How can a satellite the size of a loaf of bread take the heat of operating in the extreme conditions existing in space without overheating? In episode 56, we’re joined by Naia Butler-Craig from the Georgia Institute of Technology to discuss her open access article “An investigation of the system architecture of high power density 3U CubeSats capable of supporting high impulse missions,” which was published in November 2018 in Embry-Riddle Aeronautical University‘s open-access McNair Scholars Research Journal.

Taking Heat in Space - Naia Butler-Craig
Taking Heat in Space - Naia Butler-Craig
Taking Heat in Space - Naia Butler-Craig Taking Heat in Space - Naia Butler-Craig
@rwatkins says:
In June, Naia tweeted, quote, “Today, a man looked me dead in my eyes and told me ‘My job prospects as a white MAN are much lower than yours as a black GIRL because there’s so few of you. It’s a real problem.’” Endquote. Since breaking down the discrimination that has long plagued the scientific community has finally become a topic that’s gaining global attention, Ryan and I thought it was important to ask Naia about the challenges she, as a young African-American woman, has overcome.
@rwatkins says:
In May 2019 SpaceX’s “Starlink” project received a lot of criticism because of their deployment of 60 satellites - of 12,000 planned for orbit - in order to deliver high-speed internet to customers around the globe. In particular, astronomers objected because they believe the satellites will severely impact their scientific observations, as briefly occurred during this Starlink deployment. Listeners may remember our discussion with Alice Gorman about space junk in episode 6 of Parsing Science, available at parsing science dot org slash E 6. So we asked Naia to share her thoughts on whether we might be launching too many of these kinds of satellites.
@rwatkins says:
While simulating the conditions of outer space sounds like a lot of fun, science can also be filled with long periods of waiting as well as mishaps. With this in mind, Ryan and I followed up by asking Naia to tell us more about her experiences with testing CubeSats in those thermal vacuum chambers.
@rwatkins says:
Most of us have a concept of what a vacuum chamber is. But thermal vacuum chambers are those in which the temperature inside of the chamber can be controlled for scientific testing purposes. We asked Naia how the chambers at the NASA Glenn Research Center were used in her research, and what it was like working with them to stress test the CubeSats.
@rwatkins says:
Naia’s research into heat dispersion was a technology demonstration project, meaning she carried out her tests on actual CubeSat devices, but here on Earth, using some components designed to mimic the conditions the satellites would experience in space. Ryan and I followed up by asking Naia what some of the specific sources of heat are on CubeSats. We were also curious to learn if the the ion thrusters being researched and developed at NASA’s Jet Propulsion Laboratory also add to the heat which must be dissipated.
@rwatkins says:
Some listeners may have noticed that propane tanks on gas grills tend to get cold when the gas is being used by the grill to create heat. Given that ion thrusters use xenon gas stored in a small tank to produce the plasma for propulsion, Doug and I were interested in whether temperature changes are brought about by the xenon tanks themselves.
@rwatkins says:
CubeSats have to displace both the heat generated internally by their onboard electronics, as well as the heat they experience externally from solar radiation. So it’s critical to design various systems to ensure that the internal components of these spacecraft don’t overheat, as Naia explains after this short break.
@rwatkins says:
All of the electronics in a single CubeSat can take up no more than 1 usable liter of volume - that’s just 72 cubic inches - and weigh no more than 1.33 kilograms, or 2.9 pounds. Because of this, scientists may link multiples of these “1U” devices together into a longer satellite. For example, Naia and her team tested a “3U” system by linking three individual units together. Given the size constraints of these satellites, we wondered how scientists manage to fit their scientific payloads or telecommunications equipment into a device that’s already packed with propulsion systems and other electronics necessary for maintaining orbit.
@rwatkins says:
There are several different types of thrusters that are common among CubeSats. Because of their small size, weight and efficiency, two popular means of providing CubeSats with propulsion are Hall thrusters and ion thrusters. These electric-powered thrusters use a variety of techniques to generate and discharge the plasma that propel these satellites during maneuvers, as Naia discusses next.
@rwatkins says:
In addition to this spring-loaded deployment system, CubeSats are also interesting in that they often feature origami-like designs to maximize the small form factor of the platform. One of these is something called shape-memory alloys - materials that can be bent into almost any shape desired, and which snap back into their original shape when heated. As Naia used them in the design of her Cubesat, we asked what her experiences were using these types of metals.
@rwatkins says:
While the price to buy space aboard the rockets used to launch commercial CubeSats can cost upwards of $100,000, smaller rockets - sometimes called “sounding rockets” or “research rockets” - can provide a much more affordable means of launching them. They also have a much shorter lead time than commercial rockets, for which substantial launch backlogs exist in many parts of the world. We asked Naia to tell us more about these alternative launch vehicles.
@rwatkins says:
In physics, “impulse” refers to how well a particular rocket, jet engine or thruster performs. Ones with higher impulse allow for performing a greater number of maneuvers, but also require more propellant … and therefore more room for its storage ... and that’s a scarce commodity on CubeSats. We asked Naia to explain what kind of missions can be carried out with the sorts of thrusters that are typical on CubeSats today.
@rwatkins says:
In 1999, Bob Twiggs of Stanford University wanted to challenge his graduate students to engineer and launch satellites within the time and financial constraints of their degree program. As the story goes, Twiggs was inspired by the small plastic cubes used to display Beanie Babies, and proposed limiting the size of these spacecraft to a similar one. The first CubeSat was launched four years later. In just 16 years since that first launch, more than 1000 CubeSats have since been launched, often via the International Space Station for scientific missions, or as secondary payload on larger rockets if for commercial missions. Ryan and I began our conversation with Naia by asking her to tell us more about what these satellites are used for, as well as how she got involved with the technology.
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Websites and other resources

Embry-Riddle Aeronautical University video featuring Naia:
 

 
Video on how ion thrusters work:
 

 

An Investigation of the System Architecture of High Power Density 3U CubeSats Capable of Supporting High Impulse Missions

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Hosts / Producers

Doug Leigh & Ryan Watkins

How to Cite

Leigh, D., Watkins, R., & Butler-Craig, N.. (2019, August 20). Parsing Science – Taking Heat in Space. figshare. https://doi.org/10.6084/m9.figshare.9757793

Music

What’s The Angle? by Shane Ivers

Transcript

Butler-Craig: CubeSats are basically nanosatellites. If you think of a huge one-ton satellite, try to condense it to the size of a loaf of bread.

Leigh: This is Parsing Science the unpublished stories behind the world’s most compelling science as told by the researchers themselves I’m Doug Leigh.

Watkins: And I’m Ryan Watkins. Today, in episode 56 of Parsing Science, we’re joined by Naia Butler-Craig from the Georgia Institute of Technology. She’ll talk with us about her research into the thruster systems aboard miniature satellites known as CubeSats, along with her work protecting the electronics on board from overheating while operating in the extreme conditions that exist in outer space. Here’s Naia Butler-Craig.

Butler-Craig: My name is Naia Butler-Craig, and I am a recent graduate from Embry–Riddle Aeronautical University. I got my degree in aerospace engineering with two minors in computational and applied mathematics. I am currently a GEM fellow at Los Alamos National Laboratories in Los Alamos in New Mexico, doing some computational physics. And in the fall I will be joining Georgia Tech as a PhD student in the aerospace engineering program. And the lab that I was working in is actually called the High Power Electric Propulsion Laboratory, where I will be doing some in-depth study on plasma physics and hall thrusters, and ion thrusters, and anything having to do with ion propulsion.

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