Mars InSight LanderArtist’s conception of InSight on MarsCourse AnnouncementsAssignmentsPeriods of Flowing WaterSubsurface IceSubsurface IceCurrent Flowing WaterCurrent Flowing WaterMartian Polar CapsMartian Polar CapsMartian Polar CapsMartian Polar CapsMartian Polar CapsWhere did the water go?Martian AtmosphereMartian AtmosphereMartian Atmosphere - WeatherMartian Atmosphere - WeatherMartian Atmosphere - WeatherAtmospheric Stripping via Solar WindAtmospheric Stripping via Solar WindInternal Structure of MarsThe Moons of MarsThe Moons of MarsPhobosDeimosJupiterJupiter vs. EarthJupiter Data Sheet IOrbital PropertiesJupiter Data Sheet IIDifferential RotationDifference in radiiJupiter Data Sheet IIIMars InSight LanderCredit : NASA/JPL-CaltechArtist’s conception of InSight on MarsCredit : NASA/JPL-CaltechCourse Announcements•Thanksgiving Week planningNo classes Wednesday, 23 Nov.•Extra Credit sessions still underway•Quiz 5 Today•Quiz 6 next Wednesday, 16 Nov.•Exam 3 is Monday, 21 Nov.–Exam materials released next week•Final Exam: Thursday, 8 Dec. 2:45 – 4:45 PM•Astronomy Club Interest MeetingFriday, 18 Nov. 12:30 – 1:30 PM Nielsen 307AssignmentsReading Assignments•Chapter 11: Sections 11.1 – 11.3[Read by Friday, 11 Nov.]•Parallel LecturesCC Astronomy Episode 16: JupiterCC Astronomy Episode 17: Jupiter’s Moons[Watch before Wed., 16 Nov.]Mastering Astronomy•Chapter 10 Homework (short assignment)[Due Wed. ,16 Nov. at 11:59 EST]–Appearing on Blackboard very soonPeriods of Flowing Water•Runoff channels suggest a wet period about 4 billion years ago (end of Naochian Period) when the Martian atmosphere was thick enough to support liquid water on the surface•Outflow channels suggest a period about 3.7 - 3 billion years ago (Hesperian Period) characterized by large-scale, catastrophic periods of floodingTwo types of channels implies two different “wet” erasSubsurface Ice•NASA Phoenix Lander discovers water-ice just below surface in northern arctic•High latitudes have permafrost layer•More equatorial areas may have permafrost as well, but meters under surface–Evidenced by fluidized ejectaParts of Mars are more of a tundra than a cold desertSubsurface Ice Many Martian craters show fluid flow like features thought to be caused by fluidized ejecta•Impact melts subsurface permafrost•Spectral evidence reveals that subsurface areas (mostly polar) may be up to 50% water ice by volume (Lower amounts, ~1%, in the equatorial regions)Permafrost and fluidized ejectaMud-like, fluidized ejecta around Yuty Crater. Credit: NASACurrent Flowing WaterRecurring Slope Lineae (RSLs)Current Flowing Water•Recurring Slope Lineae (RSLs) appear in Martian summer and are long dark streaks, and disappear in colder, winter temperatures.•Spectrally associated with hydrated salts•Consistent with salty water flowing just below the surfaceIt’s salty!Martian Polar Caps•The Martian polar caps are predominantly dry ice (CO2 ice), but the residual North Polar Cap is water-iceMust consider two parts of the Martian polar caps•The seasonal cap grows and shrinks each year•The residual cap remains permanently frozenDifferent for northern and southern polar caps•At max. size, in southern mid-winter, the southern seasonal cap is ~4,000 km across•At max. size, in northern mid-winder, the northern seasonal cap is ~3,000 km across–Different because of Mars’s eccentricity. In southern winter, Mars is further from the Sun (nearer aphelion)Colder winter => larger growth for southern seasonal capTwo types: The residual and the seasonalMartian Polar CapsTwo types: The residual and the seasonalSeasonal Cap Residual CapMartian Polar Caps•The seasonal caps are composed almost entirely carbon dioxide with temperatures lower than the 150 (-120oC) required for CO2 to condense out of the atmosphere–HINT: GREAT Exam material… just sayin’•Growth and retreat of seasonal caps responsible changes the atmospheric surface pressure by nearly 30%!–That’s right! About 30% of the atmosphere “freezes” out of the atmosphere when the the sum of the seasonal caps is largest compared to when smallest•Maximum thickness thought to be ~1 m (not very thick, but that translates to a lot of CO2 gas when it sublimates)Seasonal CapsMartian Polar CapsResidual Caps – roughly scaledSouth Residual CapCO2 - iceNorth Residual CapWater-iceMartian Polar Caps•The residual caps are brighter and smaller than seasonal caps and even more marked by a north-south asymmetry–Southern: ~350 km across and almost entirely CO2–Northern: ~1000 km across and almost entirely water (H2O) ice[Again… great exam material here]•Larger because in southern summer, Mars is significantly closer to the Sun (reducing the size of cap)i.e., Northern summer (the best time to sublimate a residual cap) occurs when Mars is nearer aphelion, making it a more mild summer.Residual CapsWhere did the water go?Where is the water now? 1. Into the subsurface where it remains frozen (most of the water)2. Lost to space via the photodisassociation of H2O into H2 and O2. Having so little mass, the H2 can easily escape the low Martian gravity and escape to space, and the oxygen reacted with surface3. Some locked in permanent North Polar CapIf all the permafrost water on Mars were to become liquid, there would be enough water to cover the surface to roughly a depth of 10 metersAll this evidence points toward an ancient period when Mars was much wetter than it is nowMartian Atmosphere1/150th of Earth’s Viking 1 Image - NASAMartian Atmosphere1/150th of Earth’s •Surface Pressure: Varies from 4.0 – 8.7 mbar depending on season (mbar = millibar)•Atmospheric Composition:95.3% CO22.7% N21.6% Argon0.13% O20.07% CO0.03% water vaporTroposphere appears during the daytime, and disappears at night, i.e., the atmosphere incapable of producing convection or weather at nightMartian Atmosphere - WeatherDust storms•Mars periodically experiences large-scale dust storms–Global dust storms on average once every 5.5 years–1 – 3 continent-sized storms per Martian year[Good potential exam question] – What planet periodically experiences global dust storms?Change in opacity over 30 sols during a dust storm as viewed by OpportunityMartian Atmosphere - WeatherDust devils•Dust devils are common in the summertime and much larger than on Earth (several km tall and 10s – 100s m in diameter; can be much larger than Earth
View Full Document
Unlocking...