Space Matter is a weekly column that delves into space science and the mechanics of spaceflight. From the latest discoveries in the universe around us to the fits and starts of rocket test flights, you’ll find analysis, discussion and an eternal optimism about space and launching ourselves into the cosmos.
Recently, India made history by sending up 104 satellites on a single rocket. How is this even possible, you might wonder? How can that many satellites, with all their bulk and weight, fit onto one rocket?
The answer: They’re not as big as you think.
Nanosatellites have transformed the way we think about satellites. It used to be that satellites were for lofty things like GPS and monitoring the weather. The idea of students being able to conduct experiments in space was silly; after all, the competition for space in the limited payload bay of a Space Shuttle was fierce. There just weren’t a lot of options; space was closed to students and those without huge budgets and the ability to work with NASA for space on packed Shuttle flights.
The CubeSat, a type of nanosatellite, was first designed in 1999, but it wasn’t meant to become an industry standard. The specifications were aimed at creating a spacecraft that graduate students could work with in space. Over time, though, they became the standard for small satellites. CubeSats have a 10 cm x 10 cm x 10 cm size and are no more than about 3 lbs. It’s important to note that CubeSats can be scaled; if your project is larger than what can fit into 10 cm x 10 cm x 10 cm, you can make it 20 cm x 20 cm x 20 cm or 40 cm x 40 cm x 40 cm. The idea is that these standard specifications make it easier, cheaper, and safer to build and launch satellites.
A set of CubeSats as photographed from space after deployment. Photo courtesy of NASA/JSC
What about having a standardized satellite makes launching them safer? Well, there are a lot of risks inherent in sending anything to space. Rockets explode. Satellites fail. By having a set size and weight, and certain guidelines any CubeSat must adhere to, creators cut down on unknowns and make it more easy for launch providers to plan for the specifications of their craft.
So how do you launch a CubeSat? For a long time, CubeSats have been secondary payloads aboard large rockets, like SpaceX’s Falcon 9. These small satellite projects usually aren’t well funded enough (or large enough) to pay the $60 million Falcon 9 launch price tag, so they hitch a ride aboard already scheduled and planned launches.
Traditionally, rockets had primary payloads, or cargo, and required extra weight to balance whatever was inside. Ballast ensured that the rocket would fly straight; otherwise, the cargo within the rocket might knock it off balance. CubeSats can (and do) take the place of some of this ballast, acting as stabilizers while also hitching a lower cost ride to space. It’s a win-win situation . . . or is it?
SpaceX flies its reused first stage Falcon 9 for the second time. Photo courtesy of SpaceX
It’s actually not ideal for small satellite launches to work with larger launch vehicles. If you think about it, the Falcon 9 can carry about 50,000 lbs to low Earth orbit. If you’re an academic organization launching a CubeSat that weighs 3 lbs into space, you’re not exactly at the top of SpaceX’s priority list. Even if cost isn’t a factor (many academic organizations partner with NASA, and thus get a free ride for their small satellites), scheduling and destination are.
When your cargo isn’t the primary payload for a rocket, you get little say in when a rocket launches or where it goes. If a primary payload isn’t quite ready as the launch date approaches, and your CubeSat is launching on that particular rocket, guess what: Your launch will be delayed, and there’s nothing you can do about it.
Destination is also a factor: Your satellite will go wherever the primary payload is going. Now this may seem strange, as all rockets go into Earth orbit, but what orbit? Does your CubeSat need to be in a high polar orbit? Does it need to be in geostationary orbit, such that it is in the same position in the sky as seen from the Earth at all times? If you’re launching a small satellite on a large rocket, you don’t get much of a say. That’s why it’s important to select the primary payload and launch destination carefully, to make sure your satellite ends up in the right place at the right time.
Virgin Orbit tests the rocket motor for its small satellite rocket, LauncherOne. Photo courtesy of Virgin Orbit
With all of these advances in small satellites, and the commercial interest that’s arisen from them, demand for launch space is at an all-time high. So it makes sense that companies such as Vector and Rocket Lab are developing rockets specifically for these customers. Rather than treating small satellite operators as secondary customers, these small rocket companies are planning to give CubeSat and nanosatellite operators more choice and flexibility by making them the primary payload for their much smaller capacity rockets.
These rockets are still in development, but they’re well on their way to changing the landscape for these small satellites. The question is, where will they take us? Once space is more easily accessible to CubeSats, what can they do? Where will they go from here?
Top photo courtesy of NASA
Swapna Krishna is a freelance writer, editor and giant space/sci-fi geek.