Update: This story was updated on 4 January, when ISRO increased its launch count from 83 to 103 and moved the launch date into February.
As of November, a total of 564 nanosatellites have been launched into space. In February, the Indian Space Research Organisation aims to launch a combination of 103 satellites on a single rocket—reportedly a world record. The same month, U.S. startup Spaceflight Industries plans to send up a module designed to support the launch of up to 87 satellites.
Neither the Indian Space Research Organisation (ISRO) or its commercial arm, Antrix Corporation, responded to requests for comment. But Spaceflight Industries senior mission manager Adam Hadaller described putting together launch missions for large numbers of small satellites as “herding cats…. It’s very hard.”
Once you get them in space, nano, cube, and other small-scale satellites have several applications—from monitoring weather to helping farmers decide where to water or fertilize crops—all at a significantly lower price than traditional-scale satellites. Several startups and space agencies, such as ISRO and Spaceflight Industries, are working to launch more and more of them at the same time, further reducing costs.
Launch: The first challenge begins before launch, Hadaller says. Satellites can come from different countries, and it’s necessary to check all the various safety regulations, communication licenses, and technical requirements. The different separation systems, for example, need compatible adapters.
Then there is a choice to make: Piggyback the satellites as secondary payload on a rocket that’s already heading to space, or mount a dedicated mission? However, when piggybacking, satellites don’t have much choice in their orbits, which limits the variety of possible scientific experiments.
A SpaceX Falcon 9 rocket is set to launch a Spaceflight Industries module in February called Sherpa—containing small satellites—as secondary payload. In the mission, Falcon 9 will launch its primary payload and then deploy Sherpa after an orbital maneuver. Half an hour later, Sherpa will release its satellites.
Hadaller says that in the case of the Sherpa mission, the main limitation of the module itself is interest: As of 12 December, only 33 satellites were on the manifest for its 87-satellite vehicle.
If piggybacking isn’t needed, a dedicated launch can provide better orbital options. For example, on 12 December, Orbital ATK launched a Pegasus rocket containing eight CubeSats designed to monitor hurricane development in the tropics. The satellites deployed at a 510-kilometer altitude at an inclination of 35 degrees; over time, they spread out over the entire orbit. Their inclination gives full coverage of the tropics.
Communications: Usually, satellite owners communicate with their satellites over radio by pointing antennas on the ground at satellite locations. The better the aim, the stronger the signal, so satellite operators find their satellite’s location by using some combination of onboard GPS, trajectory estimation data, large telescope arrays, the JSpOC satellite tracker, or radio ranging.
But if all the small satellites can be identified, then radio interference can be a problem. The frequences they often use to communicate with over radio could become crowded by satellites and ground-based radios or cellphones, says Bruce Yost, who directs a NASA institute for small satellite outreach called the NASA Small Spacecraft Systems Virtual Institute.
He says one solution is to communicate at higher frequencies that are less likely to suffer interference, but this requires extra power. Another, less power-hungry solution researchers are considering is to transmit data from space to ground by laser—the drawback being that the optical link would need “even more accurate pointing” than radio communications.
Collision: Mass deployment also runs the risk of becoming a mass of space debris, some say. Spaceflight Industries says its team has not run an updated analysis of the exact probability of its satellites colliding with one another or another object in space, but Hadaller says it is “extremely low.” Also, all the tech meets international space community requirements meant to prevent debris, including deorbiting by the satellite’s 25th year. The Sherpa module itself will stay in orbit for 10 to 18 years and the satellites between 3 and 10 years, before they reenter Earth’s atmosphere and burn up.
Mike Safyan, director of Launch and Regulatory Affairs at Planet Labs, an Earth imaging company that makes small satellites, believes that the demand for launching large numbers of rockets is low for now, but “if the companies are successful, then we’ll see more of these kinds of large cluster launches.”
Yost says that there will be at least five NASA-sponsored, small, cube-shaped satellites called CubeSats on the upcoming Spaceflight Industries launch, which has been delayed from late 2016 to 2017.
“The capability of these CubeSats is really, really advancing quickly,” he says. Advancements in computer processors have made it possible to do “extensive” data processing and analysis directly on board a small satellite. Improvements in design and fabrication are also making them more robust, to better survive the harsh environment of space.
Jordi Puig-Suari, an aerospace engineer at California Polytechnic State University, in San Luis Obispo, helped design the original concept for CubeSats. “The timeline is one thing that we have to work on,” he says. “The satellites can be developed very quickly,” but getting them into space might not happen at the same speed.
But, he says, the benefits of mass deployment of small satellites are clear. “Having a larger number of lower-cost missions will allow us to go to a lot more places,” Puig-Suari says.