To Do:

Given η_Earth=1

• Find more terrestrial exoplanets.
• Find habitable terrestrial exoplanets.
• Find inhabited terrestrial exoplanets.
• Go visit.

Consider the following snippets:

Kepler discover 5 planets orbiting inside 0.1 AU
Kepler: A Transiting Circumbinary Planet in a Quadruple Star System
Terrestrial mass planet discovered around α Cen B
Kepler exoplanet survey jeopardized

Kepler has lost one of its reaction wheels.
That was the spare, one more goes, and it will not complete its mission, it will not be able to stay pointed at its target.
Because of stellar jitter, the science goal for Kepler, to quantify η_Earth the fraction of stars with terrestrial planets, will take the full extended mission, not the optimistic nominal mission.

We can not stop now

The discovery of α Cen B b really tells us all we need to know, terrestrial planets are common as dirt, as they say, and it is not just a matter of having found one and packing it in - we now want to get statistical samples studying their distribution of properties, and the individual properties of each unique exoplanet.

Discovering life on other planets is a science goal as important as understanding the nature of dark energy or dark matter, as timely, and as doable with our current and near future capabilities.

"Hammer while the iron is hot" - we need significant observational followup: high cadence searcher like MINERVA; high precision instruments like Habitable Zone Planet Finder, with new improved Laser Combs, and lots of giant telescopes on the ground and in space, finding and following up the wonders out there.

It is timely, it is doable, and it is cheap by standards of modern science.

We can not not do this.

Exoplanets were marginalized by the decadal survey, but, the survey has been overtaken by events, budgetary and scientific. Its identified priorities will not be done, and medium term decisions on research portfolios ought not be based on it.

It is a shame, much sunk effort must be written off, but then that is also what happened with the previous decadal survey, whose priorities were overturned by the mid-decade "Beyond Einstein", leading to most of the identified priorities of that survey never happening.

What should we do?

We should do the next Explorer class mission: preferably both TESS - the transit monitor of the brightest few hundred thousand stars, and FINESSE the spectroscopic characterization of exoplanet atmospheres.

The Next Generation Space Telescope should be finished and flown, if we can.

We should restart the Planet Finder spacecraft, but not making the mistake of going for a grand slam homerun of a megamission on first try.

Start with an engineering coronographic mission, a small one, and a quick one, to look for nearby planets around close bright stars.
Starting with Alpha Centauri!
The odds are good, we should play them.

Then ramp up with Jupiter Imagers and then Terrestrial Planet Finders, and stagger both coronographs and interferometric detectors.

The NSF ought to try to get funding to also strongly ramp up exoplanet studies.
We are short of telescope time, we should not be closing telescopes but going to intense monitoring programs and build new instruments - several of them exploring different technologies, not the current model of picking one desperate lotto winner every few years.

I'm picking on the US because I am worried about its direction in science, the Europeans and Australians are holding steady for now, more funding there ought also be imperative but at least they are progressing coherently.
Asia is also playing impressive catchup and may yet dominate this field.

This is a turning point in humanities existence, as a culture, as an intelligent technological species.

We now know.

We can't ignore this, or get around to it maybe sometime later.
If we have any curiosity, any drive, any ambition left as a species, we have to find out.
Now.

And yes, we should think about going for a visit.
Yes, future technology will hopefully overtake any pathetic crawler we send in α Cen's direction anytime soon, but if we don't develop such technologies by trying now, then we will not have the improved technologies in the future.
That is how we learn to get better at things.

This is our nearest neighbour, it is the next driveway over, we now know they have a building on the lot and we'll soon know if there is a light in the window.
We ought to go visit, say "Hi", it is only neighbourly.

And, you know, bring some baked goods.
Home made bread, or brownies.
Everyone likes home made bread and brownies.