December 24, 2009 — Vol. 2, Issue 12
The Next Big Thing is Small
Satellites that can fit in a backpack are shrinking technology, reframing satellite science, and providing valuable mission training and experience to the next generation of engineers.
They come in sizes small, micro, nano, and pico, with masses ranging from 500 kg (small) to 1 kg (pico). Over the past two years, global interest has grown rapidly in satellites that are a fraction of the size of Sputnik-1 (a beach ball weighing about 80 kg), ushering in a new era of missions and engineering opportunities.
CubeSat, meet NASA
A decade ago, two professors concluded that educational satellite missions took too long and were too expensive. There had to be a better way to do them, thought Jordi Puig-Suari of California Polytechnic State University (Cal Poly) in San Luis Obispo and Bob Twiggs of Stanford University. "Education satellites were not performing the education tasks well enough," said Puig-Suari. "They were too complex, too large, and we had to change it."
In early 2000, Twiggs, who was working on microsatellites (typically 50-100 kg) at the time, wondered if they could make even smaller satellites. Twiggs's group at Stanford started developing a satellite bus, while Puig-Suari's group at Cal Poly went about developing a deployment mechanism called the Poly Picosatellite Orbital Deployer (P-POD). The result was CubeSat, a 10 cm3
satellite weighing 1 kg that is considered a picosatellite. Three fully autonomous CubeSats could be configured together to form a larger nanosat that was no larger than a loaf of bread. (Picosatellites are generally considered to be spacecraft less than 1 kg, while nanosatellites are considered to be less than 10 kg.)
Engineers at Ames Research Center started collaborating with Twiggs. John Hines, currently the Chief Technologist of the Engineering Directorate at Ames, maintains close relationships with the university programs that propelled the NASA Small Satellite Program into action. "Our whole nanosat program is based on the shoulders of the university nanosatellite activities and the CubeSat activities," said Hines.
Ames conducted a pilot study, asking scientists to think about the kinds of science that could be done on nanosatellite platforms. Satellite experiments involving biological specimens typically had to be taken into space, brought back to Earth, and then analyzed after their return. Nanosatellites offered an alternative: do everything in space.
A partnership developed between Ames and three California universities: Stanford developed the satellite buses, Cal Poly provided the P-POD, and Santa Clara University performed the mission operations.
After ensuring that the hardware under development at the universities met NASA standards for space flight projects, engineers at Ames began to hone their understanding of nanosat capabilities and then push them further. "The idea to analyze and do all of your processing and measurements in situ was something that had not been done a lot," said Hines. The capabilities of nanosatellites made this feasible.
Nanosats: Not Toys
Because of their size, the value of nanosats has often been overlooked. "Four or five years ago, people would pass by and look at these things as toys," said Hines. "Now you see [those same people] showing how they are building their own and starting to have their own programs."
University satellites are primarily geared towards education and training. For NASA, nanosats offer a low-risk, low-cost, low-visibility platform for innovation, as well as the ability to use launch vehicles that are not designed for large spacecraft.
"We're starting to do real science, real technology validation, risk reduction, and gain flight heritage on new techniques and technologies. It's still a spacecraft and it's still a mission," said Hines. "It has every element and every aspect of a large spacecraft, just smaller and less expensive and sometimes less complicated. But it has all the pieces, all the elements. It's managed exactly the same. We use the same flight project management standards – 7120.5D – that big missions are required to do for all NASA missions. You have to go through the whole design, development, integration, test, and missions operations and management processes just as you would for a full mission."
Puig-Suari said that the biggest constraint in the field is mindset, not resources. "People are trying to shrink a big spacecraft," he says, "but if you do it that way, it's not going to work." He believes the way people think about the capabilities of nanosats is shifting. "People will initially say, ‘I cannot put my component on that box because my component was designed for a big spacecraft,'" explained Puig-Suari, "but now we're starting to have people say, ‘Okay, what can I put inside that box?'"
Early versions of nanosatellites included Bio NanoSat and GeneBox. Even then, the size was still too large. This led to the development of NASA's first deployable, autonomous nanosatellite, GeneSat. "We started to miniaturize something that we already thought was impossibly small into something even smaller," said Hines. GeneSat launched in December 2006, taking nanosatellite experiments to a new level of visibility in the aerospace community.
Prepping Gen Y
With a majority of NASA's engineers currently eligible for retirement, the next generation coming up through the ranks has a lot to learn before that knowledge walks out the door. With their low cost, risk, and visibility, small satellites can offer an excellent training opportunity for hands-on learning.
"As a seasoned project manager, I have a responsibility, just as my peers did when I joined the agency, to train the next generation of space enthusiasts and spacecraft developers," said Mark Boudreaux, project manager of the Fast, Affordable, Science and Technology Satellite Huntsville (FASTSAT-HSV) microsatellite at Marshall Space Flight Center.
Small satellite missions also offer young engineers the opportunity to acquire and practice essential engineering management skills such as team communications and project documentation, regardless of their specific area of expertise.
"We want to make sure that we're training those replacements to continue the things we worked so hard to get to," said Hines. "You get the discipline of having to see something all the way to the finish rather than doing it as a school exercise, doing something that you've done on paper design and then you're finished," he said. "You've got to make the thing work."
At the university level, Puig-Suari sees a noticeable change in how students approach their projects. "Interfacing with industry really puts them in the right mindset as far as the quality levels, level of seriousness, and documentation," he said. "You need to prove that it works, write it up, and show it to the right people."
Learning from NanoSats
In August 2008, Boudreaux and Hines saw NanoSail-D (Marshall) and PRESat (Ames) take off on the third SpaceX Falcon 1 from Omelek Island. The launch vehicle never reached orbit and plunged into the Pacific Ocean.
Despite the launch failure, there were lessons learned. "We learned a lot about the integration process," said Boudreaux, noting that this was their first involvement with Falcon. "That was a new paradigm for us." Working with new commercial launch providers offered valuable experience. Two years prior to the Falcon launch, the Ames team had configured GeneSat to launch on the Orbital Sciences Corporation's Minotaur-1 rocket.
"We were able to look at different launch integration capabilities, different launch sites, different launch operations, different mission and range considerations, as well as [gaining experience in] deploying a spacecraft and payload to a very, very remote launch site," said Hines. The remote location of the SpaceX Falcon launch site tested NASA's ability to react to a launch delay that would force them to replace the living specimen inside PRESat. "We got a big operational logistics effort under our belt with that as well."
The quick turnaround from authority to proceed to launch was also notable. Marshall started integrating NanoSail-D into an Ames CubeSat in November of 2007, delivered the product in April of 2008, and then launched the following August. "There were processes that we streamlined," said Boudreaux. "Sometimes these things can take years, but this took months, providing valuable insight into private sector processes. We learned a lot about a short, tailored, very efficient, fast development process."
There were also cross-agency benefits. "Ames transferred knowledge to us," said Boudreaux. "We learned from Ames the important elements associated with building a CubeSat."
Hines added that having two fully functional units (resources permitting) was a good idea. While PRESat and NanoSail-D never made it into space, their twins still had a chance.
Leveling the Playing Field
Before nanosatellites, satellite projects were primarily limited to well-funded, established space programs. This is no longer the case. Nanosats have opened space exploration up to a wider world.
The CubeSat program has expanded to South America, Asia, Europe, and South Africa. "The playing field has leveled," said Puig-Suari. "A lot of people are doing it." He cited the launch of Colombia's first satellite, Liberated-1. "Those guys were so excited. It was a very simple spacecraft, but it had national implications."
The Next Wave
Next year, the Department of Defense Space Test Program will launch several NASA small satellites including the Organics and/or Organisms Exposure to Orbital Stresses (O/OREOS) managed by Ames, and the second NanoSail-D managed by Marshall. These nanosatellites will be two of six instruments riding on FASTSAT-HSV-1 — a spacecraft bus designed to carry multiple experiments to low-Earth orbit — which will be launched aboard an Air Force Minotaur-4 launch vehicle from Kodiak Island, Alaska. The second NanoSail-D is a proof-of-concept demonstration of a miniaturized solar sail that Marshall hopes to build on a large scale for solving propulsion and space travel concerns. "It's a stepping stone to larger class technology," said Boudreaux.
For Ames, nanosats are not stepping stone to larger technologies, but toward a new class of missions. O/OREOS will investigate how components of life respond to radiation and microgravity, one of many missions in line for nanosat technology.
Scientists are starting to get interested. Biologists were the first to see the potential (Bio NanoSat), followed by astrobiologists and astrophysicists. Now nanosat programs are popping up at places like the National Science Foundation (NSF), the National Reconnaissance Office, and the Air Force.
From the NSF's space-weather nanosats to the Cube50 project, which will launch fifty nanosats into the lower thermosphere (dubbed the "ignorosphere" because so little is known about it), the capabilities of these satellites are only just emerging. Nanosats are not replacements for their larger counterparts — rather, they offer another approach to space flight. "People started saying, ‘Wait a minute, what else can I do with this?'" said Puig-Suari. "And it was just a chain reaction at that point."
Article by HS