ACRIM and ATLAS-1 FAUST and ATLAS-1

ACRIM and ATLAS-1FAUST and ATLAS-1

Mike LamptonSpace Science Lab

UC BerkeleySeptember 2012

Understanding the Sun http://acrim.com/Educational%20Material.htm

• All life on Earth depends on sunlight• The sun is a slightly variable star! (Why?!)

– Sunspot cycles; Maunder minimum; Little Ice Age...– What are all the other short and long term cycles?

• Variations in the sun’s spectrum– Controls what altitudes on Earth sunlight is delivered– Crucial separate drivers to climate & climate change– SOLSPEC (aboard ATLAS; EURECA; ISS-Columbus); SORCE/SIM...

• Variations in the sun’s total irradiance– ACRIM; SOLCON; SOHO/VIRGO; SORCE/TIM; – “Absolute”: need electrical & mechanical calibration but not thermal

2M. Lampton UCB SSL 2012

What is going on?

M. Lampton UCB SSL 2012 3

Worldwide climate:a nonlinear chaotic systemcomplex radiation budget

Solar drivers: sunspot cycles & TSI variations in spectrum

Tectonic drivers: continental plate motions ocean - land latitude coverage volcanism: SO2, sulfates, ash...

Earth orbit (Milankovich) drivers Precession cycle 26000 years Elliptical orbit rotation 21000 year Obliquity period 41000 years

Anthropogenic influences

Radiativecooling

Thermal Balance Method: can achieve absolute error <0.01%

• Solar heating power = TSI Area∙• Electrical heating power = V I∙• At null, TSI = Δ V I/Area∙• Mechanical standard: aperture A• Electrical standards: V and I


solarheat moveable

shutter

aperturearea = A

con

e 2

con

e 1

null signal

data outmeterdata out

isothermal enclosure

power amplifierbias power supply

meter

ΔT

Also: short-term missions: cross calibration Spacelab 1 (1983) ATLAS 1 (1992) ATLAS 2 (1993): comparison SARR2


Spacelab ACRIM

from “Measurement And Uncertainty Of The Long Term Total Solar Irradiance Trend,” Steven Dewitte, Dominique Crommelynck, Sabri Mekaoui and Alexandre Jouko, Royal Meteorological Institute of Belgium, (2004)


Solar Irradiance and Spectra are studied worldwide....

Transit of Venus 5 June 2012


This “transit method” for discovering planets has been in continuous use since 2009 with the KEPLER mission: so far 2200 planet detections made, and 77 confirmations.

HINODE image of sun JAXA/NASA

Historical Proxies for TSI• Total Solar Irradiance goes back ~ 30 years• Sunspots: go back ~ 400 years• Rates of growth of tree rings ~ 1000 years• 14C and 10Be content of organic matter: yet further back


http://en.wikipedia.org/wiki/Maunder_Minimum

Great Frost of 1709

Ultraviolet Astronomy and FAUST

• Astronomy at visible wavelengths...– easily done at night through Earth’s atmosphere– shows stars & galaxies under usual “main sequence”

evolutionary circumstances

• Astronomy at ultraviolet wavelengths...– reveals fluxes & spectra of very hot (short-lived) stars– reveals properties of interstellar gas and dust– starbirth: massive, very hot short-lived stars; OB’s– star death: fuel exhaustion; WDs; – variable galaxies; AGNs, BL-Lacs, LINERS, QSOs....– but of course requires spaceborne platforms.– Frequent access to space speeds technology.


UV Space Astronomyexcluding solar


What was FAUST?

• Created by L.A.M. as a rocket-borne UV camera for studies of nearby galaxies and especially star formation– used a UV intensifier and a photographic film recording canister

• Adapted by L.A.M. and UCB for Spacelab 1 (1983)– same UV intensifier and a photographic film recording canister– unfortunately SL1 β-angle did not permit dark nights

• Remanifested on ATLAS-1 (1992) for an enlarged program– Motive: star formation in our Galaxy and in other galaxies– total scientific success; 21 papers and all objectives met– allowed us at UCB to develop a new kind of photon counting imager– Spacelab HRM permitted high rate digital photon downlink– legacy for future UV missions: photon counting imager technology


FAUST ATLAS-1 Mission Highlights• Overall: 4.4% of the night sky was covered

– 19 deep fields, 4698 objects measured; fluxes & locations for all targets

– 2239 of them are stars; others are galaxies, nebulae, or unidentified

– Ten times more sensitive than previous UV catalogs

– Bowyer, S., et al., ApJS v.96, 461 (1995)– eleven other papers on sources, maps,

identifications

• Observations of the diffuse UV sky– Cohen, M., et al., ApJ v.427 848 (1994)

• Observations of terrestrial UV nightglow– Chakrabarti, S., et al., GRL v.20 535 (1993)

• Observations of the STS UV environment– Lampton, M., et al., GRL v.20, 539 (1993)

• FAUST sensor technology development – Lampton, M., et al., Proc SPIE 627, 383 (1986)



Andromeda galaxy at visible wavelengths ... and in the ultraviolet using GALEX

Hubble Space Telescope and its Upgrades

SM1STS61Dec1993

SM2STS82Feb1997

SM3bSTS109Mar2002

SM4STS125May2009

SM3aSTS103Dec1999

LaunchSTS31Apr1990

Photon counting

Photon counting

Photon counting



Photon-counting image sensor concept -- now flying on many missions

Future of Ultraviolet Astronomy• Astonishing developments in Cosmology

– 1929: Hubble and the expanding universe– 1933: Zwicky and missing mass. (Now: not even baryonic mass!)– 1963: Penzias & Wilson: cosmic microwave background & hot Big Bang– 1990: COBE satellite and gradients in the CMB; seeds for growth– 1998: Perlmutter; Riess; accelerating universe. Dark energy!– Picture emerges: denser regions collapsed first, then outer regions followed– Star formation peaked at redshift ~ 2, and continues to this day. UV traces it.

• Cosmology is now pressing hard on reconciling gravity, space, time....• Beyond that: stars, planets, nebulae, SNe, ISM, IGM....• Future UV space observatories?

– ASTROSAT (India)– World Space Observatory WSO (Russia; ESA; Spain)– Space Ultraviolet Observatory SUVO (NASA)– ATLAST (NASA + ESA)


ACRIM and ATLAS-1 FAUST and ATLAS-1

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