Talk:Field propulsion

Rename to Propellantless Propulsion

The article should be renamed to Propellantless Propulsion. This name is trivially understandable by anyone as meaning "propulsion without propellant". The term "Field Propulsion" however is unclear to anyone except those familiar with the history of this specific term (including domain experts in spacecraft propulsion). In addition I think Field Propulsion is confusing because when searching online, it returns false positives which make it seem more common than it is. Propellantless propulsion is more specific and yields more results that are more relevant to the topic of aerospace propulsion.

"Field propulsion", taken literally, means "propulsion with fields", which differs from how it's defined on this page. This makes it confusing to a scientifically literate audience. The term "field" as understood in physics is simultaneously too vague (which fields: electric, magnetic, gravitational, scalar, vector, something else? Ambient fields or self-produced?) and also too specific (not all propellantless technologies make use of "fields" of any kind, most notably solar sails and aerobraking) to be meaningful to anyone with general scientific training.

Searching for field propulsion (without quotes) online includes many hits from content using the terms "field" and "propulsion" in isolation, but not "field propulsion" as intended here. Most notably this includes articles and papers on electric propulsion technologies (ion thrusters), which uses electric fields to achieve propulsion, but in no way fits the definition of propellantless propulsion. Although the current article does mention that these are not propellantless technologies, it still includes them as "field propulsion". Some few sources use the term "electric field propulsion", however this is to be understood as "propulsion that involves electric fields"; I have yet to find an article that explicitly classifies ion thrusters as a member of the broader category "field propulsion".

It is therefore important, when searching online, to use "field propulsion" with quotes. This drastically reduces the number of unrelated hits. However, it still includes many tangentially-related topics such as nanorobotics, where magnetic fields are used to move microscopic robots.

A Google Scholar search for "field propulsion" (with quotes) returns 793 results. Of these, many are on unrelated topics (eg "Depositional Control of Macroscopic Particles by High-Strength Electric-Field Propulsion" which is about dusting crops using electrostatically-charged pesticides). Most of the articles actually using the term for spacecraft propulsion are in the domain of extreme speculation (eg antigravity) or straight-up UFOlogy (which doesn't mean they can't be cited, but since UFOlogy is generally considered a fringe science, they should be clearly indicated as such as per Wikipedia's guidelines WP:FRINGE).

In contrast, an equivalent search for "propellantless propulsion" returns 953 hits. These generally seem more on-topic, from better-established research centres on spacecraft propulsion (eg NASA), contains fewer references to speculative terms like antigravity and appears to have far fewer results relating to UFOlogy.

Obviously such a comparison is not sufficient by itself but is a strong first indicator that Propellantless Propulsion is a more commonly-understood term.

Furthermore, of the references currently used in the article, I have found only one author^[1][2][3] who actually uses the term Field Propulsion in a sense compatible with the article's definition (which, incidentally lacks a citation). However multiple sources use or define the term Propellantless Propulsion. This alone I would say is a robust argument to retitle the page - the authors of this page have presumably already done a lot of research and selected the best sources.

Improved definition and lead section

The current definition in the article's lead:

Field propulsion is a category of terrestrial and spacecraft propulsion in which thrust is generated by coupling a vehicle to external fields or ambient media rather than by expelling onboard propellant.

fails verification and is not very technically sound. As is, it includes every type of locomotion except rockets: ship sails, propellers, jet engines, cars (both ICU and electric), even human legs.

It should be restricted to aerospace research and use more technically accurate language. A proposal, based on ^[4]:

In aerospace engineering, propellant-less [or "field" if we don't rename the page] propulsion systems generate thrust via interaction with the surrounding environment (e.g., solar photon pressure, planetary magnetic fields, solar wind and ionospheric plasma pressures, and planetary atmospheres). By contrast, chemical and electric propulsion systems generate thrust by expulsion of reaction mass (i.e., propellant).

The rest of the lead section also needs some editing and better citations; it currently contains several claims that I cannot verify based on the references cited on the page. Better would be to provide citations directly in the lead section. Some statements that require direct citation as they are not trivially verifiable include: - "Within aerospace engineering research, the label spans both environment-coupled systems such as solar sails, magnetic sails, and electrodynamic tethers, and efforts to engineer field-matter coupling using electromagnetic propulsion (including electrohydrodynamics and magnetohydrodynamics), as well as speculative mechanisms that draw on general relativity, quantum field theory, or zero-point energy to alter effective inertia or couple directly to fields of space." - "Field propulsion concepts evolved alongside conventional rocketry, with origins in 17th-century observations of radiation pressure and early 20th-century electrical and electrostatic research." - "Mid-century classification frameworks organized advanced concepts under thermal, field, and photon headings, and later criteria-driven programs such as NASA's Breakthrough Propulsion Physics Program established conservation-law consistency and experimental reproducibility as central benchmarks."

It also makes reference to electric propulsion which does not fit the definition provided just a few lines above and, as I wrote previously, should be removed from the article. Furthermore, the reference (and image) to STS-75 is unwarranted, especially in the lead section: TSS-1R and related experiments made no mention of propulsion research as a goal (even though the concept of space tethers has been proposed for propulsion, it was not in relation to TSS-1R).

References