Field Science Goals for a 500-Day Campaign on Mars in the Vicinity of Terra Meridiani Rocky Persaud Interplanetary Expeditions Inc. 2nd Mars Expedition Planning Workshop August 6 - 7, 2005

Research On Mars What are the geological, geophysical, meteorological, climatic, and astrobiological research we can do on Mars? How do we decide which science goal to pursue and where on Mars? How do we organize science campaigns to maximize the science return, and minimize the operational clashes between very different modes of investigation?

MARS FIELD GEOLOGY, BIOLOGY, AND PALEONTOLOGY WORKSHOP (LPI, 1998) What are the ages of the major martian events? When did early heavy bombardment cease? How long did major volcanism continue? What was the source of water for the major flood events and when did they occur? Were they catastrophic or longer term? When did the floods occur? Where is that water now? How did the atmosphere evolve? What was the climatic history? Was there a change in climate from warm-wet to cold-dry? If so, when did each climate exist? Did Mars experience greenhouse effects? What is the resulting inventory of resources on Mars? Were there any habitats potentially suitable for life on Mars, such as lakes, oceans, and hydrothermal springs? If so, when did they exist? Is there any evidence for life on Mars, past or present?

MARS FIELD GEOLOGY, BIOLOGY, AND PALEONTOLOGY WORKSHOP (LPI, 1998) Recommended early robotic phases of human campaign: Biohazard reconnaissance Resource reconnaissance Terrain reconnaissance 125 days to explore walking-distance exploration circle (~10 km diameter) immediately adjacent to the landing site. What’s wrong with this plan? Too timid?

Too Many Questions? Need either fewer questions, or questions more specific to the location. Goals can be summarized as: determine the history of water, life, climate and crust in the Meridiani region and adjacent terrains that provided inputs and outputs for Meridiani.

Opportunity Landing Site

Eroded and exposed sedimentary rock in Sinus Meridiani

Meridiani (Squyres et al) “Fine-grained basaltic sand and a surface lag of hematite-rich spherules, spherule fragments, and other granules. Wind ripples are common. Underlying the thin soil layer, and exposed within small impact craters and troughs, are flat-lying sedimentary rocks. These rocks are finely laminated, are rich in sulfur, and contain abundant sulfate salts. Small-scale cross-lamination in some locations provides evidence for deposition in flowing liquid water. We interpret the rocks to be a mixture of chemical and siliciclastic sediments formed by episodic inundation by shallow surface water, followed by evaporation, exposure, and desiccation. Hematite-rich spherules are embedded in the rock and eroding from them. We interpret these spherules to be concretions formed by post-depositional diagenesis, again involving liquid water.” “It seems likely, then, that the area over which these aqueous processes operated was at least tens of thousands of square kilometers in size.”

THEMIS false colour image NE of Meridiani

Types of Features Sedimentary features Aeolian features Volcanic features Impact features How do we recognise these features? Photogeology 101.

Large impacts sometimes throw up large ejecta blocks that can create secondary impacts.

Fluidized Ejecta – target was ice-rich?

Lava flow margin in Daedalia Planitia. The giant shield volcano Olympus Mons, largest in the solar system, 550 km wide, 25 km high. Lava flow margin in Daedalia Planitia. Lava flows on Ascraeus Mons with a collapsed lava tube.

Platy flows Margin of a lava flow spilling into an impact crater. Overlapping, dust-covered lava flows on the southeastern flank of Olympus Mons, with leveed channels. Platy flows These features are either volcanic flow or mud flows. The material, whether mud or lava, was very fluid and had a thin crust on its surface, that broke apart and rafted a distance down the valley.

Wind-eroded material among ridges Yardangs Despite the thin atmosphere, winds on Mars raise a lot of dust and is a erosional force prevalent on Mars today. Wind-eroded material among ridges Sand dunes on Mars are usually dark, due to their mafic composition from Fe- and Mg-rich minerals and rock fragments. Large sand dunes with a light coating of dust disrupted by dust devil tracks.

Wind Streaks are usually made by a single gust of wind covering a large area, as in Figure 27, producing parallel streaking patterns. Areas behind a mass, like the walls of the crater in the left figure, produce a streaking pattern that is commonly seen in photos. Dust devils are solitary, spinning vortices of wind that produce dust devil streaks, marking paths across the landscape. Acting at different times, dust devil streaks overlap and cross. Slope Streaks occur in areas heavily mantled by fine, dry dust.

Mesas, Plateaus, and Knobs

Buttes

Fretted Terrain The fretted terrains of Mars are regions along the boundary between cratered highlands and northern lowland plains that have been broken-down into mesas, buttes, and valleys. On the floors of some of these valleys occurs a distinctive lineated and pitted texture--like the example shown here. The cause of the textures is not known, although for decades some scientists have speculated that ice is involved. While this is possible, it is far from a demonstrated fact.

A typical branching valley network in the Terra Meridiani region, with bright sand filling the valleys. Nanedi Vallis meanders, with terraces suggesting continual fluid flow and downcutting. However, it is lacking smaller channel tributaries on the surface surrounding the canyon, what tributaries exist are box-headed, and the size and tightness of the apparent meanders suggest formation by collapse.

Streamlined Islands (left) and Braided Channels (right)

Distributary fan-shaped deposit.

Layered Outcrops

I would contend that… Only a small number of science questions can be answered within ~10 km of a Mars base. Questions for which humans in the field are needed require ranging far and wide. Otherwise use robots? Increasing the science return requires ranging far and wide. Suggestion: humans are not really needed near the base for field science; can be done remotely from Earth. Far ranging mobility is essential. For a science perspective, timid exploration campaigns should be discouraged.