export control notice export or re-export of information contained herein may be subject to...

Export Control NoticeExport or re-export of information contained herein may be subject to restrictions and requirements of U.S. export laws and regulations and may require advance authorization from the U.S. Government.

NWO Science Telescope25 Aug 20082

Where Next with Space Missions for Exoplanets?

• There Has Been Stunning Progress in Study of Exoplanets– It takes 10 to 20 years to launch a space observatory– 14 years ago this field didn’t exist– where will it be in 20 years with or without space????

• A Space Exoplanet Mission Must Have A– Dramatic Leap In Sensitivity and Inner Working Angle– High Quality Spectroscopy– Capability WAAAAAY Beyond What We have Seen So Far

• Otherwise the Mission Will Be Rendered Mundane

• In Short We Need High Quality Spectroscopy of Earth-twins– And broad capability to study planetary systems in detail– Anything less would be a gamble


NWO Team Membership: Organizations, Roles and Leads

• Team consist of 43 active members– 9 organizations are participating

• Additional involvement is provided from each organization and includes technical area experts and graduate/undergraduate students

• Organizations, Roles and Leads:– Colorado University: PI, Science, Optical Design, and Systems Analysis: Webster

Cash– Northrop Grumman: Deputy PI and Starshade Development: Amy Lo– Ball Aerospace Technology Corporation: Telescope Development: Charley Noecker– USNO: Astrometry: Ralph Gaume– NASA GRC: Occulter (Starshade) Propulsion: Scott Benson– KinetX: Mission Design and Navigation: Bobby Williams– GSI: Lead Scientist: Maggie Turnbull– University College of London: Exoplanet Spectra Modeling: Giovanna Tinetti– NASA GSFC: Study Management: Kate Hartman– Space Telescope Science Institute: JWST Interface: Remi Soummer


Stars are very bright and their glare makes it difficult to see fainter objects

near them


Starshade prevents starlight from entering the telescope

• The telescope is shaded from the star by the starshade– Besides the vanishingly small residual signal, the starlight does not

enter the telescope

Starshade

100% of the planet light is reaches the telescope100% of the planet light is reaches the telescope


Fly the Telescope into the Shadow


Dropping It In

Note: No Outer Working Angle


Extinguishing The Spot of Arago

• Occulters Have Very Poor Diffraction Performance– The 1818 Prediction of Fresnel led to the famous episode of:– Spot of Arago (variously Poission’s Spot)– Occulters Often Concentrate Light!

• Must satisfy Fresnel Equation, Not Just the Fraunhoffer Equation

• Must Create a Zone That Is:– Deep Below 10-10 diffraction– Wide A couple meters minimum– Broad Suppress across at least one octave of spectrum

• Must Be Practical– Binary Non-transmitting to avoid scatter– Size Below 150m Diameter– Tolerance Insensitive to microscopic errors


NWO has an Opaque Starshade

• Opaque Starshade

Offset Hypergaussian function

Apodization Function

expn

r aT

b

• Apodizing Function

Radius

Tra

nsm

issi

on

Parameter

Occulter inner radius a

Petal 1/e length b

Hypergaussian order n

Distance to telescope z

Number of petals P


Performance

A 50m diameter occulter at 80,000km can reveal Earths at over 20pc


Target Stars: Exo-zodiacal Light

From P. Oakley1.5m 2.4m 4m 10m

4m Case


Map Planetary Systems

• Prime Goal is Exploration of the Solar Neighborhood

• NWO will allow us to make maps of over 100 nearby planetary systems from the habitable zone outward

• Detect and classify all major planets

JupiterSaturn

Uranus

Neptune

Zodiacal Light

Galaxies

10 arcseconds


Four Color Photometry – Molecules!!

Export Control NoticeExport or re-export of information contained herein may be subject to restrictions and requirements of U.S. export laws and regulations and may require advance authorization from the U.S. Government.

Simulated Image of Earthwith starshade and JWST


Planet Finding with Starshades

Five Random Systems from Raymond Database

The higher resolution of ATLAST brings weak signals out of the noise

ATLAST

JWST


• Confusion from dust structure

− “Is that a planet or a dust clump?”

− Can we tell by its color before

wasting time on a spectrum?Greaves et al. (2005)

Epsilon Eridani

Other Exozodi Issues

• Maybe …

− Solar System zodi has

red scattered light color

− Known debris disks show

red, grey, & blue colors

AU MicBlue

HD 92945Neutral

Beta PicRed


Target Stars: Exposure Times

i = 60˚

From A. Roberge


Where to Look for ExoEarths?

• Entire habitable zone : ~ 110 stars

• Half of habitable zone : ~280 stars

NWO blue IWA40 mas

Contrast ~ 10-11

NWO red IWA65 mas


Importance of Inner Working Angle

Once you can study all the stars with correctly-sized Habitable Zones, there is no further advantage in being able to study more. New Worlds can do this.


Study Exoplanets

• NWO will perform spectroscopy of discovered planets

• This will reveal their true natures

O2

H2O

CH4

NH3


Spectroscopy of Earths

JWST ATLAST

ATLAST @ High ResolutionFine Structure!


Characterizing Planets: Photometric Variability

From P. Oakley


70% of Time Available for Other Astrophysics

1. The “NWO Deep Field”

2. Galaxy interactions and evolution

3. Stellar evolution

4. The Solar System

KBO UB313


NWO Flagship Mission – ASMCS Study

Starshade and Telescope on single EELV

Stacked configuration

Starshade and telescope deploy

~50 m starshade

72,000 km

4 m telescope

Earth to L2 = 1.5 million km

Suppression 10-10

IWA 55 - 65 mas

Wavelength 120 – 900 nm

Total pointings 90 - 140

Slewing time 9 -13 days

Observation time 1 - 10 days

Simulation from E. Shindhelm, CU


Tall Poles

• Deployment of 50m shade to cm class tolerances

• Acquiring and holding line of sight

• Fuel usage, orbits and number of targets

• Stray Light – particularly solar


Starshade Critical Technology

Enabling Technologies

Precision Shape Control •Maintain edge position•Maintain structure shape

Precision Deployment •Minimize jitter•Maintain petal location

Opaque Membrane•Maintain opacity•Lightweight

2 Axes Formation Flying•Maintain 1m alignment•Minimize jitter

Enhancing Technologies

Solar Electric Propulsion•NEXT engine•Increase observable targets•Reduce propellant mass

Lightweight S/C Structures•Increase observable targets•Reduce overall mass

Thin Edge Treatment•Maintain edge stability•Minimize stray light


Lab Studies


NGS Starshade with HID source, 1000s integration

Total suppression within 200 pixel radius = 8.8e-006

wire

wire

wire

Wire3.9e-7

wire

Wire4.3e-7

(Chamber door open)

Chamber door closed


CU/NIST starshade, 200s200 micron entrance pinhole, iris=10mm, 4/24/09 data

Total suppression within 200 pixel radius = 3.0e-006

1.53e-006

1.49e-006

1.47e-006Contrast at points where mount wires cross petal edges


5.05e-010

6/19/07 Image27- 600sec


Conclusion By 2025

O2

H2O

By 2013

Demonstration Program 2009-2012Study Earths with JWST 2015Lifefinder 2022Planet Imager – 2030?

export control notice export or re-export of information contained herein may be subject to...

Documents