My Summer Internship

The past 10 weeks at Princeton Satellite Systems have been a life changing experience. During my summer off from the University of Pennsylvania, I have worked as an intern for the company. This gave me the opportunity to learn from trailblazers in the industry and to be immersed in a community passionate and dedicated to the work.

I first heard of Princeton Satellite Systems at the Dawn of Private Space Science Symposium in 2017. After that, Mike graciously agreed to come speak for the Penn Aerospace Club in the fall and the Ivy Space Coalition Conference the next spring. Everyone in attendance was fascinated by the presentation and I felt so lucky that I would have the chance to learn so much more soon. Connections like these are what drive the aerospace community and as I expand my communication I hope to stay closely in touch with the people I came to know at PSS.

Through my work, I’ve been doing a lot of Matlab modeling: sizing the components for the Direct Fusion Drive engine, testing a rotating detonation engine, and MHD plasma simulation. The idea of these technologies enhancing propulsive power and efficiency is fascinating and has great potential for the future of space travel.

My summer at Princeton Satellite Systems has helped me to enhance my technical understanding and skills: I’ve definitely gained a ton of experience in Matlab, and all of my studying of plasma modeling should give me a head start in my fluids class next semester! I’ve also gained a much better understanding of how the professional world works. I got to help write and edit proposals, sit in on phone calls, and even attend the NIAC meeting at Princeton Plasma Physics Lab.

I think that there’s a great benefit in working at a smaller company. You are given plenty of real responsibility and see the changes happening in real time. I will definitely take the lessons I’ve learned this summer and apply them to my education as well as my future career as a mechanical engineer.

I am so grateful for this opportunity. Everyone has been so kind and helpful and patient. The time has flown by, and it definitely made staying in my little Princeton dorm with no air conditioning well worth it! I’ll miss coming in to work every day but I can’t wait to see all the big things that PSS accomplishes.

 

PSS Dress Code: What is “business casual”, anyway?

Our interns always ask us, “What’s the dress code?” Our dress code at the office is business casual – which according to Wikipedia is not that well defined! We are probably on the more casual side of business casual. Here are some guidelines:

What to wear:

  • Khakis, trousers, skirts, polos, button-down shirts, blouses, sweaters
  • Dark or colored denim trousers
  • Shorts and sandals are OK in the summer – we prefer to turn the thermostat up and save money on A/C!

What NOT to wear:

  • Ripped or faded jeans
  • Very short skirts or shorts
  • Leggings – leggings are not pants! Leggings should be treated as footless tights and always paired with dresses or tunics.
  • Camisoles/spaghetti straps – camisoles are not blouses!
  • Flip-flops or sad beat-up sneakers

Anyone working on hardware should wear closed-toe shoes and tie back long hair, as in any lab space.

A side comment: my husband is a tech executive in New York, and he wears what I call the “tech uniform” to work every day: dark jeans from Banana Republic, button-down shirt, brown dress shoes, and a navy blazer. Now, guys in tech get away with this, but probably not lawyers! As PSS is solidly in the tech regime, we definitely take a more casual approach to “business casual”!

Young Women’s Conference in STEM

Princeton Satellite Systems attended the Young Women’s Conference in STEM in at the Frick Laboratory on the Princeton University campus again this year. We had an exhibit with spacecraft hardware and software. This include 3D printed models of our fusion reactor core and a 2 stage to orbit launch vehicle, star and navigation cameras, a circuit board for driving a fusion reactor and a 3U CubeSat frame . We were also running a simulation of a Lunar Landing simulation.

We met many enthusiastic students this year! It seemed that there were more high school students than in past years. A budding plasma physicist asked how we fuel the Direct Fusion Drive engine. Another student, looking at our Lunar Lander simulation display, asked what is a quaternion! The disassembled reaction wheel was very popular.  Some students wanted a detailed explanation about how the motor worked. One student wanted to know the electrical details of our RF board. Several were interested in our Army iPhone app. One wanted to know if she could get it from the App Store.

Other attendees included Lockheed Martin, the FBI and the Princeton Plasma Physics Laboratory. Click on this image to see a video about the event.

It was a fun event, albeit exhausting given the four hours of continuous conversations. We do hope that we inspired some of the attendees to pursue careers in science, math and engineering!

Inter Ivy Space Coalition Meeting

Marilyn and I attended the first Inter Ivy Space Coalition Inter Ivy Space Coalition meeting at Yale University on April 6 and 7.

The meeting was attended by students with an interest in space from the Ivy League schools. Saturday consisted of talks by speakers from a wide range of organizations followed by an exhibition and a banquet. Jonathan Li of Yale was the driving force behind this excellent conference.

The Dean of Engineering of Yale opened the meeting talking about the Yale Undergraduate Aerospace Association. They have done a wide variety of space work including some very large rockets. One student later showed me the nozzle for their latest rocket.

Dr. Fuk Li of JPL, Director Mars Exploration Directorate, talked about Mars 2020. The mission with its very sophisticated rover, will look for indigenous life, study climate and geology and prepare for Exploration. One ambitious goal is to eventually return Mars samples. The challenge of the sample return is to not contaminate the Earth as in the movie The Andromeda Strain.

Prof. Alessandro Gomez of Yale gave a nice talk on electrospray thrusters. The thrusters will be very valuable for small satellite missions.

Suresh Kannan talked about Trustable Autonomous Aerospace Systems. He had great videos from Nvidia on autonomous car control systems and videos from Boston Dynamics showing their amazing robots.

Ellen Chang, co-founder of  Lightspeed Innovations is a former U.S. Navy Intelligence Officer and a graduate of the Naval Postgraduate School. She talked about the state of investment in space. She mentioned a couple of investments organizations, including IQT, which was started by the CIA! She said a key issue for space companies is that investors can’t wait 20 years for their return on investment.

I gave the next lecture presenting the latest results on our work on Direct Fusion Drive.

Artist rendering of DFD rocket engine

We’ve been able to reduce the mass of our RF and superconducting coil subsystems dramatically. We have completed the radiation heat transfer analysis of the reactor which shows that it isn’t a big problem. Conduction will provide the major heat loads.

Here is a recent shot in our experimental facility.

I included a  teaser slide on our two stage to orbit vehicle that we are proposing to NASA and DARPA. It would be inexpensive enough for companies and universities to own their own launch vehicle. It is fully reusable and could be launched at any convenient airport. It can also shuttle around the world at subsonic speeds. It is about the size of a private jet.

Alden Richards, founder of Space Machine Advisors, gave a fun talk on the space business. He insured the PanAmSat launch on which I worked. He said that the key for space profitability is dual use,

Jason Aspiotis of Finsophy talked about sources of funding for space. These include global sovereign funds that countries like Kuwait and Norway maintain. He  is a founder of  SpaceVault online banking and SpaceXchange.

Dr. Jonathan Arenberg of  Northrop-Grumman talked about the Chandra X-Ray telescope. He also talked about future missions for imaging exo-planets. Dr. Arenberg is second from the left on the linked page.

Ulisses Ortiz of  Space for Humanity talked about his plan to make sub-orbital flights available to anyone. People selected would make a commitment to using the publicity for a good cause.

Kari Love of  Soft Robotics gave a great talk on how to win contracts. She said you need to get to know people by going to conferences and responding to RFIs. She said you can make contacts by going to non-space events, like science fiction conventions. She recommended using professional illustrators for key graphics. Kari has a interesting background. She designed the Spiderman costume for the Broadway musical!

Dr. Lin Chambers Atmospheric Scientist at NASA/LaRC, gave the final talk of the day. Unfortunately, we were setting up our table for the networking fair so we missed her talk!

Princeton Satellite Systems had a table at the networking fair. The TV is showing a lunar landing simulation. We had a disassembled reaction wheel, a sun sensor, a navigation camera and a 3D printed model of our two stage to launch vehicle, Space Rapid Transit Mini.

We talked with many students. All of our discussions were interesting. I talked at length with an English major interested in space!

Scott Willoughby of Northrop-Grumman and Program Manager of the James Webb Space Telescope  gave an overview of the program in the after dinner talk.

Here are the speakers and student organizers.

We look forward to next year’s meeting! 

Fusion Power Associates Meeting

I attended the 2017 Fusion Power Associates meeting in Washington, D.C. on December 6 and 7. Fusion Power Associates is a non-profit, tax-exempt research and educational foundation, providing timely information on the status of fusion development and other applications of plasma science and fusion research.

The annual meeting brought together experts in all areas of nuclear fusion research including scientists and engineers from ITER, the Princeton Plasma Physics LaboratoryTAE TechnologiesGeneral Atomic and many others! The meeting gave a great overview of the state of nuclear fusion power generation. We learned that ITER is 50% complete and on its way to first plasma in 2025. Planning has begun on Demo, the follow-on to ITER.

The Joint European Torus plans a D-T campaign in 2019 and hopes to set new fusion benchmarks. We learned about Korea Superconducting Tokamak Advanced Research  (KStar). It has achieved longer than 70 second pulses in H-mode and has suppressed ELM for more than 34 seconds. KStar has in-vessel control coils.

There were several speakers from the University of Rochester along with colleagues from the national laboratories talking about advances in laser compression of fuel pellets. This work is for nuclear weapons research but could be applied to inertial confinement fusion.

I gave the last talk of the meeting on Princeton Satellite Systems and PPPL’s work on DFD, nuclear fusion propulsion for spacecraft.

Rendezvous with 1I/’Oumuamua

An interstellar asteroid, 1I/’Oumuamua, was discovered on a highly hyperbolic orbit by Robert Weryk on October 19, 2017 moving with a speed of  26.32 km/s. It appears to come from the direction of the star Vega in the constellation Lyra. It would be really great to send a mission to rendezvous and fly in formation with 1I/’Oumuamua to study the asteroid. The high velocity makes it hard to do with current technology.

Direct Fusion Drive (DFD) might provide a answer. We designed a spacecraft with a 1 MW DFD power plant and assumed a launch on March 16, 2030. The following plots show the trajectory and the force, mass and power of the spacecraft during the 23 year mission. As you can see we don’t have to use the full 1 MW for propulsion so we have plenty of power for data transmission and the science payload.

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The code for this analysis will be available in Release 2018.1 of the Princeton Satellite Systems  Spacecraft Control Toolbox for MATLAB.

PRISMS Secondary School Student Builds a Sun Sensor

The Princeton International School of Mathematics and Science is a private secondary school in Princeton New Jersey.

http://www.prismsus.org

One of their students, Savva Morozov, undertook a project to build a miniature 2-axis sun sensor for a CubeSat. Here is his blog post!

My name is Savva, I’m a senior at Princeton Int’l School of Math & Science. This summer I designed, built and tested a 2-axis solar tracking sensor for Princeton Satellite Systems.

The sensor can determine the relative position of the sun using a set of photodiodes. Bearing in mind that the solar sensor would be used in vacuum environment, I decided to make the sensor out of printed circuit boards (PCBs) and solder them to each other. Originally, I wanted to 3D print the sensor, but shifted to the PCB solution to eliminate the risk of outgassing.

Picture 1: solar tracking sensor, 2nd prototype.

My solar sensor design resembles the shape of a square-based pyramid that is approximately the size of a quarter. It consists of 5 PCBs: 4 sides and a base to which the sides are attached. Each side contains a photodiode, and by measuring the voltage outputs from at least 2 of the diodes, the device can determine the sunlight’s direction.

One of the initial problems I encountered was the handling and attachment of the photocells to the side PCBs. Each cell came with an anode and cathode wires already soldered to its front and back. I desoldered the cathode wire from every cell and affixed them to the PCB using a space grade silver conductive epoxy. This way I attached the cell to the device and grounded its cathode at the same time. I thought I killed two birds with one stone, but instead I killed two photodiodes: they were damaged in the soldering process. I resolved the issue in the second prototype: I threaded the cathode wire into a hole in a side PCB and then glued the diode to that same board. This way I didn’t have to use soldering iron at all, preventing possible risks. I then connected the cathode of every photodiode to a common ground and outputted the voltage readings from each cell in a single data bus.

Picture 2: Solar sensor, 2nd prototype, quarter for scale.

The diode, being attached to the outer side of the satellite, might be exposed to light that is reflected off the Earth or satellite surfaces. To partially prevent this, I soldered a shield to the edge of the sensor. Each surface of the shield would be covered with non-reflective material to further decrease the amount of ambient light.

To protect the diodes from the impacts of micrometeoroids and other space debris, I plan to cover the diodes with a thin shield of hard glass crystalline window (tempered glass or sapphire).

Testing the first prototype indicated a number of drawbacks that were solved in the second. Such problems are attaching the shield and the cells to the device, decreasing sensor’s size while increasing its aperture, and making the assembly process simpler.

I also calibrated photocell’s voltage outputs and their exact positions to account for manufacturing imperfections and for those created during the manual assembly of the device. I wrote a program to calculate the vector of sunlight direction and using Processing IDE created a visual representation of my sensor as well as its output result:

Picture 3: Visual illustration of a working solar sensor.

In order for my sensor to survive the vacuum environment, I attempted to use only space qualified materials in the device’s assembly: PCBs, solder, epoxy, and sheets of copper. I have finished working on the development stage of designing the solar sensor. Testing procedures on my last prototype showed that such device would be ready for further usage and launch.

A Great Quote!

For everyone doing cutting edge work, here is a great quote from a pioneer in rotary wing aircraft:

Every very radical research needs an eccentric person who, by a certain amount of freedom from convention is not too afraid to go far afield for solutions.

 

Gerard Herrick

Richard Whittle, “The Dream Machine: The Untold History of the Notorious V-22 Osprey,” Simon & Schuster Paperbacks, 2010, p. 20