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Counting the craters of the Moon

May 15, 2016
Stuart Robbins of the Southwest Research Institute in Boulder does that others don’t even dare to start: he counts the craters of the Moon.
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How many craters are there on the moon?
“It’s a question that cannot be answered.  You have to define a diameter first.  And once you do, any number quoted must be taken with the caveat that every individual will vary in what they consider to be an impact crater (e.g., Robbins et al., 2014).  Based on how I identify craters (which appears to be similar to many others in the field), I can say there are about 9300 craters larger than 15 km on the moon — I’ve mapped all of these, globally. My projection for craters ≥1 km on the moon is approximately 1.1 million.  There are several ways to estimate this based on the areas I’ve completed so far (35% of the moon — see this poster), but in the end, a simple linear extrapolation at this point is about as good as a more detailed one based on fraction of maria versus highlands.  I should know the answer in a few months.”
Is there any crowd-sourcing involved or you are counting one by one? 
“I am involved with a crowd-sourcing crater effort (CosmoQuest), but this global moon database is only me, it does not involve any crowd-sourcing.”

 

For morphological attributes, if there will be funding, are you going to inspect all craters individually or is there an automation for that?
“Individually.  I am aware of one or two automated methods, but they are even worse than automated crater detection and it would be more work to correct them than to just do it all manually.”
What was the fun in this work, if any?
“To be blunt, the only fun is when it’s done and you can look back and see the fruits of your labor.  Tracing circles is incredibly tedious and boring.”
Did you have to redo some parts?
“I have re-done a few very large impacts that I originally did several years ago (in support of some CosmoQuest work).  I have also re-done parts of the south pole within a few degrees of the pole with LOLA GDR that were originally done with LROC WAC mosaics because the GDR is significantly better quality there.  I learned from that for the north pole and started with LOLA GDR rather than LROC WAC within 5° of the lunar north pole.”
Major discoveries so far or predicted using this dataset?
“I have had little time to do a look-back and actually analyze the data beyond producing basic density maps which are, at the moment, only for about 1/3 of the lunar surface.  The only thing I think I’ve found that I have not seen reported elsewhere is that the moon’s north pole is saturated with kilometer-scale secondary craters.”
When you finish it, are you going to throw out all craters smaller than 1 km?

“Craters smaller than 1 km will be available on an as-requested basis, considered supplementary material.  People misuse and abuse datasets an extraordinary amount, and crater populations that are not “complete” are abused more often (this has been encountered and is still being encountered by Nadine Barlow for her 1980s Mars crater database).  The “just contact me for the rest” is a trivial hurdle but it would allow me to personally, individually remind people of all the caveats of those craters.  This is also the model followed for the Mars database published in 2012 (Robbins & Hynek, 2012).”

What’s the main difference compared to the making of the Mars crater catalog? (not the result, but the process of producing the catalog).
“Mostly this comes down to experience.  I had to re-do a non-trivial portion of Mars because it was done early in my graduate student career and I got “better” at it and didn’t want there to be regional biases based on how I had changed.  I also did different “passes” through Mars where I went to different diameters for completeness or other things, and these were saved as individual files that lead to a book-keeping nightmare and numerous very large files due to duplicating topography datasets.  This time, things are streamlined with “passes” corresponding to what datasets were mapped on ONLY (so all WAC is done together), and just the basic “how am I going about this” did not require trial and error. Additionally, I’ve grown faster with how quickly I can measure and catalog each crater, so while constructing the Mars database I started out at 1500-2500/day, and by the time I was done was up to 2000-3000/day, at this point with the moon, 5000/day is below average, and 10,000/day is a good day.”
robbins-counted
A portion of the Moon, showing all cataloged craters in green (outlines for crater ≥15 km in diameter, dots for 1-15 km). Source

Exploration Zone maps – annotated

May 6, 2016

Annotated maps of the proposed Mars Landing Site Exploration Zones in support NASA’s Human Mission to the Surface of Mars.

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Geologic features are from here.  Our call for mapping is here. 

Checklist (EZ minimum criteria)

  1. ResourceROI: resources needed to keep humans alive, especially H2O (within 3 km, in flat terrain), and building materials (cobble, regolith).
  2. ScienceROI:
    1. important science targets (active forms; recently exposed Noachian rock; hydrated, water/ice-related forms; past refuge for life; fossils);
    2. diverse regions of interest (ROIs) that can be reached within ~100 km of a central landing site;
  3. Landing:
    1. A central landing site (LS) or multiple sites of at least 5 × 5 km area that are favorable for landing (low slopes (<10°), few meter-scale hazards (boulders, craters), not covered by thick dust/sand);
    2. Equatorial location for thermal management and ease of ascent from Mars surface (±50 Lat); near surface water ice in excess of 100MT
    3. low elevation / sufficient atmosphere for ease of entry, descent, and landing (EDL) with large masses and protection from radiation (below +2km elevation) (high pressure)
      (Source: McEwen et al., Background)

 

List of EZs

E. Melas Chasma. McEwen et al 2015.
RSL and/or hydrated sulfates for water, mafic bedrock, regolith, and aeolian materials; landslides.

00
Coprates Chasma. Mojarro et al 2015.RSL, cross-cutting alluvial fan deposits, tilted valley walls, impact craters, olivine deposits, clay mineral deposits, exposed deep crustal lithologies. 01

Viking/Chryse Planitia. Farrell 2015.
Volcanic plain resurfaced by deposits from floodwaters and deflation from aeolian processes. Impact crater ejecta and stratified drift deposits, petrologic samples with trapped atmospheric gases in vesicles, datable volcanic wrinkle ridges and landforms shaped by water floods and later aeolian erosion. Changes to the Martian surface (e.g., ventifacts, scouring, dust tailing) (and the VL-1) in the location of VL-1 since 1982.02

Valles Marineris Mouth / southern Acidalia Planitia. Kochemasov 2015.
Stream sediment sampling. It is located between Viking 1 and Pathfinder landing sites.

03

NE Marineris. (E Outlet of Valles Marineris) Clifford et al 2015.
Smooth canyon floor – rocks and sediment transported from both local and distant sources; chaotic terrain, streamlined islands, and likely paleo lakes, on the canyon floor, and valley networks on the nearby plateau which caps ~3-km exposures of older Noachian stratigraphy.

04

SE Marineris. Mitchell and Christensen 2015.
Close to Recurring slope lineae, sites containing hydrated minerals and seven sites containing chlorides, possible evaporative products.05

Gale Crater. Calef et al 2015.
Peace Vallis delta deposits, confirmed habitable environments, evidence of a lake, insitu methane observations, existence of indigenous Martian carbon both ancient and active, 5 km sedimentary stack of Mt. Sharp (Aeolis Mons). Water only as bound in minerals and adsorbed to loose grains.06

Gale Crater 2. Yun 2015. 07

Gale Crater 3.  Montano et al. 2015.
08

SW Sinus Meridiani. Anonymous.
Fluvial fan, sedimentary stack 800-900 m thick, with hematite nodules.

09

S Meridiani Planum. Clarke et al. 2015.
The landscape is “boring” but trafficable. Crewed rovers could cover the distance that Opportunity needed a decade to cross in a few hours. Hydrated evaporitic sulfates for water & Mg extraction, Surficial hematite-rich eolian deposits (blueberries) for Fe extraction, Potential resource extraction of Cu, Zn, Pb, As, and Se from sulfide mineralized bedrock; Middle Noachian bedrock, clay altered (hydrothermal, water and magma history, and potential past habitats); Late Noachian dendritic channels, Hesperian inverted channels, Early Hesperian depositional environments, Amazonian pedestal craters providing past and present ice and habitability potential.

10

S Meridiani Planum 2. Cohen and Seibert 2015.
Bedrock is composed of sulfate salts mixed with weathered basalt exhibiting both aeolian and fluvial sedimentary structures with later groundwater interaction that formed hematite concretions. Etched terrain, finely layered deposits of apparent sedimentary origin, embaying older, phyllosilicate- bearing terrain cut by fluvial features. The juxtaposition of phyllosilicates and sulfates.11

Gusev crater. Longo 2015.
Columbia Hills igneous units, carbonate outcrops formed in a Noachian ephemeral lake, orbitally-detected phyllosilicates in polygonal terrain, sulfates, and opaline silica outcrops bearing a resemblance to biogenic structures found on Earth.

12

Gusev-Apollinaris Sulci. Rice et al. 2015.
Noachian Gusev crater rim materials/massifs and ancient fluvially dissected cratered plains. Hesperian lava flows and dissected fluvial plains. Hesperian-Amazonia lava flows and fluvio-lacustrine deposits. Amazonian Medussae Fossae Formation materials, thick deposits of pyroclastic material and welded ash flow tuffs interbedded with aeolian deposits.

13

Apollinaris Sulci. Kerber et al. 2015.
Yardangs on the dichotomy boundary. Noachian highlands with two types of valley networks, Hesperian basaltic plain, kipukas, good conditions for observing dust devils, chaos terrain, the terminus of the giant volcanic fan of Apollinaris Mons, (Hesperian/Amazonian), yardangs (wind-eroded ridges) of the Medusae Fossae Formation, voluminous fine-grained deposits from volcanic ash fall deposits that preserves underlying geological features.Yardangs provide natural roadcuts into the Medusae Fossae Formation, allowing access to underlying units.

14

Zephyria Planum. Yakovlev 2015.
Sand dunes, conical hills interpreted as hydrolaccoliths with recent activity, channels of brine in flow from interpermafrost or subpermafrost.

15

Hebrus Vallis. Davila et al. 2015.
Within a broad outflow channel system. Exposure of the Vastitas Borealis Formation (VBF), a possible remnant of a Late Hesperian ocean. Hebrus Valles is an intricate system of individual pits, pit chains, troughs and channels. Pits and trough may have captured catastrophic floods into networks of caverns. Features interpreted as mud volcanoes cluster into linear ridges (potential fossil biosignatures). Crater provides accesss to explore subsurface materials.

16

Hyspanis delta. Gupta et al. 2015.
Situated on the dichotomy boundary, includes fluvio-deltaic deposits at the termini of Sabrina Vallis (in Magong crater) and >3.7 Ga old Hypanis Vallis, recently exposed by deflation.

17

Jezero crater watershed. Mustard et al. 2015.
Jezero Crater open basin lake with delta deposits at the stratigraphic contact between the Noachian Isidis basin and the Hesperian Syrtis Major volcanic flows.

18

Nili Fossae. Markle 2015.
Craters, flows, crustal regions, and canyons (fossae).

19

Aram Chaos. Sibille et al. 2015.
Several past episodes of groundwater recharge and infilling by liquid water, ice, and other materials. Chaos terrain caused by melting of deep ice reservoirs that triggered the collapse of terrain followed by catastrophic water outflows such as Ares Vallis .Groundwater represents a protected subsurface environment. Past water also indicated by high concentrations of hematite, Fe-oxyhydroxides, mono-hydrated and poly-hydrated sulfates.

20

Cerberus. Wright et al. 2015.
West of Zunil Crater including its 1-2 Ma ejecta rays and distal secondary crater fields. Knobby terrains likely Hesperian/Noachian sedimentary rocks subjected to aeolian processes. Faults may have interior groundwater/ground ice flow. Basaltic Cerberus lava flows. The EZ has a localized magnetic field. Rootless cones, flood features suggest flooding of water and nearsurface ground ice/water either during or after the most recent volcanism. Candidate RSLs in alluvial fans.

21

S Nectaris Fossae. Boatwright 2015.
Transition zone between Thaumasia Noachian volcanics and Noachis Terra cratered highlands reworked by tectonism and subsequent incision of valley networks. The degraded Protva Valles, Nectaris Fossae, a volcanic edifice and an unusual double crater.

22

Hadriacus Palus. Skinner et al. 2015.
Exhumed, structural (principally non-crater) basin. Napo Vallis and Huallaga Vallis channel systems terminate in this basin. Hadriacus Cavi is a 50-km long series of depressions that expose >800 m thick stratified rocks suggestive of volcanic (tuff and/or lava), fluvial (channel cross-section), aeolian (dark sand), and impact (breccia and faulting) origin.

23

Mawrth Vallis. Horgan et al. 2015.
It contains the most extensive, >200 m thick light-toned layered deposits, exposed outcrop of clay-rich rocks emplaced as sediments and weathered in situ to form clayrich soils in the Noachian. Clay mineral abundances in excess of 50 wt.%, the largest clay abundance detected on Mars. Also includes the dichotomy boundary and the outflow channel with streamlined islands potentially preserving flood deposits. Hydrothermal deposits may be present within halo-bonded fractures on the plateau.

24
McLaughlin Crater. Michlski et al. 2015.
McLaughlin Crater is a Noachian impact crater that contained a deep (~500 m) lake >3.8 Ga. The clays and carbonates on the floor of the crater are overlaid by dark airfall deposit that is likely volcanic ash. McLaughlin Crater is located at the boundary of a) the ancient Noachian crust, b) the northern plains, and c) the Mawrth Vallis deposits.

25

South of Firsoff Crater in Arabia Terra. Ori et al. 2015.
Possible spring mounds and layers aligned along a fissure ridge in a terrain that consist of sulfate bearing light-toned layered deposits; possible spring, travertine-like, terraces; Middle Noachian highland; Middle Amazonian Ridged Plains; aeolian cross bedding; aligned mounds and possible playa deposits. 26

Terra Sirenum / Columbus crater. Lynch et al. 2015.
Diverse aqueous environments with the largest diversity of hydrated minerals in Columbus crater, including the only detection of jarosite and alunite, suggesting groundwater/ mineral interaction. Bathtub ring deposits, crater floor covered by a darker rock unit interpreted as a lava flow draped by fine-grained materials interpreted as regional aeolian loess.

27

Huygens crater. Ackiss et al. 2015. (2 proposals)
Landing site 1 has a larger phyllosilicate/carbonate deposit and mafic plains that can be age dated while Landing site 2 gives access to the crater wall and valley networks that flow into the crater. Carbonates within the Huygens basin are exposed by the cratering process and are associated with phyllosilicates.

28

Noctis Landing. Lee et al. 2015.
Canyon floors. Aqueous features and deposits, including sinous channels and valleys, slope gullies, lobate debris aprons, impact craters with lobate ejecta flows, and “bathtub ring” deposits.

29

Deuteronilus Mensae. Head et al. 2015.
Latitude-Dependent Mantle deposits on the crater floor (nearly pure ice intercalated with ice-cemented debris); ice in Lobate Debris Aprons and Lineated Valley Fill ; Hesperian/ Noachian Ridged Plains (basaltic) wrinkle-ridge-like structure; Noachian crater central peak.

30

Hellas rim. Rice et al. 2015.
Reull Vallis and valley networks. Noachian age massifs/mountains uplifted during the Hellas impact event. Hesperian age fluvial plains formed by the overbank flow of Reull Vallis. Amazonian age lobate debris aprons thought to be dust/debris covered glaciers, ice dominated deposits covered by a thin veneer of regolith likely formed during a recent climatic episode favorable to glacial processes.
31

Hellas rim 2. Levy and Holt 2015.
Ancient volcanic deposits and early martian material with evidence for ~3-4 Ga of hydrological activity. A lava-capped open basin lake, several large valley networks (shores and headwaters of Reull Valles). Rampart craters, possible eskers and supraglacial channels indicative of Amazonian-aged hydrological activity. Numerous lobate debris aprons composed of water ice

32

Deuteronilus Mensae. Plaut 2015.
Dichotomy boundary. Near a small massif partially surrounded by a lobate debris apron consisting primarily of nearly pure water ice hundreds of meters thick. Hesperian age plains terrain showing indications of periglacial processes; chaotic terrain that is interpreted to be a remnant of the central peak.

33

Ismenius Cavus. Mangold et al. 2015.
Fluvial and deltaic landforms, clay-bearing sedimentary deposits and glacial landforms. In Ismenius Cavus six valley networks converge including Mamers Vallis. Most valley floors are overlaid by lineated valley fills and lobate debris aprons. Layered unit contains iron-rich smectites. Phyllosilicates are found in meters-scale thick layers. Low albedo is due to pyroxene containing dark sand. Several deltaic landforms with sedimentary deposits that are bottom-sets of the paleolake. Arabia Terra dust is supposed to contain as much as 10% of water.

34

“Mesopotamia”. Gallegos and Newsom 2015a.
Between Niger/Dao Vallis and Harmakhis Vallis. Noachian age rocks within the moraines and till eroded from the high-relief massifs. Volcanic units. Negele Crater is a young, complex crater in Hesperian volcanics and possibly the ice-rich apron units.35

Hale Crater. Stillman et al. 2015.
Impact-induced hydrothermal activity: Hale formed in the Amazonian (>1 Ga) and released ~10 km3 of liquid water, fluvially modifying nearby channels. Hundreds of RSL occur in the large uplifted mountains of the crater’s central peak.36

W Noachis Terra. Hill and Christensen 2015.
The closest occurrence of chloride deposits to glacier-like forms. Chloride deposits are located at the center of an ~40km diameter basin with both inlet and outlet channels, suggesting it was once an overfilled paleolake system where water would have ponded and evaporite minerals could have formed. A ~25km diameter crater contains features associated with subsurface water ice, including lineated valley fill, pasted terrain, viscous crater fill, gullies, and possibly recurring slope lineae. Outcrops of Late Noachian material that lie within a region of remnant crustal magnetism.37

Arcadia Planitia. 38

Erebus Montes. Viola et al. 2015.
Within Amazonian lava flows, two different exposures of Hesperian-Noachian transition terrain. Evidence for glacial and periglacial landforms such as ice-altered secondary craters and ice-rich lobate debris aprons and a recent ice-exposing impact.39

Acheron Fossae. Viola et al. 2015.
A series of grabens and ridges surrounded by later Hesperian/Amazonian lava flows from the Tharsis region. Evidence for Amazonian glacial and periglacial activity. Meandering channel-like features in close proximity to apparent ice flow features. Material interpreted as rock glaciers on the floors of the grabens.

40

Newton Crater. Laine 2015.
Heavily cratered region with preserved crustal magnetism, that has ground ice present. Gullies.

41

Protonilus Mensae. Gallegos and Newsom 2015b.
Situated on the planetary dichotomy boundary (Noachian knobs and mesas and intervening Hesperian aprons). Moreux Crater with intense glacial modification, evidence for large amounts of H2O ice. Four large, unnamed outflow channels.42

Arcadia/Phlegra Dorsa. Barket et al. 2015.
Several ~10-15 km diameter fluidized ejecta craters and numerous exposures of hydrated minerals.43

Copernicus Crater. Westenberg and Zucker 2015.
Ancient crust, gullies and olivine dunes.
44

Ausonia Cavus. Hamilton et al. 2015.
At the beginning of Dao and Niger Valles, downslope of the Tyrrhenus Mons volcano. Hadriacus Mons. Ausonia Cavus and nearby Peraea Cavus may be paleolakes from the Hesperian. Ice-rich lobate debris features (glaciers covered with a layer of rocks and dust), glacial cirques, fan shaped deposits and drop moraines.45
Kasei Valles. Hamilton et al. 2015.
A Noachian drainage basin/aquifer system subsequently filled lava, sediments, and volatiles. Strong flow features, teardrop outcrops indicating depositional opportunities downslope with evidence for several episodes of flooding and possible glacial activity. Outflow channels show inner channels suggesting activity over a significant period of time and likely involved several separate flood events.

46

All maps by H Hargitai, NASA ARC.

 

References

Abstracts of the First Landing Site/Exploration Zone Workshop for Human Missions to the Surface of Mars (2015)

Blue Moon 2015: The new LOLA topographic map of the Moon

May 2, 2016

It may be the signature color for the next generation of planetary topographic maps.
In addition to standard geologic maps, USGS also produces outreach maps of planets and moons. The last in this series is the Image Mosaic and Topographic map of the Moon, released in April 2015. Its press release reached 3.3 million viewers, and it has printed 5000 copies so far for distribution.

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Trent Hare with the SIM3316 map at LPSC 2016

Lunar Colors

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Children’s maps exhibited at NASA Ames

April 28, 2016

This is our exhibit booth at NASA Ames Research Center on the “take your child to work day 2016”.

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kidscarto The website of our children’s planetary maps

Mapping the geomorphology of Sputnik Planum

April 25, 2016

“Looking at the surface of a planet or moon for the first time can be bewildering, particularly when confronted by a variety of terrains and landforms. This is certainly what NASA’s New Horizons team felt when we received the first close-up pictures of Pluto after the flyby in July 2015. None of us were expecting to see such a diverse range of landforms like mountains and glaciers of exotic ice on such a small, cold and distant world.

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Proposed Exploration Zones

April 22, 2016

This page contains overview maps all proposed Exploration Zones (EZ) (human landing sites for the 2035 Mars mission). The EZs are 200 km in diameter. More details here and here. Annotated version with geologic features here.

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Call for maps: Mars Exploration Zone Map Design Competition

April 22, 2016

International call for mapping candidate 2030s human landing sites on Mars.

What kind of map is needed to best aid human explorers of Mars? Design Exploration Zone maps and participate in planning the first human mission to Mars.

This call is open to students, cartographers, and graphic artists from all countries.

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The 2030s is the target decade for the first human visit to Mars as planned by NASA. In 2015, 47 landing sites or Exploration Zones (EZ), each 200 km in diameter, have been proposed by the planetary science community. These should be mapped in high detail in the forthcoming years to enable proper comparison of the 47 sites and the selection of the 1 finalist.

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