15 June 2019

Sols 2437-2439: An oasis of rock in a sea of pebbles

Posted by Ryan Anderson

The ridge, with Mount Sharp in the background


We are investigating the ridges which are such a prominent feature in this section of Glen Torridon. The ridges appear to be composed of sand and pebbles, capped with layered bedrock (see image above). The Rover Planners (RPs) at JPL assessed the ridge imaged, known as ‘Teal,’ and gave a GO for driving up onto it. We broke the ascent into two drives, aiming to get halfway in yestersol‘s plan (sol 2436) and the rest of the way in this weekend’s plan. The RPs got us exactly to where we wanted to be for this plan, and we ended up on a very small outcrop of more coherent bedrock, surrounded by pebbles and sand.

Those of us in the Geology theme group (GEO) were very excited to find ourselves here, as this is the most substantial piece of bedrock we have seen this week. APXS will analyze the ‘Iapetus’ target on the bedrock, and do a 2-point raster ‘Almond’ across small grey pebbles and sand. The rover was too close to Iapetus to allow ChemCam to shoot it with the LIBS laser without danger to the rover, so ChemCam focused on documenting pebbles here, looking at the targets ‘Angus,’ ‘Braan,’ and ‘Tweed.’ A Mastcam multispectral image, using multiple filter types, will examine spectral variability of the pebbles and sand between Tweed and Almond.

Before climbing up onto the ridge, Mastcam will take some colour imagery, looking at the rubbly material in the lower part of the ridge, and documenting the transition from the rubbly material to the capping material.

Our drive will hopefully take us to the bedrock in the left-hand side of the image. Once there, we will acquire imagery (Mastcam and Navcam) of our new workspace and future drive direction, to be ready for a full week of exploration on top of this ridge when we come back after the weekend. Mastcam will also get a post-drive image of the workspace under one of our wheels, as part of a long-running observation of bedrock, pebbles, and soils along our traverse.

The Environmental theme group (ENV) planned paired Mastcam observations for each sol of the plan, to determine the amount of dust in the crater (‘crater rim extinction’ measurements) and to measure the optical depth of the atmosphere and constrain aerosol scattering properties (‘full tau‘ measurements). The Rover Environmental Monitoring System (REMS) will acquire hourly temperature, pressure, humidity, and UV radiation measurements. DAN (Dynamic Albedo of Neutrons) continues its search for subsurface hydrogen, with frequent passive (utilizing cosmic rays as a source of neutrons to measure hydrogen) and post-drive active (actively shooting neutrons from the rover) measurements. Finally, ENV planned a number of movies, used to document clouds and dust devils. ‘Zenith’ cloud movies look upwards, whilst ‘suprahorizon’ movies look at clouds and variations in optical depth in a more horizontal direction. Dust devil movies can give information on surface heating and winds near the surface.

Written by Catherine O’Connell, Planetary Geologist at University of New Brunswick-Cooper