Creating an off-world economy in low Earth orbit is one of the goals of U.S. space policy. After a week at the 26th AIAA/Utah State University Conference on Small Satellites, it is clear that there is more to it than funding commercial vehicles to take astronauts to the International Space Station (ISS). The enthusiastic young engineers at the conference cutting their teeth on tiny cubesats have already made their presence felt in space with the increasingly sophisticated spacecraft they have invented.
The innovation that goes into stuffing all the elements of spacecraft buses and scientific payloads into a few cubes 10 cm (3.9 in.) on a side, and the willingness to take risks to give their handiwork a spaceflight checkout, is right in line with the New Space philosophy rooted in Mojave and Hawthorne, Calif., and in garages around the country. An early glimmer of the potential symbiosis between the human-spaceflight enterprises such asand the cubesat community came at a workshop on getting cubesats to orbit.
Joseph Carroll of Tether Applications Inc. told a room full of cubesat developers that the regular flights to the ISS envisioned for.'s Cygnus and particularly the flight-tested SpaceX Dragon (see photo) are perfect for launching their tiny birds.
“The goal is to look beyond what makes secondary payload launches possible to what makes them attractive,” says Carroll, an experienced engineer who launched experimental secondary payloads on Delta II rockets carrying GPS satellites to orbit in the 1990s. On one of those missions, McDonnell Douglas was able to manage a delay in payload delivery by swapping the upper stage that had been modified to accommodate it with the next one in the flight sequence. For the same reason, relatively frequent launches on commercial cargo vehicles would give flexibility to cubesat launching, he says, a real advantage when the spacecraft suppliers are students or startups.
The commercial station-cargo carriers have the added advantage of being U.S.-owned, which eases International Traffic in Arms Regulations and other export control issues presented by non-U.S. launchers such as Russia's Dnepr. Multiple launches by the same operators also provide a stable company policy on accepting secondary payloads. And sinceand the Pentagon are showing more interest in small satellites, the government customers actually make it less expensive to carry secondaries (AW&ST Aug. 20, p. 31).
“Most commercial launches are insured, and most government launches are not, so that kind of pushes you toward government launches,” Carroll says, explaining that secondaries to commercial payloads will find that the insurance on the primary adds cost to launching their payloads as well. “This may not fit the ideology of New Space being fully commercial, but . . . you may find that you're back in the world of government payloads.”
Carroll cites the example of's old Get Away Special (GAS) program as evidence that government launches can support secondary payloads. There were 127 secondary payloads launched from GAS canisters in the space shuttle payload bay, he says, and the program was pitched toward the same “novice” community that flies cubesats. That they flew on a human spacecraft suggests the current restrictions on cubesat propulsion and electronic interference can be surmounted by applying the GAS lessons.
SpaceX plans to fly an Orbcomm 2 smallsat on its next ISS resupply mission, after pulling it from its first flight to the station because of NASA safety concerns. NASA is flying its small Phonesat experiment as a secondary payload on Orbital's Antares station-resupply rocket. Those precedents can lead to regular cubesat rides to orbit.
NASA already has programs to launch cubesats as secondary payloads on its scheduled missions, as does the Pentagon. In February, the civilian space agency picked 33 more small satellites to fly under its Educational Launch of Nanosatellites program, and this month issued another call for proposals for launches in 2013-16.
Added to the U.S. National Laboratory Facility on the ISS, there are a lot of free rides to space for small scientific payloads, and secondary payloads are another source of government funds for launch service providers. There is increasing commercial interest in small satellites—ATK recently expanded its line of smallsats downward in scale—so the launch market is likely to grow.
But Carroll warns that there are some risks. Of particular concern is the space-debris issue. Most current cubesats are short-lived, uncontrolled and right at the lower size limit of what can be tracked from the ground.
“The real solution to my mind is to launch on Dragon but attach to the Falcon second stage,” Carroll says. “After [main engine cutoff], the Dragon goes its separate way, and the Falcon is available for use” to place secondary payloads in safe orbits, using the stage's excess capacity.