CubeSats give students the chance to do real work in space and a student can see every step, Justin Foley, an aerospace graduate student and a member of PolySat, said.
So, Puig-Suari considered shortening the process. The answer: build smaller satellites.
“I thought, ‘How small can we make these things and still be useful in education?” Puig-Suari said.
PolySat has completed five CubeSats and three more are still in the works. Three of the team’s CubeSats are in orbit now.
“I have had students that come into lab having launched more than one spacecraft, which is pretty impressive,” Puig-Suari said.
Along the way, the team has learned how to make small satellites work, stay within a budget and deal with space exploration.
Puig-Suari and professor Bob Twiggs, of Stanford University at the time, created the smaller version of satellites called CubeSats. They are 4-by-4 inches on each side and weigh about 2.2 pounds, he said.
Big satellites, such as the National Aeronautics and Space Administration’s (NASA) commercial satellites, are thousands of times bigger than Cal Poly’s CubeSats, Foley said.
Scientific satellites such as NASA’s could take several years to build, but the the team can build a CubeSat in about one year to 18 months, Puig-Suari said.
The biggest problem with the small satellites is power, Foley said. The challenge is to get enough power from the solar panels that only cover the 4-inch sides of the CubeSat, he said.
“The trick is that they are so small and that’s why a lot of people, at the beginning, think that you can’t get anything useful in that,” Foley said.
CubeSats average about one watt of power, in comparison to NASA’s communication satellites’ thousands of watts of power, Puig-Suari said.
“We make our missions very low power, which is a good thing in space,” Puig-Suari said.
CubeSats are not the primary satellites on launches. Initially, people didn’t want Cal Poly’s CubeSats launching on the same rocket as the primary, Foley said.
“They didn’t want our little $100,000 toy messing up their $5 million satellite,” Foley said.
Small satellites are becoming more popular now, Puig-Suari said. NASA has missions as short as a week since good detail can come from a short mission and is using CubeSats for testing as well.
“Cal Poly kind of ended up in the middle of this whole CubeSat frenzy,” Puig-Suari said.
PolySat tests how nontraditional space materials and technology work in space, Puig-Suari said.
“We use parts that haven’t gone into space before, then we fly them and see how well they work,” he said.
PolySat uses cheaper, off the shelf parts such as cell phone batteries to fit into the small box, Austin Williams, a graduate student in electrical engineering and a member of the team, said.
“We are taking the technology of cell phones and making it applicable to space,” Williams said.
The team is proving that it doesn’t necessarily have to use space-rated parts to be successful, Foley said. The missions are short, so the team can get away with cheaper parts.
“We are learning all the same concepts (featured) in a career in aerospace but doing it on a university budget,” Foley said.
PolySat is testing the mission life of its CubeSats, which is usually six months to a year. NASA’s commercial satellites mission life could be about 10 years, Foley said.
One of the main goals of PolySat is for a student who is working on the CubeSat to have the opportunity to build and launch it before his or her graduation. PolySat is now building a CubeSat called CP5; its mission is to de-orbit quicker, Foley said.
The higher the satellite is and the faster it is moving, the longer it will stay in orbit, Foley said. A thin film will be deployed, similar to a parachute, to slow the satellite and bring it down quickly. Additionally, PolySat wants to decrease orbital lifetime in order to cut down on the junk in space, Foley said.
“This will demonstrate that we can bring them down on demand,” Foley said.
The CubeSat also tests the temperature in space, which gives the team an idea of how fast the satellites are rotating, Foley said.
CubeSats CP3 and CP4 were launched together and are now in orbit. They were both sending the same data but their temperature readings were different. It was odd because they are both in the same orbit, but CP3 is rotating much faster, Foley said.
“Like roasting a marshmallow, if you rotate it faster it will get brown at the same time and evenly on each side, but if you leave it on one side it will burn and cool down,” Foley said.
PolySat also learns how to deal with vibrations in space. CP7, another CubeSat the team is working on, is a vibrational damping experiment, Foley said.
There are fixed metal beams attached on one end of the structure and free on the other end, and the team is testing if the particles on the free side of the beam will dampen vibrations, he said.
“It is similar to if we attached a salt shaker on one end,” Foley said.
Testing CP7 will show how well the experiment works, Puig-Suari said.
“The vibrational experiment has been successful on the ground, and we would like to use it in space because it is very useful,” he said.
NASA has a program where universities can submit proposals to test an experiment on NASA’s zero-gravity plane and NASA will fund the flight, Foley said. PolySat submitted a proposal to NASA and were chosen to test CP7 on the zero-gravity plane.
Some changes happened to the dampeners of CP7 in zero gravity, Puig-Suari said. Knowing the changes is useful information because it helps PolySat design a better spacecraft for when the team actually launches it into space.
“We wanted to make sure that we could get the readings that we needed,” Puig-Suari said.
The team’s ground station is the PolySat lab, Foley said. There are antennas on the roof that allow the team to communicate with its CubeSats orbiting in space now.
The CubeSats are only overhead about 20 minutes each day, which translates to pretty low coverage, Foley said. PolySat uses the Global Educational Network for Satellite Operations (GENSO) software that links ground stations all over the world.
Foley said the software allows someone’s ground station to talk to the team’s satellite.
The first CubeSats the team built, CP1 and CP2, were destroyed in a failed launch held in Russia in 2006, Puig-Suari said. On the rocket were 14 CubeSats from 11 universities and four to five different countries.
The launch vehicle failed. The team was told that the rocket took off, and shortly into flight the main engine stopped working, Foley said.
“That was a pretty big blow because they were Cal Poly’s first satellites,” Foley said.
The PolySat team received support from industry and other teams it launched with, Foley said, so the team was able to recover from it. The members pushed through the disappointment easier because they already had new satellites in the works, he said.
“We were already in work mode so we just went back to work,” Foley said. “That’s how we dealt with it, we stayed busy.”
Puig-Suari’s primary mission has been to give students experience and failures are part of the experience.
“When we started, we said about 95 percent of the learning was before the launch,” Puig-Suari said. “The students are able to go to NASA and say, ‘this thing is ready to launch.'”
This article was written by Carly Haneke