MPI Project Review

BepiColombo-a planetary mission to Mercury Focal plane instrumentation for the MIXS instrument

Ringberg, 24.4.2007

Mercury as seen on 16.9.2004 Johannes Treis MPI Halbleiterlabor 1 Institutions

Johannes Treis MPI Halbleiterlabor 2 Contents

¾ History of Mercury observation ¾ The Planet Mercury ¾ BepiColombo ¾ The MIXS Instrument ¾ The FPA detector for MIXS

Johannes Treis MPI Halbleiterlabor 3 History of mercury observation

~ 3000 B.C: First known evidence of Mercury observations by sumerian priests in mesopotamia. Planet known as Ubu-idim-gud-ud Ziggurat of Ur

~ 1000 B.C: Detailed recordings of Mercury observations by babylonian astronomers Planet known as Nabu or Nebu, referring to the babylonian messenger of gods, due to its swift movement and partial Babylonian record of Venus observation visibility.

Johannes Treis MPI Halbleiterlabor 4 History of Mercury observation

~ 500 B.C: Greek astronomers give Mercury two names, Stilbon and Hermaon, depending whether it is visible in the morning or evening. Pythagoras of Samos proposes that the two observations refer to a common body, which is then called Hermes, after the greek messenger of gods, which is later identified with the roman god Mercury.

In roman/greek mythology, Mercury is not only the messenger of gods and the god of travellers, but also the god of merchants,

of crooks, liars and highwaymen. Statue of Mercury by Giambologna

(16th century, Florence) Johannes Treis MPI Halbleiterlabor 5 History of Mercury observation

Always displayed with the winged herlad’s staff wound by two snakes (caducaeus), winged sandals (talaria) and winged traveller’s hat (petasos), which inspired the astronomical symbol

Rarely displayed alone, but either participating onfor assemblies Mercury: of gods (mostly just arriving or leaving) or while delivering a message to a recipient. Is also said to explain the somewhat obscure messages of the

Engl.: godsFrench: to the mortals. Merchant Merci Commerce Mercredi Mercury (Hg) Mercenary Mercury in the staircase fresco by Gianbattista Tiepolo th century). Wednesday at the Wuerzburg residence (18 Johannes Treis MPI Halbleiterlabor 6 History of mercury observation

~ 1610: First telescopic observations of Mercury by Galileo Galilei 1631: The Mercury transit predicted by Johannes Kepler is observed by Pierre Gassendi, which is the first known observation of a planetary transit. 1639: Giovanni Zulpi discovers Mercury’s phases by telescopic observation, Transit of Mercury, 7.5.2003 which proves that mercury orbits around the sun. 1737: John Bevis records the first his- torically observed Mercury occul- tation by Venus (28.5.1737) Next: 2133. 1800: First observation of surface features by Johann Schroeter. 1881: First surface map of mercury by Giovanni Schiaparelli. Johannes Treis MPI Halbleiterlabor 7 History of Mercury observation

~ 1930: Mercury’s orbit irregularities are explained by GRT! ~ 1960: Discovery of anomalous tidal locking of orbital period to rotational period by radio observations 1965: Precise measurement of the planet’s orbital period. Guiseppe (Bepi) Colombo suggests an anomalous resonant tidal locking with a 3:2 ratio, i.e. Mercury rotates three times for every two revolutions round the sun. 1974: Until 1975, Mariner 10 passes Mer- cury 3 times. Flight plan suggested by Bepi Colombo included Venus- Swing-Bys. Unexpectedly, the revolu- tion period of Mariner 10 in this or- bit was exactly twice the revolution period of Mercury, so that only ~45 % of mercury could be cartographed. Mariner 10 2000: Lucky imaging observations at Mount Wilson reveal details of the uncartographed region. Observation with x-ray satellites. Johannes Treis MPI Halbleiterlabor 8 Future of Mercury observation

2004: Launch of the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) probe by NASA.

January 2008: First Mercury flyby October 2008: Second Mercury flyby September 2009: Third Mercury flyby March 2011: Entering Mercury orbit

1 year of mission lifetime Payload similar to BC, but simpler Pathfinder for BC

Johannes Treis MPI Halbleiterlabor 9 Future of Mercury observation

2013: Launch of ESA’s mission BepiColombo

Johannes Treis MPI Halbleiterlabor 10 The planet Mercury

Earth Venus Mercury Sun (to scale)

Radii to scale

Johannes Treis MPI Halbleiterlabor 11 Mercury fact sheet

Orbital radius: 0.46 – 0.3 AU (70 – 46 x106 km) Radius: ~2440 km (34% of earth) 23 Mass: 3.302×10 kg Least well-known of 3 Density: 5.43 g / cm the terrestrial planets Surface gravity: 3.7 m / s2 Rotation period: ~58 d Orbital period: ~85 d Axial tilt: 0.01° Incination: ~ 7 ° Albedo: 0.1 Atmosphere: Traces (H, He, O, K, Na, Ca)

Surface temperatures: ¾ Very small magnetic field Equator North pole (1% of earth) Mean: 70 °C -70 °C ¾ No moons Min: -170 °C -190 °C ¾ Ice? Sulphur? Max: 430 °C 107 °C Johannes Treis MPI Halbleiterlabor 12 Mercury surface

¾ Moon-like surface, heavily cratered ¾ Basins (volcanism) ¾ Geologically inactive for a long time ¾ Weird morphologhic features

Rupes

Weird terrain

Caloris basin

Johannes Treis MPI Halbleiterlabor 13 Mercury mass

Anomal density! Inhomogeneous mass distribution (spin-orbit • Terrestrial planet bulk composition resonance)! derives from equilibrium condensation from the solar nebula. • Not for Mercury – unpredicted large uncompressed density • Large core – thin mantle – high Fe content, observations imply low Fe. • Possibilities 1. Selective accretion 2. Post Accretion Vaporisation 3. Massive Impact

Johannes Treis MPI Halbleiterlabor 14 Mission targets

Giuseppe “Bepi“ Colombo (2.10.1920 – 20.2.1984)

ESA cornerstone mission:

 Origin and evolution of a planet close to the parent star  Mercury as a planet: form, interior, structure, geology, composition and craters  Detect traces of Mercury's vestigial atmosphere (exosphere): composition and dynamics  Mercury's magnetized envelope (magnetosphere): structure and dynamics  Origin of Mercury's magnetic field  Test of Einstein's theory of general relativity Mercury surface as seem by Mariner 10 ...collaboration with JAXA Johannes Treis MPI Halbleiterlabor 15 BepiColombo

¾ Launch 2013 ¾ Platform: Soyuz Fregat B ¾ MCS: Mercury composite spacecraft ¾ 6 year long journey

¾ Main challenges: • Thermal management Mercury composite spacecraft (MCS) • Power (!) • Radiation damage • Flight plan

Johannes Treis MPI Halbleiterlabor 16 BepiColombo

MCS exploded view

Mercury magnetospheric orbiter (MMO)

Mercury planetary orbiter (MPO)

Solar shield

Mercury transfer module (MTM)

Johannes Treis MPI Halbleiterlabor 17 BepiColombo

¾ Scheduled arrival: 2019 ¾ On arrival: Deployment of MPO and MMO in their respective orbits ¾ 1 year of expected mission lifetime ¾ Possible prolongation by another year

Johannes Treis MPI Halbleiterlabor 18 Mercury magnetospheric orbiter

Instruments:

¾ MERMAG-M: Magnetometer ¾ MPPE: Mercury plasma particle experiment ¾ PWI: Plasma wave experiment ¾ MSASI: Mercury Sodium Atmospheric Spectral Imager ¾ MDM: Mercury dust monitor

zum Selberbasteln...

Johannes Treis MPI Halbleiterlabor 19 Mercury planetary orbiter

Instruments: ¾ BELA: Laser altimeter ¾ ISA Accelerometer ¾ MERMAG: Magnetometer ¾ MERTIS: Thermal infrared spectrometer ¾ MGNS: Gamma-ray and neutron spectrometer ¾ MIXS: x-ray spectrometer ¾ MORE: Radio science Ka-Band transponder ¾ PHEBUS: UV-Spectrometer ¾ SERENA: Neutral and Ionized particle analyzer ¾ SIMBIO: High resolution and stereo camera, visible and NIR spectrometer ¾ SIXS: Solar monitor

Johannes Treis MPI Halbleiterlabor 20 The MIXS Instrument

• Incident solar X-rays induce X-ray fluorescence from the surface • Potentially an additional component induced by incident protons and electrons • Precise intensity monitor needed!

Johannes Treis MPI Halbleiterlabor 21 The MIXS Instrument

¾ MIXS : Mercury Imaging X-ray Spectrometer ¾ Measure fluorescent X-rays from Mercury surface ¾ First few micron of depth are explored ¾ Solar Intensity X-ray Spectrometer (SIXS) provides reference information ¾ Detection of characteristic lines allows to determine element abundance ¾ Combination with IR measurements (MERTIS) yields mineralogy information ¾ Combination with soft γ-ray measurements (MGNS) yields element abundance in depth of ~1 m ¾ Average composition of Mercury’s ¾ Correlation of surface Na, K and Ca crust with complementary measurements of ¾ Compositions of the major terrains exosphere ¾ Composition inside craters and ¾ probe of the surface-magnetosphere- crater structures exosphere system ¾ Detection of iron globally and ¾ Sulphur at the poles and in the crust locally globally ¾ Chromium to Nickel ratio globally to constrain formation models

Johannes Treis MPI Halbleiterlabor 22 MIXS

¾ Two cameras ¾ Telescope: MPC optics ¾ Same focal plane detector ¾ MIXS-C: Wide field imaging ¾ Different optics ¾ MIXS-T: Precise Mapping ¾ Collimator (MIXS-C) and Telescope (MIXS-T) Footprint size: ¾ 14 km for periherm ¾ 52 km for apoherm MIXS-T FPA

MIXS-C FPA

Johannes Treis MPI Halbleiterlabor 23 MIXS-T Optics

¾ MCP optics (3 concentrical rings) ¾ MCP pore width: 20 μm ¾ Aperture: 21 cm ¾ Focal length: 1 m ¾ Effective area : 120 cm2 @ 1 keV 15 cm2 @ 10 keV ¾ Wolter type 1 geometry ¾ Conical approximation ¾ Iridium-coated lead silicate glass ¾ Angular resolution: ~ 1.7 arcmin FWHM Prototype ¾ Total FOV: 1° FWZM

Johannes Treis MPI Halbleiterlabor 24 MIXS-C Optics

¾ Much simpler system ¾ Radially bent collimator with 8 degree fov ¾ Uses a 2x2 array of square pore square packed MCPs ¾ 64mm by 64mm aperture ¾ Detector distance 230mm

¾ Collimator setup drawing ¾ Collimator angular response

Johannes Treis MPI Halbleiterlabor 25 FPA design

FRONT END ELECTRONICS Thermal strap

FPA MAIN ASSEMBLY

Sensor assembly Baffle Front bracket

Johannes Treis MPI Halbleiterlabor 26 Sensor assembly

SENSOR MOUNTING FRAME SENSOR ADAPTER COOLING BLOCK

CERAMICS SUPPORT BARS THERMAL STRAP SUPPORT

THERMAL STRAP

¾ Radiation enters from backside ¾ Frame and cooling block are made of high-perfromance beryllium alloy ¾ Support bars of composite carbon fiber material ¾ Details need to be fixed

Johannes Treis MPI Halbleiterlabor 27 Detector characteristics I

Sensor and pixel size

¾ FOV & focal length: Minimum sensor area 1.75 x 1.75 cm2

¾ Tradeoff between: 2 Alternatives: • Spotsize in focal plane (~1 mm) ¾ 64 x 64 pixels of 500 x 500 μm2 • Oversampling PSF ¾ Sensor size: 3.2 x 3.2 cm2 • Angular resolution ¾ 96 x 96 pixels of 500 x 500 μm2 • Number of readout channels ¾ Sensor size 2.8 x 2.8 cm2 • Resolution & charge splitting • Spectral purity

¾ Resolution element size: • 0.2 km (periherm) and 0.8 km (apoherm) @ 300 μ pixel size • 0.3 km (periherm) and 1.3 km (apoherm) @ 500 μ pixel size

Johannes Treis MPI Halbleiterlabor 28 Detector characteristics II

Energy range

¾ Energy range: Fe L 0.71 keV K K 3.31 keV < 0.5 keV to > 7.0 keV 3.59 keV Na K 1.04 keV Ca K 3.69 keV ¾ Detection of Fe using 1.07 keV 4.01 keV the Fe-L line Mg K 1.25 keV Ti K 4.51 keV 1.30 keV 4.93 keV

Al K 1.49 keV VK 4.95 keV 1.55 keV 5.43 keV

Si K 1.74 keV Cr K 5.41 keV 1.84 keV 5.95 keV

P K 2.02 keV Mn K 5.90 keV 2.14 keV 6.49 keV

S K 2.31 keV Fe K 6.40 keV 2.47 keV 7.06 keV

Mercury key element emission lines

Johannes Treis MPI Halbleiterlabor 29 Detector properties

Parameter Value Comments Format 1.92 x 1.92 cm2 O.K. sensitive area Array dimension 64 x 64 pixels O.K.

Pixel size 300 x 300 mm2 O.K.

Energy resolution ≤ 200 eV FWHM Depends on @ 1 keV temperature QE ≥ 80 % @ 500 eV O.K.

Time resolution 128 μs (192 μs) Depends on FE speed Radiation hardness Depends on - Ionizing 20 krad temperature - Non-Ionizing (10 MeV p) 3 x 1010 p/cm2 Operation temperature -40 ˚C (-45 ˚C) Depends on Temperature annealing scenario most critical issue! Power consumption ≤ 2.5 W Detector plus FEs

Johannes Treis MPI Halbleiterlabor 30 Detector concept

FPA detector: DEPMOSFET Macropixel array

¾ Monolithic Array of silicon drift chambers ¾ DEPMOSFET devices as readout nodes ¾ Scalable pixel size ¾ High QE due to high fill factor ¾ Bidirectional row-wise readout ¾ High readout speed ¾ Low power consumption

Johannes Treis MPI Halbleiterlabor 31 X-type DEPMOSFET device

Johannes Treis MPI Halbleiterlabor 32 Implementation: Pixel substructure

Polysilicon separators

P+ -driftring implants

¾ MIXS-T requirement: 300 x 300 μm2 pixels „readout node“ ¾ Can be implemented using 3 driftrings per pixel RB in R1 in ¾ Driftring voltage cascade V_inner_substrate applied externally or generated by integrated resistive voltage divider

Johannes Treis MPI Halbleiterlabor 33 Implementation: Central readout node

¾ Place DEPFET device instead of„conventional“ readout anode or JFET ¾ Charge integration capability for every cell

Johannes Treis MPI Halbleiterlabor 34 Implementation: Matrix arrangement

Pixel matrix

N-type high resistive bulk (common)

Radiation entrance window (common) Ultra-thin p+

¾ Array of pixels on common bulk ¾ Common outermost drift ring (RB) ¾ Common thin homogeneous entrance window ¾ Common backside contact voltage ¾ Shared driftring voltages ¾ No insensitive inter-pixel gaps ¾ But: charge sharing between pixels possible

Johannes Treis MPI Halbleiterlabor 35 Readout scheme

N WE S

¾ 2 Hemispheres (North and South) ¾ 32 x 64 Pixels each ¾ Read out by 1 CAMEX each ¾ Controlled by 2 Switchers each

¾ Readout speed: target 4 μs / row ¾ 6 μs / row might be necessary ¾ Depends on FE performance, temperature, capacitance...

Johannes Treis MPI Halbleiterlabor 36 Detector overview

CAMEX

Switcher Switcher

Thermal Bias pads diodes

Switcher Switcher Voltage divider CAMEX

Johannes Treis MPI Halbleiterlabor 37 Entrance window configuration

¾ Thermal reasons require external optical filter ¾ Incorporates also UV- filtering properties

QE larger than QE for 50 nm Entrance window: ¾ No UV-Filter ¾ As thin an aluminum layer as necessary (~30 nm) ¾ Required for entrance window radiation hardness

Johannes Treis MPI Halbleiterlabor 38 Front End ICs

Switcher ICs: CAMEX / VELA ICs: ¾ Vital control element of detector ¾ Readout mode has been ¾ Present technology radiation decided. tolerant ¾ Source follower is baseline in ¾ Design not radiation tolerant spite of intrinsic speed limit ¾ Esp. digital part ¾ Design to be submitted ¾ New radiation tolerant design is ~02/07 going to be submitted after first ¾ Devices ready ~ 07/07 tests of PXD 05 devices ¾ Speed is critical issue ¾ Radiation tests required ¾ Radiation test to be done

Johannes Treis MPI Halbleiterlabor 39 Radiation damage

1000 1000 Energy resolution 1000 @ 1 keV (eV) Energy resolution Energy resolution @ 1 keV (eV) @ 1 keV (eV) 60.00 80.00 60.00 800 60.00 800 100.0 800 80.00 80.00 120.0 100.0 100.0 140.0 120.0 120.0 160.0 140.0 m) 140.0 m) 180.0 m) 160.0 μ 160.0 μ μ 600 600 200.0 600 180.0 180.0 220.0 200.0 200.0 240.0 220.0 220.0 260.0 240.0 240.0 280.0 260.0 260.0 300.0 280.0 Pixel size ( Pixel size ( 400 280.0 Pixel size ( 400 400 300.0 300.0 White Line: 200 eV White Line: White Line: 200 eV 200 eV 200 200 200

20 0 -20 -40 -60 -80 20 0 -20 -40 -60 -80 20 0 -20 -40 -60 -80 Operating temperature (deg. C) Operating temperature (deg. C) Operating temperature (deg. C)

¾ Start of mission ¾ Mission halftime ¾ Full mission lifetime (half of the dose) (full dose)

10 2 Φtot = 3 x 10 10 MeV protons /cm

Calculations based on experimental results both of ROSE and operating experience with XEUS devices

Johannes Treis MPI Halbleiterlabor 40 Comparison: Annealing vs. no annealing

350 350 Energy resolution Energy resolution FWHM @ 1 keV FWHM @ 1 keV 300 300 60 60 100 s) 100 s) μ 250 (μ 250 140 140 180 180 200 6 μs / row 200 6 μs / row 220 220 260 260 300 Integration time time Integration Integration time ( 150 150 4 μs / row 300 4 μs / row White line: White line: 200 eV requirement 100 200 eV requirement 100

-30 -35 -40 -45 -50 -55 -60 -30 -35 -40 -45 -50 -55 -60 Temperature (°C) Temperature (°C)

¾ Operating temperature of -41 ˚ C requires regular annealing cycle to remedy bulk damage and reduce leakage current ¾ Operation without annealing requires lower operation temperature, depending on speed ~ -46 ˚ C

Johannes Treis MPI Halbleiterlabor 41 Detector response Input flux Response for 200 eV keV @1 ¾ Similar to lunar anorthosit ¾ Similar to lunar basalt

Calculations provided by J. Carpenter University of Leicester Johannes Treis MPI Halbleiterlabor 42