Astronomy and Space

EmDrive

The EmDrive is a controversial device first proposed in 2001, purported by its inventors to be a reactionless drive. While no mechanism for operation was proposed, claims about the EmDrive appear to violate the law of conservation of momentum and other laws of physics. The concept has at times been referred to as a resonant cavity thruster. Physicists and engineers generally regard the EmDrive concept as pseudoscience. Neither person who claims to have invented the EmDrive committed to details about the device beyond showing prototypes they have built. While the lack of a published design or mechanism makes it hard to say whether a given object is an example of an EmDrive, over the years prototypes based on its public descriptions have been constructed and tested but results have been mixed to negative and often minor or attributed to errors. In 2016, Harold White's group at NASA observed a small apparent thrust from one such test, however subsequent studies suggested this thrust was a measurement error caused by thermal gradients. In 2018 and 2021, Martin Tajmar's group at the Dresden University of Technology replicated and refuted White's results, observing apparent thrusts similar to those measured by his team, and then made them disappear again when measured using point suspension. No other published experiment resulted in apparent thrust greater than the experiment's margin of error. Tajmar's group published three papers in 2021 claiming that all published results showing thrust had been false positives, explaining each by outside forces. They concluded, "Our measurements refute all EmDrive claims by at least 3 orders of magnitude."

Also on this shelf

See also

• ▸Deep Space Climate Observatory
• ▸German Brazilians
• ▸Comet NEOWISE

Uncatalogued shelf

Text from Wikipedia; plate via Wikimedia Commons. Text CC BY-SA 4.0; plate freely licensed (see Commons). Source record. Images and catalogue data are reproduced from open-access collections.