A team of five students at Carter Middle School in Knoxville, Tennessee is sending an experiment to the ISS through the Student Spaceflight Experiments Program (SSEP) in partnership with DreamUp. This is the first year their school has been involved in SSEP. Their project, “The Effect of Microgravity on Tooth Decay,” is one of 34 SSEP experiments scheduled to launch June 29, 2018 on the SpaceX CRS-15 mission.
The experiment fits into a rigid sealed tube called a Fluids Mixing Enclosure (FME), or “MixStix,” manufactured by NanoRacks. The tube has two chambers separated by a clamp. One chamber will contain a tooth; the other will contain a mixture of saliva and plaque to mimic the typical conditions in an astronaut’s mouth. Last week, the team prepared three tubes—two control tubes and one flight tube—and sent the flight tube to NanoRacks for processing.
We recently asked the team about their project. Meet Samara, Elijah (7th grade), Nate (8th grade), Braxton (8th grade), Blake (7th grade), and Mrs. Katrina Whipple (their teacher facilitator).
Your experiment studies tooth decay. Where did you get the teeth?
SAMARA: They’re Braxton’s baby teeth! We have three of them. We’re going to send one, and we’ve got a couple for our control experiments.
ELIJAH: I had permanent teeth pulled, and we thought they might be better to simulate the astronauts’ teeth because they’re adult teeth, but they were too big to fit in the tube.
How did you choose this topic?
NATE: We had two massive sheets of paper on the wall, and we just kind of wrote down ideas. I had a green marker, a yellow marker, and a red marker. For each idea, we all showed how much we liked it using a color. If one person really liked it, they put a green mark next to it. If someone didn’t want to do that one, they put a red mark. Yellow means “not sure.” And we all really liked the whole teeth thing!
SAMARA: Originally, someone said something about Coke and a tooth.
ELIJAH: We were looking at the pH of different liquids. We looked at soda, and we looked at apple juice.
SAMARA: So we were going to use a low pH to see how quickly that would decalcify the tooth in the microgravity environment. But over time we changed our plan to use a mix of the things that would normally be in your mouth.
ELIJAH: We just thought, hey, saliva and plaque, you know.
SAMARA: We wanted our experiment to be helpful to the astronauts. If we find out that teeth decay at a different rate in microgravity, then they might need to change how they care for their teeth.
How did you create a substance to mimic the conditions in a person’s mouth?
SAMARA: What the substance is made of is the saliva from the person who donated it (Braxton), which contains bacteria, along with plaque from his teeth. Because plaque is another thing that helps in the decay of teeth. So we basically mixed plaque with spit.
MRS. WHIPPLE: Several months ago, when we were preparing our proposal, we tested the saliva and plaque mixture in feasibility experiments. We tested to see if the bacteria were viable.
How did you determine that the bacteria were viable?
SAMARA: We had him (Braxton) spit in a Petri dish.
MRS. WHIPPLE: We watched it over the course of several weeks. We checked it in the microscope. We could see the clusters of bacteria showing that they survived and grew.
How did it go when you prepared the experiment tubes last week?
MRS. WHIPPLE: We got fresh samples of saliva and plaque from Braxton to put in the tubes with his baby teeth.
NATE: It was kind of gross handling one of my best friends’ spit, but it was satisfying knowing that what I was doing was a product of the team’s hard work and commitment.
ELIJAH: Loading the experiment was really interesting. It was really cool to see the experiment that we imagined actually coming to real life. It was a moment of realization that we did it, and we are actually doing this!
BRAXTON: The FME has one clamp. It separates the tooth from the saliva mixture on the other side. Oh, and the root of the tooth is embedded in acrylic to imitate how our teeth are rooted in our jawbone.
How will the experiment work in orbit?
ELIJAH: An astronaut on the space station will open the clamp and shake the tube to expose the tooth to the saliva mixture.
What are your plans for control experiments?
MRS. WHIPPLE: It’s two FME tubes for the control. We’re going to do them simultaneously.
SAMARA: We want to look separately at the decay that happens in microgravity and the decay that happens in Earth gravity. But after the clamp is opened on the flight tube and the tooth touches the saliva mixture, the tooth will stay in contact with the saliva even after the experiment leaves the space station. We might not get the tube back for a couple of weeks after the SpaceX Dragon returns to Earth. During that time, the tooth will keep decaying in Earth gravity. We didn’t want that to mess up our results. So we decided to use two control tubes so we know how much it decayed while it was in microgravity.
What measurements will you make?
MRS. WHIPPLE: For one thing, we look at the teeth under a microscope. We took pictures of the teeth before we loaded them into the FME tubes.
ELIJAH: We’re going test the saliva mixtures too. We’re going test their pH levels to see if they differ or how they compare. And we’re going to see how much calcium is in them.
SAMARA: The calcium levels can measure how much calcium went from the tooth into the saliva mixture.
BRAXTON: The main reason we’re checking the calcium too is that it’s better than just looking at the tooth. We will look at the tooth and we will describe what we see, but it will be hard to put that into numbers. The calcium measurement will give us actual numbers.
MRS. WHIPPLE: There’s a way to measure the amount of calcium in the liquid with some drops and a color code.
Has this experience affected your thoughts about the directions you want to take in school or a career?
BLAKE: I want to be an accountant.
SAMARA: I have wanted to be a zoologist since I was six, and I still want to.
ELIJAH: I wanted to be a lawyer and I still want to do that. I’m also going to be in the Olympics.
NATE: I want to be a director. I’m going to make movies and be in Hollywood and be awesome.
BRAXTON: I already wanted to be an engineer before we did this project, and I still want to.
What has been especially challenging about working on the project?
MRS. WHIPPLE: We had to have a plan for flight safety testing in our proposal. In order to send human samples, we must have them tested for certain diseases, and so they were trying to find somebody that could test the saliva.
ELIJAH: And that was hard to figure out.
SAMARA: We had to call in a dentist and everything.
ELIJAH: Yeah, we had to call in a dentist!
MRS. WHIPPLE: That was a big challenge, because I didn’t want to do it for them; I wanted them to do it. The problem was that when they would call a dentist’s office, the office assistant wouldn’t take the kids seriously.
BRAXTON: We had to write a script. So we sounded more professional.
MRS. WHIPPLE: It turned out that there’s not a way to test saliva for diseases around here. So we ended up having Braxton get blood work done.
BRAXTON: It was a lot! They filled, like, three long tubes. I can literally say that I gave up my blood for these four!
What has been especially fun about working on the project?
NATE: I made friends, and we got to do gross stuff together.
BRAXTON: We didn’t always get along, but overall we became great friends. We’re almost like a family.
ELIJAH: I really had a lot of fun just making more friends. I mean, it was just fun to do all sorts of stuff together and crack jokes when we were supposed to be working.
SAMARA: My favorite part was probably, like everyone else has said, it was just about making good friends.
MRS. WHIPPLE: I enjoyed seeing the kids working as a team to get something accomplished. It still amazes me how crazy they can be and then snap to work when it is time to be serious. As you can tell, they really bonded together in the process. They are like siblings at this point! And they learned a lot.