Formation-Flying Interferometry in Geocentric Orbits

arxiv.org

46 points·belter··5 comments

Reminds me of GRACE, which consists of two spacecraft in the same orbit, one following the other. By measuring the separation distance between the two spacecraft (which I believe is done through interferometry), the gravity field of the Earth can be measured precisely. In turn, this allows us to measure mass transport in the world (mainly of water). Very cool experiment.

(Many of my coworkers at the Albert Einstein Institute in Hannover, Germany were working on this project. The focus at the institute was on optical interferometry for the detection of gravitational waves, i.e. LIGO and LISA. LISA would be a formationa-flying interferometer in heliocentric orbit.)

https://en.wikipedia.org/wiki/GRACE_and_GRACE-FO

Not a dupe, but a somewhat similar post that might be of interest to readers of this post [0]

[0] https://news.ycombinator.com/item?id=38414380

> A low Earth orbit with a separation of approximately 0.1 km may be suitable for experimental purposes.

Wouldn't that also suit an Earth surveillance array with unprecedented resolution?

In general, the smaller the separation, the smaller the synthetic aperture.

Precise ranging and relativistic corrections are what permit large scale experiments like LIGO and LISA to work as a device the size of the complete aperture.

The GP was presumably thinking about downward looking optical sensors. An 0.1km aperture in the visible at LEO would have quite significant resolving power.

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