Environmental monitoring and investigations in Gale Crater by MSL:

Highlights from the first 360 sols

Claire Newman (Ashima Research) and the MSL Science Team

with special thanks to members of the MSL Environmental Working Group

Overview of MSL’s environmental instrument suite

Dedicated environmental sensors on MSL

The Rover Environmental Monitoring Station

(REMS)

(E) UV sensor on the rover deck

(B) Wind sensor on boom 1 (not shown, and was damaged on landing) and boom 2 (shown)

(F) Pressure sensor inside the rover body

(C) Relative humidity sensor on boom 2

In this self-portrait,

boom 1 is hidden

behind the rover mast

(D) Air temperature sensor on boom 1 (not shown) and boom 2 (shown)

(A) Ground temperature sensor on boom 1 (not shown)

The Radiation Assessment Detector

(RAD)

[see later talk by Zeitlin et al.]

Measures a broad spectrum of energetic

particle radiation

Dedicated environmental sensors on MSL

The Dynamic Albedo of Neutrons

instrument(DAN)

Measures thermal and epithermal neutrons to infer sub-surface water abundance and (in active mode) vertical distribution in 1st ~m below surface

Dedicated environmental sensors on MSL

Pulsed neutron generator (used in active mode)

[see later talks by Litvak et al. and Moersch et al.]

Detector and electronics

• ChemCam spectroscopy [see e.g. Wednesday talk by Mcconnochie et al.]

• Sample Analysis at Mars (SAM) instrument [see e.g. later talks by Mahaffy et al. and Webster et al.]

Many investigations also being performed by:

• MSL’s cameras (Mastcam, Navcam, MAHLI, …) [see e.g. previous talk by Bell et al.]

Why do we care about the environment in Gale Crater?

• Gives context for wide range of studies & experiments

• Provides data for future mission planning

• Massively expands record of in situ Mars meteorology

• Measuring the current environment helps identify ancient vs. new features and processes

• Understanding the current environment is vital for extrapolating to the past

• Provides insight into past climate states

Motivation for environmental monitoring

Selected highlights from MSL’s environmental investigations

Water in the atmosphere [REMS RH]Diurnal cycles of temperature and relative humidity over three sols

NOTE: Data are preliminary. See Harri et al., JGR (2013) for more details of the RH sensor

Local time of day00:00 12:00 00:00 12:00 00:00 12:00 00:00

sol 15 sol 16 sol 17

RH simulated for vmr = 140 ppmRH simulated for vmr = 100 ppmRH simulated for vmr = 60 ppm

Measured RHTemperature (K)

Rela

tive

hum

idity

100

50

-50

0

Tem

pera

ture

(°C)

0

-20

-40

-60

-80

-100

Water in the atmosphere [REMS RH]

Mission sol0 50 100 150 200 250 300 350

Volu

me

mix

ing

ratio

(ppm

)

20

40

60

80

100

120

140

Tem

pera

ture

(°C)

-80

-70

-60

Leave blast zone

Arrive in Rocknest

Leave Rocknest

Arrive at Yelloknife

Start rapid transit route

Seasonal evolution of early morning temperature and water volume mixing ratio consistent with orbital data

Southern spring Southern summerSouthern Winter

NOTE: Data are preliminary. See Harri et al., JGR (2013) for more details of the RH sensor

Water in the surface [DAN]

DAN modeled weight % water along rover track

Most DAN active data fit a 2-layer model with a relatively water-poor top layer; wt% consistent with SAM soil analysis

water in top layer (~top 10-20cm)

water in bottom layer

See later talks by Litvak and Moersch, and papers by Jun, Litvak, and Mitrofanov, et al., JGR (2013)

Aeolian features and processes [cameras]

JakeMatijevic rock

Rocknest ‘sand shadow’ Obstacles

Ventifacts in HottahDunes near Mount Sharp (from orbit)

sand

Inferred directions wind comes from based on ventifact orientations[From Bridges et al., JGR (2013)]

Plausible wind directions based on dune morphology

Sol 38-55

Sol 55-120

Sol 121-160

N09:00-10:00 13:00-14:00

18:00-19:00 21:00-22:00

REMS wind directions at 4 times of day in 3 periods

REMS team

Aeolian features and processes [REMS wind]

• REMS (and model) wind directions more consistent with winds implied by dunes than by rock abrasion features [see tomorrow’s Bridges et al. poster]• May indicate dunes more recent, while rocks hold record of ancient winds

If change detected => REMS peak winds give upper limit on thresholdIf NO change seen => REMS peak winds give lower limit on threshold

Found NO change between images, and peak REMS winds ~16m/sSuggests surface stress must exceed ~0.02-0.04 Pa for particles to move

Image1: sol 232, 12:03 LMST Image2: sol 232, 12:46 LMST

Aeolian features and processes [REMS, Mastcam]

Experiments to estimate threshold for particle motion:Constant REMS wind monitoring between 2 Mastcam images

3 sets of experiments, each using a pair of images of a post-drilling dump pile

N

Sol 38-55

Sol 55-120

Sol 121-160

N09:00-10:00 13:00-14:00

18:00-19:00 21:00-22:00

As shown before, flow is not simply ‘daytime upslope / nighttime downslope’ with respect to Mount Sharp

REMS team

Downslope during the day

Upslope at night

Topography and the circulation [REMS wind]

Enhanced daily range in REMS surface pressure compared to ALL prior landing sites measured

3 sols of pressure data

sol 9

2 sols of pressure data

Schofield et al., 1997

Pres

sure

(Pa)

650

660

670

680

sol 19

Mars Pathfinder MSL

Peak amplitude ~ 4.5%

Peak amplitude ~ 13%

Topography and the circulation [REMS pressure]

Main cause is hydrostatic adjustment along major slopes in Gale in response to daily air temperature cycle [Richardson et al., JGR 2013]

Haberle et al. 2013b

Modeling REMS’s daily ground temperature cycle

• Vary model parameters – e.g. thermal inertia, albedo, atmospheric opacity – until find best fit to observations• Overall, best fit parameters are consistent with sand-sized soil particles• Remaining mismatches suggest a more complex response to incident solar insolation, due to e.g. sub-surface layering

Hour (LMST)0 4 8 12 16 20 24

Hour (LMST) Hour (LMST)0 4 8 12 16 20 24 0 4 8 12 16 20 24

Surface properties [REMS Tground]

See e.g. Renno/Martinez et al. poster on Tuesday, Hamilton et al. poster on Thursday, Vasavada talk on Friday, and upcoming Hamilton et al. JGR paper

See Hamilton et al. poster on Thursday

Observed daily δTground and contours of predicted δTground as a function of season and thermal inertia (assuming constant albedo and opacity)

Mission sol

Dai

ly m

ax-m

in g

roun

d te

mp

(K)

0 50 100 150 200 250 300 350

100

95

90

85

80

75

70

65

60

Surface properties [REMS Tground]

Atmospheric dust and impact [Mastcam]

MSL Mastcam opacities are very similar to those at Opportunity, except during e.g. the Ls~208° regional storm

Courtesy of Mark Lemmon

MSL and Opportunity visible opacities up to ~sol 350

In fact, storm onset was first detected via

the increased amplitude of the

semi-diurnal pressure tide (shown in black)

0 4 8 12 16 20 24 Hour, LMST

Pres

sure

, Pa

880870860850840830820810800790780770

REMS semi-diurnal pressure tide amplitude Opportunity optical depth THEMIS 9μm optical depth x5 MSL optical depth

*

+

Nor

mal

ized

tidal

am

plitu

de (%

)

Opti

cal d

epth

Big change in shape of daily pressure cycle

from sol 96 to sol 97 as a regional dust storm

develops near Gale

sol 96sol 97

From Haberle et al. 2013b

Atmospheric dust and impact [REMS pressure]

• REMS has measured dozens of vortices in pressure data• A few may also be associated with small fluctuations in UV• However, NO definitive dust devils have yet been imaged

Atmospheric dust and impact [REMS, Navcam]

Signature of vortex passage in REMS pressure data

From Harri et al., 2013a

Courtesy of Henrik

Kahanpää

Vortex incidence around noon (11am-1pm LMST)

Dust devils (dust-filled convective vortices) are thought to be important for ‘background’ dust lifting on Mars

And many more studies and findings…

• SAM atmosphere and rock isotope studies provide insight into past environment in Gale [see earlier Mahaffy et al. talk]

• RAD monitoring shows impact of solar cycle and air mass on surface radiation environment [see later Zeitlin et al. talk]

• MSL environmental data are helping calibrate present day Mars models & improving their ability to simulate the past

• Stay tuned for lots more from MSL’s environmental instruments and investigations!

• First comprehensive environmental monitoring instrument suite to be landed on the Martian surface

• First UV and energetic particle radiation measurements from the surface of Mars

• First measurements of sub-surface water abundance and distribution from the surface of Mars

• First attempt to measure threshold for particle motion on Mars

• Gale Crater is first landing site to provide ability to study the effects of major topography on the environment

• First comprehensive 1Hz meteorological dataset for Mars

• Also first surface meteorology since Phoenix, and first long-term environmental monitoring since Viking

Firsts for MSL’s environmental investigations