Lecture 8.2: Astronomical Instruments on the Moon: Concepts for fully-steerable and survey VLSTs at a manned base at the Moon’s south pole В. Г. Турышев Jet Propulsion Laboratory, California Institute of Technology 4800 Oak Grove Drive, Pasadena, CA 91009 USA Государственный Астрономический Институт им. П.К. Штернберга Университетский проспект, дом 13, Москва, 119991 Россия Курс Лекций: «Современные Проблемы Астрономии» для студентов Государственного Астрономического Института им. П.К. Штернберга 7 февраля –23мая 2011 LUNAR LASER RANGING Planned NASA Lunar Flight Program FY08 FY09 FY10 FY11 FY12 FY13 FY14 FY15 Lunar Research and Analysis + NLSI Missions of Opportunity + International Coop. (Science-Funding & Opportunity Driven) Lunar Mapping Project ILN Operation (Goal) Possible International Partner Early Operations C/D E MMM + Mini-RF (Chandrayaan/ISRO) C/D E LRO BC & DCruis E e GRAIL SDT Science Definition A BC & D Cruis E e LADEE SDT Science Definition A B TBDB/C/D during duration Phase finalized A during A E Node I & II Operations Mini Landers Launch date to be set during Phase A 020308 LUNAR LASER RANGING International Lunar Robotic Mission Plans 07 08 09 10 11 12 13 14 15 16 17 18 19 20 NASA LRO/ LCROSS LSAM Comm/Nav HLR China Change-E Soft Lander Lunar sample return Mars Lunar Lander/Sample Return ?? sample (NExT) return Germany/DLR LLO Orbiter Lander ?? India/ISRO Chandrayaan I Chandrayaan 2 Italy/ASI Lunar mission Japan/JAXA Selene I Selene II Lander Rep. Korea Lunar Orbiter Russia Luna-Glob Launch Date Final Hardware Delivery UK/BNSC Begin Hardware MoonLITE MoonRaker ?? Development Finalize Agreements LUNAR LASER RANGING ALSEP’s First generation Lunar Network Lunar Landing Sites Red=Russian Luna Yellow=Surveyor Green=Apollo LUNAR LASER RANGING Proposed International Lunar Network (ILN) • International Lunar Network (ILN): – NASA’s SMD is initiating an effort to coordinate future lunar landed missions into an ILN. – The ILN is designed to emplace 6-8 stations on the lunar surface, forming a second-generation geophysical network. – Individual stations could be fixed or mobile. – Each ILN station would fly a core set of instrument types (e.g., seismic, laser retro-reflector, heat flow) requiring broad geographical distribution on the Moon. – Each ILN station could also include additional passive, active, ISRU, or engineering experiments, as desired by each sponsoring space agency. • US-ILN contributions: – The US is committing now to two ILN nodes, launched to the lunar poles, in 2013/2014. – The US is studying the option for a lunar comm relay orbiter enabling lunar far-side access for ILN nodes. – The US is planning a second pair of ILN nodes in 2016/2017. • Next Steps: – 12 March 2008: ILN Informational Briefing to Potential Partner Agencies at LPSC (Houston). Form ILN charter WG. – 20 July 2008: ILN Charter Signing Ceremony (NASA/Ames). Form ILN Landing Site and Core Instrument Definition WGs. – 20 December 2008: ILN Core Instrument Agreement. ASTRONOMICAL INSTRUMENTS ON THE MOON Outline • The trends in building telescopes • Possible locations for future observatories – Antarctica, Dome C – The Moon – South Pole of the Moon •Prosfor astronomical instruments on the moon – Interferometers and telescopes on the moon – Optimistic scenario for astronomy from the moon – Examples of proposed instruments • Cons against astronomy from the moon – Comparative environments – Technologies needed, advantages and disadvantages – Realistic scenario for astronomy from the moon ASTRONOMICAL INSTRUMENTS ON THE MOON Telescopes over past 50 years • Space – From sounding rockets to great observatories – Each successive mission is uniquely powerful – Typically scientific and failure lifetime ≤10 yr – Hubble exception • Ground – Not much size increase – Huge increase in power by better detectors, multiplexing and adaptive optics – Long-lived, rejuvenation on ~ 5-10 year timescale as science goals and technology change ASTRONOMICAL INSTRUMENTS ON THE MOON Lifetimes of Current Generation Space Observatories Observatory Spectrum Dates Life Orbit Lifetime set by Compton gamma 1991‐2000 9 LEO Gyro failure Hubble optical 1990 – 2005? 15? LEO Gyro failure, orbit decay; +5? Final servicing Aug. 28, 2008 Chandra x‐ray 1999 – 2013? 14? elliptical Gyro failure? Spitzer infrared 2003 ‐ 2009 2.5 Drift Cryogen exhaustion away Webb infrared 2015 ‐ 2025 10 L2 Fuel to maintain L2 orbit ASTRONOMICAL INSTRUMENTS ON THE MOON Next 50 years on ground (you must put future space plans in this context) Several telescopes in 20 – 100 m range • Adaptive Optics (AO) should mature to give all sky diffraction limit at 0.5 mm, especially if placed on • Antarctic plateau (L2 of ground) – 25 m in Antarctica (Giant Magellan Telescope II) would rival JWST for spectroscopy – 100 m in Antarctic for terrestrial exoplanets • detection at 10 mm • spectroscopy in optical ASTRONOMICAL INSTRUMENTS ON THE MOON AO will work well in Antarctica Atmospheric turbulence mostly at low altitude, unlike temperate sites 1E-14 DomeDCI C - I 1E-15 DomeDCIII C - III ) -2/3 1E-16 (m.s Mauna Kea 2 MK N C 1E-17 Dome CDCII – II (AO) 1E-18 10 100 1000 10000 Height Above Ground Level (m) Atmospheric turbulence profiles projected for Dome C by Lawrence et al (2003). ASTRONOMICAL INSTRUMENTS ON THE MOON Thermal environment is good in Antarctica … though 10 micron background 105 higher GMT and JWST point source sensitivity for l>2.5 mm, 10s, 105 sec ASTRONOMICAL INSTRUMENTS ON THE MOON Next 50 years in Space, beyond JWST • Unique space attributes are – No atmospheric absorption in UV, thermal IR – Pristine wavefront – No thermal emission if optics cold • Large, cold telescopes will outperform ground in UV/ thermal IR • Very big space telescopes – with huge capital investment, like on ground telescopes should have multi decade lifetime, and be refitted every decade ASTRONOMICAL INSTRUMENTS ON THE MOON Requirements for Location & Possibilities • Far from Earth, to avoid its thermal radiation (for thermal telescope) • Accessible by astronauts as well as robots •LEO – Easiest for astronaut access – Warm, thermal cycling, reduced duty cycle – Re-boosts needed to maintain orbit •L2 – Cold, all sky access with 50% duty cycle – Hardest for astronaut access – Expendable fuel needed to maintain orbit – Pointing gyros subject to failure • Moon S pole – Cold, 100% duty cycle for 50% of sky – If base established, astronauts are nearby – No expendables needed, no gyros – 3 x mass penalty if no established base ASTRONOMICAL INSTRUMENTS ON THE MOON The Longer the Better… • Requirements for Longevity – Stable orbit – avoid LEO and L2 – No gyros – No expendable cryogens – Provision for occasional repair and upgrades by astronauts – Long life against radiation damage • If our telescope is a million miles away, we may have trouble getting astronauts to visit. • But if they are at a long term moon base, we should think about locating our telescope nearby ASTRONOMICAL INSTRUMENTS ON THE MOON The Moon as a Telescope Site • Basics are fine – All wavelengths accessible, vacuum of space – Orbit stable on billion year timescale – Telescopes can be “safed” for decade and then brought back to service • Moon’s spin axis 1.5 degrees from ecliptic pole – Sun moves around within 1.5 degrees of horizon – Very low temperatures by simple shielding of sunlight • 3x mass penalty to descend from lunar orbit – No air braking, as for Earth and Mars; requires rocket – Apollo vehicle and fuel weighed 2½ times the payload mass delivered to surface – 18.3 tons rocket carried a payload of 7 tons (the fueled ascent stage and crew) ASTRONOMICAL INSTRUMENTS ON THE MOON Needs a Lunar Polar Base • Telescope on moon makes sense if there is a long term, manned polar base • Why the pole? – Frozen volatiles in permanently dark, cold craters – Ice can be recovered from regolith in craters – Ice converted to hydrogen/oxygen fuel by locally produced by solar power – Cryo storage of fuel – Reusable ferry vehicle from surface to lunar orbit powered by local fuel - removes mass penalty ASTRONOMICAL INSTRUMENTS ON THE MOON Needs Astronauts! • Polar base astronauts will need range of skills: – Install and maintain mining gear. Need to get > 0.5 km down 45 degree slope below crater rim to get permanently-shadowed ice- containing regolith – Install and maintain water extraction, photolysis and fuel storage equipment – Maintain reusable rocket ferry – Maintain atmospheric conditioning equipment • Grow plants using local water • Given these capabilities, assembling and maintaining 20 m telescopes would be present little additional challenge ASTRONOMICAL INSTRUMENTS ON THE MOON ASTRONOMICAL INSTRUMENTS ON THE MOON The Lunar South Pole-Aitken Basin . The South Pole-Aitken Basin is the biggest, deepest impact basin in the solar system; . This view is centered at 56°S, 180°E. The rim crest D~2500 km; to ~13 km in depth; . Average depth is about 10 kilometers. Possible Future Base Site: . Cold traps with water . Solar illumination . Stable temperatures (~220±10K) 19 ASTRONOMICAL INSTRUMENTS ON THE MOON Ice at south pole Ice at south pole as measured by neutron flux (Lunar prospector) ASTRONOMICAL INSTRUMENTS ON THE MOON Possible Lunar Locations South Pole Region of the Moon: Malapert Mountain 21 ASTRONOMICAL INSTRUMENTS ON THE MOON LATOR Architecture on the Moon Benefits of The Moon: . No atmosphere (10-9 Earth) . Stable platform [orbit to 1 cm] . Seismic activity 8 orders less . ~98% solar illumination . Temperature 220±10K Unique features: . Longer baseline ~ 1km