Mission to AntarcticMission to Antarctic

PhD: first yearPhD: first year

Ing. Alberto RivaIng. Alberto Riva

Prof. Aldo Treves, Dott. Filippo Maria ZerbiProf. Aldo Treves, Dott. Filippo Maria Zerbi

SummarySummary

The IRAIT-AMICA projectThe IRAIT-AMICA project

The AMICA cameraThe AMICA camera

Design of AMICADesign of AMICA

Evolution of projectEvolution of project

The IRAIT-AMICA projectThe IRAIT-AMICA projectWHAT IS THE SCIENCE?WHAT IS THE SCIENCE?

Infrared astronomyInfrared astronomy– From near to medium infrared (1-From near to medium infrared (1-

28 microns)28 microns)Ground based astronomyGround based astronomy

– Costs lower than space astronomyCosts lower than space astronomyLong time surveysLong time surveys

– Polar “night”Polar “night”

The IRAIT-AMICA projectThe IRAIT-AMICA projectWHY ANTARCTICA?WHY ANTARCTICA?

ATMOSPHEREATMOSPHERE– Infrared windows at 3, 10 micronsInfrared windows at 3, 10 microns– Low background emissionLow background emission– Good seeingGood seeing

TEMPERATURETEMPERATURE– Mean temperature -50°CMean temperature -50°C– Max -30°C, Min -90°CMax -30°C, Min -90°C

CLIMATECLIMATE– Low precipitationsLow precipitations– Negligible humidityNegligible humidity

The IRAIT-AMICA projectThe IRAIT-AMICA projectWHERE?WHERE?

DOME C CONCORDIA (Ita-Fra)DOME C CONCORDIA (Ita-Fra)– Antarctic plateauAntarctic plateau– 3500 m a.s.l. 3500 m a.s.l. – 4000 m barometric quote4000 m barometric quote

The IRAIT-AMICA projectThe IRAIT-AMICA projectIRAITIRAIT

IRAIT (IRAIT (InfraRed Antarctic Italian InfraRed Antarctic Italian TelescopeTelescope))

Aperture = 80 cm Aperture = 80 cm F# = 21,165F# = 21,165 Curvature primary mirror = 480 cmCurvature primary mirror = 480 cm Secondary wobbledSecondary wobbled

The AMICA camera The AMICA camera WHAT IS AMICA?WHAT IS AMICA?

AMICA (Antarctica Multiband Infrared AMICA (Antarctica Multiband Infrared Camera)Camera)

Two channelsTwo channels– From 1 to 5 micronsFrom 1 to 5 microns– From 5 to 28 micronsFrom 5 to 28 microns

Inaf – PNRA Inaf – PNRA – Teramo – Padova – Brera (Merate)Teramo – Padova – Brera (Merate)

The AMICA camera The AMICA camera WHAT IS THE TASK?WHAT IS THE TASK?

Map the infrared tramsission Map the infrared tramsission in the 1-28 microns bandin the 1-28 microns band

Perform long observation of Perform long observation of interesting bodies interesting bodies

Make surveys of the sky in Make surveys of the sky in the infrared bandthe infrared band

The AMICA camera The AMICA camera WHAT ARE THE CONSTRAINTS?WHAT ARE THE CONSTRAINTS?

TECHNICALTECHNICAL

CLIMATICSCLIMATICS

LOGISTICSLOGISTICS

The AMICA camera The AMICA camera TECHNICAL CONSTRAINTSTECHNICAL CONSTRAINTS

Two detectors, operated at very low Two detectors, operated at very low temperaturetemperature– NIR (1-5microns) detector at 30K NIR (1-5microns) detector at 30K

((Raytheon CRC – 463 InSb 256Raytheon CRC – 463 InSb 256256 array)256 array) – MIR (5-28 microns) detector at 7K MIR (5-28 microns) detector at 7K

((DRS MF – 128 SiAs BIB 128x128 arrayDRS MF – 128 SiAs BIB 128x128 array))

Reliability of materials and systemsReliability of materials and systems– Electronic part and systemElectronic part and system– Motorized functionsMotorized functions

The AMICA camera The AMICA camera CLIMATIC CONSTRAINTSCLIMATIC CONSTRAINTS

VERY LOW TEMPERATUREVERY LOW TEMPERATURE– MaterialsMaterials– SealingsSealings

DIAMOND DUSTDIAMOND DUST– ProtectionsProtections

DARKNESS DURING WINTERDARKNESS DURING WINTER– About 6 months of unaccessibilityAbout 6 months of unaccessibility

BAROMETRIC QUOTE OF 4000 mBAROMETRIC QUOTE OF 4000 m– Low or negligible natural convectionLow or negligible natural convection

The AMICA camera The AMICA camera LOGISTICS CONSTRAINTSLOGISTICS CONSTRAINTS

LIMITED ON SITE WORKSHOP CAPABILITIESLIMITED ON SITE WORKSHOP CAPABILITIES– Optical facilitiesOptical facilities– Transportation facilitiesTransportation facilities

LIMITED ON SITE TECHNICIAN LIMITED ON SITE TECHNICIAN CAPABILITIESCAPABILITIES– MechanicsMechanics– OpticsOptics

LIMITED ON SITE SUPPLIESLIMITED ON SITE SUPPLIES– Power limitedPower limited– Materials availabilityMaterials availability

The AMICA camera The AMICA camera WHAT ARE THE DESIDERATA?WHAT ARE THE DESIDERATA?

Best efficiency at 3 and 10 micronsBest efficiency at 3 and 10 micronsField of view as larger as possibleField of view as larger as possibleMinimal aberrationsMinimal aberrationsFull band coverage from 1 to 28 Full band coverage from 1 to 28

microns with high efficiencymicrons with high efficiencyAt least 12 filter positionsAt least 12 filter positions

Design of AMICADesign of AMICAWHICH IS THE PHILOSOPHY?WHICH IS THE PHILOSOPHY?

REFLECTIVE ELEMENTSREFLECTIVE ELEMENTS HOMOTHETIC SHRINKINGHOMOTHETIC SHRINKING MINIMUM NUMBER OF MOTORIZED MINIMUM NUMBER OF MOTORIZED

FUNCTIONSFUNCTIONS INTERNAL MOTORSINTERNAL MOTORS COMPACTNESS AND LIGHTNESSCOMPACTNESS AND LIGHTNESS TWO DETECTORS, ONE CHANNEL TWO DETECTORS, ONE CHANNEL

PER EXPOSUREPER EXPOSURE

Design of AMICADesign of AMICATHE STARTING POINTTHE STARTING POINT

Design of AMICADesign of AMICATHE ALTERNATIVESTHE ALTERNATIVES

Double channel with a toggling Double channel with a toggling elementelement– THREE ALTERNATIVESTHREE ALTERNATIVES

Design of AMICADesign of AMICAALTERNATIVE AALTERNATIVE A

Design of AMICADesign of AMICAALTERNATIVE BALTERNATIVE B

Design of AMICADesign of AMICAALTERNATIVE CALTERNATIVE C

Design of AMICADesign of AMICAEVALUATION – LAYOUTEVALUATION – LAYOUT

A) A) 40x60 cm:40x60 cm: 7 mirrors 7 mirrors 44 asphericsaspherics symmetric symmetric

B) B) 40x50 cm:40x50 cm: 6 mirrors 6 mirrors 3 3 asphericsaspherics not symmetric not symmetric

C) C) 20x45 cm:20x45 cm: 5 mirrors 5 mirrors 4 4 asphericsaspherics symmetric symmetric

Design of AMICADesign of AMICAEVALUATION – SPOTSEVALUATION – SPOTS

A) A) 1515m RMSm RMS 30 30 m GEO m GEO final f# final f# 6.5 6.5

B) B) 30 30 m RMSm RMS 75 75 m GEO m GEO final f# final f# 13 13

C) C) 40 40 m RMSm RMS 90 90 m GEO m GEO final f# final f# 10.3 10.3

Design of AMICADesign of AMICAEVALUATION – MOVEMENTSEVALUATION – MOVEMENTS

A) A) 2 axial rotations2 axial rotations

B) B) 1 axial rotation and 1 1 axial rotation and 1 mirror to extractmirror to extract

C) C) 2 axial rotations2 axial rotations

Design of AMICADesign of AMICAEVALUATIONEVALUATION

All the alternatives present All the alternatives present advantages and disadvantagesadvantages and disadvantages

Aspheric mirrors are difficult to Aspheric mirrors are difficult to produceproduce

Some difficulties in alignment Some difficulties in alignment operationsoperations

Design of AMICADesign of AMICATHE INNOVATIVE IDEATHE INNOVATIVE IDEA

Design of AMICADesign of AMICASUMMARY OF ADVANTAGESSUMMARY OF ADVANTAGES

2 active mirrors, commercial2 active mirrors, commercial

Compactness (as the alternative C)Compactness (as the alternative C)

Detectors very nearDetectors very near

1 filterwheel compact1 filterwheel compact

Design of AMICADesign of AMICATHE QUALITY OF THE SPOTSTHE QUALITY OF THE SPOTS

Design of AMICADesign of AMICATECNICAL DATATECNICAL DATA

NIR NIR – field of 2.29 arcmin squaredfield of 2.29 arcmin squared – samples of Airy disc with 4 pixels (30x30 samples of Airy disc with 4 pixels (30x30

microns each) at the wavelength of 3.426 microns each) at the wavelength of 3.426 microns; 0.54 arcsec/pixel; 256x256 pixelmicrons; 0.54 arcsec/pixel; 256x256 pixelss

MIRMIR– field of 2.86 arcmin squaredfield of 2.86 arcmin squared – samples of Airy disc with 4 pixels (75x75 samples of Airy disc with 4 pixels (75x75

microns each) at the wavelength of 8.57 microns each) at the wavelength of 8.57 microns; 1.34 arcsec/pixel; 128x128 pixelsmicrons; 1.34 arcsec/pixel; 128x128 pixels

EVERYTHING SEEMS GOODEVERYTHING SEEMS GOOD

BUT?BUT?

Evolution of projectEvolution of projectPROBLEMS ON THE FUTUREPROBLEMS ON THE FUTURE

Producing this nice toy is not so Producing this nice toy is not so simplesimple– Temperature of 7K of MIR Temperature of 7K of MIR

detector to mantain for 6 detector to mantain for 6 months continuoslymonths continuosly

– External temperatureExternal temperature– Cryocooler and pump are not Cryocooler and pump are not

designed for theese conditionsdesigned for theese conditions

Evolution of project Evolution of project POSSIBLE ROADSPOSSIBLE ROADS

In order to solve problems of electronic In order to solve problems of electronic parts and sealing materials we can parts and sealing materials we can encapsulate all the system (camera, encapsulate all the system (camera, pump, cryocooler, electronic devices) into pump, cryocooler, electronic devices) into a rack mantained in a rack mantained in pressurepressure and at some and at some degrees degrees above 0°Cabove 0°C

ButBut this seems to present higher costs in this seems to present higher costs in term of power (term of power (WattWatt on total budget) and on total budget) and weight (weight (KilogramsKilograms that can be loaded on that can be loaded on the telescope)the telescope)

Evolution of project Evolution of project POSSIBLE ROADSPOSSIBLE ROADS

We would prefer to mantain the We would prefer to mantain the camera at room (antarctic) camera at room (antarctic) temperaturetemperature

AdvantageAdvantage– Less power requested to the cryocoolerLess power requested to the cryocooler

ProblemsProblems– Urgent need to study the cryo-dynamic Urgent need to study the cryo-dynamic

of the system, with particular attention of the system, with particular attention to the cryocooler and the path of the to the cryocooler and the path of the cold fingercold finger

Evolution of project Evolution of project OTHER TASKSOTHER TASKS

Mirrors, coatingMirrors, coating

TolerancesTolerances

Turbolences to the telescopeTurbolences to the telescope

Site inspection at DOME CSite inspection at DOME C

PRODUCTION!!!!PRODUCTION!!!!

MY ROLE: pastMY ROLE: past

ResponsibleResponsible of the optical of the optical subsystem of AMICAsubsystem of AMICA

DesignerDesigner of the optical system of the optical system (solutions A,B,C and final one)(solutions A,B,C and final one)

MY TASK: futureMY TASK: future

Study and design the solutions to the Study and design the solutions to the problem presented (mainly problem presented (mainly cryocooling, and procurement of the cryocooling, and procurement of the optical elements)optical elements)

Improve the astronomical Improve the astronomical background of my knowledgebackground of my knowledge