A Clarification The Constellation program was for space exploration and lunar/planetary science. It was not going to be prospecting for water! (As we learned last week, that wouldn’t make sense.) The cancellation of Constellation doesn’t affect humanity’s fresh water problems, but it means that for the first time in about 50 years, the U.S. will not have a government-run manned launch vehicle. We will be dependent upon other government agencies, and eventually private industry, to get astronauts to and from orbit.

The Moon The only celestial body people have walked on (other than Earth) The only celestial body for which we have radiometric ages (other than Earth and meteorites) The only celestial body for which we have seismic data (other than Earth) Only 1 geologist has been there We’ve only explored a tiny amount of the surface – 6 landings – longest sortie <20 km

Lunar contributions to Planetary Science “Pristine surface”, in Earth’s neighborhood Absolute age determinations (Apollo and Soviet samples) Calibration for relative age dates used throughout the Solar System Heavy Bombardment

Dating Absolute – Radiometric age dating – Compare (radioactive) parent & (radiogenic) daughter isotopes with non-radiogenic isotopes – Look at different crystals, different isotopes, to get a good estimate Relative – Concept: older surface has had more time to be hit by meteorites – Complications: exhumation, “secondary craters”

Earth’s surface: types of rocks Images from

Surface Processes Erosion Tectonics Volcanism Impacts Images from and

The Moon’s surface Images from and

New lunar images

Earth’s interior

Earth’s interior, cont. P waveS wave

The Moon’s interior

Earth’s atmosphere Gas NameChemical FormulaPercent Volume NitrogenN278.08% OxygenO220.95% *WaterH2O0 to 4% ArgonAr0.93% *Carbon DioxideCO % NeonNe0.0018% HeliumHe0.0005% *MethaneCH % HydrogenH % *Nitrous OxideN2O % *OzoneO % * variable gases From

The Greenhouse Effect