About Michael Paluszek

Michael Paluszek is President of Princeton Satellite Systems. He graduated from MIT with a degree in electrical engineering in 1976 and followed that with an Engineer's degree in Aeronautics and Astronautics from MIT in 1979. He worked at MIT for a year as a research engineer then worked at Draper Laboratory for 6 years on GN&C for human space missions. He worked at GE Astro Space from 1986 to 1992 on a variety of satellite projects including GPS IIR, Inmarsat 3 and Mars Observer. In 1992 he founded Princeton Satellite Systems.

Our Visit to ITER in the South of France

On September 22 Marilyn, Eric, and I visited ITER, the International Tokamak Experimental Reactor in Saint-Paul-lez-Durance, France, about 45 minutes from Aix-en-Provence. We took the TGV from Paris to Aix-en-Provence.

Our tour started with a talk by Akko Maas who gave a great presentation on fusion. He talked about building ITER. The complexity of the project and the large international team both present challenges. He also discussed the advantages of fusion in comparison to wind and solar. He noted that while a fusion reactor would have some waste, both wind and solar, when decommissioned, have waste. He talked about the next phase after ITER called DEMO. ITER is designed to produce 500 MW of fusion power from an input of 50 MW heating power. Akko had a slide listing some of the commercial fusion efforts.

Katya Rauhansalo was our tour guide. She had a couple of assistants. They were all really helpful and very knowledgeable. We discussed many fine points of Tokamak design and fusion in general. Marilyn, Eric, and I were combined with a larger group, due to Covid absences. We chatted with members of the other group about PFRC.

A Tokamak is shown below. The green coils are the center stack coils used to induce a current in the plasma. The gray coils are the poloidal coils. The purple coils are the toroidal coils. In ITER, all coils are superconducting. The green donut in the middle of the D coils is the plasma.

The following image shows the Tokamak building.

The first stop was the manufacturing facility for the poloidal coils. The following video shows a crane in operation in the assembly hall.

The top and bottom coils are small enough that they can be shipped complete. The others need to be manufactured. The following figure shows the cryostat for testing the poloidal coils.

This poster gives the details of the testing.

We then moved through the entrance to the Tokamak. We were able to enter the Tokamak building itself. Here is Eric in front of an installed toroidal superconducting coil.

The coil is shaped like a D which works better than a circular coil.

First plasma was scheduled for 2025 but may be delayed. This was partly due to Covid and partly due to the inevitable technical glitches in such a complex project.

Annie Price Presents, “Nuclear Fusion Powered Titan Aircraft” at IAC 2022 in Paris France

Annie Price, who was an intern at Princeton Satellite Systems during the summer of 2021, presented our paper, “Nuclear Fusion Powered Titan Aircraft,” at session C4,10-3.5 which was the Joint Session on Advanced and Nuclear Power and Propulsion Systems.

There were many interesting papers. One was on generating electric power in the magnetic nozzle of a pulsed fusion engine. Another was on the reliability of nuclear thermal engines. The lead-off paper was on a centrifugal nuclear thermal engine with liquid fission fuel.

Annie’s paper covered the design of a Titan aircraft that can both do hypersonic entry and operate at subsonic speeds. Her design uses a 1 MWe nuclear fusion power plant based on PFRC and six electric propeller engines.

She discussed the aerodynamic design, why Titan is so interesting and how the available power would enable new scientific studies of Titan. Annie also described how a PFRC rocket engine or power plant operates. She included a slide on our latest results.

The paper was well received. She had a couple of good questions after her talk and engaged in interesting discussions after the session. Great job Annie!

International Astronautical Congress (IAC) 2022 in Paris, France

IAC 2022 is underway! Annie Price, a former PSS intern, and Mike Paluszek are attending. The Congress has hundreds of technical talks and poster presentations. In addition, there is a huge technology showcase area. Both companies and government organizations have booths. Here are some photos from the show floor.

A 1 N green propellant thruster. It is a few centimeters in length.

The green propellant thruster is from Thalinia Space.

Batteries

Enersys showed its advanced space batteries.

This is a 2-axis sun sensor and a simulator. The sun sensor is the world’s smallest.

Needronix also has a nice transceiver.

The European Space Agency has an enormous booth!

I also met engineers from Boeing, DLR, Teledyne, Lockheed Martin, MDA, Sierra, Rolls-Royce, Saudi Arabia, South Korea, Slovakia, Sweden, and many other companies and countries. There were at least three robot arms on display, including one by Kinetik Space.

This one has selectable end-effectors.

I met an engineer who worked on the Apollo program. His area was radiation hardness. He said back then, no one knew much about the problem.

There were excellent talks on Tuesday on formation flying and rendezvous. Annie is presenting our talk on a fusion-powered Titan aircraft on Thursday, in SESSION 10-C3.5, Joint Session on Advanced and Nuclear Power and Propulsion Systems,” In W08 at 13:45.

2022 HiSST Meeting in Bruges, Belgium

I attended the 2022 HiSST meeting, the 2ND INTERNATIONAL CONFERENCE ON HIGH-SPEED VEHICLE SCIENCE AND TECHNOLOGY, in Bruges, Belgium. Bruges is a lovely city and I highly recommend a visit. It is walkable and has many excellent restaurants, museums, breweries, and chocolate shops.

Our session was on Rotating Detonation Engines. Ralf Deiterding (University of Scotland) and Sarah Mecklem (University of Queensland) were the chairs. There were three talks, mine on “Rotational Detonation Engine for Hypersonic Flight”, a talk by Prof. Deiterding of the University Of Southampton on, “Design and testing of a low mass flow RDE running on ethylene-oxygen,” and one by Yue Huang on, “Study on Fuel Injection and Geometry of Plane-radial Rotating Detonation Combustor.”

Prof. Deiterding’s talk showed his team’s impressive experimental work. He had movies of their experiments in operation.

Yue Huang discussed fuel injection into an RDE showing the pros and cons of three different approaches. His team’s work looked at mixing in the combustor instead of pre-mixing.

My talk gave an overview of RDE technology. I discussed research at Princeton University on the stabilization of the RDE flame front. Good results have been obtained with ozone injection and plasma injection. I gave the results of our analysis showing performance advantages over a conventional turboramjet. We use a turbocharger to pressure the RDE at low Mach number.

I discussed applications including hypersonic boost guide passenger airliners and two stage to orbit launch vehicles. An RDE might allow first-stage Mach numbers in excess of Mach 7.

On Thursday the Conference dinner was held. It was a three course dinner at a restaurant on the North Sea. The rain cleared for the event.

The venue was beautiful. A band played throughout the reception and dinner.

It was announced that the 2024 HiSST meeting will be held in Pusan, South Korea.

Nuclear Thermal Propulsion to Mars

For orbital transfers to Mars, a Hohmann transfer is often proposed since it minimizes the fuel consumed. Here is what that looks like.

This was generated by the Spacecraft Control Toolbox function DVHoh.m. 255.2 days is a long time for a crew to be exposed to cosmic radiation. NASA has proposed using a nuclear thermal engine to speed things up. The best combustion engines, like the RL10B-2, use hydrogen and oxygen and have a specific impulse of 465 seconds. This is obtained by running them hydrogen-rich. Nuclear thermal, which is only heating hydrogen, can reach 900 seconds. The higher your specific impulse, the less fuel you use for a given velocity change.

A mission to Mars consists of an Earth escape segment, a heliocentric segment, and Mars entry. You can do them all with the same rocket or use separate stages or methods. For example, you could depart from low-Earth orbit (LEO), do the transfer, and enter low-Mars orbit (LMO) with one stage. As an alternative, the launch vehicle could take the Mars transfer vehicle into a heliocentric orbit. Instead of using the transfer stage to do a powered entry into Mars orbit, you could use aerobraking. Aerobraking could be used, in theory, for both Mars entry and to replace the burn into Mars heliocentric orbit (that is, to match the heliocentric velocity of Mars).

We wrote a MATLAB script in the Spacecraft Control Toolbox to explore some of these concepts. Here are the results:

Specific impulse nuclear thermal 900.00
Specific impulse H2/O2 465.00
Tank Fraction 0.10

Time Hohmann 255.23 days
Time Fast Transfer 150.23 days

Mass fraction Nuclear Thermal Hohmann 0.30
Mass fraction Nuclear Thermal Fast 0.12
Mass fraction H2/O2 Hohmann 0.05
Mass fraction H2/O2 Lambert Only 0.03

Total Delta-V Hohmann 9.03 km/s
Delta-V Hohmann 4.41 km/s

Total Delta-V Fast Transfer 14.35 km/s
Delta-V Fast Transfer Lambert 9.73 km/s
   Departure 4.43 km/s
   Arrival 5.30 km/s
Delta-V Earth Escape 3.19 km/s
Delta-V Mars Entry 1.43 km/s

The Tank Fraction is the fraction of the spacecraft’s dry mass that is proportional to the fuel mass. This is composed mostly of fuel tanks. The mass fraction is how much mass is left when the spacecraft reaches Mars, not including the fuel tanks. The total Delta-V assumes one stage is used to go from LEO to LMO. Lambert’s law is used for the fast transfer. We break up the Lambert maneuver into departure and arrival velocity changes. In principle, you could aerobrake 5.3 km/s + 1.43 km/s.

The fast transfer is shown below. Contrast it with the Hohmann transfer.

Lambert fast transfer.

This was generated using the Spacecraft Control Toolbox function, PlanetTransferLambert.m.

PFRC Fusion Article in the Proceedings of the National Academy of Sciences

This is a really excellent article on nuclear fusion, “Small-scale fusion tackles energy, space applications,” by M. Mitchell Waldrop, written January 28, 2020, Vol 117, No. 4 for the Proceedings of the National Academy of Sciences of the United States of America (PNAS). The article quotes team Dr. Cohen and Mr. Paluszek and provides an excellent and technically accurate discussion of FRCs, heating methods, and fusion fuel physics.

PNAS has many interesting articles!

The HiSST and IAC Conferences

I’ll be attending two conferences in Europe this September. The first is HiSST, the 2nd International Conference on High-Speed Science and Technology, 11-15 September in Bruges, Belgium. Our paper is “Rotational Detonation Engine for Hypersonic Flight.” My co-authors are
Dr. Christopher Galea, Mr. Miles Simpkins, Dr. Yiguang Ju, and Dr. Mikhail Shneider. The last three authors are from Princeton University. The conference is organized by CEAS, the Council of European Aerospace Societies. We are in session 1a on September 12.

The next conference is the International Astronautical Congress (IAC) in Paris, France 18-22 September. We are presenting the paper, “Nuclear Fusion Powered Titan Aircraft,” with co-authors Annie Price, Zoe Koniaris, Dr. Christopher Galea, Stephanie Thomas, Dr. Samuel Cohen, and Rachel Stutz. Annie will give the presentation. Dr. Samuel Cohen is the inventor of the reactor discussed in the paper and works at the Princeton Plasma Physics Laboratory.

My first overseas conference was IAC in Paris in 1982. I was working at Draper Laboratory at the time.

IAC is also famous from the movie, “2001: A Space Odyssey.” While on Space Station V, Heywood Floyd is asked by Elena, “Well, I hope that you and your wife can come to the I.A.C. conference in June.” To which he replies, “We’re trying to get there. I hope we can.”

After the conference, I’m heading to Aix-en-Provence to visit ITER, where a new experimental Tokamak is under construction. A Tokamak is a toroidal fusion reactor.

Please get in touch with me if you will be at any of the conferences or at ITER!

DOE Awards Princeton Fusion Systems Three INFUSE 2022a Grants

The Department of Energy announced the First Round of the FY 2022 Public-Private Partnership Awards to Advance Fusion Energy. The awards list contains 18 awardees. Princeton Fusion Systems, a doing-business-as name for Princeton Satellite Systems, received three awards:

Electron density profiles on PFRC with USPR: Ultrashort Pulse Reflectometry (USPR) is a plasma diagnostic technique that would be used on the Princeton Field-Reversed Configuration (PFRC) to measure electron density profiles. Such profile measurements provide insight into the structure of PFRC plasma and can improve our estimates of confinement time. Our University partner is University of California, Davis, PI Dr. Neville Luhmann.

Evaluating RF antenna designs for PFRC plasma heating and sustainment: We intend to analyze RF antenna performance parameters critical to the validity of robust PFRC-type fusion reactor designs. Team member University of Rochester will support TriForce simulations and contractor Plasma Theory and Computation, Inc. will support RMF code simulations. Our national lab partner is Princeton Plasma Physics Laboratory, PI Dr. Sam Cohen.

Stabilizing PFRC plasmas against macroscopic low‐frequency instabilities: This award will use the TriForce code to simulate several plasma stabilization techniques for the PFRC-2 experiment. Our lab partner is PPPL and the team again includes the University of Rochester.

These awards will help us advance PFRC technology. Contact us for more information!

TriForce model of the PFRC-1 experiment

Ford Mach-E

Princeton Satellite Systems has been marketing SunStation electric vehicle charging stations for some time. We are also EV enthusiasts. One employee owns a Tesla Model 3. I now own a Ford Mach-E. It replaces a Nissan Leaf that was purchased in 2012.

Before we purchased the Mach-E we looked at the Hyundai Ioniq 5, the Volkswagen ID 4 and the Kia EV 6. They are all nice cars. It was a close decision between the Mach-E and the Ioniq 5. The good thing is that there are many EVs from which to choose. Even within models, there are many options so that you can pick the car that meets your needs. EV-specific requirements are range, charging network, and charging speed. Otherwise shopping for an EV isn’t much different than shopping for any other car. EVs are available in almost every form factor, including pickup trucks like the Ford F-150 Lightning.

The Mach-E is a 2021 model rear-wheel drive Premium Model with an extended range battery.

This gives a range of 335 miles, 10% more than the EPA value.

Fully charged!

The Level 2 charger is in the background. This is more than sufficient to reach all of the places we visit without charging along the route. The FordPass app will find a route for your trip and tell you when and where to charge. For our planned trips, it is showing that no en-route charging is needed, as long as we start near full charge. Tesla has an extensive Supercharger network that makes intercity driving really easy. All other EVs rely on networks such as ChargePoint and EVGo. There are many apps, besides FordPass, that will plan your trip including required charging stops.

We have a Level 2 charger at home that we bought for the Leaf. We also own a Prius Prime Plugin. The Prime is a plugin hybrid with about 30 miles range using the battery. The charging pattern during the week, when the Mach-E is used for commuting and shopping, is much like a gas car. We typically only charge the Mach-E once a week using the Level 2 charger at home. It takes about 10 hours to fully charge the battery. The Prius charges in 4 hours using a Level 1 charger. That is done daily.

If you owned a Mach-E and didn’t have a charger at home, it would mean you would only have to charge at a DC fast charger once a week if your driving patterns were like mine. If only Level 2 chargers were available, you’d need to find a Level 2 charger where you could park for 10 hours. In my town that would be hard because there only 6 Level-2 chargers!

Most recently we drove from Princeton to the Berkshires, then to Boston and then back to Princeton. The trips were made without any charging on the way. We used Level 2 chargers at our destinations. The Williams Inn, in Williamstown, had ChargePoint chargers, as did the Cambridge Marriott in Kendall Square in Cambridge, MA.

A great resource for those interested in EVs can be found at

Electric Vehicles 101: Everything You Need to Know

Our cars are charged mostly by our solar power system. This is supplemented by PSE&G’s network which gets a large portion of its power from a nuclear fission plant. We are working on compact nuclear fusion power plants. Perhaps, in the not too distant future one of our PFRC reactors will be the source of power for EVs.

Hohmann Transfer Simulation with the Spacecraft Control Toolbox

Hohmann transfers are a well-known maneuver used to change the semi-major axis of an orbit. The Spacecraft Control Toolbox allows you to compute the required velocity changes, and integrate them into a full simulation.

In this demonstration, we create a 6U CubeSat that has 3 orthogonal reaction wheels and a single hydrazine thruster. The thruster is aligned with the body x-axis and must be aligned with the velocity vector to do the maneuver. An ideal Hohmann maneuver is done with impulsive burns at two points in the orbit. In reality, with a thruster, we have to do a finite burn.

The Hohmann transfer is computed with the following Spacecraft Control Toolbox code:

rI = [-7000;0;0];
vI = [0;-sqrt(mu/Mag(rI));0];
OrbMnvrHohmann(Mag(rI),rF);
[dV,tOF] = OrbMnvrHohmann(Mag(rI),rF);

The first time OrbMnvrHohmann is called, it generates the plot below of the planned Hohmann transfer. The function computes the delta-V and also the time of flight, which will be used to determine the start time of the second thruster burn.

We create a short script with numerical integration to implement the maneuver using a thruster. The burn durations are computed based on the thrust and the mass of the spacecraft. In this case, they are about three minutes long. The maneuver is quite small, so the mass change is not important. The attitude control system uses the PID3Axis function which is a general-purpose attitude control algorithm. The simulation is a for loop, shown below. The ECI vector for the burn is passed to the attitude control system, which updates every step of the simulation.

% Simulation loop
for k = 1:n

  % Update the controller
  dC.eci_vector = uBurn(:,kMnvr);
  [tRWA, dC]    = PID3Axis( x(7:10), dC );

  % Start the first burn
  inMnvr = false;
  if( t(k) > tStart(1) && t(k) < tEnd(1) )
    inMnvr = true;
  end

  % Switch orientation
  if( t(k) > tEnd(1) )
    kMnvr = 2;
  end

  % Start the second burn
  if( t(k) > tStart(2) && t(k) < tEnd(2) )
    inMnvr = true;
  end
  
  if( inMnvr )
    dRHS.force = thrustE*QTForm(x(7:10),dC.body_vector)*nToKN; % kN
  else
    dRHS.force = [0;0;0];
  end
  el = RV2El(x(1:3),x(4:6));
  xP(:,k) = [x;tRWA;Mag(dRHS.force)/nToKN;el(1);el(5)];

  % Right hand side
  dRHS.torqueRWA = -tRWA;
  x = RK4(@RHSRWAOrbit,x,dT,0,dRHS);
end

The maneuver logic just waits a quarter orbit then performs the first burn, by applying the thrust along the body vector. It then waits for the time of flight and then starts the next burn. The start and stop times are pre-computed. RK4 is Fourth Order Runge-Kutta, a popular numerical algorithm included with the toolbox.

At the final orbit radius an attitude maneuver is needed to reorient for the final burn.

The spacecraft body rates, in the body frame, during the maneuver are shown below.

The reaction wheel rates are shown below. The simulation does not model any particular wheel. Friction is not included in the simulation, although the right-hand-side function can include friction.

The wheel torques and rocket thrust are shown below. The thruster is a 0.2 lbf hydrazine thruster that is based on the Aerojet-Rocketdyne MR-103. The PID controller does not demand much torque.

The semi-major axis and eccentricity are shown below. The middle portion is during the transfer orbit.

The eccentricity is zero at the start and finish. Note the slope in both eccentricity and semi-major axis due to the finite acceleration. At the end of the simulation, we print the achieved orbital elements:

Final SMA        7099.72 km
  SMA error         0.28 km
Final e          1.3e-05

The result is very close to the ideal solution!

This post shows how you can easily integrate attitude and orbit control. Email us for more information! We’d be happy to share the script. We can also offer a 30 day demo to let you explore the software.