The final frontier
DAVID HAMBLING reports on how propellentless space drives are now facing their biggest test
The argument over propellentless space drives has raged for decades. Advocates say the drives will transform the space industry and open up the Solar System, critics see them as a scam (see FT320:12). Now the debate has moved to a new level as the first such drive is tested in space.
The debate is simple. Newton’s laws of motion say that you can only move forward in space by ejecting exhaust material backward. There are a few potential tricks to get around this, for example using light sails, which capture the momentum of light from the Sun, but these are theoretical rather than practical methods. In practice, all space propulsion – from the giant rocket boosters on a Space Shuttle to tiny thrusters which steer satellites – relies on ejecting propellent.
Proponents of propellentless drives say that quirks of relativity allow an apparently closed system to generate net thrust by bouncing electromagnetic waves around. For example, British engineer Roger Shawyer’s EmDrive reflects microwaves inside a truncated cone and produces small but measurable thrust.
It would be an understatement to say that the two sides do not see eye-to-eye. Shawyer’s critics dismiss his science instantly and refuse to look at his work. Any demonstration or experimental finding quickly degenerates into an exercise in finding flaws or loopholes, or accusations of fraud. Negative results, such as the tests by Prof Martin Tajmar at the University of Dresden, are seized on by the mainstream media with headlines like “Scientists just killed the EmDrive” in Popular Mechanics (FT369:14).
The tiny levels of thrust involved – at best, around the weight of a paperclip – make measurement contentious. While this is the same level of thrust as is produced by small space thrusters, it is low enough that a myriad of small effects in the laboratory, from air currents to stray magnetic fields, may produce an illusory positive result.
The other challenge is the lack of an agreed theoretical understanding of how the drive works. Every group working on this area seems to have a different theory, and designs its drives differently as a result. Hence they do not even accept that each other’s designs could work.
Despite the resistance, numerous independent tests of propellentless drives have apparently produced anomalous thrusts. These include projects at Northwestern University in Xi’an in China, NASA’s Eagleworks team, University of Plymouth, and various private organisations. Rumours claim that major aerospace companies have also successfully tested propellentless drives. US military defence agency DARPA has also carried out research in this area, with apparent success (FT419:14).
The argument could be resolved at a stroke by putting a drive on a satellite and testing it in space. Regardless of theory, if it works it will be a huge breakthrough for the space industry. The lifetime of a satellite is dictated by how much propellant it carries to adjust position, and this can take up to half of the launch weight. A solarpowered propellant-free drive could operate indefinitely, giving a satellite an unlimited lifetime.
Satellites are expensive though, and putting one into orbit pushes the price up even more. Few organisations would be willing to gamble millions on testing something which accepted science says is impossible.
Access to orbit has recently become far more affordable with the advent of cubesats, miniature satellites based on a modular architecture of 10cm cubes. A 1U cubesat is one such cube, a 3U cubesat is three cubes – and thanks to modern electronics all the necessary controls and communications can be packed into a cubesat with room for sensors or other payloads. Launch companies now provide arrangements for large numbers of cubesats from different customers to be launched in one mission.
On 11 November 2023 one of Elon Musk’s fleet of SpaceX Falcon 9 rockets lofted a batch of some 90 cubesats including a 3U unit called BARRY-1 built and operated by start-up Rogue Space Systems. Rogue are in the business of payload hosting, and BARRY-1 includes hardware and software from different customers being tested in space for the first time. It has a Scalable Compute Platform to test artificial intelligence applications. And it also has a Quantum Drive.
The Quantum Drive was designed by IVO Systems Developers based on the Quantized Inertia (QI) theory developed by Mike McCulloch, formerly a lecturer at the University of Plymouth, whose work was funded by DARPA. McCulloch completed the DARPA project in 2023 and delivered a report showing positive experimental results. The IVO drive was tested in the laboratory for over 100 hours and reportedly produced thrust. But what really matters is whether it can work in space.
For the first few weeks after launch, BARRY-1 did nothing, settling down so its precise obit could be tracked. Some satellites can shift slightly due to ‘outgassing’ from components and other effects. On 4 December, Rogue Space Systems announced they were ready to begin the real work. “The team is preparing to begin payload testing of the Rogue Scalable Compute Platform and the IVO Quantum drives,” according to a press release on 4 December.
The drive will be activated and the test will begin with the goal of raising the orbit by 60 miles/100km. Rogue say they expect the test to be completed by the end of the year. The satellite is being tracked, so success or failure should be obvious.
The drive was tested extensively before launch, but there is a lot to go wrong with experimental space launches. Critics will seize on a failure as proof the design does not work, and will either ignore a success or put it down to trickery. But if BARRY-1 does soar, McCulloch says there are plenty of people in the industry who are more interested in building technology that works than arguing about the weird physics behind it. Meanwhile, two more cubesats with different propellentless drives are set to launch in 2024…
Access to orbit has recently become more affordable with the advent of Cubesats