NIAC Phase II Awards Focused on Astronomy

Kilometer Space Telescope. A single pixel from a galaxy in the Fornax Cluster (left) could appear more like a HST image of the Large Megallanic Cloud (right). (Credit: Devon Crowe)

The NASA Innovative Advanced Concepts (NIAC) program recently awarded 25 grants for the development of visionary new technologies. Here we’re going to take a closer look at the following two Phase II awards focused on space astronomy.

Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens Mission
Slava Turyshev
NASA Jet Propulsion Laboratory

Kilometer Space Telescope (KST)
Devon Crowe

Each award is worth up to $500,000 for a two-year study. Descriptions of the awards are below.

Graphic depiction of Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens Mission (Credit: Slava Turyshev)

Direct Multipixel Imaging and Spectroscopy of an Exoplanet
with a Solar Gravity Lens Mission

Slava Turyshev
NASA Jet Propulsion Laboratory

We propose to build upon our Phase I study of a mission to the regions outside our solar system, with the objective of conducting direct high-resolution imaging and spectroscopy of a habitable exoplanet by exploiting optical properties of the solar gravitational lens (SGL). A mission to the focal area of the SGL (which lies beyond 548.7 astronomical unites (AU) on the line connecting the center of the exoplanet and that of our Sun, called the focal line of the SGL) carrying a modest telescope and coronagraph could deliver direct megapixel imaging and high-resolution spectroscopy of a habitable Earth-like exoplanet orbiting a host star at a distance of up to 30 parsec.

The remarkable optical properties of the SGL include major brightness amplification (~1e11 at \lambda=1 um) and extreme angular resolution (~1e-10 arcsec) in a narrow field of view. The entire image of such an exo-Earth is compressed by the SGL into an instantaneous cylinder with a diameter of ~1.3 km in the vicinity of the focal line. Moving outwards while staying within the image, the telescope will take photometric data of the Einstein ring around the Sun formed by the light from the exoplanet and will process the data to reconstruct the image of the exoplanet with a few km-scale resolution of its surface, enough to see its surface features and signs of habitability.

Under a Phase I NIAC program, we evaluated the feasibility of the SGL-based technique for direct imaging and spectroscopy of an exoplanet and, while several practical constraints have been identified, we have not identified any fundamental limitations. We determined that the foundational technology already exists and has high TRL in space missions and applications. Furthermore, the measurements required to demonstrate the feasibility of remote sensing with the SGL are complementary to rotational tomography measurements and ongoing microlensing investigations, so our effort would provide high-value scientific information to other active astrophysics programs.

Under the Phase II program, we will continue to advance our understanding of the SGL-based imaging and spectroscopy, improve on the computational methods developed in Phase I, evaluate specific hardware implementations, and ultimately produce a roadmap for the direct high-resolution sensing of exoplanets. We will refine our understanding of mission architectures and the technology roadmap. To that extent, we will refine the Phase I mission concepts: i) a single probe-class spacecraft, ii) a swarm of small and capable spacecraft, iii) a “string-of-pearls” mission concept using multiple sets of moderate size spacecraft, and will consider other concepts, if identified.

Our main objective for this effort is to study i) how a space mission to the focal region of the SGL may be used to obtain high-resolution direct imaging and spectroscopy of an exoplanet by detecting, tracking, and studying the Einstein ring around the Sun, and ii) how such information could be used to detect signs of life on another planet. We will deliver a list of recommendations on the mission architectures with risk and return trade offs and discuss an enabling technology development program. The resulting mission concept could allow exploration of exoplanets relying on the SGL capabilities decades, if not centuries, earlier than possible with other extant technologies.

Phase II will provide us with a clear understanding of the scientific value of the mission and the trades needed to define the most cost-effective mission design and architecture. If no showstoppers will be identified, we will have all the needed tools and mission rationale to present the SGL imaging mission to the science community for a broader support. As the concept may be the only way to view a potentially habitable exoplanet in detail, it would generate the public interest and enthusiasm that could motivate the needed government and private funding.

Kilometer Space Telescope. A single pixel from a galaxy in the Fornax Cluster (left) could appear more like a HST image of the Large Megallanic Cloud (right). (Credit: Devon Crowe)

Kilometer Space Telescope (KST)

Devon Crowe

A Kilometer Space Telescope (KST) will provide over three times the diameter and ten times the collecting area of the Arecibo groundbased radio telescope with diffraction-limited performance at optical, infrared, and millimeter wavelengths. This capability is orders of magnitude improvement over the Hubble (HST) and James Webb (JWST) instruments. This Phase 2 NIAC proposal extends Phase 1 technology to measure the optical performance at the meter laboratory scale to predict the performance of a one-kilometer space telescope. Each aspect of the technology, science, development, and mission science will be examined to produce these products:

  • Science Requirements
  • Lab Measurement of spherical primary optical quality
  • Telescope Architectural Trades
  • Telescope Design
  • Telescope Performance modeling
  • Launch and deployment methodology
  • Mission Operations
  • Science Data Reduction
  • Simulated Science data, imagery, and results
  • Development and Deployment Plan for KST
  • Mission Plan

Dramatic increases in resolution and sensitivity will enable breakthrough science in the discovery and study of terrestrial planets, including spectroscopic search for signatures of life and intelligent life, and the study of some of the very early light emitting objects in the universe.

Unlike other proposed approaches to kilometer class apertures such as interferometers or the Aragoscope, which are all photon starved, the filled aperture KST will be photon rich. A KST would revolutionize astronomy in ways we cannot now imagine. For example, no one predicted that the most stunning images from HST would be of Planetary Nebulae. And HST was only one order of magnitude finer than its predecessors.

We will certainly spend more time in Phase II looking at what might be some of the driving science issues, but for now we simply state that the KST will give us an unparalleled new view of the Universe. Wherever it looks it will make new discoveries. A detailed set of lab experiments will demonstrate the viability of excised portions of spheres as primary mirrors. Optical performance will be measured interferometrically.

We will study both passive and active ways to maintain diffraction-limited performance and to offer both wide field search and narrow filed detailed study modes of operation. The enabling technology also can be used for sun shades for the KST itself, as well as star shades for coronagraphic examination of terrestrial exoplanets.

An early use of this technology could even be to launch star shades for use with JWST. It is possible to deploy structures 100 million times the volume of the launch vehicle payload bay, so in fact a large number of star shades for JWST could be deployed simultaneously, speeding surveys of star planetary systems. As noted in the Phase 1 report, the technology could also be used for large solar sails or habitats.

  • Andrew Tubbiolo

    Andrew’s attempt, let’s see if I qualify for the grant.

    * Get a reasonably sized telescope. It does not need to be that big if I remember. This was a take home exam in my optics class back in the day. — Put it in orbit.

    * Get a really bit radio dish, throw in a LASER just to be sure.

    * Attach those to a nuclear reactor.

    * Throw stuff at the reactor and let it go overboard after getting hot.

    * Wait.

    * Once you’re a few thousand AU out, turn around, look directly at the Sun.

    * Look at the stuff close to the Sun.

    * Enjoy.

    Our great great great grandkids are going to have all kinds of fun with these things. Gravitational optics is no end of fun. The most likely path to these stepping stones to starships will probably be based off of technologies developed for fast interplanetary transfers for people and, moving asteroids. A must is a very deep and capable understanding and operation of nuclear power plants. These systems are 100 to 200 years out.

  • Paul451

    You’ll want an independently flying vehicle which has a deployable sun-shield.

    Even with lensing, the Einstein ring will be lost against the glare from the sun. Logically, the sunshade would have the big-dish to talk to home, the telescope just a little’un to reach the sunshade.

  • Andrew Tubbiolo

    I wonder if you’d really need one at 500 AU? We talked about it. We were thinking a old fashioned heliograph might work? Perhaps, as you state, a small one a few km’s from the spacecraft. I imagine that’ll be one of the subjects of the concept studies. I’ll be looking for it. Should make for great reading before bed.

  • Paul451

    AIUI, the reason for a more distant sun-shield is to avoid edge effects. (Diffraction of such a bright light source (even at 500-1000AU) would still be significant.)

  • Andrew Tubbiolo

    If you’re going to build a proto-starship to image exo-planets you can go overboard on the imaging system. Well within my estimated 100+ year timeframe for these systems to be built, you could pave the imaging plane with the best of imaging technology of the day. No doubt each pixel will have individual readout, variable gain, and absolutely noiseless charge transfer from one photo site to another. 🙂 And of course a QE of 1 🙂 I would imagine they’ll image the entire Einstein ring live and do all sorts of things like virtual stack and track, selective reading of bright spots and pegging the gain on weak signals. Some version of HAL will probably do all the image processing the way we do depth perception. I wonder how that future AI crew will deal with the concept that they’ll become a spent hulk in interstellar space. Maybe they’ll refuel in the Oort cloud and come back?

  • therealdmt

    Solar gravity lens exoplanet imaging mission — this I want to see!

    Waiting patiently…waiting, waiting

    Sigh. ‘Twould be awesome, no doubt.