CubeSat Launch Tests Satellite Innovations
A series of tiny satellites equipped with an array of sensors will take a jarring ride above the California desert on a small rocket June 15 and tell designers whether they are on track to launch into orbit next year.
Built by several different organizations, including a university, a NASA field center and a high school, the spacecraft are 4-inch cubes designed to fly on their own eventually, but will remain firmly attached to the rocket during the upcoming mission. Each of the CubeSats, as they are called, is focused on a specific experiment related to spaceflight.
Success at this point could clear the way for more such spacecraft missions that scientists say could have a big impact on how satellites are designed in the future and what kind of stresses they actually face during the climb into space.
The flight also is being watched closely as a model for trying out new or off-the-shelf technologies quickly before putting them in the pipeline for use on NASA’s largest launchers.
“Overall it’s a very exciting mission because we’re looking at new things, developing new things that are going to benefit us in the future,” said Garrett Skrobot, project manager for the effort under NASA’s Launch Services Program. “We can test the environments, and then we know when we put it onto a flight system, we have confidence the system’s going to work confidently.”
The rocket will carry four CubeSats and conduct a test of a lightweight, nano-launcher and carrier.
The new launcher weighs one-third as much as the standard rack that held three CubeSats. With the same size and capacity as the previous design known as a poly-picosat orbital deployer or P-POD, the lower-weight carrier and launcher will give satellite designers about two more pounds to work with.
“An extra two pounds for a nanosatellite is huge,” said Roland Coelho, program lead at CalPoly, the California Polytechnic Institute in San Luis Obispo. The extra allowance provides designers significantly more versatility in their designs and widens the CubeSat’s abilities.
For this mission, the prototype carrier will hold CubeSats loaded with instruments that will measure vibration, heat and other conditions. Those readings will be used to find out whether the lightweight carrier is as strong as the previous model.
“We’ve had the P-POD design for over a decade and we have a lot of lessons-learned,” Coelho said. “In this instance we could design something from scratch and see how it works.”
Engineers at Kennedy working through Rocket University designed and built a CubeSat called RUBICS-1 that will test a low-cost avionics system Garvey could use on its rocket for future launches. The RUBICS-1, which is short for Rocket University Broad Initiatives CubeSat, is one of the measurement satellites that will ride in the new, lightweight carrier.
The structure and components of the satellite, are built modularly, so a cube can be adapted easily to specific missions.
The RUBICS-1 includes, for example, a GPS, radio unit and antenna, plus a small suite of sensors.
Designing and building a functioning spacecraft that can power itself, communicate with ground stations on Earth and still collect useful information while keeping to the strict 4-inch requirement is a great challenge to satellite designers and teaches them how to adapt, the CubeSat managers said.
“We’re seeing big satellites and now we’re seeing guys drive down the size,” Skrobot said. “They think about all the different ways they can get smaller and smaller to fit in that cube. We’re a 4-inch cube and you’re trying to get power, instrument and all that stuff into that package, they get very creative. It’s fascinating what they come up with.”
There also are high hopes for the rocket itself, which was designed with CubeSats in mind. Built by Long Beach, Calif.-based Garvey Spacecraft Corp., the Prospector-18 rocket, as it’s called, flew several test flights starting in 2011 and completed a successful operational mission in December 2012. It is powered by a single engine burning liquid oxygen and ethanol.
The flight will take the satellites between 15,000 and 20,000 feet into the air before a parachute releases, and the launch vehicle and its payloads float back to Earth.
Skrobot said his excitement is no less than it would be for a mission to another world.
“I’m excited about all launches,” he said. “This is no different, even though we’re only going to 15,000 feet. We’re launching a vehicle, we’re educating young engineers, and they get to see the fruits of their efforts as well.”
Though short, the mission is expected to show engineers exactly how much vibration, heat and other conditions to expect on future launches.
“It’s a testbed to launch in a launch-like environment,” said Shaun Daly, the lead mentor for the StangSat, which is the cube designed and assembled by high school students. “It should be a harsher shock environment than what we will have on a launch.”
One of the CubeSats, called PhoneSat, was built by engineers at NASA’s Ames Research Center in California. As its name implies, the satellite is made from a smartphone to utilize the sophisticated features and high-powered memory and power systems, not to mention the phone’s camera.
A PhoneSat recently flew into space on an Orbital Sciences Antares rocket that was making a test flight. Since that mission, designers made a couple changes to the satellite and now can test the effects before placing another model in orbit.
“The smartphone today has more power than a desktop computer did five years ago. You can leverage that into a system that can do meaningful science in space for a fraction of the cost of a large satellite,” said Scott Higginbotham, a veteran of space shuttle era processing.
The changes and testing highlight the main advantage of being a primary payload on a small rocket rather than a secondary payload on a huge rocket: engineers can make changes and experiment with them in much shorter time.
Higginbotham also is the project manager for another of the CubeSats, this one built by CalPoly, the California Polytechnic Institute in San Luis Obispo.
The PolySat spacecraft will work in conjunction with the StangSat to gather and record data from inside the rocket during the flight. Housed inside a container designed specifically for the CubeSats, the PolySat and StangSat will transmit information between each other over a Wi-Fi network, a first for CubeSats.
About a month before heading to California’s Mojave desert for the launch, Daly and the high school students who had been working on StangSat tested their systems with the PolySat. Sitting on a bench in a lab at NASA’s Kennedy Space Center in Florida, the two satellites were put through startup sequences, communication patterns and other tests.
It was a final exam of sorts for the satellites and the builders before the mission.
“We’ve been coasts apart, we’ve been sharing information, but you’re operating in a bubble on that kind of stuff,” Daly said. “Both systems have to get a sense that there’s a launch and they have to wake up. For us, we turn on very quickly but we can’t send them anything until we have a Wi-Fi network established. You have to prevent yourself from burning through your battery.”
The hope is that a successful test of the ability will allow future CubeSat networks to gather data and send it to a specialized, central cube that will downlink data to the ground.
With that promise still on the horizon, researchers say there will be near-term tangible benefits for this flight.
“The first benefit that we get is an actual flight data collection experiment,” Higginbotham said. “We have an interest in understanding what the true environment is so we can perhaps relax some of the criteria for design on our spacecraft so that might let them do more things.”
This flight will not spell the end of the mission for the satellites. The PolySat is to be refurbished and a new StangSat will be built to fly together into orbit in 2014 as a secondary payload on a cargo resupply mission to the International Space Station. Riding together into space, the satellites will be ejected into space soon after launch to put their data collection and recording system to their highest test.
“If we’re fortunate and the future holds like we think it will, there will be many, many more in the years to come,” Higginbotham said. “It would not surprise me to see 100 to 150 a year launched in the not too distant future.”
Designers say the tests can show new ways to improve satellite designs of all sizes from then on.
“From a technical perspective, you can move down a magnitude to build a satellite and test a satellite,” Daly said. “You can drastically reduce the cost of testing and developing a satellite.”
