Tag: National Academies of Sciences

Why Not Assemble Space Telescopes In Space?

Artist rendering of an in-space assembled observatory concept with a 20-meter diameter primary mirror. (NASA’s  In Space Assembled Telescope Study, iSAT)

As we grow more ambitious in our desires to see further and more precisely in space, the need for larger and larger telescope mirrors becomes inevitable.  Only with collection of significantly more photons by a super large mirror can the the quality of the “seeing” significantly improve.

The largest mirror in space now is the Hubble Space Telescope at 2.4 meters (7.9 feet) and that will be overtaken by the long-delayed James Webb Space Telescope (JWST) at 6.5 meters (21.3 feet) when it launches (now scheduled for late 2021.)  But already astronomers and space scientists are pressing for larger mirrors to accomplish what the space telescopes of today cannot do.

This is evident in the National Academies of Sciences Decadal Survey underway which features four candidate Flagship-class observatories for the 2030s.    Three proposals call for telescope mirrors that are significantly larger than the Hubble’s, and the most ambitious by far is LUVOIR  which has been proposed at 15.1 meters (or 50 feet) or at 8 meters (about 30 feet), or maybe something in between.  A primary goal of LUVOIR, and the reason for the large size of its mirrors, is that it will be looking for signs of biology on distant exoplanets — an extremely ambitious and challenging goal.

The LUVOIR team would have argued for an even larger telescope mirror except that 15.1 meters is the maximum folded size that would fit into the storage space available on the super heavy lift rockets expected to be ready by the 2030s.

This desire for larger and larger space telescopes has rekindled dormant but long-present interest in having an alternative to sending multi-billion dollar payloads into space via one launch only.  The alternative is “in-space assembly,” and NASA has shown increased interest in pushing the idea and technology forward.

Nick Siegler, Chief Technologist of NASA’s Exoplanet Exploration Program at the Jet Propulsion Lab, and others proposed a study of robotic in-space assembly in 2018.  The idea was accepted by the NASA Director for Astrophysics Paul Hertz and Siegler said the results are promising.

The International Space Station’s robotic Canadarm2 and Dextre carry an instrument assembly after removing it from the trunk of the SpaceX Dragon cargo ship (upper right), which is docked at the Harmony node of the ISS. (NASA

“For space telescopes larger than LUVOIR, in-space assembly will probably be a necessity because it’s unlikely that heavy-lift rockets will be getting any bigger than what’s being built now,” Siegler said. … Read more

A National Strategy for Finding and Understanding Exoplanets (and Possibly Extraterrestrial Life)

The National Academies of Science, Engineering and Medicine took an in-depth look at what NASA, the astronomy community and the nation need to grow the burgeoning science of exoplanets — planets outside our solar system that orbit a star. (NAS)

 

An extensive, congressionally-directed study of what NASA needs to effectively learn how exoplanets form and whether some may support life was released today, and it calls for major investments in next-generation space and ground telescopes.  It also calls for the adoption of an increasingly multidisciplinary approach for addressing the innumerable questions that remain unanswered.

While the recommendations were many, the top line calls were for a sophisticated new space-based telescope for the 2030s that could directly image exoplanets, for approval and funding of the long-delayed and debated WFIRST space telescope, and for the National Science Foundation and to help fund two of the very large ground-based telescopes now under development.

The study of exoplanets has seen remarkable discoveries in the past two decades.  But the in-depth study from the private, non-profit National Academies of Sciences, Engineering and Medicine concludes that there is much more that we don’t understand than that we do, that our understandings are “substantially incomplete.”

So the two overarching goals for future exoplanet science are described as these:

 

  • To understand the formation and evolution of planetary systems as products of star formation and characterize the diversity of their architectures, composition, and environments.
  • To learn enough about exoplanets to identify potentially habitable environments and search for scientific evidence of life on worlds orbiting other stars.

 

Given the challenge, significance and complexity of these science goals, it’s no wonder that young researchers are flocking to the many fields included in exoplanet science.  And reflecting that, it is perhaps no surprise that the NAS survey of key scientific questions, goals, techniques, instruments and opportunities runs over 200 pages. (A webcast of a 1:00 pm NAS talk on the report can be accessed here.)

 


Artist’s concept showing a young sun-like star surrounded by a planet-forming disk of gas and dust.
(NASA/JPL-Caltech/T. Pyle)

These ambitious goals and recommendations will now be forwarded to the arm of the National Academies putting together 2020 Astronomy and Astrophysics Decadal Survey — a community-informed blueprint of priorities that NASA usually follows.

This priority-setting is probably most crucial for the two exoplanet direct imaging missions now being studied as possible Great Observatories for the 2030s — the paradigm-changing space telescopes NASA has launched almost every decade since the 1970s.

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