Stanford Report, January 31, 2001
|A rocky road to outer
But one year later, student satellite still flying high
BY KATHARINE S. MILLER
Against all odds, the first satellite designed and built entirely by Stanford students is still sending data on its first anniversary in space.
The satellite, called OPAL (for orbiting picosatellite automated launcher), was first conceived by students in the 1995 microsatellite design class taught by Consulting Professor Robert Twiggs of Stanford's Space Systems Development Laboratory. Since then, almost 200 students have participated in building satellites at Stanford. Launched aboard an Air Force rocket on Jan. 26, 2000, OPAL now orbits 500 miles above Earth's surface.
But before the launch, events seemed to conspire against OPAL's success: Funding was interrupted two years out, a major design feature was scrapped at the eleventh hour, and the project could only afford a simple, low-power communication system, one of the most important features of any satellite.
When OPAL did poorly during a final test, one project adviser told the students, "there's nothing wrong with OPAL -- it just doesn't work."
Stanford electrical engineering graduate student Jamie Cutler admits, "OPAL is kind of hard to talk to -- you have to tweak it." But a year after the launch, Cutler, OPAL's project manager, is still receiving data from the satellite and talking to it from his Internet-based ground station.
OPAL is considered a microsatellite because its weight falls in the 25- to 50-kilogram range. "It's about the size of a big lady's hatbox," Twiggs says. If that sounds small, consider this: OPAL's job was to launch six even smaller satellites called picosatellites. They're the size of an ice cream bar.
Stanford students built OPAL. Two picosats were made by Aerospace Corp., a space technology company based in El Segundo, Calif. Three were built by students at Santa Clara University, and one by a ham radio group in Washington, D.C.
By launching the picosats successfully, OPAL completed the most important part of its mission, says Twiggs. And that's a small miracle, if you ask Cutler.
The first hurdle was funding. NASA's Jet Propulsion Laboratory (JPL) initially supported OPAL to prove the viability of picosatellites. But when NASA decided to fund JPL's own picosatellite program, JPL withdrew its support of the Stanford program. Twiggs had to fundraise again, and found support from Aerospace Corp. and the Defense Advanced Research Projects Agency.
OPAL (left) and Sapphire
(right). OPAL was launched with a rocket at
Vandenberg Air Force Base on Jan. 26, 2000. Sapphire is scheduled
to launch from Kodiak, Alaska, in August of 2001.
Deciding to scrap the design "was one of the hardest things we did," Cutler says. "Students spent many long hours designing the original launcher, and it was a struggle trying to make the best decision for the team and for OPAL."
Graduate students Santiago Alban and Jeff Williams led the effort to redesign the picosat launcher just six months before it was shot into space. The new design featured a chamber the size of a small textbook with a door on one end and a pusher mechanism on the other. They built two: Each launcher would eject three picosats.
On Jan. 26, 2000, OPAL hitched a ride on a rocket out of Vandenberg Air Force Base, just north of Santa Barbara, Calif. The first people to communicate with OPAL were amateur radio operators in France.
Stanford students, however, could not establish reliable contact with OPAL. Something seemed to be wrong with the ground station -- the radio and computer system on the Stanford campus.
To get around that problem, they moved the whole operation up to the Stanford foothills to the 150-foot-wide "Dish" radio antenna.
"It was pretty exciting, because the contacts we got at the big dish were better than any contact we got here on the ground," Cutler says.
Still, OPAL was a lousy communicator. Cutler couldn't talk when OPAL was talking. They had to take turns, reducing how much data got through.
After OPAL was in orbit and communication established, the first attempt to eject the picosats failed. So the students tried their backup system. That failed too. Finally, the main system succeeded and the picosats launched. And contrary to expectations, military tracking systems could see all six picosats, despite their minute size.
The two satellites built by Aerospace Corp. successfully communicated with their ground station, but the other four never made contact.
"Imagine trying to talk to a 3-inch satellite that is traveling 17,000 miles per hour! It's an amazing feat!" Cutler says. The Aerospace picosats "may have been the smallest functioning spacecraft ever launched," he adds.
Since Cutler's thesis research is about Internet access to space systems, he has done his best to make OPAL easier to talk to. OPAL communicates by radio with a computer that can be accessed over the Internet.
According to Twiggs, "Operation of a satellite over the Internet by a university is probably globally unique."
Surviving in space
Since OPAL is made of commercial parts not built to withstand the harsh radiation of outer space, no one expected it to work as long as it has. Computer models predicted OPAL would start to fail within six months to a year.
Radiation effects cause "upsets" that are like computer crashes, but OPAL can reset itself. Over time, though, the electronics could get so boggled by radiation they might stop working. But OPAL has had only a dozen upsets in a year, says Twiggs: "I wish Windows operated that well on my computer."
Besides being physically sound, OPAL is also fiscally fit. On the rocket that it shared with several other university-sponsored satellites, OPAL, the only one built entirely by students, was the least expensive satellite at $75,000 for parts.
And if parts were cheap, so was labor. Volunteer mentors consulted with the students every Monday night. "I paid them in pizza," says Twiggs, who recruited the mentors primarily at ham radio club meetings in the Bay Area. "But they're not to do the work for the students. I tell the mentors, 'If I find you doing it and the student doesn't do it, I'll fire you.'"
Twiggs waxes philosophical about his projects. "The satellite is secondary. The primary thing is the education of the students and the experience of the students," he says. But more often, he's simply enthusiastic: "We're having fun. That's what makes it such a good educational program."
The next frontier: Stanford CubeSats on Russian rockets
In 1994, Twiggs' plan was to design, build and launch a satellite within the lifetime of a master's degree program -- about a year and a half. With OPAL and other microsatellites, that turned out to be impossible because they were too complex.
But Twiggs has a new idea: CubeSats, picosatellites the shape of a 4-inch cube and weighing less than a kilogram (2.2 pounds). His original model for CubeSat was a plastic Beanie Baby box.
CubeSats cost $5,000 to build and $30,000 to launch. They can be built and launched in a year. The first launch is set for November 2001.
Although CubeSats are considered picosatellites, they are about three times bigger than the picosatellites launched by OPAL. Why? The bigger size allows the CubeSat to collect more solar energy, ensuring that it can power the electronics inside, says Twiggs.
The first 18 CubeSats are scheduled to ride on a retrofitted Russian missile next November with the help of One Stop Satellite Solutions (OSSS), an Ogden, Utah, firm. The missile will carry six picosatellite launchers, or P-PODs (for poly-picosat orbiting deployer), built by students at California Polytechnic State University (Cal Poly). Each P-POD can shoot three CubeSats into space.
OSSS will pay Russia $10,000 per kilogram of CubeSat and also will get all the licenses, transport the CubeSats and P-PODs to Russia, and load them onto the rocket. For these services, OSSS will charge universities $30,000 per CubeSat.
Now racing to meet the July deadline for completing their CubeSats are students from universities including Stanford, Cal Poly, Montana State University, the University of Arizona, Dartmouth College, Taylor University in Ohio, the University of Tokyo and the Tokyo Institute of Technology. OSSS is already taking reservations for a 2002 launch, Twiggs says.
Twiggs sees the CubeSats as "satellite buses." Each one includes a payload space about the size of a juice box. "We call that the TSFR space," says Twiggs, "and TSFR stands for This Space For Rent." Twiggs hopes to sell the space for $50,000.
Some people are excited about CubeSats because they might be used cooperatively, Twiggs says. Instead of taking measurements at one point in space, researchers will take measurements with a constellation of CubeSats over a large area.
the potential applications for picosatellites are really unknown,
Twiggs says. He compares them to the Apple computer and the
Internet. When each first came out, people didn't know what they
would use them for. "And what do they use them for today? Tons of
stuff," Twiggs says. "I'm thinking it's the same sort of
The sky's no limit, Consulting Professor Robert Twiggs teaches his students, who build tiny satellites like CubeSat, model in hand. An antenna atop the Durand building aids communication with the orbiting satellites. Photo: L.A. Cicero
Earth to OPAL: Jamie Cutler shows one of six picosatellites that OPAL launched in response to commands issued from this Internet-accessible ground station. Photo: L.A. Cicero