Proceedings from 12th Australian Space Science Conference, 2012 Page 65 Possible Architectures for Near-Future Venusian Atmosphere in situ Missions Graham E. Dorrington 1 and Colin F. Wilson 2 1 School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Bundoora, VIC 3083, Australia 2 Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, UK Summary: a discussion of possible near-term options to obtain scientific measurements of the atmosphere of Venus between 45 and 75 km altitude. It is concluded that further study of a solar- powered, fold-out, fixed-wing aeroplane, similar to previous proposals by Landis et al., should be given future study priority alongside alternative aerostatic platform options. One of the key design drivers identified is the data rate limit prescribed by direct to Earth transmission. Keywords: Venus, planetary exploration, aerial platform, probe, ultraviolet (UV) absorber, solar aeroplane, aircraft, balloon, aerostat, clouds, atmospheric science. Introduction Since 1967, there have been 17 in situ probes from 14 missions to Venus (Table 1). The last Soviet Venus-Halley (or “VEGA”) missions [1] involved the first successful flights of long duration aerial platforms in the atmosphere of another planet: two helium-filled meteorology balloons. After a gap of nearly three decades, the scientific desire to resume in situ exploration of Venus is likely to grow again. One key question is what mission architecture should be adopted for this return? Table 1: Previous successful Venus probe missions adapted from Dutta et al. 2012 [2]. Launch date Probe Name Probe entry mass / kg Science Payload mass /kg Probe diameter /m Ballistic coefficient (kg/m 2 ) Peak entry deceleration / (1 g) 1 1967 Venera 4 408 1 519 450 2 1969 Venera 5 431 1 549 450 3 1969 Venera 6 431 1 549 450 4 1970 Venera 7 532 1 677 452 5 1972 Venera 8 526 1 670 500 6 1975 Venera 9 1660 2.4 367 150 7 1975 Venera 10 1660 2.4 367 170 8 1978 Pioneer-Venus (north) 91 3.6 0.765 190 487 9 1978 Pioneer-Venus (night) 91 3.6 0.765 190 350 10 1978 Pioneer-Venus (day) 91 3.6 0.765 190 219 11 1978 Pioneer-Venus (large) 316 29.15 1.423 188 276 12 1978 Venera 11 1701 2.4 376 167 13 1978 Venera 12 1715 2.4 379 167 14 1981 Venera 13 1751 2.4 387 167 15 1981 Venera 14 1751 2.4 387 167 16 1984 VEGA 1 plus balloon 1864 2.4 412 130 17 1984 VEGA 2 plus balloon 1864 2.4 412 139 A recently proposed NASA “Flagship” class mission to Venus, estimated to cost $3-4B (2009), specified an orbiting spacecraft, two surface landing probes and two long duration super-pressure balloon platforms [3]. In the near term, fiscal constraints may not permit such an ambitious venture. Instead, a much lower cost mission (e.g., of the “Discovery” class) with more focused scientific returns may be more likely of receiving approval from one of major space agencies.