Hubble isn’t ‘far.’ Any of the commercial orbital rockets could reach it, and at a cost much lower than the SLS.
It’s what happens *after* a rendezvous that is important. Right now, the answer is ‘nothing.’
NASA hasn’t asked for bids to service the Hubble.
Because SLS is draining the lion’s share of available appropriations for NASA, and when it’s finally operational, each launch will cost near a billion dollars. NASA doesn’t have the funding to sink another billion plus into Hubble. The ‘plus’ represents the engineering and construction of the part of the mission which would dock with Hubble and push it to a new orbit, and do some equipment repairs to extend its serviceable life, which are necessary if the expense of pushing it to a higher orbit is to make any practical sense at all.
The equipment repair part of that mission would be problematic. In the past, Hubble repairs were done by humans. The US doesn’t have any man-rated launch vehicles yet, and it doesn’t have specialized robots that could do the work, either. The Russian man-rated option, Soyuz, doesn’t have the ability to move large cargoes; it’s basically a delivery van for packages, not a substitute for the Shuttle.
But the elephant in the room is SLS. So long as NASA has to keep funding an obsolete single-use rocket system whose launch costs will be truly exorbitant, the money to rescue Hubble just isn’t in the budget. So the big question to ask is, when will SLS be canceled? When will NASA switch gears to harness cheaper, reusable rockets for its missions? Once SLS is gone, NASA will be able to afford all sorts of missions that it can’t afford today.
Ethan is correct: if something doesn’t start happening soon, Hubble will fall. But Congress and NASA won’t cancel SLS until at least one of the commercial lift providers proves a low-cost heavy lift rocket. (By ‘low cost,’ for Falcon Heavy, we’re talking about a cost reduction of something on the order of one-fifth to one-eighth of SLS’ launch cost. It’s a *huge* cost reduction, and it will free up a *lot* of room in NASA’s budget.)
Falcon Heavy’s first test launch might come as soon as November. But it’ll take a string of successes over a couple of years before NASA will seriously contemplate SLS’ future in light of it. Even then, there are stakeholders in NASA and in Congress who will be displeased with killing the SLS program. They will fight tooth and nail to preserve their pork.
It’ll take years to get rid of SLS. I have no doubt it will happen. I do have doubt that it will happen in time to rescue Hubble.
The clock is ticking.
What I’d like to see happen is this: I’d like for NASA to solicit bids to repair Hubble and boost it to a higher orbit. This should be a solicitation which grants plenty of time for bidders to assemble their bids, and it should be a performance solicitation; it should not specify engineering approaches (or even specify whether humans must do the job). Identify what needs to be repaired, identify the desired orbit, let the bidders figure out how to do it and what it will cost. By the time bids are being evaluated, we will be closer to SLS cancellation.
NASA would still have the option to do nothing; but at least it will have *something* in hand resembling a plan that they can weigh against their budget priorities.