cryogens

Heat management becomes easier when you can afford liquid cryogens like Spitzer or a larger and cheaper (more ground-like) cryocooler.

Not allowed to fly cryogens on the shuttle as a safety feature.

Ideally larger satellites with 25/50/100 years of cryogens available for long-duration missions?

Scanners are really expensive: the machine costs a lot, it needs fairly particular conditions (shielded room, cryogens), and trained operators and analysts.

MRI machines don't actually use liquid cryogens, do they?

The problem would be very hard even without cryogens.

Cost of cryogens, cost of steel, cost of working nitronic, cost of Beryllium, and cost of superconductors are the dominant sources to track.

I figure Virgin wanted to avoid cryogens, though.

It's a certification requirement that the magnet can quench with a patient inside and the patient is not affected – the cryogens are supposed to vent outside the room, or, in the even that does not happen, at least safely within the room.

The equipment costs at least four million dollars, plus some ongoing costs (cryogens, typically a full-time tech or two, and maintenance; the power bill is probably not trivial either).

The main field may be ramped down for servicing in a controlled manner with minimal loss of cryogens in about 30 minutes and restored in a few hours, but this is performed only occasionally.

Benchtop NMR spectrometers already exist (for decades now), and some are already cryogen-free, permitting room-temperature measurements, eliminating the dewar and cryogens which account for a lot of the mass and volume of traditional NMR spectrometers.