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.

Moon Lander Design

Our last post showed the mission planning script for our lunar lander. The next step was to layout the lander. We did this using the BuildCADModel function in the Spacecraft Control Toolbox. The propulsion system is designed to meet the requirements of the mission plan. We use six 1 N HPGP thrusters for attitude control and one 220 N thruster for orbit maneuvers and landing. We have two HPGP tanks for the fuel. There are two cameras. One is used as a star camera for attitude determination and navigation and the second, which is articulated, is used for optical navigation, descent navigation and science. The IMU and C&DH box can bee seen in the drawing.


The solar array has two degrees-of-freedom articulation. The high gain antenna is also articulated. We adapted the landing legs from the Apollo Lunar Module. The thruster layout is shown in the following figure and is done using the ThrusterLayout function in the toolbox.


We get full 6 degree-of-freedom attitude control and z-axis velocity change control. We use the 220 N engine as the primary engine for landing but can also use four of the 1 N thrusters for fine terminal control.

We are working on the science payload for the mission. One experiment will be to mine helium-3 from the surface. Helium-3 would be a fuel for advanced nuclear fusion power plants and nuclear fusion propulsion systems.

Landing on the Moon

There is a lot of interest in lunar landing missions for both scientific exploration and commercial purposes. Commercial applications might include mining helium-3 for future nuclear fusion power plants on earth and mining water for rocket fuel.

The Spacecraft Control Toolbox makes it easy to do preliminary planning for lunar missions. In this blog we present a single MATLAB script that takes a spacecraft from a low Earth parking orbit to the lunar surface! Here is the final segment, the descent to the moon.


We ended up with a 30 kg dry mass for a spacecraft that can use an ECAPS 220 N HPGP thruster for delta-v.

The published script can be found here:

Lunar Mission Planning as a published MATLAB script

You can also send us an email to find out more about our Lunar Mission Design Tools.

2014 International Astronautical Congress

From the movie “2001: A Space Odyssey”, 1968. Dr. Heywood Floyd is talking with Elena, a colleague from Russia:

Elena, “Well, I hope that you and your wife can come to the I.A.C conference in June.”
Floyd, “We’re trying to get there. I hope we can.”

I was able to attend the IAC conference in 2014 in Toronto, Ontario, Canada. I presented two papers:

“Direct Fusion Drive for a Human Mars Orbital Mission”


“Space Rapid Transit – A Two Stage to Orbit Fully Reusable Launch Vehicle”.


2001: A Space Odyssey was the “theme” for my two papers. I had a photo of the Discovery II spacecraft in my DFD talk and an image from an online simulator of the full Orion III launch vehicle in my SRT talk. Both papers were well received. I got a good question from an engineer from Reaction Engines Limited about separation. We have done some separation simulations but have not testing our separation control mode in depth. He noted that the D-21 program, and example of high speed separation I gave, was not really successful.

When I wasn’t in my sessions, I spent my time in the exhibits hall talking with the representatives at the booths, handing out business cards and flyers about Princeton Satellite Systems. Some of our customers, including KARI from Korea and the Canadian Space Agency, had exhibits.

I spoke at length with Astrobotics, a company that plans to land a rover on the moon. They were founded by a professor from Carnegie Mellon. I suggested that our flight control experience could be of value to them. Their work shows the feasibility of helium-3 mining on the moon. We would need helium-3 mining if we were ever to use DFD for base load terrestrial power generation.

I chatted with the Aerospace Corporation. I worked with them on GPS IIR while at GE Astro Space. I explained that they might be interested in working with us on DFD particularly in applying it to Air Force applications like space based radar.

SpaceX had the crew chairs and displays from their Dragon Capsule in their exhibit. It was the coolest exhibit in the hall! I had a nice chat with their marketing person on DFD. SpaceX and Boeing recently were awarded contracts to develop the Commercial Crew vehicle.

Lockheed Martin had a huge exhibit. They had a 3D printer running


I talked with them about A2100, a comsat under design at GE Astro Space when I left. I also talked about ControlPlan applications for MUOS, a satellite Lockheed Martin is building for the Navy. We developed antenna beam optimization for MUOS using our ControlPlan multi-objective optimization package.

I spoke with Surrey about their new comsat program and suggested that we could help as we have extensive comsat experience. Surrey now has a U.S. branch. I spoke with the Canadian Armed Forces about their satellite programs. They were interested in our Kestrel Eye work.

The CN Tower is in the middle of the convention center:


On the way home I ate at the Apropos restaurant in the Air Canada terminal. It is really cool! You order through an iPad and pay using a credit card terminal next to the iPad. Besides being high tech, the food was really good! The restaurant can be seen in the following picture.


Attitude Maneuvers with the CubeSat Control System

The CubeSat control system is designed to work with either thrusters or reaction wheels. It has a number of handy built in maneuver modes such as pointing at the sun, nadir pointing or pointing at a specific latitude and longitude on the ground. Here is the spacecraft shown in the VisualCommander interface.


The movie in the link below shows attitude maneuvers in the VisualCommander interface. The interface has pages for the various subsystems and attitude control system functions. We start by seeing the spacecraft in a polar orbit on the Summary page. The solar arrays are reorienting themselves so that their cell faces are pointed at the sun. We switch the 3D display to look along the boresight of the telescope. We then go to the ACS page and select a sun pointing maneuver. We go back to the Summary page and see that the sun appears in the display. We then return to the ACS page and command nadir pointing. The remainder of the movie shows the reorientation maneuver to nadir pointing.

CSCS Reorientation Movie

For more information on our simulation frameworks including our real-time control system framework, ControlDeck, go to Simulation Framework page.

For more information on VisualCommander go to VisualCommander page.

You can also send us an email to find out more about our CubeSatControl System. All of these products are available now.

Spacecraft CAD Design in the Spacecraft Control Toolbox

AutoDesk Inventor and SolidWorks are powerful software packages for the computer-aided design of spacecraft. Ultimately you need to use one of those packages for the mechanical design of your satellite, but what about the preliminary design phase when you are still determining what components you even need? The CAD software in the Spacecraft Control Toolbox can provide you with a valuable tool to do your conceptual layouts and early trade studies, and the same model can be used as the basis for disturbance analysis in later design phases.

A CAD model in SCT is built in a script which allows you to build your models algorithmically. You can call design functions, use for loops and revision-control your source code. For example, within the script you can do an eclipse analysis and compute the battery capacity. This number can generate the volume of your batteries which you can then use to size your spacecraft.

The function BuildCADModel provides the model-building interface. The CreateComponent function is used to generate the individual components using parameter pairs as arguments. Components are grouped into bodies to allow for rotation and articulation. A GUI displays your finished model and allows you to visualize it in 3D. You then store your finished models as mat-files. Our disturbance model uses every triangle in your model for disturbance analysis.

The example figure shows a solar sail design, with the spacecraft bus in the middle. BuildCADModel allows you to group components into subsystems as on the left-hand side, which can then be highlighted using transparency.


The figure below shows the BuildCADModel GUI which allows you to verify the body and component properties.BuildCADModel-Vehicle

There are many examples of spacecraft models in the SCT to help you get started, and a lengthy chapter in the User’s Guide discussing the finer points of component location, orientation, and physical properties such as drag and optical coefficients. Your CAD model essentially functions as a database for your entire spacecraft model!

Why Use Princeton Satellite Systems’ MATLAB Toolboxes?

Almost all aerospace organizations have extensive libraries of software for simulation, design and analysis. Why then should they use our MATLAB toolboxes?

I’ve been working in the aerospace business since 1979. My experience includes:

  1. The Space Shuttle Orbiter Dynamics Analysis
  2. The GPS IIR control system design
  3. The Inmarsat 3 control system design
  4. The GGS Polar Platform control system design
  5. The Mars Observer delta-V control system
  6. The Indostar-1 control system
  7. The ATDRS momentum management system
  8. The PRISMA formation flying safe mode guidance

Continue reading

Optical Navigation for Geosynchronous Transfer Orbits

Optical navigation, using the Earth’s chord width and angles between nadir and stars, is an alternative to GPS based navigation for autonomous spacecraft. The Optical Navigation System, developed under a NASA contract, is well suited for this application.

In the Spacecraft Control Toolbox, we provide an easy-to-use demo script in the 2014.1 release that shows you how to implement optical navigation. The system uses Unscented Kalman Filters (also known as sigma point filters) with non-linear dynamics and measurement models.

This demo uses our new UKF functions shown below:

ukf.t = t;
ukf = UKFPredict( ukf );
ukf = UKFUpdate( ukf );

ukf is a data structure that includes all filter information. Measurements are passed as data structures to UKFUpdate which have pointers to the measurement functions. In this way, any type of measurement can be used in the filter and introduced at any time.

The following plots show some results from the script. The first shows the orbit and the estimated orbit which are essentially the same.


The second shows the position errors. Of course, actual errors would depend on the accuracy of the sensors, particularly the Earth sensor. Great care needs to be taken when setting up the UKF parameters. As you can see, the largest errors are at perigee and if the UKF parameters are not set properly, the filter might think a hyperbolic orbit was a valid solution!


Check out our Spacecraft Control Toolbox page for more information on the 2014.1 release! More information about optical navigation can be found on our Deep Space Navigation page.

SunStation in Operation!

SunStation is in operation! The system produces a peak of 7.8 kW solar power. It has 14 kWh of lithium batteries. The SunStation electronics are shown below. The inverter is on the left. The batteries are in the cabinet on the right.


The SunStation has a web interface. You can see that when this screen shot was made the SunStation was selling 5.1 kW back to the power company! The batteries are fully charged. Usage was very small. The house has a whole house ventilator that is drawing most of the power. The homeowners also own a Nissan Leaf and a Toyota Prius Plugin. The solar array is enough to fully recharge those cars and run the house electrical devices when the air conditioning is not on.


Unlike gasoline, diesel or natural gas systems SunStation provides power year round! There is no noise and no toxic emissions. SunStation has no moving parts and is zero maintenance. Solar power systems are eligible for Solar Renewable Energy Credits which are cash payments for having an operating solar power system. It is estimated that this system will bring in $3700/year revenue between selling power and SRECs.

SunStation Installed!

The first SunStation installation is done! This system includes 14 kWh of Valence lithium batteries and an Outback inverter. Unlike most other solar power systems, the solar panels will deliver power to the house with or without the grid active.


An existing 3.8 kW array was augmented with the new Panasonic solar panels on the right. They are about the same size as the older Sharp panels but much more efficient. In the bottom picture you can see the Outback inverter. The cabinet on the lower right houses the Valence batteries. The system will power the entire house in an outage with the exception of the central air conditioning system.

Unlike gasoline, diesel or natural gas systems this system provides power year round! There is no noise and no toxic emissions. SunStation has no moving parts and is zero maintenance. Solar power systems are eligible for Solar Renewable Energy Credits too which are cash payments for having an operating solar power system so you save money two ways.

Check out our SunStation page for more information!

Adaptive Cruise Control

The automotive industry continues to incorporate advanced technology and control systems design into new vehicles. Features such as adaptive cruise control, lane keep assist, autonomous park assist, and adaptive lights are becoming more common in the automotive market. These exciting technologies greatly increase vehicle safety!

Adaptive cruise controls measure the distance and speed of nearby vehicles and adjust the speed of the vehicle with the cruise control to maintain safe following distances. Typically a system will use a radar that measures range, range rate and azimuth to vehicles in its field of view.

A typical situation is shown below. The car with adaptive cruise control is traveling near three additional vehicles. Two cars have been tracked for awhile but a third is passing and plans to insert itself into the space between the tracking car and one of the tracked cars. How does the cruise control keep the three cars straight?


Every measurement has uncertainty. The following drawing shows the uncertainty ellipsoids for the three vehicles. As you can see they overlap so a measurement could be associated with more than one car.


The Princeton Satellite Systems Target Tracking Module for MATLAB implements track oriented Multiple Hypothesis Testing (MHT). MHT is a Bayesian method for reliably associating measurements with tracks. The system is shown below:


The system includes a powerful track pruning algorithm that eliminates the need for ad-hoc track pruning. Without track pruning the number of tracks maintained would grow exponentially. The system generates hypotheses that are collections of tracks that are consistent, that is the tracks do not share any measurements. Measurements are incorporated into tracks and tracks are propagated using Kalman Filters. The MHT system also can handle multiple sensors for automobiles with cameras and radar.

Check out what all our MATLAB toolboxes have to offer!
Core Control Toolbox
Aircraft Control Toolbox
CubeSat Toolbox
Spacecraft Control Toolbox