In the April 16, 2015, issue of Nature, I published an article that was entitled "Hubble's Legacy." In that article, I argued that the lesson from the amazing success of the Hubble Space Telescope has been that it is better to fund the right experiment fully than to compromise so as to fit a tight budget. I further proposed that future major astronomical endeavors should "identify the most important question that needs to be answered; determine what it would take to answer that question and the technical feasibility of doing so; estimate the full cost of such a project; evaluate whether the goal is worth the investment; and act accordingly. That is, establish the necessary funding profile and keep it stable. Avoid cost overruns through careful planning and oversight."
I went on to express my personal view that the most intriguing question in astronomy is whether life exists in our galaxy beyond the Solar System.
Now a committee convened by the Association of Universities for Research in Astronomy (AURA) has issued a comprehensive, extremely thoughtful report that advocates the same strategic philosophy and has also identified finding extrasolar life as the main goal for a future ultraviolet-optical-infrared space telescope.
The massive report, entitled "From Cosmic Birth to Living Earths: The Future of UVOIR Space Astronomy," was written by a team of 17 active astronomers and technologists. (The committee was co-chaired by Julianne Dalcanton from the University of Washington and Sara Seager from MIT.)
The committee writes:
We conclude, after careful consideration of the science cases and technological approaches, that a 12-meter class space telescope with sufficient stability and the appropriate instrumentation can find and characterize dozens of Earth-like planets and make transformational advances in astrophysics.
Provisionally, the report calls the proposed space telescope the "High-Definition Space Telescope" (HDST). It further states (bracketed asides mine):
HDST will achieve unprecedented angular spatial resolution [in other words, sharpness of vision] and sensitivity [ability to observe faint objects] in the UV and optical and will reach the extreme contrast required to separate Earth-like planets from the glow of their parent stars [an Earth-like planet next to a Sun-like star is 10 billion times fainter] and search them for signs of life.
To give you an idea of how the proposed HDST compares with the Hubble Space Telescope, Figure 1 shows an analogy with the comparison between an old TV set and an ultra-HD screen. Basically, HDST will not only have the ability to find biosignatures in the atmospheres of extrasolar planets (or at least place meaningful constraints on the rarity of life); it will literally revolutionize all of astronomy.
Figure 1. The proposed High-Definition Space Telescope (HDST) will produce images that are 24 times sharper that those of the Hubble Space Telescope.
Now all we have to do is to make this wonderful telescope, a "high-definition Hubble," if you like, happen as soon as possible!