It's hard to believe that it's been more than a week since the flight. Aliya has made a first pass through the data and we have beautiful clouds between 1.8 - 0.5 g but in microgravity the dust escapes from the potential well we've created and gets pinned to the glass wall of our vacuum vessel. Once the plane noses over the top of the parabola and gravity increases, we can watch the dust stream back into the center of the chamber and self-organize itself back into a cloud.
As I boarded the plane that would take me back to New Jersey, I couldn't help but laugh. It was a 737, similar to the 727 that we few at NASA and it looked so odd so see it full of seats and luggage and people. The wait to take-off was long, the ascent slow and gradual, the seat uncomfortable. It seems like it wasn't two days ago that I was on the world's most amazing roller coaster, but two years ago. But to call the "Weightless Wonder" a roller coaster is a disservice to both.
But amazing things happen everywhere. First, I watched "Vicky Christina Barcelona," Woody Allen's latest movie about love, lust, passion, and feelings, with the message that life is short, stop thinking, stop analyzing, and just live. Then, we passed a lightning storm at the same altitude that the plane was flying. Below us, the sky was clear but a few miles outside my window was the most spectacular display of lightning. It seemed to be concentrated in two regions, one off in the distance that lit up over and over like the sky on the 4th of July. The other was much closer and much less frequent and we made no obvious attempt to stay clear of it. At one point, a bolt of lightning shot across the sky right next to us and I was both amazed and a little bit scared. 10 minutes later, we were past the storm.
I don't know how any of this is related to my adventures over the last ten days, but it somehow seems the right way to end this trip. The photos from NASA of our flight were posted on the web today, and I'm going to put together a slide show tomorrow and post it here. The photos are incredible and make the flight vivid again in my mind.
That's a slogan that NASA uses, and it permeates everything they do. Today we had a tour of Johnson Space Center that was just for our group. A behind-the-scenes tour of a small part of the 1,600 acres and 17,000 people that make up JSC. We began in the building that has full-scale mock-ups of a space shuttle, parts of the space station, and a robotics laboratory. This is where the astronauts practice a variety of tasks and one of the first things we saw was a group working on a new generation of space suits. Doug, the head of the Microgravity program pointed out that the person in the center of the group was an astronaut that had spent 3 months on the space station and was scheduled to go up on a future shuttle flight.
Here I am sitting in an actual chair used in the space shuttle
and it is definitely designed for function and not comfort. We also saw a floor that was sort of like a gigantic air hockey table. The chairs that are put on it "float" as the astronauts practice performing tasks on this chair, moving around as if they were weightless.
Next we went into a robotics lab and met
"Robonaut." This is a prototype of a robotic assistant for space walks and some day might be controlled from inside the space station by an
astronaut wearing gloves and a virtual reality visor. If the astronaut closes a hand, so does Robonaut. Versions of this might go on a future Mars rover or help repair something on the space station.
NASA is also working on a version that moves like a spider. "Spidernaut" has 8 legs and distributes it's weight among them in order to travel over a
variety of terrains such as the surface of Mars.
Next was the observation area of Mission Control for the space shuttle and we were
just in time to see a ceremony hanging a large patch honoring the team for the last shuttle mission, the one that successfully repaired the Hubble Telescope for the last time. 6 of the 7
astronauts from that mission were there and the Mission Director handed out awards to most of the teams. He gave a special award to the team that supported the space walks and they got to hang the patch.
From here, we went to Mission Control for the Apollo missions. This was the actual room
where they did all of the missions, including landing on the moon. Hanging from the ceiling
was a flag flown on the moon and then brought back to Earth. Hollywood recreated it perfectly for the movie Apollo 13.
Tomorrow, our alternate flyer, Aliya, gets to fly with one of the other schools and we'll be there to support her. After that, I'm headed to the airport to return home. The official NASA photos of our flight will be posted next week and we will have the video in a few weeks. It's hard to believe that the trip is almost over.
There is absolutely now way I can fully explain what I felt today. Awesome? Amazing? Unique? Sure. But it was so much more.
Our day started at 7:30 am with check-in and our ground crew (Rachel, Russ, Chaz, and Ailya) going to the plane to get everything set-up. I realized last night that our laser was in a good position for normal gravity but not for zero gravity. So I asked the ground team to raise the laser into a better position and to figure out how to firmly attach our accelerometer cable to the port on the plane. They did all of that and more and left the plane knowing that the equipment was set up optimally.
Meanwhile, Darrick, Chris, and I went to our pre-flight briefing. Take off around 9:15 am,
landing around 10:45 am, we'd be doing 30 normal parabolas cycling between
0 g and 1.8 g, and a single parabola each at lunar gravity and Martian gravity. The flight surgeon that would be on the flight told us more about the optional anti-nausea medication and then gave us our pills. Basically, I took 5 mg of speed and 2.5 mg of a depressant with a group of undergraduates and the government not only approved it, they paid for it.
About 15 minutes later, the speed kicked in and I got the giggles. In between, Chris, Darrick, and I reveiwed the experimental plan for the flight, hung out, and all of a sudden, it was time to board. The plane is a 727 jet with about 30 seats in the back. We climbed the ladder in the tail, checked our experiment and sat down for the take-off. By now, the adrenaline had kicked in and I felt fine.
After 10 minutes, the plane leveled off and we were allowed to move to our experiment while we continued the flight out over the Gulf of Mexico. Everything looked great, we had a large cloud, the computer was recording video from both cameras, there was nothing to do but wait.
When we got the "1 minute" call we sat down with our backs against the padded wall which is the optimal position for the hypergravity portion. Our plan called for the first two parabolas to be practice-only and we weren't going to look at our experiment. There are no windows around us, so we can't see the horizon and as the plane lifted its nose, all we could feel is the increase in the gravitational force making our legs and arms really heavy. On computer monitors in the cabin and also on our own experiment, you could watch g increase from 1 g to 1.8 g and then start to decrease towards 0 g.We sat together in the lotus position, smiling, nervous, ready to float.
As we got near the zero-gravity part of the parabola, we started to float just a bit. Then, all of a sudden, we floated off the ground entirely and headed right to the padded ceiling! I have no idea how to describe it, but we just pushed ourselves back down and then the call for "feet down" came and gravity "turned back on." Sitting up, we rode out the next hypergravity portion and then right back into zero gravity. This time, I tried to keep my movements small and I felt I had much more control as we floated around the ceiling.
Now we got ready to start the experiment. Chris lay down on his belly with a direct view of the plasma and dust cloud. I headed to the other end of our box so I could control the power supply voltage and the argon pressure. Darrick was in the middle, mostly just spacing out. This time, when we went into zero-g, we all held onto our box which was bolted down to the floor. Our bodies, however, lifted off and so we were all at a 45 degree angle up, with our feet higher than our heads, our sneakers pressing against the back wall holding us in that position. One hand held onto the handles of our box and the other was used to make adjustments. We had a small computer monitor attached to the top of our box and I floated above it, looking down for the clouds.
For the next 15 parabolas, we had a beautiful cloud in 1 g and hypergravity but nothing in zero-gravity. And that's what we ended up with. We haven't done any analysis yet, but it appears that the cloud fell apart in zero-g and then reformed as gravity turned back on. With our wide-view camera, we could watch this process over and over. It also looked like we had a varying-gravitational field-induced dust acoustic wave. (That last sentence was just in case any plasma physicists are reading this!)
After the 17th parabola, the plane turned around and did another 13. Bottom line is that we got excellent data today with a variety of interesting phenomena to study. (Aliya is spending the summer in my lab working on this.)
During all this time, NASA had photographers and videographers taking video and photos of all of us. We had plenty of time to "play," I spun Chris in a summersault, we had a catch with a rubber band that just floated through the cabin, and I tried to use both Chris and Darrick as weights over my head as I exercised by doing pull-ups on them.
We ended by doing a parabola at lunar gravity (hopping around the cabin was fun) and Martian gravity (not so interesting). Throughout, I was very conscious of not moving my head back and forth too much and felt really good throughout the flight. I wouldn't call it normal, but I never felt nauseous at all.
We returned to the airfield, took a group photo, had a post-flight briefing, and then went to get lunch. In the afternoon, we packed everything up. Tomorrow is a behind-the-scenes tour of Johnson Space Center.
First Flight Day. We met at 7:30 am to prepare for the 9:15 am take-off. Justin, Darrick, Chris, Aylia, and I are the ground crew while Rachel, Russ, and Chaz are the flyers. The flyers put on their olive NASA jumpsuits and head into the pre-flight briefing. At 8:00 am, they take their anti-nausea medication, called SCOP-DEX. It is available to participants by prescription only from a NASA Flight Surgeon and distributed just prior to flight. SCOP-DEX is a controlled substance used by NASA for thirty years with almost no adverse effects. It is a combination of Scopolamine (0.4 mg) and Dexedrine (5 mg) tablets. Basically, that's a dangerous street drug (at much higher dosages) combined with an upper. Wow! Historically, 60% of first-time student flyers in the Reduced Gravity program experience significant motion sickness, including nausea and vomiting. However, when students carefully follow the instructions of the flight personnel, and use the recommended dosage of SCOP-DEX, this motion sickness rate drops to 15% or less. I wonder if I should take it tomorrow? Okay, done wondering, give me the maximum dose!
While all of this is going on, we are in the plane powering up the experiment and checking all the last minute details. All systems are go! We have a beautiful cloud, it's stable, happy, and reproducible. The only issue is that NASA loaded the bottle of argon we were using in the lab and it is almost empty (about 100lbs left when 2,500 lbs is full) and there is no replacement bottle. If it runs out, the experiment won't work and there's nothing we can do. I had been roughly keeping track of our argon consumption rate in the lab and while I don't know it exactly, I'm fairly certain we have enough for the flight. We quickly talk about what we can do if the argon runs out, and NASA assures us that they will have a full bottle of argon for us in the afternoon. As we're getting off the plane, the line of students getting ready to fly approaches. That's Rachel in the middle of the photo waving to me. NASA does an amazing job with documenting all of this and there are photographers and videographers recording all of this. (They are also on the flight and we'll have copies of everything in a few weeks.)
At 9:30 am, they take off and we watch the plane slowly lift it's nose off the ground and then pull up into a steep ascent and bank sharply towards the Gulf of Mexico to the south. Nothing at all like the gentle ascent of a commercial airline flight. At that point, there's nothing for us to do so we head off to get some breakfast and watch the landing at 11:00 am.
Touchdown is perfect and as the entire group gets off the plane, we're on the runway to greet them. Rachel is smiling and bouncing, Chaz is grinning, and Russ manages a weak smile but looks a little pale. (You can imagine how each of them did.) Unfortunately, we didn't get any data at all! The cloud was stable in 1g but disappeared once the parabolas started and nothing they did could get it to come back. On top of that, the cable that we ran to the accelerometer port fell off because the only way to hold it in place was duct tape. As we reviewed the video, we confirmed that we only had accelerometer data for the first few parabolas and there was no evidence of a dust cloud. That was frustrating.
As I write this, we don't know why we didn't see any clouds during the flight. The team tried just about everything except for moving the laser and that's probably what needed to happen. Turns out that the gravitational acceleration along the axis of the plane is not zero and so, like the force you feel when you quickly accelerate in your car from a stop, our cloud most likely shifted out of the laser beam, to the back side of the chamber. That's what we'll look for tomorrow and with any luck, we'll find the cloud.
The other issue is that NASA is not flying their own plane with their own pilots this year, and have contracted out to a private company. The quality of the parabolas, like the accelerometer port connectors, is significantly reduced compared to previous years. Last year, the changes in gravity were smooth and the parabolas did not vary much. That's not the case at all this year. It is already tremendously difficult to work in a zero-g environment and this makes data collection nearly impossible.
Finally, we saw two more amazing aircraft. The one on the right is an Air Force cargo jet and while it's hard to tell from the photo, it is absolutely enormous. The one on the left is a WB-57 high altitude aircraft, one of only two in the world. It can fly up to FL600 (60,000 ft) for a variety of research missions. The other one is behind it, undergoing an extensive maintenance. As I wrote before, NASA has all the cool "toys."
The day started at 7:30 am as the team finished the last minute preparations before the safety inspection at 10:30 am. Everything was going well until we turned on the vacuum pum
p. It didn't sound good, sort of the sound we heard back at PPPL when it was full of water vapor and the worst case scenario was that the valves were bad and would have to be replaced. We had the spare parts but it would be a huge job and we were told that if we passed the safety inspection we would load onto the plane around 1:30. It took a couple of hours before we
(meaning Rachel) found a loose connection on the pressure sensor and once that was fixed, everything was working well. We made a dust cloud just in time before about 15 people surrounded our experiment for the safety inspection. Russ did a gre
at job leading them through all of the potential hazards and they asked plenty of questions. In the end, they wanted a few calculations redone, some sharp corners covered, and that was about it. We then took our experiment in its metal box to be weighed. There was a 300 lb limit and we weighted in at 295 lbs. Phew!
Then Ailya, Chris, and Chaz left to go in the hyperbaric chamber and I decided we should try to work on the laser alignment because there were a lot of reflections from our glass chamber. What's that saying, "If it ain't broke, don't fix it?" Should have listened to that. The good news was that we found that the screw that was holding our laser lens was so loose that it
had almost fallen out. If it had during the flight, we wouldn't be able to see our cloud. The bad news was that after we fixed that, we could never get our cloud back into a sharp focus. It's good enough to take data, but not of the quality we had before I started messing around with things. And in the end, it's also a lesson for next year to work harder on the imaging system.
Around 1pm we loaded the experiment onto the plane with a forklift. Our holding bracke
ts fit perfectly and all four bolts easily fit into the floor of the plane. In this photo, you can see Russ talking to the NASA technicians that are bolting the experiment to the floor. We hooked the argon gas line up to our chamber and we're set. Hard to believe that tomorrow
Rachel, Russ, and Chaz will be flying.
Finally, behind our plane is NASA's 747 that they use to transport the shuttle from where it lands in California to where it takes off in Florida. It's a huge plane and you could see the brackets on the top of it where they attach the space shuttle to the plane. It was spectacular to see it up close like that.
Sunday started when Rachel, Darrick, and Russ picked me up for brunch at a crepe restaurant. Every day in Houston so far has been sunny and beautiful and we ate outside and watched the people on the sidewalk. We then met up with the rest of the team, minus Justin, for 90 minutes of jet skiing. That was fun. Finally, we went to see the movie, The Hangover, at a theater that serves dinner and beer. Seems that Texas has these all over the place and I wonder why we don't see them in New Jersey. The movie was sophomoric, immature, played up to a variety of male stereotypes, and was probably one of the funniest movies I've ever seen. Throughout it, people brought us food and drink. How can you go wrong with that?
Tomorrow is a big day, our Test Readiness Review (TRR). A safety team will inspect our experiment and determine if it is safe to fly. To prepare, the team put together a document that discussed all of the potential hazards associated with our experiment and a calculation to show that it would not break apart, hurt someone, etc. If we pass the review then we can load the experiment on the plane and fly on Tuesday/Wednesday. I'll let you know tomorrow how it goes.
The hyperbaric room is a steel box, about 8 ft wide by 20 ft long. There's one door and it can be sealed tight and there is a system to control the air in the room so that they can simulate the atmosphere at different levels. Inside the room are 16 seats with connections for each seat that have oxygen hook-ups and a communication port. Inside our mask is a microphone and speakers. Eight people sit on one side of the room, eight on the other. When we got to FL250 (25,000 ft) after breathing pure oxygen for 30 minutes, half the group took off their masks. My side got to watch them for 5 minutes as the person controlling the chamber asked them questions, and they wrote down any symptoms they might have at each minute. A couple of people clearly had some difficulty and put their masks back on before the 5 minutes was completed. Then it was my group's turn. My mask was incredibly uncomfortable, not designed for a long face and a big nose and it leaked no matter how tight they made it. So they decided just to increase the oxygen pressure in my mask and flow it continually. That kept me from breathing in the room air until I unhooked it and I remember how good it felt to finally get the mask off. The air smelled stale and I felt nothing at first. We had a clipboard with a worksheet on it and a pencil so I wrote my last name backwards without a problem. At one minute, I wrote that I had no symptoms and my handwriting was neat. Then I wrote the last 4 presidents in reverse order through Bush Senior and couldn't remember anyone after that. At two minutes I wrote that I had no symptoms. I tried a math problem on the worksheet. 82-45. I instantly realized that I would have to carry a 1 over to do this problem and that just seemed like too much of a bother so I decided to skip the math. At 3 minutes I wrote "slight lightheaded" and my handwriting is a little messy. Then my vision got a little fuzzy, and I was still lightheaded. I wrote "slight vision, lighthead vision" and it's getting tough to read my writing. Finally, at 5 minutes I wrote "same as four min" and they had us put our masks back on. The instructors had talked about how we might feel drunk or euphoric and I was really looking forward to that. The instructor asked each of us through our headsets what we felt and I said, not much, and I was really looking forward to feeling "giddy." He replied that he wouldn't normally use that type of word when talking about himself. Ahh, the ex-military comes out.
It actually had such a big build-up that the actual experience was slightly disappointing. I'm hoping that there is some type of connection between doing well in the chamber and doing well in microgravity but I've been assured that is not the case.
The weekend is ours to explore so Saturday morning I found an outdoor cafe for a Tex-Mex brunch and then met up with the entire team. We went to the 31st Annual Johnson Space Center FOD Chili Cookoff. (I have no idea what FOD stands for.) There were hundreds of people there, about two dozen teams, and elaborate booths and nicknames for each team.
The education office camped out overnight and had a great time though they didn't win any awards. It was all the beer and chili you could eat for $10 and the NASA folks not only work hard, they play hard. (I was jealous. At PPPL, we have a picnic once every two years with volleyball and pepsi.)
Then we went to the JSC science museum, checked out the gift shop and the activities. There wasn't much, but we had a good time acting like kids, going through an obstacle course, riding a virtual roller coaster. The photo is a mock-up of the cockpit of the shuttle which was pretty cool.
By now it's around 7 pm so Rachel, Darrick, Russ, and I decide to drive up to Houston and go to the 20th Annual Accordion Kings & Queens Festival. We had no idea what to expect but there were several thousand people there, a dozen accordion bands, all at a park with a stage, seats, and a lawn. They also named the best accordion player under 25 from either TX or LA. It was amazing, lots of traditional bands, bi-lingual banter between songs, and some big names. (Not that we recognized them but people around us cheered loudly when they heard
who was playing.) We also got to try playing an accordion during a free mini-lesson/demonstration. Last year's under-25 winner was there playing and we hung out with him for a bit. Near the end of the concert, there was one zydeco band from LA, four generations of one family, and a 10-year old drum player. They just rocked! Incredible energy, great music, jamming and having a good time. We bought their CD and had the lead singer and accordion player sign it, dedicated to Team DPX. We left around 10:30 pm to get some dinner (more Tex-Mex) with big smiles on our faces. Sometimes, when you have no expectations, you end your day with a perfect margarita and a smile. Sunday, I will wear my accordion festival t-shirt proudly and we're going jet-skiing.
Hey, why don't you get to Johnson Space Flight Center at 7:00 am, we'll have shuttle buses take all 80 participants to the building that houses Mission Control, put you in an auditorium for a 4-hour powerpoint presentation, give you a quick lunch break, a quick tour, more powerpoint, then we'll put you in a sealed metal box attached to a big vacuum pump, drop the oxygen level down to the equivalent of 25,000 ft. (or FL 250, more on that later), and see what happens?
Actually, the correct answer is HELL YES!
So we walk into this building and the first thing we see is the real entrance to the real Mission Control. We get to go inside next week during our big tour but it's just really amazing to see people walking into it and all the photos of rocket launches and shuttle missions.
Justin and Rachel did this last year so they are back at Ellington Field working on the experiment, but the other 5 students and myself march into the auditorium with the rest of the group. We sit in the back, a really bad idea because that's the easiest place to get a nap, or crack some jokes. And we've been warned about falling asleep but the auditorium is about 50 degrees so it should be good.
NASA considers us "mission crew" during our microgravity flight and our responsibilities are significantly more than if we were flying a commercial flight. We've all heard the video about a loss of cabin pressure and the "dixie cup" oxygen masks that will drop down. Remember, put the mask on yourself first, then any small children. Well NASA wants us to know what it would feel like if there was a loss of cabin pressure on the Vomit Comet since we won't be sitting and there are no dixie cup masks in the ceiling. At 25,000 feet, the oxygen level has dropped down significantly and breathing this air causes hypoxia. Symptoms include blurred vision, euphoria, nausea, dizziness, fatigue, headaches, and so on. Let's do it!
Our instructors are all retired military, very serious, and the lectures are actually quite interesting. Of course NASA is a government agency so acronyms are common (just like at PPPL but worse) and we learn about the atmosphere and oxygen levels and the types of hypoxia. (FL 250 = 25,000 ft above SL (sea level) and at FL250 you have about 3-5 minutes of TUC or EPT (time of useful consciousness or effective performance time)) Oh, here's a little trivia fact. Above FL630, called Armstrong's Line, the boiling temperature of bodily fluids is 98.6 F so without a full pressure suit you will just boil off your blood and die. I wanted to ask who Armstrong was and how they found this out but kept quiet.
I missed some of the lecture on Trapped Gases and how to correct for them, because I had a work meeting with some of the NASA education people about future collaborations. It was an excellent meeting but I did miss some critical information. Not on the usual ways of releasing trapped gases, naturally I'm an expert. I missed the discussion of "valsalva." The technique is named after Antonio Maria Valsalva, the 17th century physician from Bologna and is a way to clear trapped gases from your ear canal. You pinch both nostrils closed, take a breath of air, close your mouth tight, tilt your head back 10 degrees and blow out your nose. Our instructor was very, very enthusiastic about the technique and it became the catch-phrase for the rest of our day. "Hey, I just valsalved." "Don't forget to valsalva before bed." "Sometimes I feel the need to valsalva every single day." Darrick and I found that hysterically funny and I know it won't translate to those reading this, but I'm laughing as I type.
Right before lunch was the spatial disorientation lecture and both Darrick and Chris got picked for the demonstration. Basically it just consisted of sitting in a rotating stool that had a seat belt with your head down and your eyes closed while the instructor spun you around. We all got a good laugh as they got dizzy, but the point was to demonstrate that when we're in microgravity, we will lose our sense of up and down and our eyes and body can be out of sync with the messages they send to our brain.
After lunch, half the group headed back to work on the experiment (Chris, Chaz, and Aliya) while Darrick, Russ, and I got ready for the chamber. Those that didn't go today will go on Monday. We had some time to kill so we stopped in "Rocket Park" a large hangar with an actual Saturn V rocket lying on it's side. 363 ft long, 103 tons and breath-taking.
Then it was time for our tour of the Neutral Buoyancy Lab, the world's largest indoor pool. 100 ft wide x 200 ft long x 40 ft deep, it holds more than 6,000,000 gallons of water and the filtration system can get through all that water in less than 24 hours. Astronauts train for space walks in the pool, and when we were there a full-size mock-up of part of the International Space Station was submerged. A mock-up of the Hubble Telescope was off to the side of the pool, the repair job finished by astronauts last month. (Every thing at NASA is very big and very impressive.)
The hyperbaric chamber is next to the Neutral Buoyancy Lab and, finally, we had our pre-flight briefing and got fitted with oxygen masks. Once in the chamber, we had to breathe pure oxygen for 30 minutes to reduce the amount of nitrogen in our bodies so we would not get the bends. Then it was a "climb" to FL250 at 5,000 ft/minute where we would level off for our hypoxia experience. Then we "descend" to FL 200 at 3,000 ft/min before heading back to ground level at 2,000 ft/min. While our oxygen masks were off, we had to do a simple worksheet and list any symptoms we felt. Also, we were told it was important to not keep any trapped gases inside our body so if we had to do a "one cheek sneak," just let it go and don't worry about it.
I realize that this is a long post so I'm going to stop here, save the hypoxia experience for tomorrow, and try to upload some actual photos of us. NASA videotaped the experience and we will get a copy of the tape in a few weeks. Just to let you know, I did not have any issues with trapped gases and did not even valsalva once during the "flight." That was a little disappointing, actually.
And away we go! After an easy flight from Philadelphia to Houston, I picked up my bright orange Chevrolet HHR and headed to the Hotel Icon downtown. It seems like everything in Texas is far apart and the NASA sight is about 35 minutes from where I'm staying. I could have found an Extended Stay hotel or something like that but my hotel is one of those boutique hotels, an old converted bank, and worth the drive. The bathroom is bigger and nicer by itself than some hotels I've stayed in while traveling for work.
8:00 the next morning, I report to hangar 990, the NASA site at Ellington Field. The field was created in 1917 during WW I and is one of the few airfields built for training at that time that is still in use. Besides the microgravity program, the field is the location of the astronaut training aircraft, used by astronauts to practice flying.
The coast guard and national guard also have space at the field which primarily consists of 3 huge runways, old hangars, and low metal buildings. I eventually find our hangar, park my gangsta car, and walk up to the gate where an enormous security guard with a gun greets me, directs me to the check-in, and lets me know that he flew in microgravity 20 years a
go and I'm going to love it.
The hangar doors are open and I immediately see a parked NASA plane. It's huge and one of the planes used for microgravity research, though not the one we're going to fly. This one just escorted the space shuttle back to florida and is now undergoing maintenance. It's right next to where we spend most of our time and just dwarfs us as we move around the hangar.
I checked in, got my NASA badge and we heard multiple times to stay in our area, right next to us is a military hangar, and if we wonder over there we will be arrested. (Sure enough, there are 6 military helicopters parked at the next hangar over and they look impressive.) There are about 10 teams from school over the country, though most are large universities and not a small school like The College of New Jersey. All together, there are about 80 students and we all hear about the program, our schedule for the week, and safety issues.
That takes most of the morning and the rest of the day is spent assembling our experiment which takes the entire day. But we manage to put together the metal box that will be bolted to the floor of the plane and hold our equipment and make a plasma before we all head over the Fuddruckers for a group burger. (Or in my case a veggie burger.)
It's a good first day, but the action really starts on Friday when we are put in the hyperbaric chamber. I'll probably never breathe in the air at the summit of Mount Everest, but I'll soon know what it would feel like when they put us in a sealed room and reduce the oxygen level to the equivalent of being on the summit.
We've got a plasma in our chamber, there's a cloud of dust suspended in our plasma, and now we're going to start changing gravity. The balance between the electric force and the gravitational force is lost and the cloud begins to move up as gravity decreases and down as gravity increases. We can measure that with our wide-field video camera and work out the shape and strength of the electric force. We will also use a camera with a zoom lens to look at the movement of individual dust particles in the cloud as gravity varies between 1.8g and 0g. Our on-board computer stores the video at 30 frames/second and each frame is automatically marked with the pressure in our chamber and the gravitational force. (Thanks to Brandon and Will for writing the computer program that handles all of this!) The only other variable we can control is the strength of the electric force by changing the voltage on our power supply. If it all works as planned, the experiment will practically run itself and all we'll have to do is monitor the voltage on the power supply and adjust the pressure so we can study the dust motion at different pressures.
So if plasma is 99% of the visible universe, the foundation of a new energy source, and used to make fluorescent light bulbs and computer chips, why in the world would we want to mess things up by adding dust? Well, it turns out that space plasmas are full of dust. The tail of a comet, the rings of Saturn, and interstellar clouds are all dusty plasmas. On Earth, dust is a contaminant in a plasma processing device and a concern for the edge of future fusion energy reactors. Dusty plasmas are also of fundamental interest because they can help us understand changes between different states of matter and how systems of particles organize themselves. Thus, understanding how dust behaves in a plasma has both practical applications and satisfies our purely scientific curiosity.
In our lab, we make nice, steady DC glow discharges and then we add dust to the plasma. Our dust can be different things but normally is silica (basically sand) that is about 40 millionth of an inch in diameter (a bit less than the diameter of a strand of hair). Sometimes we use a fluorescent dust instead, one that glows when we illuminate it with a UV light. (More on that below.) In each case, we put the dust on a tray at the bottom of our vacuum vessel.
Sometimes we bathe the dust in the plasma, sometimes we speed things up and send small arcs of plasma to the tray. In both cases, the dust picks up some of the free electrons and now has a negative charge instead of remaining electrically neutral. That charge is the key to making a dusty plasma and everything that happens to the dust. It means that the dust will be repelled from anything else that has a negative charge (remember that like charges repel, opposite charges attract) such as other dust grains. It also means that if the plasma has an area of positive charge (near one of our electrodes that is attached to a power supply) the dust grains will be attracted to that area. If conditions are just right, there will be a cloud of dust floating in the plasma, with an electrical force pulling the cloud up and the force of gravity pulling it down.
Now all we have to do is see the cloud of dust particles. For that, we take a laser pointer and shine it through a lens that makes a vertical line of laser light. Then we look through a vacuum window (with our eyes or a video camera) and observe the laser light that reflects off of the dust. That's what you're seeing when you look at the photo at the end of my last post. There's a piece of metal at the top of the photo and a strong electrical force pulling the cloud into that area. At the bottom is a pile of dust on a tray. In the middle is the cloud and our red laser is going through the center of the cloud which is shaped like a funnel. We are seeing just the "slice" of the cloud illuminated by the laser. If you look closely at the dust cloud, you will see at the bottom the individual larger particles while at the top the individual dust grains are too small for us to see.
Sometimes we try to observe all of the dust grains at once. Instead of a laser line, we switch the dust to a type that glows brightly when we shine an ultraviolet light on it. That helps us study the cloud formation process but the glow from this dust is not as bright as what we can see from a laser.
Finally, here's a video of us forming a cloud with the glowing fluorescent dust. You will see us jump start the process by forcing the plasma down to the tray and then, after a short period of time, the dust organizes itself into the cloud that we observe.
Tomorrow I will write about what happens when you "turn off" gravity and then it's time to fly to Houston.
Sure, the idea of floating in the air for 30 seconds at a time puts a smile on my face every time but this is not just about the adventure and fear that I'll toss my cookies, it's about the science. And we're doing some really cool science up there. So this post is the technical post, the one for you science nerds out there. Everything you ever wanted to know about dusty plasmas in microgravity but were afraid to ask.
It all begins with plasma. Not the stuff in out blood, but the stuff that's 99% of the visible universe. The fourth state of matter. Solid - Liquid - Gas - Plasma. Heat up ice (solid) what do you get? Heat the water (liquid) and you turn it into a gas. But what happens when you add energy to the water vapor? Or any gas? Plasma. In a plasma, there is enough energy added to the gas that some of the electrons that normally orbit around the nucleus are no longer bound and are free. When that happens, it's no longer a gas but a unique state of matter. We know it as the stuff inside a fluorescent light bulb, inside a neon sign, or lightning. It's also inside some flat-screen televisions and has a variety of industrial applications, including making computer chips with plasma processing. Away from Earth, plasma is everywhere. The sun and all the stars are plasma as is the stuff between stars. Plasma is also the foundation of a source of virtually unlimited, clean energy if we can heat and confine a hydrogen plasma to the point that it will "burn" in a fusion reactor.
But our plasma is cold (the electrons are a frigid 10,000 Celsius) and we allow it to fill our vacuum chamber. It is something called a DC Glow Discharge.
Our plasma is made by removing the air from a glass container with a vacuum pump and then flowing a small amount of gas (Argon) into the chamber. We heat the gas with an electrical current (about 400 V, 1-2 mA) to create a plasma. Then we have neutral argon atoms, some free electrons, and some argon ions (neutral atoms that have lost an electron). To this mixture, we add some "dust" to create a dusty plasma.
So what is a dusty plasma and why do we care? I'll answer that in my next post. For now, here's a photo of one that also won an art competition a few years ago.
I'm the Head of Science Education for the Princeton Plasma Physics Laboratory and a Lecturer in the Writing Program at Princeton University. When I can, I spend summers in microgravity, 22 seconds at a time.