Auroral emission at Jupiter through Juno's UVS eyes

Denis Grodent Bertrand Bonfond G. Randy Gladstone Jean-Claude Gérard Jacques Gusn Aikaterini Radio Maïté Dumont Benjamin Palmaerts the Juno Science Team

LPAP, Université de Liège, Belgium Southwest Research Instute, USA UVS

D. Grodent ULg TheJuno UltravioletUltraViolet Spectrograph on Spectrograph UVS NASA’s Juno Mission (PI: G.R. Gladstone)

Fig. 4 An opto-mechanical schematic of the Juno-UVS sensor showing light rays traced through the main apertureGladstone et al. 2014 door, reflecting from the OAP primary, passing through a focus at the slit, diffracted off the toroidal grating, and imaged onto the XDL MCP detector UV light D. Grodent ULg

3.3 Detector and Detector Electronics

The Juno-UVS detector configuration includes an XDL microchannel plate (MCP) detector scheme housed in a vacuum enclosure with a one-time opening door containing a UV-grade fused-silica window (for limited UV throughput during testing). The door was spring loaded for opening with a wax-pellet-type push actuator. The vacuum enclosure has a vacuum pump port and a small, highly polished region which functions as a zero-order reflector (directing zero-order light from the instrument grating into the zero-order trap on the side of the in- strument housing). The vacuum enclosure also utilizes four female connectors for the anode signals, and two high-voltage (HV) connectors for the MCP and anode gap voltages. The detector’s MCP configuration uses a Z-stack that is cylindrically curved to match the 150-mm Rowland circle diameter to optimize spectral and spatial focus across the Juno- UVS bandpass. The detector electronics provide two stimulation pixels that can be turned on to check data throughput and acquisition modes without the need to apply high voltage to the MCP stack or to have light on the detector. The MCP pulse-height information is output as 5 bits, which, together with the 11 bits of spectral and 8 bits of spatial information, results in the 3-byte output for every photon. The input surface of the Z-stack is coated with an opaque photocathode of CsI (Siegmund 2000). ArepellergridabovethecurvedMCPZ-stackenhancesthedetectivequantumefficiency (DQE). Each of the three nested MCPs has a cylindrical 7.5-cm radius of curvature matching the instrument’s Rowland circle radius (i.e., 15.0 cm diameter). The approximate resistance per MCP plate is 130 M!.TheMCPformatis4.6cmwideinthespectralaxisby3.0cm height in the spatial∼ axis with 12-µm diameter pores and a length-to-diameter (L/D) ratio of 80:1 per plate. The XDL anode is a rectangular format of 4.4cm 3.0cm.Thecombination anode array and MCP sizes gives an active array format of 3.5cm× 1.8cmnecessaryto capture the entire 68–210 nm instrument bandpass. The pixel readout× format is 2048 pixels (spectral dimension) 256 pixels (spatial dimension). The active area is 3.5cm 1.8cm, with 1500 spectral× pixels and 230 spatial pixels. The XDL anode uses two orthogonal× ∼ ∼ 0.2° Dog bone shaped slit 2.5°

0.025° 2° 01prpae h D nd sarcaglrfra f4 of of ratio format (L/D) rectangular a length-to-diameter is a anode and XDL pores The diameter plate. 12-µm per with 80:1 axis spatial the resistance in approximate height The is diameter). plate cm matching MCP curvature 15.0 of per (i.e., radius radius 7.5-cm circle cylindrical Rowland a instrument’s has MCPs the nested three the of Each with (DQE). coated is Z-stack is the of information, information (Siegmund surface spatial CsI pulse-height of input of bits The MCP photocathode 8 photon. The and opaque every spectral an for detector. of output the bits 3-byte 11 the on voltage the in high with light results together apply have which, to bits, to need 5 or as the turned output without stack be modes MCP can acquisition the that and pixels to throughput stimulation data two Juno- check the provide to across electronics on focus detector spatial and The spectral bandpass. optimize UVS to diameter circle voltages. Rowland gap 150-mm anode the in- and the MCP the of anode for side the connectors the for (HV) connectors on high-voltage female two trap four and utilizes zero-order signals, also the enclosure (directing into vacuum reflector The grating zero-order housing). a instrument strument as the functions from which light region pump polished zero-order vacuum highly a small, has enclosure a vacuum and The loaded port actuator. spring push was wax-pellet-type door UV-grade a The a with testing). opening containing during for door throughput opening UV one-time limited a (for window with detector fused-silica enclosure (MCP) vacuum plate a microchannel in XDL housed an scheme includes configuration detector Juno-UVS The Electronics Detector and Detector 3.3 toroidal the off diffracted slit, the detector at MCP focus XDL a the through onto imaged passing primary, and OAP grating, the from reflecting door, aperture 4 Fig. Mission Juno NASA’s on Spectrograph Ultraviolet The atr h nie6–1 misrmn adas h ie edu omti 08pixels 2048 is format with readout 3 pixel of The format bandpass. dimension) instrument array (spectral nm active 68–210 an entire gives the sizes capture MCP and array anode Ar e p e l l e rg r i da b o v et h ec u r v e dM C PZ - s match t a to c ke curved n cylindrically h a is n that c e Z-stack st a h ed uses e configuration t e MCP c detector’s t iThe v eq u a n t u me f fi c i e n c y ∼ not-ehnclshmtco h uoUSsno hwn ih astae hog h main the through traced rays light showing sensor Juno-UVS the of schematic opto-mechanical An 50seta iesand pixels spectral 1500 ∼ 3 M 130 × 5 ies(pta ieso) h cieae s3 is area active The dimension). (spatial pixels 256 ! .TheMCPformatis4.6cmwideinthespectralaxisby3.0cm ∼ 3 pta ies h D nd sstoorthogonal two uses anode XDL The pixels. spatial 230 2.5° 2000 ). . 4cm . 5cm × 3 . D. Grodent 0cm.Thecombination × 1 . 8cmnecessaryto . 5cm

× 0.2° 1 ULg . 8cm,

Slit projected onto XDL MCP detector

256 "pixels" (spaal) / 2048 pixels (spectral) The Ultraviolet Spectrograph on NASA’s Juno Mission electronically digized pixels

Fig. 4 An opto-mechanical schematic of the Juno-UVS sensor showing light rays traced through the main aperture door, reflecting from the OAP primary, passing through a focus at the slit, diffracted off the toroidal <- 256 px -> grating, and imaged onto the XDL MCP detector

3.3 Detector and Detector Electronics

The Juno-UVS detector configuration includes an XDL microchannel plate (MCP) detector scheme housed in a vacuum enclosure with a one-time opening door containing a UV-grade fused-silica window (for limited UV throughput during testing). The door was spring loaded higher spaal res. for opening with a wax-pellet-type push actuator. The vacuum enclosure has a vacuum pump port and a small, highly polished region which functions as a zero-order reflector (directing zero-order light from the instrument grating into the zero-order trap on the side of the in- strument housing). The vacuum enclosure also utilizes four female connectors for the anode signals, and two high-voltage (HV) connectors for the MCP and anode gap voltages. 200 illuminated pixels The detector’s MCP configuration uses a Z-stack that is cylindrically curved to match the 150-mm Rowland circle diameter to optimize spectral and spatial focus across the Juno- UVS bandpass. The detector electronics provide two stimulation pixels that can be turned on to check data throughput and acquisition modes without the need to apply high voltage to the MCP stack or to have light on the detector. The MCP pulse-height information is output as 5 bits, which, together with the 11 bits of spectral and 8 bits of spatial information, results in the 3-byte output for every photon. The input surface of the Z-stack is coated with an opaque photocathode of CsI (Siegmund 2000). ArepellergridabovethecurvedMCPZ-stackenhancesthedetectivequantumefficiency (DQE). Each of the three nested MCPs has a cylindrical 7.5-cm radius ofD. Grodent curvature matchingULg the instrument’s Rowland circle radius (i.e., 15.0 cm diameter). The approximate resistance per MCP plate is 130 M!.TheMCPformatis4.6cmwideinthespectralaxisby3.0cm height in the spatial∼ axis with 12-µm diameter pores and a length-to-diameter (L/D) ratio of 80:1 per plate. The XDL anode is a rectangular format of 4.4cm 3.0cm.Thecombination anode array and MCP sizes gives an active array format of 3.5cm× 1.8cmnecessaryto capture the entire 68–210 nm instrument bandpass. The pixel readout× format is 2048 pixels (spectral dimension) 256 pixels (spatial dimension). The active area is 3.5cm 1.8cm, with 1500 spectral× pixels and 230 spatial pixels. The XDL anode uses two orthogonal× ∼ ∼ Slit projected onto XDL MCP detector 256 "pixels" (spaal) / 2048 pixels (spectral) The Ultraviolet Spectrograph on NASA’s Juno Mission

Toroidal diffracon grang

PSF < 0.6 nm

"Data Cube" (x , t , λ) Events List Fig. 4 An opto-mechanical schematic of the Juno-UVS sensor showing light rays traced through the main aperture door, reflecting from the OAP primary, passing through a focus at the slit, diffracted off the toroidal grating, and imaged onto the XDL MCP detector

3.3 Detector and Detector Electronics

The Juno-UVS detector configuration includes an XDL microchannel plate (MCP) detector scheme housed in a vacuum enclosure with a one-time opening door containing a UV-grade fused-silica window (for limited UV throughput during testing). The door was spring loaded for opening with a wax-pellet-type push actuator. The vacuum enclosure has a vacuum pump port and a small, highly polished region which functions as a zero-order reflector (directing zero-order light from the instrument grating into the zero-order trap on the side of the in- strument housing). The vacuum enclosure also utilizes four female connectors for the anode signals, and two high-voltage (HV) connectors for the MCP and anode gap voltages. The detector’s MCP configuration uses a Z-stack that is cylindrically curved to match the 150-mm Rowland circle diameter to optimize spectral and spatial focus across the Juno- UVS bandpass. The detector electronics provide two stimulation pixels that can be turned on to check data throughput and acquisition modes without the need to apply high voltage to the MCP stack or to have light on the detector. The MCP pulse-height information is output as 5 bits, which, together with the 11 bits of spectral and 8 bits of spatial information, results in the 3-byte output for every photon. The input surface of the Z-stack is coated with an opaque photocathode of CsI (Siegmund 2000). D. Grodent ULg ArepellergridabovethecurvedMCPZ-stackenhancesthedetectivequantumefficiency (DQE). Each of the three nested MCPs has a cylindrical 7.5-cm radius of curvature matching the instrument’s Rowland circle radius (i.e., 15.0 cm diameter). The approximate resistance per MCP plate is 130 M!.TheMCPformatis4.6cmwideinthespectralaxisby3.0cm height in the spatial∼ axis with 12-µm diameter pores and a length-to-diameter (L/D) ratio of 80:1 per plate. The XDL anode is a rectangular format of 4.4cm 3.0cm.Thecombination anode array and MCP sizes gives an active array format of 3.5cm× 1.8cmnecessaryto capture the entire 68–210 nm instrument bandpass. The pixel readout× format is 2048 pixels (spectral dimension) 256 pixels (spatial dimension). The active area is 3.5cm 1.8cm, with 1500 spectral× pixels and 230 spatial pixels. The XDL anode uses two orthogonal× ∼ ∼ Juno orbit

NASA

D. Grodent ULg electronic (dark) noise when in/close to radiaon belts

D. Grodent ULg 33 14-Day orbits UVS segment: ~6 hours of connuous operaons 2.5 hrs aurora N UVS observes Also near-apojove aurora UVS obs. (aurora 1 hr ~few pixels) < 2% of orbit we need HST for 2.5 hrs the rest (> 98%) aurora S of the me Grodent et al., 2015 HST White Paper (ArXiv) D. Grodent ULg Juno is spin stabilized at 2 RPM: 1 rotaon every 30 seconds in a plane containing the UVS boresight

NASA

Use this rotaon to scan the auroral region

D. Grodent ULg The Ultraviolet Spectrograph on NASA’s Juno Mission

Fig. 4 An opto-mechanical schematic of the Juno-UVS sensor showing light rays traced through the main aperture door, reflecting from the OAP primary, passing through a focus at the slit, diffracted off the toroidal grating, and imaged onto the XDL MCP detectorScan Mirror

3.3 Detector and Detector Electronics

The Juno-UVS detector configuration includes an XDL microchannel plate (MCP) detector scheme housed in a vacuum enclosure with a one-time opening door containing a UV-grade fused-silica window (for limited UV throughput during testing). The door was spring loaded for opening with a wax-pellet-type push actuator. The vacuum enclosure has a vacuum pump port and a small, highly polished region which functions as a zero-order reflector (directing zero-order light from the instrument grating into the zero-order trap on the side of the in- strument housing). The vacuum enclosure also utilizes four female connectors for the anode signals, and two high-voltage (HV) connectors for the MCP and anode gap voltages. The detector’s MCP configuration uses a Z-stack that is cylindrically curved to match the 150-mm Rowland circle diameter to optimize spectral and spatial focus across the Juno- UVS bandpass. The detector electronics provide two stimulation pixels that can be turned on to check data throughput and acquisition modes without the need to apply high voltage to the MCP stack or to have light on the detector. The MCP pulse-height information is output as 5 bits, which,steps < 1° together with the 11 bits of spectral and 8 bits of spatial information, results in the 3-byte output for every photon. The input surface of the Z-stack is coated with an opaque photocathode of CsI (Siegmund 2000). ArepellergridabovethecurvedMCPZ-stackenhancesthedetectivequantumefficiency (DQE). Each of the three nested MCPs has a cylindrical 7.5-cm radius of curvature matching the instrument’s Rowland circle radius (i.e., 15.0 cm diameter). The approximate resistance per MCP plate is 130 M!.TheMCPformatis4.6cmwideinthespectralaxisby3.0cm height in the spatial∼ axis with 12-µm diameter pores and a length-to-diameter (L/D) ratio of 80:1 per plate. The XDL anode is a rectangular format of 4.4cm 3.0cm.Thecombination anode array and MCP sizes gives an active array format of 3.5cm× 1.8cmnecessaryto capture the entire 68–210 nm instrument bandpass. The pixel readout× format is 2048 pixels (spectral dimension) 256 pixels (spatial dimension). The active area is 3.5cm 1.8cm, with 1500 spectral× pixels and 230 spatial pixels. The XDL anode uses two orthogonal× D. Grodent ULg ∼ ∼ HST GO-12883

D. Grodent ULg Night Side Day Side North, Observer at ∞ Average UV aurora (dayside)

0° +20° +10° UVS Swath Orbit PJ3 Radiaons Credit: B. Bonfond, LPAP-SwRI 2015 D. Grodent ULg 5-min steps 15:00 to 21:00

Credit: B. Bonfond, LPAP-SwRI 2015 D. Grodent ULg Extrapolate missing aurora

latude longitude (S3)

2D map of HST aurora

Simulate 3rd dimension with

⟹ Build 3D map Chapman funcon (z0, H)

Use 143 maps accumulated for 10 sec (STIS ag) ⟹ 4D

Build H2 spectrum for each pixel ⟹ 5D D. Grodent ULg D. Grodent ULg D. Grodent ULg Start: 02 Nov 2016 15:00:04 End: 02 Nov 2016 15:10:34 Orbit #3

Aurora sing on dayside terminator (50% night-50% day) Altudestart = 3.6 RJ Instantaneous spat. res. ~ 156 km x 893 km / pix2 Dark count rate ~ 216 kC/s Dark counts Daylight 1st HST frame

Aurora

= 5 angles = 5 rotaons = 5 x 30 sec Flare = 2 (1) angles = 2 (1) rotaons = 2 (1) x 30 sec D. Grodent ULg 10.5 min D. Grodent ULg Start: 02 Nov 2016 16:15:04 End: 02 Nov 2016 16:23:04 Orbit #3 75 min later

Aurora almost fully in nightside Altudestart = 2.04 RJ Instantaneous spat. res. ~ 89 km x 509 km / pix2 Dark count rate ~ 6 kC/s D. Grodent ULg Daylight Dark counts 1st HST frame

= 5 angles Aurora = 5 rotaons = 5 x 30 sec D. Grodent ULg Flare = 2 (1) angles = 2 (1) rotaons = 2 (1) x 30 sec D. Grodent ULg 8 min D. Grodent ULg Start: 02 Nov 2016 17:15:04 End: 02 Nov 2016 17:19:04 Orbit #3 1 hr later

Aurora fully in nightside S/C magnec footprint on main emission Altudestart = 0.66 RJ Instantaneous spat. res. ~ 29 km x 165 km / pix2 Dark count rate ~ 72 kC/s D. Grodent ULg 1st HST frame Daylight

Dark counts Aurora = 7 angles = 7 rotaons = 7 x 30 sec D. Grodent ULg = 2 (1) angles = 2 (1) rotaons = 2 (1) x 30 sec

4 min D. Grodent ULg Start: 22 Aug 2017 22:49:53 End: 22 Aug 2017 23:12:48 Orbit #24 ~10 months later

Aurora fully in nightside S/C magnec footprint on main emission Altudestart = 1.6 RJ Instantaneous spat. res. ~ 70 km x 397 km / pix2 Dark count rate ~ 1112 kC/s ⟹ 40 kC/s D. Grodent ULg 7 angles per 30 sec frame (should be 1 angle/frame)

23 min Just 1 year to go! D. Grodent ULg D. Grodent ULg 0.017 s

D. Grodent ULg