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. Ignaev (IKI RAN), G. Piccioni (INAF IAPS), E. D’Aversa (INAF IAPS) CUVE TEAM includes experts in: Venus’ atmospheric composi5on, chemistry, dynamics and radiave transfer; Mission and Instrument Design; Venus mission concept formulaon studies; Design, fabricaon and operaon 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 radiaon (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 unidenfied absorbers in its top cloud layer • Petrova, 2018, support ferried chloride through analysis of glory Venus is an ideal target for SmallSats deep space exploraon: 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 S5ll open compelling ques5ons 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 ar5cles 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 boaom 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 contribu5on Ø Public is very interested in Venus exploraon (CUVE > 70 SCl2, HClO4) (e.g., Pollack et al., 1980; Zasova et al., 1981; Toon et and EPSC 2018. ar5cles 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 ResoluKon 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-scaered by atmospheric cloud par5cles. 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 informaon about Akatsuki UVI 293-365 nm 72 nm scaering par5cles 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 scaered solar radiaon. CUVE Spectrometer 200-400 nm 0.2 nm Data Telemetry Inhomogeneity in spaal and/or ver5cal distribu5on of CUVE Imager 320-570 nm 4 nm the unknown absorber produces the famous UV Ø Difficult to inves5gate the UV absorber from Earth’s surface features – used also to study the dynamics of the due to strong UV absorp5on in Earth’s atmosphere clouds. Ø Pioneer Venus -> not high spectral resolu5on 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/spaal coverage Ø Venus Express bands not resolved both in VIRTIS and SPICAV spectrometers MISSION OVERVIEW CUVE can provide high resoluon 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 Geostaonary Transfer Orbit (GTO) spectrometer (200 – 400) nm derive the science objecKves: Ø Other possible rideshare opportuni5es: LEO missions, Heliophysics, in red 1) Nature of the UV-absorbers; 2) Abundances and Discovery, New Froners CUVE lower res SO2 and also distribu5ons 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 correlaon with the UV absorber; 3) Atmospheric and 320 nm Ø At Venus, spacecra will be placed in high al5tude polar orbit dynamics at the cloud tops, structure of upper clouds and Uniden&fied wind measurements from cloud-tracking Ø Spacecra establishes direct communicaon with DSN during cruise, absorbers instrument check-out, inser5on, operaons 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 protec5on concerns) program and NASA/GSFC .