The Planets Where we are headed in the next few lectures Nuclear energy Layers of the Sun Sun’s energy Light producon and transport Other planets Helioseismology 2 Missions to other planets - Mercury Mariner 10 (US, 1973), MESSENGER (US, 2004), BepiColumbo (ESA/JAXA, 2015) Missions to other planets - Venus Venera 1-16 (USSR, 1961-1983), Pioneer Venus 1-2 (1978), Magellan (US, 1989) Venus Express (ESA, 2005) Missions to other planets - Mars Mariner 3-9 (USA, 1964-1971), Viking 1-2 (USA, 1975), Mars Express (ESA,2003) Missions to other planets - Jupiter Pioneer 10-11 (USA, 1972-1973), Voyager 1-2 (USA, 1977), Galileo (USA, 1989) Missions to other planets - Saturn Pioneer 11 (USA, 1973), Voyager 1-2 (USA, 1977), Cassini (USA, 1997) Missions to other planets - Uranus Voyager 2 (USA, 1977) Missions to other planets - Neptune Voyager 2 (USA, 1977) Missions to other planets - Pluto New Horizons (USA, 2015) Mars Mars in a nutshell • Orbital distance = 1.5 AU • One Mar7an day = 24.6 hours • One Mar7an year = 687 days • Mass = 0.11 x Earth’s Mass • Radius = 0.53 x Earth’s Radius • Temperature: Min = -87o C, Max = 20o C • No global magne7c field Mars Topography Atmospheric Composi7on Venus Earth Mars • 96.5% CO 2, • 77% N, • 95.3% CO 2, 3.5% N, 21% O, 2.7% N, traces of SO2, traces of Ar , 1.6% Ar, Ar, H2O CO2 traces of O, H2O What was the past atmospheric composi7on like? Water on Mars ? Current Mar7an Atmosphere Earth surface pressure ~ 1 bar Dust Storms! Side Note – Dust is also a BIG problem at the Moon Mar7an Landers Mars Exploraon Rovers (MER) – Spirit and Opportunity Launched June 10 and July 7, 2003 Landed January 3 and January 25, 2004 Dust Devils at Mars… MER cleaning crew Mar7an Landers Mars Exploraon Rovers (MER) – Spirit A 3 month mission turned into a 7 year adventure… Mars Exploraon Rovers (MER) – Opportunity A 3 month mission turned into a 7 year (and coun7ng) adventure… Mars Science Lab – Curiosity Launched November 26, 2011; Landed August 5, 2012 Gale Crater Water on Mars ? Current ‘seepage channels’ MGS: NASA/JPL/Malin Space Science Systems Water on Mars ? Water prevalent up to late Noachian (~ 3.5 Gya) Episodic events during the Hesperian (> 2.0-2.5 Gya) Arid during the Amazonian with some break-out events (< 2.0 Gya) Manning et al., 2006; and references therein Former Ice flows? Atmospheric Composi7on Past liquid water: 150 mb of CO2 Current : 7-8 mb of CO2 Old Convensional Wisdom: More CO2 → greenhouse effect → carbonate rock (not seen, originally) Then Opportunity landed! Blueberries = concre7ons Form in aquious fluids In every layer looked at in Eagle crater Surrounding rock is Jarosite : requires a pH < 5 to form on Earth typically forms for pH 1-3 VERY acidic water – can’t form carbonate rock in CO2 atmosphere (e.g Fairen et al., Nature, 2004) But then Phoenix landed… But then Phoenix landed… Water ice found pH ~ 8-9 • good for bacteria • good for asparagus And Spirit Broke a Wheel…. and found salt, lots of salt. Plus evidence of past geologic hot springs. Mar7an Polar Caps North Pole South Pole Water on Mars Es7mated from thermal and epithermal neutrons What about magne7c field? Acuna et al., Connerney et al. 1999 Mar7an Aurora Solar Wind Interac7on with Mars Solar wind density N Vsw High Resolu7on Simulaons Solar Wind Hydrogen Oxygen Density Density Density N Vsw .