DFD for Europa Exploration

Europa-luna

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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6U CubeSat to Mars

We’ve been working on Asteroid Prospector, a 6U CubeSat to explore Near Earth Objects, for the past two years. It is quite a challenge to pack all the hardware into a 6U frame. Here is our latest design:

APExploded

CAD

The nadir face has both an Optical Navigation System camera and a JPL designed robot arm. The arm is used to grapple the asteroid and get samples. The camera is used both for interplanetary navigation and close maneuvering near the asteroid.

Our fuel load only allows for one way missions but could be increased for sample return missions by adding another xenon tank, making it more of a 12U CubeSat. With that in mind, we wondered if we could do a Mars orbital mission with our 6U. It turns out it is possible! We would start in a GPS orbit, carried there by one of the many GPS launches. The spacecraft would spiral out of Earth orbit and perform a Hohmann transfer to Mars. Even though we are using a low-thrust ion engine, the burn duration is a small fraction of the Hohmann ellipse time making a Hohmann transfer a good approximation. We then spiral into Mars orbit for the science mission as seen in a VisualCommander simulation.

SimSummary

The low cost of the 6U mission makes it possible to send several spacecraft to Mars, each with its own instrument. This has the added benefit of reducing program risk as the loss of one spacecraft would not end the mission. Many challenges remain, including making the electronics sufficiently radiation hard for the interplanetary and Mars orbit environments. The lifetime of the mechanical components, such as reaction wheels, must also be long enough to last for the duration of the mission.

We’ll keep you posted in future blogs on our progress! Stay tuned!

Brand New Free SCT Textbook Companion App for MATLAB

We are happy to announce the release of our free Textbook Companion App for MATLAB (2012b or later).  Based on four Chapter 2 walk through tutorials, the goal is to design a geostationary spacecraft, maintaining an exact orbital position, delivering a -126 dB in the Ku band, and 7 year lifetime.

app_cover

The GUI allows us to look at the results of various gravity models, summing various types of disturbances caused by the sun-angle, a basic geo-synchronous orbit simulation, and then a full simulation that incorporates the orbit, disturbances, and Control and Link parameters. app_results

The app is available on the textbook support page: http://support.psatellite.com/sct/theory_textbook.php.

 

Europa Report

Europa Report is a movie about a human mission to Europa, a moon of Jupiter, to explore the moon for signs of life. Europa has an oxygen atmosphere and a surface composed of water ice that has led to the hypothesis that there is an ocean under the ice.

Europa Report does a great job of being scientifically accurate. The spacecraft shown in the movie addresses the major issues that travelers would experience on a voyage to Jupiter. The crew section of the spacecraft is spun for artificial gravity and accommodations are made to deal with the high radiation environment around Jupiter.

Our Spacecraft Control Toolbox can be used to design the spacecraft and simulate every phase from Earth Orbit to Europa landing. We have a script for a powered Europa landing. Here are the results!

EuropaLanding

For more information about how you can design your space missions visit our Spacecraft Control Toolbox page!

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).

SatelliteBlog

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.

RelativePos

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.

Temp

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.

Flux

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

FlowCharts

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.

DetectIm1

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

IRImaging

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!

http://www.youtube.com/user/PSSToolboxVideos.

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

Kepler Telescope Reorientation Maneuver

The Kepler telescope has suffered the loss of two reaction wheels. This means that it cannot use the wheels to control orientation about all three axes.

One option is to use thrusters and reaction wheels at the same time as actuators. Princeton Satellite Systems Core GN&C Bundle does just that.

Aero/Astro vehicle control products.

We’ve simulated the system for the Kepler spacecraft

Kepler

You can see a movie of a reorientation here:

Kepler Mixed Actuator Reorientation.

Visit to the Canadian Space Agency

I visited the Canadian Space Agency in St Hubert Canada on Tuesday, August 27 to give a talk on our Asteroid Prospector Spacecraft. The talk was fun and we had a great discussion on the challenges of near asteroid operations and building small interplanetary spacecraft.

After the talk Dr. Alfred Ng gave us a tour of the facility. Here I am with my wife and son standing in front of Dextre and Canadarm.

FamilyPhoto

You can see Dextre to the left. The Canadarm is the to the right. Both are in operation on the ISS. Dextre is used for many of the tasks formerly done by astronauts during EVAs.

Here I am with our host Dr. Alfred Ng:

AlfredNg

We saw the MOST satellite, a small astronomy satellite. It has a mass of only 60 kg. It can stare at a star for up to 7 days!

MOST is an excellent example of how a small satellite can do big science! We were very impressed with all of the amazing engineering and science being done at the Canadian Space Agency and hope to continue collaborating with them in the future!

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.

SCARA

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

Direct Fusion Drive to Mars – A FISO Talk

The Future In-Space Operations (FISO) working group invited us to give a talk in their weekly seminar track. On Wednesday, July 24, 2013, we gave a presentation entitled “Direct Fusion Drive for Fast Mars Missions with the Orion Spacecraft”. You can find the slides we presented in their online archive here.

We first discussed the need to get to Mars and back home fast (see our recent blog post on the risks of extended durations in space). We then presented some preliminary studies on the double rendezvous problem of Earth -to- Mars -to- Earth, and introduced the Direct Fusion Drive (DFD) as a future propulsion technology that can make this mission happen.

Dozens of people dialed in from around the country. Dr. Dan Lester (U Texas) and Dr. Harley Thronson (NASA Goddard) gave us a warm introduction, and there were a number of insightful questions throughout the talk that sparked interesting dialog. We were also joined by colleagues at MSNW who are developing another form of fusion propulsion, called the “The Fusion Driven Rocket“.

It was an honor to be part of the FISO working group. The questions and feedback we received from this group have been extremely valuable, and it is another sign of the growing interest in fusion propulsion!