Thread by @bmac_astro

First, I wanted to highlight with the major NASA recommendation of the Decadal Survey: a 6-m class telescope capable of imaging Earthlike worlds orbiting sunlike stars. @theNASEM #astro2020.

JWST, and the Extremely Large groundbased telescopes, can study potentially habitable planets huddled close to the coolest stars - a critical capability - but a world like our own Earth is beyond the reach of anything but a dedicated space telescope

The work of the whole community, distilled into the @luvoirtelescope and @nasahabex visions, makes it clear that this is possible. Uncertainties that existed in 2010 have been resolved - we know how to build such a telescope. We know how it would operate.

We know how many planets it would find. From Kepler and TESS we know that Earth-sized worlds are common. This is now our chance to answer the question of whether they are Earth-like. To image entire solar systems like our own.

We won’t just make fuzzy blue dot images. Visible and near-infrared spectroscopy of planetary atmospheres can see components of their atmosphere - water, carbon dioxide, ozone, methane - that tell the planet’s story and may mark the presence of life. (Figure from Habex)

It won’t be easy; we also know that developing powerful telescopes in space is hard. The report lays out a careful technological path to reach confidence in the mission’s cost, schedule, and capabilities before it is committed to.

The 6-m scale is intermediate between LUVOIR and HABEX. It’s large enough to study a robust sample - a hundred stars - and to be an incredible resource for all astrophysics.

The intent isn’t to define a completely new mission instead of HABEX and LUVOIR. The studies for those are detailed and represent key points in a huge mission phase space, both have amazing teams, and both have distinct and excellent features.

The report recommends that NASA and a larger community team combine the ideas from both concepts, and carefully mature and develop this into a mission

It will take a long time - this won’t take data until the early 2040s. But I have faith that my colleagues, scientists and engineers and managers, will be able to do this.

When this flies, it could answer a truly fundamental question: are worlds like our own - temperate rocky planets, with just enough water and atmosphere, common, or so rare as to make Earth unique

Even a non-detection would be combined with detailed studies of hundreds of other worlds - if we don’t see oxygen, we will have the planetary and stellar context to understand why, and if the barriers to life on these worlds are fundamental or transient.

And if we do see oxygen, the framework that astronomers and planetary scientists and astrobiologists have built will allow us to say with confidence - not certainty, but confidence - if it comes from life.

Either answer would be transformational for my perception of the universe, and I believe the same would be true for many many people. Knowing that we’re not alone, or knowing that life-bearing worlds are utterly precious and unique.

And we can do this.