Nov 4, 2021 - Science

An ambitious new plan aims to find an Earth twin

Illustration of an earth-like planet orbited by three moons

Illustration: Sarah Grillo/Axios

A new once-in-a-decade influential report urges NASA to double down on developing the technology needed to find another Earth.

Why it matters: Settling whether life is rare and unique in the cosmos would fundamentally change our view of the universe.

  • "When we see the first hint of life out there in the universe and see the fingerprints of life in a distant world, humanity’s place in the universe is fundamentally changed," says John O'Meara, chief scientist at the W. M. Keck Observatory and a senior member of the team behind LUVOIR, one of the space-based telescope mission concepts considered in the new assessment.
  • On the flip side: "If we looked at 25, 50 or 100 exoplanets and saw nothing, that also fundamentally changes our view of the universe," he adds.

Driving the news: The decadal survey — released Thursday — is a long-awaited document that gives NASA and the National Science Foundation a mandate to develop the technology needed to actually find an Earth twin in the coming decades.

  • One of the highest priorities in the new report is that NASA fund and build a telescope much larger than the Hubble Space Telescope, which would have the ability to find Earth-like planets around Sun-like stars.
  • The decadal survey suggests the telescope — which would look out into space in ultraviolet, optical and infrared wavelengths — would cost about $11 billion to build and would launch in the early 2040s.
  • Other pillars in the survey center around building new ground-based observatories, focusing efforts on learning more about the early universe and gravitational waves and addressing diversity and harassment in the field.

State of play: Other missions have focused on characterizing and searching for planets that could be habitable around other stars, but this mission would allow researchers to confirm another Earth around a Sun-like star, something that isn't possible with current technology.

  • A big hurdle has been the ability to block the light from stars as bright as the Sun, in order to reveal any relatively small planets that might orbit them. That depends on building an ultra-stable space telescope and an instrument called a coronagraph.
  • Those technologies aren't here yet but have been developed far enough that there is now a path, O'Meara says.
  • The telescope envisioned by the decadal survey will be able to search 100 or more Sun-like stars to figure out what types of planets orbit them.
  • "Then for the most exciting ~25 planets, astronomers will use spectroscopy at ultraviolet, visible, and near-infrared wavelengths to identify multiple atmospheric components that could serve as biomarkers," the report says.

Between the lines: Decadal surveys typically pick a large space-based mission that the astronomy community can rally behind. (The James Webb Space Telescope and Roman Space Telescope were prioritized in previous reports.)

  • For this decadal, however, the committee behind the report ultimately didn't choose to endorse any of the four flagship missions studied for the document.
  • The high-priority space telescope put forth by the report combines some elements of two of the four possible missions and leaves room for two other spacecraft to be developed in the future as part of a newly recommended NASA program to advance big telescope ideas.
  • "You can't do it all with one telescope or one wavelength region. You need them all working together, synergistically," astronomer Rachel Osten, who was part of the steering committee for the document, told Axios. "That said, it's impractical to try to do these observatories at the same time."

The big picture: The two other mission concepts would use different wavelengths to give scientists the full breadth of what's going on out in the universe.

  • X-ray observations would help determine how elements that are critical for life are born in the explosions as giant stars merge. With far infrared data, astronomers could watch the rise of water throughout the universe.
  • This panchromatic data tells "the story of life" from the Big Bang to the biosignatures that might be spotted on exoplanets, O'Meara says. "That is more enriching than any mission alone."

But, but, but... This next-generation fleet of space telescopes will have to clear technical hurdles and still needs Congress' support.

  • The experience of the JWST — long delayed and massively over budget — could give some lawmakers pause in funding what astronomers tell Axios is an ambitious plan. But the new survey appears to incorporate some lessons learned from JWST's development, including the flexibility to adjust the mission design.
  • The four proposed mission concepts — LUVOIR, HabEx, ORIGINS and Lynx — were also more developed than the plan put forth for JWST.
  • "We have put a lot of thought into trying to avoid or mitigate the issues JWST ran into," says Aki Roberge, an astronomer at NASA's Goddard Space Flight Center who was a study scientist for LUVOIR.

Go deeper: Read the public report.

Go deeper