Case Study: Salami Tactics

Episode 6 is about “how to waste money and human ingenuity”, this bonus article is a case study on how the habits on publishing – sometimes described as “minimum publishable unit” – actually hinder scientific and engineering progress. How this results in the waste of public money in government grants and how bright minds are kept in a hamster wheels instead of actually making progress. This is not only bad for the space industry this is also bad for society. Let’s have a look!

Note: the example that I have selected for this is the Fluid Dynamic Actuator (FDA). The FDA is a new and innovative attitude control actuator. It is an example from TU Berlin which I have chosen not to say that this university is better or worse than any other but just because it is my Alma Mater and so I know the particulars best.

Why University Research

Before we start with this article, I would like to draw attention to the question why we do research at universities and other publicly funded institutions. It is certainly not merely to amuse researchers and engineers but to drive our nations and humanity forward. For this reason society puts aside resources to fund research that is so far out and thus would otherwise (under market economy) not have been done.

Public funded research boldly goes where no one has gone before. It is a precious resource and should be applied with great care.

Every country struggles to generate enough funds to pay for those and there is the expectation that society will benefit from this in the long run. It is therefore important to imagine this money as a precious resource that should not be squandered. The same is true for the bright minds that do this research. There are never enough people who want to do an academic career when an industry job is often more financially rewarding. We can therefore consider these researchers an equally important public resource and as such we need to carefully apply it.

Unfortunately, it does not pay to conclude research and innovate

The problem is well known to anyone who has worked in academia: your prestige and career is dependent on the number of publications (and citations) as well as the amount of third party research money you have towed in for your institution. More often than not this is also rewarded financially in your payslip. As you may have noticed efficiency, thus getting the job done is not included in either of these two markers. If you are working on a scientific topic it is better to continue researching instead concluding it and you are valued on how much money you towed in (and spend) rather than how much you have achieved. These two things lead to the following negative effects, first you are incentivized to write and publish as many publications in peer reviewed journals as humanely possible.

In public funded research your success is measured by your publications, not how much you have progress you have achieved

As the exciting facts of your research are a limited resource this leads to an effect also described as “minimum publishable unit” [1] where the researcher will publish the results of its research in the smallest steps accepted by the community. In turn this means that the adding to the body of knowledge is delayed.

You are incentivized to publish often and consequently spread your research in slices. This delays progress.

At the bottom line and as an unintended consequence this will slow down progress and thus squander both money to pay the researcher as well as its lifetime. The second effect is that each researcher is incentivized to A) apply for as much funding as possible to save its own job for many years and also get a good standing with the university and B) do not report sudden success (if it should happen) as this would cut end the project, unspent money is returned to the grant giver and the scientist would end its own source of salary, something that – especially considering the tedious nature of applying for grants – only very few people would be inclined to do.

If you are achieving success faster than anticipated you are at risk losing your funding. So nobody ever is.

To give a bit life to this otherwise dry topic I would like to draw your attention to a project of the German Research Association (DFG). Under number 184525799 and from 2010 to 2016 the Technical University of Berlin (TU Berlin) received a grant to perform “Investigations of Fluid-Dynamic Actuators for Attitude Control of Pico- and Nano Satellites”. Before we dig deeper I would like to state that unlike many other research projects that TU Berlin performed in the last two decades, this is one that I particularly like. It’s new and innovative and far away from normal stuff that industry would likely not dare to do it self funded. Therefore, it saddens me specially when I see that much of its innovative potential went to waste due to moral hazard of the parties involved… but I am getting ahead of myself. Let’s do this proper and so before we look into what makes the Fluid Dynamic Actuator (FDA) unique, we need to establish the state of art.

State of the Art of Attitude Actuators for Small Satellites

Many applications of satellites require the precise orientation of the satellite in a specific direction. In addition to attitude sensors, there are devices that control this movement. These attitude control devices are called actuators. Small satellites have access to all attitude actuators (propulsion based actuators are admittedly very rare) that exist in large satellites, too. In the following I will describe the different classes from simple to complex.


Magnetorquer rods or air coils are among the simplest attitude control actuators. They make use of the reaction force between a magnetic field in the space craft and the earth magnetic field. The main drawback is that they can only actuate a force that in an angle to the direction of the earth magnetic field. Magnetorquers are thus always under actuated.

No alt text provided for this image

Reaction Wheel

A reaction wheel makes use of the fact that the angular momentum of a satellite stays the same unless external forces are applied. That means if you have a rotating disc inside the satellite and spin it up the satellite will spin in the other direction so that the resulting angular momentum is zero. The first small satellite reaction wheel in space was flown on TUBSAT B in 1994. It was designed the tutelage of Professor Udo Renner. Since then reaction wheel have become a staple for small satellite missions. Including wheels for 1U CubeSats which were, too demonstrated first at TU Berlin and have now found wide spread adoption by industry.

No alt text provided for this image

Control Moment Gyro

One drawback of reaction wheels is the limited amount of torque available. This limits the dynamic of the wheel. One way to work around it is to not speed up the wheel but rather tilt the entire wheel assembly and work with the reaction moment. The first space object to have a CMG was the Skylab space station in 1973. Since then it has been used in various satellites that require very high agility most notably high resolution EO satellites such as Pleiades HR. In recent years miniaturization has brought CMGs to small satellites, too. The smallest CMG available are likely Honey Bee Robotics [3].

No alt text provided for this image

Spherical Reaction Actuator

While a reaction wheel normally can only support one axis and a fully actuated satellite thus needs a minimum of three wheels a reaction actuator in ball form theoretically could actuate all three axis. During my studies at TU Berlin Prof. Udo Renner often spoke of the possibility of such a design but would dismiss it due to inherent complexity issues. And even today, outside research they have very little application. Indeed, what is sold as a spherical reaction actuator by Tensor Tech [7] is to my understanding more a two axis CMG than a real spherical wheel.

No alt text provided for this image

Reaction Thruster

The utilization of reaction thrusters is actually one of the oldest means of attitude control. It was already used in the early day of crewed spaceflight. Since a reaction control system (RCS) requires a multitude of thrusters and valves it is more difficult to include it into a small satellite. That said there are ongoing developments to make this technology accessible and thus allow interplanetary small satellites.

How to achieve high torque at low system complexity?

The challenge of reaction wheels is that despite their simplicity it is difficult to achieve high torque profiles. One can implement a motor with higher torque profile but at the expense of high power consumption. On the other hand a CMG can implement a high torque profile at the expense of high system complexity and cost. Therefore there was a need for an alternative solution.

What’s new?

The researchers at TU Berlin thus came up with the idea of a fluid dynamic actuator [5]. This innovative concept replaces the rotating disc with a liquid metal inside a round tube which is pumped in the circle by, well an actual pump.

No alt text provided for this image

This approach allows a simple implementation and very high torques at low power consumption. I did mention that this is a cool concept?

The fluid dynamic actuator (FDA) creates angular momentum by using a pump to move a liquid metal inside a tube.

And since I like it, I offered the research team of TU Berlin the possibility to collaborate on multiple occasions. Unfortunately, even though this would have drastically decreased time to market, the researchers were incentivized against it and so the technology was confined in TU Berlin for 5 years.

What’s wrong?

No alt text provided for this image

The test flight of the first FDA was planned on the TechnoSat of TU Berlin. Since this satellite was delayed and I was personally very interested to see this technology in space I offered a free flight opportunity on one of BST satellites. This was however declined because FDA was promised to first fly on a TU Berlin satellite. This meant that it would fly 2 years later than it should have and we all know that new technologies have no chance to get into operational use until proven.

The researchers insisted to fly it on a TU Berlin satellite in 2017, which delayed the in orbit application of FDA by 2 years.

In addition in 2017, once the unit was built and tested I requested to purchase three units and again fly it on one of BST’s satellites where fast reaction capabilities of FDA could have been used to increase mission performance. This was again refused because this 3-axis implementation would have jeopardized the chances of an add on research grant which was aiming to establish 3 axis control using FDA [10].

In 2017 a request to purchase multiple of the now flight proven FDA was declined because that would endanger further grants

In the end the project that started and was innovative in 2010 is still ongoing in 2021. Beyond the prove of concept and building of a first prototype was launched on Technosat [8], three units of a marginally improved version were launched on SalSat [10] and half sized picoFDA tested on a sounding rocket [12] and was launched on BeeSat9 [11].

Three DFG grants were provided to keep the FDA project running from 2010 to 2021. One grant would have been more than enough.

In my opinion, latest after the first prototype was qualified in space this project should not have received any further funding as the improvements that have been achieved afterwards are only incremental and the government R&D money would have been better spent on something new and innovative. Consequently, the FDA which was patented [9] would have better fared as a commercial product from that point onward.

positive news! You now can buy the FDA at www.ElmSpace.Space 🙂

No alt text provided for this image

There are however also positive news: in 2019 the leading researcher of the FDA project founded the company Elmspace. So if today you wanted to buy a flight proven fluid dynamic actuator for your mission – you can!

What could be done different

I personally think the academic system of university rankings, peer reviewed papers and public funded research projects is fundamentally broken and needs nothing short of a major overhaul. It would lead too far and I feel myself not sufficiently qualified to propose something better. However, there are a few suggestions: first of all you cannot blame the (junior) researchers who do the work and are trapped in this mill. I see the responsibility with the supervisors as well as the grant giving organizations. They need to realize their responsibility towards society and show a better stewardship of public money. One potential avenue of improvement would be to judge not by number of publications but by content. How much and how long did the researcher take to solve a specific problem. Unlike today it should not be to their disadvantage to be fast. Therefore, a paper containing the full solution needs to be valued more or at least as much as a series of salami publications. Secondly, it needs to be beneficial for the researcher to do the work faster and with less resources. My suggestion is that if a project is concluded early the researcher can move the remaining money over to a new project (of a different nature) including supported commercialization.

Salami tactics which are common in academia are bad for society. We need to come up with better incentives.

No alt text provided for this image

As a practical example for the fluid dynamic actuator one could have done the following: once the researcher realize, that they will finish the FDA in 2014 (instead of 2016) they report that to the grant giver. The grant giver would then freeze the grants and two options are provided to the researcher; either spin-off the technology using an Exist spin-off support [13] in such case the not used funds could either be added to the Exist grant to the free peruse of the newly born founder or they are kept with the research organization (in is case this would be TU Berlin) to purchase FDA flight models for their satellites from the new company. Or, in case the researcher does not want to do spin-off, the remaining research funds are allocated for the team to do new research of their chosing. They will further will receive extra points for finishing their research topic ahead of time which will then be increasing their score when applying for new grants.

How can you help:

This text is part of a series of articles in which the author sets the framework to start a discussion about the wrongs of the space industry. If you have experienced similar things, leave a comment. Other views and opinions are very welcome, too, as they may present a way forward. Please be kind to each other.


The author’s views are his own do not represent the views of Berlin Space Technologies.


[1] Minimum Publishable Unit – Wikipedia

[2] Control moment gyro – Wikipedia

[3] Honey Bee Small Satellite CMG – honeybee website 02.10.2021

[4] Microwheels – TU Berlin website 02.10.2021

[5] Fluid Dynamic Actuator – TU Berlin website 02.10.2021

[6] DFG grant FDA – DFG webpage 03.10.2021

[7] Spherical Actuator – Tensor Tech webpage 03.02.2021

[8] FDA on technosat

[9] FDA patent

[10] Three Axis FDA on Salsat

[11] CubeSat FDA – TU Berlin website 02.10.2021

[12] Cubesat FDA on sounding rocket

[13] Exist grant






Leave a Reply

Your email address will not be published. Required fields are marked *