expanding the frontiers of space astronomy

EXPANDING THE FRONTIERS OF S PACE AS TRONOMY

The James Webb Space Telescope

Massimo Stiavelli

July 22nd, 2019

Plan of the talk

• The James Webb Space Telescope

• Observing plans and opportunities

• JWST status

We need a newer and bigger telescope

JWST is an international collaboration between NASA, ESA and CSA

What will JWST do after it’s launched?

Attempt to find and characterize Earthlike planets in the Habitable zone

HST UDF

Simulated JWST Image

Summary of JWST instrument capabilities

jwst.stsci.edu/instrumentation

Spectroscopy and JWST

JWST has many spectroscopic capabilities:

• NIRSpec supports MOS, IFUs, and single slit spectroscopy

• NIRcam supports slitless spectroscopy

• NIRISS support slitless spectroscopy and single object slit spectroscopy

• MIRI supports IFU spectroscopy and low-res slit spectroscopy

Near Infrared Camera – NIRCam (US)NIRCam Capabilities2 channel imager from λ = 0.6 to 5.0 microns, get λ < 2.5 & λ > 2.5 micron

simultaneously

Nyquist sampling of diffraction limit at 2 microns (0.032”/pixel) and 4 microns

(0.065”/pixel)

2.2’ x 4.4’ field of view

Short and long wavelength coronagraphy

Slitless spectroscopy for λ = 2.4 – 5.0 micron

Check NIRCam pocket guide: jwst.stsci.edu/instrumentation/nircam

Near Infrared Spectrometer – NIRSpec (ESA)

NIRSpec CapabilitiesNear Infrared wavelength coverage of λ = 0.6 to 5.0 micronsThree different spectral resolutions of R = 100, 1000, and 2700Modes: Single Slit Spectroscopy (slits with 0.4” x 3.8”, 0.2” x 3.3”, 1.6” x 1.6”)

Integral Field Unit (3.0” x 3.0”)Multi Object Spectroscopy (3.4’ x 3.4’ with 250,000 - 0.2” x 0.5” microshutters)

Check NIRSpec pocket guide: jwst.stsci.edu/instrumentation/nirspec

NIRSpec enables multi-object spectroscopy

248,000 microshutters!

Mid Infrared Instrument – MIRI (US-EC)

MIRI CapabilitiesHigh resolution imager with sensitivity from λ = 5 to 28 microns, 10 broad-band filtersλ = 5.0 to 28.3 microns with 0.11” pixels1.23’ x 1.88’ field of view Coronagraphy at 10.65, 11.4, 15.5, and 23 microns (24” to 30” field of view)Integral Field Unit with R = 2200 to 3500, at 4 wavelengths (image slices 0.18” to 0.64”)Single Slit Spectroscopy from 5.0 to ~14 microns in 0.6 x 5.5” slit (R ~ 100 at 7.5 microns)

Check MIRI pocket guide: jwst.stsci.edu/instrumentation/miri

Near Infrared Imager and Slitless Spectrograph – NIRISS (CSA)

NIRISS Capabilities

Imaging - λ = 0.9 to 5.0 microns over a 2.2’ x 2.2’ field of view with 0.065” pixelsWide Field Slitless Spectroscopy - λ = 1.0 to 2.5 microns at R ~ 150Single Object Slitless Spectroscopy - λ = 0.6 to 2.5 microns at R ~ 700Aperture Mask Interferometry - λ = 3.8 to 4.8 microns, enabled by non-redundant mask

Check NIRISS pocket guide: jwst.stsci.edu/instrumentation/niriss

JWST Point Source Sensitivity

Data cube-based ETC available on the web

Plan of the talk



• JWST status

16

7/27-8/7/2020

GO Cy1 TAC

Commissioning

(L+6 mo.)

(L+6)

Cycle 1 obs. begin

JWST Science Planning Timeline (July 2019)

2018 2019 2020

5/1/2020

GO Cy1

prop. due

L+11

GO Cy2 Call

2021

Cycles 1 & 2 Call for Proposals

6/25/2019

GTO and ERS Cy1 APT

files submitted

DD ERS observations

2022

L+9

GTO Cycle 2 deadline

1/23/2020

GO Call re-opened

L+13

GO Cy2 deadline

L+15

GO Cy2 TAC

• Astronomer’s proposal tool (APT)

• Exposure time calculator (ETC)

• Quantitatively validated with instrument teams

• Runs on Amazon Web Services to guarantee scalability and adequate CPU resources

• Calibration pipelines

• More sophisticated than those on HST after 25 years in operations

• New JWST Help Desk portal

• Web-based, includes comprehensive documentation search and user forum.

• User documentation (JDOX)

• Wikipedia-style integrated web documentation

• Data analysis tools

• Many new applications, including spectroscopic viewer, multi-object and IFU tools

• Written in Python and integrated with Astropy

• Data simulators

• STIPS imaging simulator to be released

JDOX

JWST ETC

JWST User Tools

Plan of the talk



• JWST status

James Webb Space Telescope status

We have three months of schedule reserve to a launch date at the end of March 2021

Technical progress

OTIS completed cryovac testing at JSC

ISIM backside at NGAS : a radiator deployment test

Aft sunshield UPS deployment

Preparations for sunshield deployment test

Diving board inspections


Flight control room during the Ground Segment test 2

JWST is still planned for a March 2021 Launch

Conclusions

• JWST is now planned for launch in 2021

• The instruments and optics (ISIM) have completed and passed their final test.

• There are no know technical issues. Aside for the complexity of the observatory and its consequent vulnerability to human errors.

Lessons learned from JWST, HST/ACS, HST/WFC3, VLT

• Design and planning• Reuse with modifications doesn’t exist

• Reserves are important (time and money)• Any dollar not spent when needed, will cost 2-3 dollars in the future

• Materials are cheap, people are not – e.g. WFC3 pins• How does your mission cost compare to its weight in gold?

• Simplicity and common sense – e.g. ACS camera head, WFC3 UVIS channel

• When complexity is unavoidable• focus on interfaces and clear communications

• Lots of simple things put together are complex

• Develop a design reference mission

Lessons learned from JWST, HST/ACS, HST/WFC3, etc

• Implementation• Hard parts are hard but simple things are also hard - e.g. thrusters

• It pays to have a system scientist i.e. the science analog of a system engineer, who worries about beginning to end science flow – e.g. VLT “Porsche” manager, LEP

• Balance between descopes and new requirements• System engineers can use the design reference mission to guide choices, assess mechanism

lifetime etc.

• When in doubt, document it

E X P A N D I N G T H E F R O N T I E R S O F S P A C E A S T R O N O M Y

expanding the frontiers of space astronomy

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