What is Docksat

DockSat is an initiative of Corvos Astro Engineering. Its main goal is to discuss, promote and possibly produce a network of satellites that are assembled in parts using docking techniques and robotic support.

A way to think about it is to have small component satellites dock together and in addition have some of these components with robotic appendages that can be remotely operated for further structural integration tasks or maintenance checks. This is the fundamental idea but the implications are much more wide ranging.

Satellites could self-dock. They could also carry specific payloads rather than being complete all-in-one systems. Each satellite could be largely focussed on a system capability rather than have limited size for payloads.

A paper describing this in detail as well as a reframing of risk can be found at BIS-RS-2019-29-Breaking-The-Monolith-Corbett.pdf

What would this mean in practice:

  • Reducing satellite redundancy cost - aimed squarely at the "1 in 12 Problem" of space missions. On average 1 out of every 12 missions fails to reach a successful LEOP (Launch and Early Operations Phase)
  • Spurring the division of the space sector into sub-satellite stack component suppliers - The more specific types of satellite e.g. PowerSat, AntennaSat, PayloadSat, the more opportunities for expansion in the economy i.e. the power of the division of labour, as per Adam Smith
  • Creating the groundwork for the Configurable Satellite - much like using a Cloud Service, such as Amazon Web Services (AWS), time on a satellite stack could be purchased but with the extra addition of being able to configure the payload for different types of space survey or experiment.

All of this sounds exciting but it will not be possible without two key technologies: Viable Docking and the Space Battery.

Viable Docking is already being studied by various satellite maintenance programs, as well as small satellite projects such as CPOD (Tyvak) and within the European Space Agency. DockSat will propose its own type and test this on ground with drones.

The Space Battery is a concept of a lighter weight battery, either a form of Radioisotope Thermal Generator (RTG) using different radioisotope salts - Sr is an option, rather than plutonium or Americium - or using a different charge creation mechanism (proprietary). As a fallback, various solar panel arrangements could be envisaged. However the concept of having a simple 20 W battery per small satellite for example, coupled with the ability to create stacks of small satellites, means that the cost of implementing a larger power capacity would be cheaper than trying to create a large scale RTG as is currently being done.

Recent cost estimates for the Mars Science Laboratory RTG included the cost of the fuel. The RTG contained 23 kilograms of Pu which was approximately $2000 dollars per gram, or roughly $46M dollars per kilogram. At an optimistic 5W/kg this is 115 W per $46M dollars (not taking launch costs of $10,000 per kilo into account). Or $400,000 per W for the fuel.

Of course, the RTG will last for at least 20 years so the time cost is worth it, especially as there is no way to maintain or upgrade the power system. However for a satellite stack within easy launch reach, this type of development could be seen as an indulgence. For a Sr-based battery (with half-life of 28 years), assuming an optimistic 1W/Kg, the production cost of using Sr would be a factor of a hundred less. Sr is considered a waste product of nuclear processing - it could almost be given away.

Including launch cost and development cost, an estimate may be say $2 million to produce the 20W generator satellite. The same 120W could be achieved for $10M. This is not taking into account improvements in component development and cost reduction.

What this also doesn't address, is that the power supplies do not have to last as long either, as replacements can be brought up, as well as allowing the opportunity to safely park used satellites. DockSat after all involves satellites that can manoeuvre and dock.

Another option is a different charge creation mechanism, one that could be even more light weight and cheap to create. At the moment, DockSat has some proprietary ideas about how this will be achieved.

Plans

The main goals of this site at the moment are the promotion of the idea of splitting a satellite system into components that can assemble (even self-assemble). And that this opens up the possibility of scaled satellite development as opposed to monolithic development. If this sounds familiar it is because the same concept can be found in web applications with serverless technology, as well as product development using various agile or lean practices. These days it seems if you cannot scale, you are dead.

DockSat plans to achieve the same thing in the space sector. To further this a number of projects are ongoing.

The main one being the Overhead SSA web application - more information can be found at Overhead web app description

The web app can be found at Overhead @ Docksat