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11/22/2019
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Astronomy 4800 – Space Science: Practice & Policy
ASTR 4800 - Space Science: Practice & PolicyToday: Can we afford Astrophysics Flagship Missions?: JWST & WFIRST
– Next Class on Dec. 2 at the Fiske Planetarium: Einstein and Interstellar Travel.
– Reading: article referenced on class webpage for Dec. 2.
Astronomy 4800 – Space Science: Practice & Policy
Space in the News: Space exploration and nuclear proliferation
Presenter : Jeremy Schlagel
NASA is proposing to develop a reactor called Kilopower that could be ready to support lunar bases in the latter half of the 2020s, but the choice of fuel for that reactor worries nuclear nonproliferation experts.
Can We Afford Astrophysics Flagship Missions?
JWST and WFIRST
Presenters: Alex Baughman and Colin Brown22 November 2019
What are “Flagship” Missions?- Large missions, typically
costing upwards of $1 billion
- Exist in Astrophysics, Earth science, Heliophysics, and Planetary Science
- JWST and WFIRST fall into Astrophysics category
- Other similar missions: Hubble Space Telescope, Chandra X-ray Observatory, Kepler, TESS
JWST and WFIRSTJWST WFIRST
Location L2 L2
Projected Cost $10 Billion $3.2 billion
Projected Launch March 2021 2025
Lifespan (years) 5 (design), 10 (goal) 5 (design)
Goals ● Use infrared to study
origins of the galaxy and
universe
● Study exoplanets for
building blocks of life● Learn more of our own
solar system
● Large field of view
images with high
precision and accuracy
● Address questions for
dark energy and exoplanets
Beginning of Development 1996 2010
Brief History of JWST Program- 1990’s
- In the 1991 Astrophysics Decadal Survey:- Strong emphasis on using infrared light to study distant galaxies - General consensus to build a larger, more powerful space telescope
- Led to the Next Generation Space Telescope in 1996- Estimated to cost $500 million and launch in 2007
- 2000’s- Renamed to James Webb Space Telescope- Project was re-planned in 2005; updated budget of $4.5 billion- Launch date continually pushed back: 2007->2011->2015->2020->2021
- 2010’s- Final construction finished in 2016- Multiple testing failures have delayed things further- Current estimate (Oct. 2019) - $10 billion, launch in 2021
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What / Where is L2?- What are Lagrange Points?
- Essentially a 3-body gravitational problem- Point where the gravitational pull of two
larger bodies equals the centripetal force on a smaller body (i.e. spacecraft)
- This allows the smaller object to maintain its relative position with the two other bodies
- Why L2?- Clear view of deep space- Close enough for communication with
Earth (~1.5 million km)- Can still receive solar power via halo orbit- Relatively stable orbit (~23 days)
James Webb Space Telescope (JWST)- Pros v cons:
- Pros: - Potential for new science discoveries- New technologies developed which could be used for future space
telescopes
- Cons: - Cost- Schedule- Risk of failure
Pros: Science Discoveries- Infrared vision can look over 13.5 billion years into the
past- Understand how first stars and galaxies formed- Comparison with our own current galaxy will help to
understand evolution of the Milky Way
- Ability to see through heavy clouds of dust- Allow us to see other stars and planetary systems that could not
be seen by Hubble
- Observation of the atmospheres of exoplanets- Help us better understand the planet/atmospheric compositions- Potentially find building blocks of life across the universe
- Ability to better study objects in our own solar system
Pros: Notable New Technologies Developed- Infrared detectors
- Near-infrared and mid-infrared
- Sunshield- Tennis-court sized- Five human-hair thick layers to reflect sun’s heat
- Cryocooler/Cryogenic DAQ- To suppress background heat generation from the payload- DAQ is able to convert A-D at extremely low temperatures
- Backplane/Lightweight hexagonal folding mirrors- Large area to collect more light (~6.5 meters across)- Aligned to 1/10,000 of a human hair
Cons: JWST Cost and Schedule Over the Years- In 2011, congress proposed to
cancel the project- Proposed a $1.9 billion cut from
NASA’s total budget
- The American Astronomical Society and Senator Barbara Mikulski voiced support for the program
- Congress agreed to reverse cancellation and instead cap program at $8 billion
- How can we better manage a mission such as this?
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Cons: Mission Risk- With L2 point being 1.5 million km from Earth, it is incredibly difficult to reach
- Designed to be unserviceable
- For reference, Hubble experienced a serious issue within weeks of its launch:- Primary mirror was polished to the wrong shape on outer perimeter- Required collectively 5 spacewalks of over 35 hours to replace 10 instruments and fix the mirror
- Deployment of JWST:- https://www.youtube.com/watch?v=vpVz3UrSsE4
- Incredibly small tolerances, particularly on mirror alignment- What do we do/what CAN we do if something goes wrong?
JWST Summary- Lots of great science to be done
- Learn a great deal about the formation of our galaxy and uncover unknowns of the universe- Potentially discover traces of life on exoplanets
- But is the science worth it?- Poorly managed, inflating costs and schedule- Unforeseen, yet routine setbacks that were not accounted for in schedule margin- Why was the project not shut down?- How much are taxpayers willing to tolerate for large, important flagship missions like JWST?- Just this week, NASA’s Science Mission Directorate hinted towards even FURTHER delays
Class DiscussionWhat will happen if the JWST experiences a major failure at L2? How would this affect future flagship Astrophysics missions?
Wide Field Infrared Survey Telescope (WFIRST) WFIRST OverviewScience Goals
● Attempt to answer questions in areas of dark energy, exoplanets, and infrared astrophysics
● Will have panoramic field of view 100x greater than Hubble
Logistics
● Planned 2025 launch● Projected cost of $3.2 billion● 5 year lifespan
Unusual History
● #1 mission for 2010 Astrophysics decadal survey○ Combination of multiple white papers with similar concepts to produce a “broadly capable
mission”■ Never been done before for a decadal survey■ Essentially went against decadal survey procedures to create this project
○ Multiple design changes from conception
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WFIRST Science● Primary mirror is 2.4 m in diameter
(same as Hubble)● Two on-board instruments:
○ Wide Field Instrument■ Enables larger portion
of sky to be imaged (100x greater than Hubble)
○ Coronagraph Instrument■ Blocks direct light from
stars to resolve nearby objects (exoplanets)
Comparison to Hubble
Coronagraph
WFIRST Science Cont.● Wide Field Instrument
○ Provides stable observations for implementing the Dark Energy, Exoplanet Microlensing, and Near Infrared surveys.
● Coronagraph Instrument ○ Part-per-billion suppression of
starlight to enable the detection of planets smaller than Mars, orbiting at distances closer than Venus to their host stars
Dark energy distribution
Exoplanet Microlensing
WFIRST History● The EOS panel of the Astro 2010 Decadal Survey created WFIRST by combining the science proposed by
several similar hardware concepts (i.e.; JDEM-Omega, MPF, and NIRSS; all wide field, near-infrared telescopes)
● NASA HQ formed a Science Definition team in late 2010 to perform a two year study to develop a Design Reference Mission (DRM) responsive to the NWNH report.
2010 2011 2012
JDEM-Omega (2010)● 1.5 m obstructed
telescope● 3-channel payload-
H2RG’s● 5 year mission● Atlas V launch
vehicle● Estimated $1.21 B
WFIRST-IDRM (2011)● 1.3 m unobstructed
telescope● 3-channel payload-
H2RG’s● 5 year mission● Atlas V launch
vehicle● Estimated $1.63 B
WFIRST-DRM 1 (2012)● 1.3 m unobstructed
telescope● 1-channel payload-
H2RG’s● 5 year mission● Atlas V launch
vehicle● Estimated <$1.6 B
WFIRST-DRM 2 (2012)● 1.1 m unobstructed
telescope● 1-channel payload-
H4RG’s● 3 year mission● Falcon 9 launch
vehicle ● Estimated $945 M
WFIRST Funding Year Funding
(millions)
Comments
2014 $56 Project study / Conceptual designs
2015 $50 Estimated total cost of $2 billion
2016 $90 Entered “formulation phase” i.e. officially became a NASA mission
2017 $105 Independent review projected $3.9 billion for total cost
2018 $127 WFIRST de-scoped to $3.2 billion
2019 $312 Presidential budget proposed to cancel WFIRST, denied by Congress
2020 $542
(NASA requested)
Again, Presidential budget proposes to cancel / delay WFIRST
Projected
Total Cost
$3.2 billion Currently on track for 2025 launch, $3.2 billion cost, unless funding declines
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WFIRST Funding and Recent Status● Proposed to be cancelled in President’s
FY19, Congress passed bill in 2018 to continue its funding○ Congress "rejects the cancellation of
scientific priorities recommended by the National Academy of Sciences decadal survey process"
● President’s FY20 budget proposed to delay WFIRST to focus on JWST○ Should we wait for JWST to finish
before going forward with WFIRST? ● PDR concluded Nov 1st, 2019, but still
awaiting formal mission confirmation in early 2020○ Say they’re on track but current
proposed Senate budget threatens to delay it further
WFIRST Summary
Pros Cons
● “Best of both worlds” i.e. large field of view + precise measurements
● Advance science in areas of dark energy, exoplanet detection, and near infrared surveys
● “Design-to-cost” instead of “Design-to-mission-success”○ Says they’re on schedule
(2025) and within budget ($3.2 billion)
● Is the science worth the total cost? Can we do the same science differently?
● Like JWST, located at L2 so difficult to repair if something goes wrong
● Combination of white papers, mission thrown together without much preparation
● Uncertain future
Class DiscussionIf we invest all this time and money into flagship missions, should we cancel one if it’s taking too long or too much money?
Flagship Missions: Final Thoughts● Are Flagship missions becoming too large?● How much are we willing to spend?● Are we getting a good return on our investments?● What are we not able to spend money on because of these
missions?● Is there a different way to do the same science?
Referenceshttps://www.jwst.nasa.gov/
https://wfirst.gsfc.nasa.gov/
https://www.nasa.gov/sites/default/files/atoms/files/wietr_final_report_101917.pdf
https://wfirst.gsfc.nasa.gov/science/sdt/meetings/2012_Nov/MMelton.pdf
https://solarsystem.nasa.gov/resources/754/what-is-a-lagrange-point/
https://www.aip.org/fyi/2016/nasas-large-strategic-science-missions-under-microscope
https://web.archive.org/web/20081110180605/
http://www7.nationalacademies.org/bpa/CAA_Nov2005_Presentation_Mather.pdf
https://www.nap.edu/nap-cgi/skimchap.cgi?recid=1634&chap=72-90
https://www.skyandtelescope.com/astronomy-news/james-webb-telescope-launch-delayed-until-2020/
https://www.theguardian.com/science/2011/jul/09/nasa-james-webb-space-telescope
https://hubblesite.org/mission-and-telescope/mission-timeline#h4-4ba19dbc-c864-47fd-9056-ff82666b149f
https://www.forbes.com/sites/startswithabang/2017/04/05/how-much-gold-is-in-the-james-webb-space-telescope/#77d6285769e5
https://astronomynow.com/2017/05/09/james-webb-space-telescope-shipped-to-texas-for-its-biggest-test-yet/
https://wwwastro.msfc.nasa.gov/lynx/docs/documents/hertz-astro2020-kickoff-slides.pdf