CUVE – Cubesat UV Experiment Unveil Venus’ UV Absorber with CubeSat UV Mapping Spectrometer V. Co ni (UMD), S. Aslam (NASA GSFC), N. Gorius (CUA), T. Hewagama (UMD), L. Glaze (NASA GSFC), N. Igna ev (IKI RAN), G. Piccioni (INAF IAPS), E. D’Aversa (INAF IAPS)
CUVE TEAM includes experts in: Venus’ atmospheric composi on, chemistry, dynamics and radia ve transfer; Mission and Instrument Design; Venus mission concept formula on studies; Design, fabrica on and opera on of spectrometers for remote sensing
WHY VENUS? VENUS CLOUD TOP SCIENCE KNOWN AND POTENTIAL UV ABSORBERS
Credit: JAXA - Akatsuky Known absorbers: Venus is almost Ø SO2 varies from 0.1 to 1 ppm at the cloud top (Barker 1979, featureless in the visible Conway et al. 1979, Stewart et al. 1979, Esposito et al. 1988, Bertaux et al. 1996 Marcq et al. 2011) Ø SO about 30% of SO2 (Na et al., 1990) In the UV we observe Other candidate species for the observed UV contrast features: Credit: NASA – Mariner 10 dark and bright regions Credit: ESA – Venus Express Ø Sulfur-bearing species - sulfur Sx, S8, S2O, OSSO – FeCl3 : Ø Venus clouds reflect in the visible most of the incoming solar • Zasova 1981 proposes 1 % FeCl3 in 80% H2SO4 and Krasnopolsky radia on (albedo ~75–90%) (1986) favored it Ø ~50% of the solar energy received by Venus is absorbed in the UV Recently: Credit: JAXA - Akatsuky by a uniden fied absorbers in its top cloud layer • Petrova, 2018, support ferried chloride through analysis of glory Venus is an ideal target for SmallSats deep space explora on: Ø This absorbed energy is the primary atmospheric engine of Venus on Venus Ø Clouds top structure and UV absorbers nature are key parameters Ø Reachable by an independent small spacecra • Messenger MASCS found best fit for S2O and OSSO (Perez-Hoyos Ø ~1/3 of low-mass stars have planets in the Venus-zone for understanding Venus’ atmospheric dynamics and energy balance et al. 2018) (interior to HZ) Ø Venus science is achievable with cost efficient compact • Lab results fit Pioneer Venus data with OSSO (Wu et al. 2018) Ø S ll open compelling ques ons that needs to be addressed spacecra • Carlson 2016 suggests cyclo-octal S8 and polymeric sulfur Sx (>500 Ø Ø Public is very interested on Venus (> 70 ar cles on CUVE in few UV measurements must be acquired from space nm we can discriminate it from FeCl3) – Ø Venus science achievable with cost efficient compact months from more than 10 countries in the world) see bo om Other proposed absorbers: Sn, SCl , Cl and many others (C O , page – and see Jessup, K.-L. et al. Mo va ons for a Detailed In-Situ 2 2 3 2 spacecra CH2O, NOHSO4, NO2 , N2O4, NH3NO2, (NH4)2SO4, (NH4)S2O5, NH4Cl, Cl2, Inves ga on of Venus' UV Absorber. VEXAG 2017- LPI contribu on Ø Public is very interested in Venus explora on (CUVE > 70 SCl2, HClO4) (e.g., Pollack et al., 1980; Zasova et al., 1981; Toon et and EPSC 2018. ar cles in few months from more than 10 countries) We need a Venus UV spectrum al., 1982; Na and Esposito, 1997; Krasnopolsky 2006)
CUVE – CubeSat UV Experiment Sun Venus UV absorber PREVIOUS UV OBSERVATIONS – on a polar orbit around Venus in its clouds top: CUVE VENUS SIMULATED DATA drives Venus thermal Mission Instrument Channel Spectral Range Resolu on radiative balance, Pioneer Venus OUVS 110-340 nm 1.3 nm produces high contrast Nadir Observa,on Nadir UV dayside spectrum is mostly composed of solar Venus Express VIRTIS (M Visible) 290-1100 nm 2 nm features. light back-sca ered by atmospheric cloud par cles. Venus Express SPICAV (SUV) 110-310 nm 1-1.5 nm Still unknown! Venus Express VMC (UV) 345-384 nm 40 nm => From the spectrum we can derive informa on about Akatsuki UVI 293-365 nm 72 nm sca ering par cles and gases encountered in the HST STIS (low/med Res) 115-555 nm var. 0.27 nm Messenger MASCS VIS 300-1000 nm 4.7 nm atmosphere by the sca ered solar radia on. CUVE Spectrometer 200-400 nm 0.2 nm Data Telemetry Inhomogeneity in spa al and/or ver cal distribu on of CUVE Imager 320-570 nm 4 nm the unknown absorber produces the famous UV Ø Difficult to inves gate the UV absorber from Earth’s surface features – used also to study the dynamics of the due to strong UV absorp on in Earth’s atmosphere clouds. Ø Pioneer Venus -> not high spectral resolu on and some CUVE Payload Venus UV spectrum noise (e.g., Stewart et al, 1979) UVUV absorbers absorbers nature nature - UV image spectrometer and UV Nightglow Ø VMC on Venus Express and Akatsuki gave us amazing UV 200 – 400 nm, 0.2 nm images but not spectra spectral resolution Min (green), max (black), - UV multispectral imager UV absorber distribution mean (red) expected SO Ø Hubble Space Telescope acquired few UV spectra (Jessup et 2 Venus UV spectrum 320 – 570 nm and atmospheric dynamics and SO abundances has mul=ple al. 2015), but might not be able to acquire many more due absorp=on features between 200 and to Sun-avoidance requirements. Good spectra but limited 550 nm dataset/spa al coverage Ø Venus Express bands not resolved both in VIRTIS and SPICAV spectrometers MISSION OVERVIEW
CUVE can provide high resolu on UV spectrum of Venus, Ø 1 unique 12U spacecra CUVE high res image with large coverage and imaging of cloud top structure to Ø Can be deployed from Geosta onary Transfer Orbit (GTO) spectrometer (200 – 400) nm derive the science objec ves: Ø Other possible rideshare opportuni es: LEO missions, Heliophysics, in red 1) Nature of the UV-absorbers; 2) Abundances and Discovery, New Fron ers CUVE lower res SO2 and also distribu ons of SO and SO at and above Venus’s cloud tops SO bands mul=spectral imager 2 Ø Spacecra reach Venus using internal electrical propulsion system between 200 (320 – 570) nm in blue and correla on with the UV absorber; 3) Atmospheric and 320 nm Ø At Venus, spacecra will be placed in high al tude polar orbit dynamics at the cloud tops, structure of upper clouds and Uniden&fied wind measurements from cloud-tracking Ø Spacecra establishes direct communica on with DSN during cruise, absorbers instrument check-out, inser on, opera ons above 320 nm Acknowledgements: We acknowledge the support of NASA Ø Mature TRL: Most component have high TRL (6-8). Planetary Science Deep Space SmallSat Studies (PSDS3) Ø Mission end: orbital decay into Venus (no planetary protec on concerns) program and NASA/GSFC