DFD for Europa Exploration


The Galileo moons of the Jovian system are of great interest for future space exploration due to the belief that three of the four of the largest moons (Europa, Ganymede, and Callisto) contain water (in liquid and/or ice form). So far the eight spacecraft that have visited the vicinity of Jupiter are Pioneer 10 and 11, Voyager 1 and 2, Ulysses, Galileo, Cassini, and most recently New Horizons. NASA has ambitions to send another probe to further study Europa.

At Princeton Satellite Systems, in collaboration with Dr. Samuel Cohen at the Princeton Plasma Physics Laboratory, we’ve been working on the Direct Fusion Drive (DFD) engine, an advanced technology for space propulsion and power generation. Using the DFD, we have simulated two potential missions to Europa, an orbiter mission and a lander mission. The simulations were completed in MATLAB using functions contained within our Spacecraft Control Toolbox.

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IR Imaging with the Spacecraft Control Toolbox

Many spacecraft are incorporating cameras, both visible and IR, to image other nearby objects. These may be other satellites or space debris. This blog entry shows how you can simulate imaging with the Spacecraft Control Toolbox.

In this simulation a target 1U CubeSat is illuminated by several sources of radiant flux and imaged by a camera located on a chase vehicle. The CubeSat panels have different optical and thermal properties. An exploded view is shown below. The surface properties are for radiators (black), solar panels (blue) and gold foil (yellow).


The target is located in a circular orbit and the chase vehicle is in a similar but slightly eccentric orbit. A camera is mounted on the chase vehicle. The chase vehicle keeps its camera pointed at the target. Solar radiation, earth radiation, and earth albedo illuminate the target. The motion of the two vehicles is simulated for one revolution. The target spacecraft remains between approximately 75 m and 150 m from the chase vehicle.


As the target and chase vehicle move in their respective orbits, the change in temperature of the target CubeSat is simulated. Each of the 6 panels are composed of two triangles. The temperatures of the panels vary based on the thermal properties of each face and the orientation of the spacecraft. The orientation affects the incoming flux for each particular face.


Solar radiation is the dominant source over the course of the simulation but earth radiation and earth albedo also effect the total flux. The solar radiation, plotted in dark blue, clearly shows the times when the earth is blocking the line of sight from the spacecraft to the sun.


A photon detector model is assumed for the IR imaging device. The following flow chart describes the imager model.


The initial output observed by the imager is shown below. It should be noted that for the particular orbit and orientation initial conditions specified, the z component of the relative position is always equal to zero. This means that only the x and y panels of the cube will be visible throughout the simulation. It is possible to specify different initial conditions that would result in a z relative position, and in this case, up to three faces of the cube can be detected.


We have created a video that displays the imager results as a sequence.


SCT Seminar – Sheffield UK

Yosef and Amanda are giving a seminar on our Spacecraft Control Toolbox in Sheffield, England on October 1, 2013. This event has been arranged through our UK distributors, MeadoTech Ltd. A big thank you goes out to Dr. Mohamed Mahmoud and Ruth Jenkinson!

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

PSS MATLAB Toolbox Tutorial Videos

Over the summer we worked on developing some videos to help customers get started using our MATLAB products. Our MIT intern, James Slonaker, did a fabulous job! Come check out our Toolbox Tutorial Videos on our YouTube Channel!


If you have any feedback or suggestions for future content, please contact us at info@psatellite.com.

SmallSat Conference in the Cache Valley!

PSS attended the Small Satellite Conference in Logan, Utah, Aug 12-15. The conference site, on the campus of Utah State University, couldn’t have been more beautiful!
View from the SmallSat venue, Logan Utah

The technical program, conference organization, and venue were all outstanding!  I bumped into several PSS MATLAB Toolbox customers and representatives from companies PSS has teamed with on past projects.

SmallSat signs guiding the way!

I also had the pleasure of connecting with a number of new companies and teams working on advanced small satellite projects. We presented our Asteroid Prospector paper as part of the Strength in Numbers Session. The presentation was well received and we had a number of individuals express interest and provide feedback on the concept afterwards.

Amanda on the last day of the conference

On Wednesday evening, I was able to take advantage of the organized group activities and participated in the hike in Logan Canyon. It was a great week! Hope to see you all again next year!

New PSS MATLAB Product – Core Control Toolbox

We have just released our new MATLAB product – the Core Control Toolbox (CCT). We created the Core Control Toolbox as a base product for those customers who may have interests outside of aircraft and spacecraft modeling and simulation. It features many of the general purpose functions found in our Spacecraft Control Toolbox. Like all our Toolbox products, CCT comes with complete source code. Users can view and modify any function in the toolbox to suit their particular needs. We’ve included a number of our filtering, graphics, mathematics, quaternion, robotics, and other general purpose functions.

Below one of our robotics functions is featured! The Selective Compliance Articulated Robot Arm (SCARA) is used in many industrial applications requiring assembly in a plane, like manufacturing a PC board.


The SCARA movie shows a SCARA robot following a straight line trajectory. The trajectory is computed by a dedicated SCARA inverse kinematics routine.

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

Next Stop….Enceladus!

In October of 1997, the Cassini spacecraft launched on a mission to explore the depths of the Saturnian system. After traveling over 3.5 billion km, the orbiter set out to discover more about the composition and features of Saturn, study its rings and satellites, and investigate the magnetic environment. Flash forward to 2013, Cassini is in the midst of it’s second extended mission! Over the past decade, we have received countless images from this amazing spacecraft including shots of the spectacular icy plume geysers from the Saturnian moon Enceladus. 1024px-Enceladus_geysers
Image Source: NASA

This tiny moon is creating a LOT of excitement as it is thought to have the greatest potential for extraterrestrial life in our Solar System. A robotic lander may explore Enceladus in the future.

Using our Spacecraft Control Toolbox (SCT), we have created a simulation of the soft landing of a small exploratory craft. Starting in a 5 km circular Enceladus equatorial orbit, the lander tracks a minimum time descent profile. An altimeter monitors the local vertical distance the spacecraft needs to travel before touchdown, and a three axis PID controller is used to orient the spacecraft so that the thrusters align with the prescribed thrust direction.


When the spacecraft approaches the surface of Enceladus, we switch to a landing mode in which the vehicle assumes a vertical landing orientation and thrust is applied in the local vertical direction, proportional to the distance to touchdown. This is all done using functions readily available in SCT! Next stop: Enceladus! Who’s on board?

Check out what our MATLAB toolboxes have to offer!

PSS at Princeton Plasma Physics Lab Open House

On Saturday April 1, PSS participated in the Princeton Plasma Physics Lab Open House to show case our Direct Fusion Drive and our conceptual nine-month manned space mission to Mars in 2024! Our new fusion engine enables shorter transfer times and total mission durations, critical for interplanetary manned space flight. We had great interest in our human mission and many budding astronauts were ready to sign up for the trip.


Please see our educational page for some fun DFD material for your space enthusiast:


More information on this exciting project is available on our Fusion webpage:


Our SunStation products for Home Back-Up and EV Charging were also on display at the PPPL Open House. SunStation is a green way to provide emergency power to critical loads in your home during an electrical service interruption or to charge your electric vehicle without using any grid power!


New Attitude Profiling Functions and Visualization in SCT v11

Creating attitude profiles just got easier! Satellites typically have multiple antennas and sensors that must be pointed in different directions at various times. We often want to point a sensor payload or a directional antenna at a certain location on Earth, while keeping the solar panels aligned with the sun and aiming the star camera away from bright areas of the sky. The group of new attitude profile functions in SCT v11 allow high-level directives to be defined, and facilitate the automatic computation of an attitude profile that meets the target alignment objectives while satisfying all pointing constraints. Detailed time-history plots and 3D visualization with playback enable you to explore and understand the attitude profile in depth.

The 2D plot below shows a time history of the rotation angle about the primary body axis. The primary body axis is aligned with the primary target. We can then rotate about this axis to align a secondary body axis as closely as possible with a secondary target. At the same, we have one or more pointing constraints which impose time-varying bounds on the rotation angle. The dark gray regions illustrate how these bounds change over time.


The 3D view below shows the orbital path (cyan) of the satellite about the Earth, with a CAD model at the current orbit location in the center of the figure. The sun vector is shown (yellow) and the Earth lighting is based on the sun location. The primary alignment vector (green) is directed towards a coordinate on the Earth, and the secondary alignment is pointed in the orbit-normal direction. Constraint directions are shown in red with angular sweeps to show their size. The sensor cone is a star camera that has to keep the sun, Earth and moon out of its field of view.