Sagittarius A*, the black hole in the Milky Way galaxy, is a harder target. It is less than one-thousandth the mass and size of the M87 hole and, therefore, evolves a thousand times faster. The M87 black hole barely budges during a weeklong observing run, but Sagittarius A* changes its appearance as often as every five minutes.
https://www.nytimes.com/2022/05/12/science/black-hole-photo....
It also sounds like this is the combination of an image-generating model hypothesis as well as the raw data itself. Ie, this is the image that the model produces which best-fits the sparse interferometry data.
Would it be possible to use the same trick in space? IE: get a baseline the diameter of Earth's orbit (roughly)?
Even on Earth they resort to shipping cases of hard drives instead of transferring over the Internet.
One technique where simply waiting 6 months works very well is in measuring parallax. The Gaia spacecraft takes advantage of this.
But I'm optimistic that some institutions (hopefully including mine!) will be able to transfer these data over the network after the next run of EHT observations. Exciting stuff for sure.
I wish I could shed some more light on the ins-and-outs of exactly how these observations work, but I just run the computers, man. :) What I can tell you is that in order to move data off of the collector machines, they typically use m5copy, which is a part of the JIVE project (they have a Github repo: https://github.com/jive-vlbi/jive5ab). All communication between the control computer and the collectors happens within a private, physically-distinct network, but it's just standard commodity networking equipment between the control computer and the collectors. The folks in charge of the node's design are in the process of removing some of the bottlenecks to make electronic transfers more viable (the current spec doesn't even include a 10Gbps uplink!).
Space-based very long baseline interferometry (VLBI) has been done at lower frequencies, most recently with the RadioAstron satellite[0]. There hasn't yet been a VLBI satellite observing at the same frequencies that the EHT uses, but there are mission concepts being discussed. [1] discusses some of the technical challenges.
(1) https://www.smbc-comics.com/comic/delta-v
edit: We could also send the (super)computer that will process these images in LEO, so we don't even have to worry about atmospheric re-entry.
Let's say I'm 6 feet tall... what object would I have to hold out at arm's length, to have the same angular width as the entirety of this image?
A bacteria? A virus?
The answer is ~200 picometers.
Wolfram lists some helpful comparisons:
1/2 the distance between base pairs in DNA
3x the atomic diameter of helium (the smallest atom)
Suffice to say you'd have a hard time seeing it as it would be 3,000x smaller than the wavelength of visible light.
The reason it looks blurry is that the black hole features are close to the resolution of EHT so it's only a dozen or so pixels worth of information enlarged to typical image size.
EHT is essentially a radio telescope with a dish the size of the Earth. The only way to get higher angular resolution is to use higher frequencies (which they are working on) or use radio telescopes in space to get longer baselines than the diameter of the Earth.