More expensive, harder to maintain and keep current, and a tangent to the core matter; Starlink satellites leak radiation and could be shielded, Starlink satellites could be {switched off | turned low} off over Quiet Zones but are not.
Statements were made that shielding would improve after Ver 1.0 .. it got worse. Statements were made that sats would go low power over quiet zones, they do not.
Returning to your erudite point "and stuff"
The NASA Cosmic Background Explorer (COBE) satellite orbited Earth in 1989–1996 ...
Inspired by the COBE results, a series of ground and balloon-based experiments measured cosmic microwave background anisotropies on smaller angular scales ...
The sensitivity of the new experiments improved dramatically, with a reduction in internal noise by three orders of magnitude.
As of 2024, Xuntian is scheduled for launch no earlier than late 2026 on a Long March 5B rocket to co-orbit with the Tiangong space station in slightly different orbital phases, which will allow for periodic docking with the station.
Leaving aside the fact that an optical telescope isn't a microwave array nor is it a Square Kilomtre Array of radio telescopes with each component larger than your example ...
Putting an instrument in orbit has all the costs of development of a ground based instrument, additional costs to space harden and test, additional costs to lift, limited ability to tune, tweak or extend when in orbit, hard constraints on size and weight, and other issues.
Xuntian allows for periodic docking, sure. How will this not be more expensive and limited than (say) walking | driving out daily or weekly to much lager instruments on the ground?
This band of electromagnetic radiation lies within the transition region between microwave and far infrared, and can be regarded as either. )
> Putting an instrument in orbit has all the costs of development of a ground based instrument, additional costs to space harden and test, additional costs to lift, limited ability to tune, tweak or extend when in orbit, hard constraints on size and weight, and other issues.
Who is to say they won't pull a Space-X, maybe even overtaking it, going fully reusable?
Which allegedly lowers the costs, giving more economically access to space and lessening the constraints on payloads, while giving all the advantages of being in space?
So .. all the cost, time, and resources of building an instrument on the ground.
With the additional cost of lifting it to orbit, the additional cost of difficulty of in orbit maitainaince, and the additional weight and dimension restraints of going to orbit, the additional costs of over designing to harden for space and limited access.
Yes, there are advantages to being in space. They vary by application.
That aside it's still cheaper to build an instrument or instrument array that's deployed on the ground.
Unconvinced. Because building the whole system, not some isolated dishes somewhere amounted to 1.3 Billion EUR, operating it up to 2030 adds another 0.7 Billion EUR. 2 Billions. Chump change for sure.
Now we can compare that with the JWST and typical cost overruns in american boondoggle style, or look at the latest shining star, EUCLID. Just 1.4 Billion EUR for the latter.
Then there was GAIA at about 740 Million EUR, with the orbiting article at 450 Million EUR alone, plus another 250 Million EUR for the data-processing org.
All of these with more or less conventional rocketry, and not co-orbiting anything for more easy maintenance and upgrading.
My gut feeling tells me we will have cheaper and more reliable access to space, with larger payload capacity, necessitating less 'origamics' for the space parts, and that chinese concept seems sound, too. Very much so, in fact.
How much that will cost I have no clue.
But again, if something like this is becoming reality, no matter by whom, some former assumptions about cost, feasibility (at all, because payload weight and dimension constraints are relaxed, needing less 'origamics') will have to be rethought.
That was my point, in general. Not limited to any special application.
Sure, when we get there again, can make regular trips, and have consequence free energy to burn that'd be great.
In the interim, and as a general rule for all private entities, it'd be nice to not pollute the commons with unnecessary discharges and sparkles and to carry through on pinky promises to maybe do something about that.
Statements were made that shielding would improve after Ver 1.0 .. it got worse. Statements were made that sats would go low power over quiet zones, they do not.
Returning to your erudite point "and stuff"
~ https://en.wikipedia.org/wiki/Cosmic_microwave_backgroundHmmm, it appears the ground based results were a dramatic improvement over the sat based data.