-flying industrial and research craft will keep station. Tinkerbell will serve as a testbed for the technologies of propulsion, command and control, and automation, which will allow the development of standards, which will allow reuse of equipment and technology, which will cut the cost of servicing free-flyers, and open new free-flyer possibilities. 
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The Tinkerbell Proposal 

(Link to Tinkerbell Design Notes) 

The initial Tinkerbell proposal is for a cheap, safe, free-flying inspector robot. It can perform close inspection (up to 10x magnification), or provide a "God's eye" view of docking or other activities in the neighborhood of the Shuttle or the Space Station. It is expected to travel less than one kilometer in a given mission, and its operating period without recharge (or special conservation methods) is roughly eight to twelve hours. 

As a testbed, Tinkerbell will have design features that go well beyond the minimum requirements for the initial mission. In point form, Tinkerbell has the following features: 

  • Modular and Extensible 
  • Flying Camera 
  • Two Light Booms 
  • Portable Remote Control 
  • Designed for Manufacture 
  • Off-the-Shelf and Cheap 
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Crucial Design Strategies 

The cheapest and simplest way is always used, and the discovery of new ways of reducing cost (technical, developmental, and operational) is an intentional objective of research. 

We keep the ship cheap by using simple technologies and the maximum of off-the-shelf components. We keep the ship safe by giving it a low-power, pressurized nitrogen propulsion system, and by other simple measures. 

The Initial Design 

At this point, the concept is for a craft that is basically cylindrical in overall form, about one foot in diameter, and about 2.5 feet in length. The craft masses about 40 lb. The four basic modules are the tug, the main video camera, the remote control unit, and the berthing system. 

The Tug 

The Tug is the part of the project that serves as the functional core for the ship, and the testbed for future developments. The tug contains the microcontroller, control bus, propulsion, power, ship radio communications, and grappling systems. 

The Main Video Camera 

The Main Video Camera contains the camera, separate power, light booms, and a grapple fixture that mates with the tug. 

The Remote Control Unit 

The Remote Control Unit is built around a laptop PC, which interfaces with the control transmitter/receiver, the video receiver, and the video windowing unit, which displays the video image from the tug in a window on the PC screen. 

The Berthing System 

The Berthing System can serve as a launch cradle for the free-flyer, but normally serves on the Space Station as the stowage and recharge facility for Tinkerbell when the craft is not in service. It contains a microcontroller, gas reservoir, and solar power collector to recharge the spacecraft and camera system batteries. 
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The Tug & Grapple Approach 

The architecture of the tug is the basis for the flexibility of the system. The tug is studded with grapples at the fore, aft, top, bottom, port, and starboard. The grapples are attached to a strong frame within the skin of the tug, and they extend the control, power, and video busses from the tug to any manipulator with a compatible grapple fixture. The main video camera and the berthing system are both manipulators from the tug's point of view. 

In fact, any piece of equipment is a manipulator, so long as it has a compatible grapple fixture. 

The tug & grapple approach is one of the main research areas for Tinkerbell: can we design and demonstrate a highly reusable, low-cost core system that can lower the cost of a wide range of free flyers in the Space Park? Is this architectural approach effective? 
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Reuse in Other Applications 

For an example of one potential application (and there are others), some free-flyers in the Space Park will be used for specialized materials manufacture that needs more perfect microgravity or vacuum than what can be achieved in the immediate environment of the Space Station. How will these factory free-flyers be serviced and operated economically? 

Planning to use regular manned missions to these factories, with or without EVAs, would make many potential factories economically unfeasible. Making the factories capable of significant amounts of flight operation would add to the cost of the factories, and require a large expenditure on risk analysis and engineering, due to operation of massive fliers in close proximity to the Space Station. 

Using Tinkerbell, a less expensive approach to free-flier factory design and operation becomes possible. The factory is designed with no propulsion system for flight. One module of the factory contains all parts that do not need to be moved after the factory is in position (solar panels, for example), and the other contains a portion of the factory (the "nut") that needs to be handled for frequent servicing and collection of the finished product. 

This kind of factory can be placed in the Space Park using a disposable, once-only propulsion subsystem (possibly, this "subsystem" could be nothing more than an extra nitrogen tank for the Tinkerbell tug). Tinkerbell grapples the factory, guides it slowly to its station in the Space Park, and releases. With the factory in position, Tinkerbell flies to it from time to time, to swap the "ripe" nut for a "green" one. At the Space Station, the ripe nut is held for pickup by the next shuttle, or taken aboard for human handling. 

The things to note about this example: 

  • Modularity and interface standards make this kind of cost reduction possible, 
  • There is no organization on Earth that has announced an initiative with a similar industrial development plan, and 
  • Canada is well-positioned to do the early engineering in this new field, and to set the international standards. 
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Benefits to Canada 

The benefits to Canada could be very significant. Assuming that the financing can be arranged, some Canadian academic institutions and space engineering businesses will receive direct compensation for the spacecraft research and development. Success in creating the standards for interface (power, video, data) and control, and demonstrating the capacity to fly a working vehicle, will create opportunities for free-flyer projects that might not be possible without the space tug capability. 

Grasping a leadership role in the technology will create opportunities for international participation in newly-enabled free-fliers by Canadian corporations. Working with international standards organizations will consolidate the Canadian reputation in the field, thus helping to realize international projects. 

Correct development of standards will allow the same technologies to be used in other areas (heavier vehicles, greater distances), such as satellite servicing and the lunar return mission. 
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How the CSS Can Help 

The Canadian Space Society can be involved in several ways. There are countless details that need work, even in the simplest spacecraft we can imagine. Here are some of the things that need to be started as soon as possible: 
  1. mission and applications plans 
  2. requirements analysis and preliminary design 
  3. research (off-the-shelf components, interface and control engineering, risk analysis, low-power propulsion, communications....) 
  4. contact with potential participants and financing sources 
Thinking it through and talking it up: these are the things that CSS teams can do, if the members are interested. CSS has agreed to at least one presentation in the '96-'97 season of the CSS Speaker Series. In the meanwhile, send your comments to the author, care of the Canadian Space Gazette, or via email to edt@myna.com. 
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This article is a slightly altered version of one that was originally published in the Canadian Space Gazette of Sept/Oct 1996.