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Update on the Mars Exploration Rovers

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Will look for evidence of water by observing and dissecting Martian rocks and soils. Each rover has a suite of ... Infrared spectrograph mounted in the mast ... – PowerPoint PPT presentation

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Title: Update on the Mars Exploration Rovers


1
Update on the Mars Exploration Rovers
  • University of Pennsylvania
  • Peter Allen

2
Outline
  • Goals
  • Landing Sites
  • Getting There
  • The Rovers and their Instruments
  • Science so far
  • The Future

3
Goals of the Mission
  • To find evidence of previous (or current) liquid
    water on the surface of Mars
  • Note NOT looking for life!

4
Goals cont.
  • Will look for evidence of water by observing and
    dissecting Martian rocks and soils
  • Each rover has a suite of instruments (more
    later)
  • Also ground observations will provide
    calibrations of orbital observations

5
Landing Sites
  • Need landing sites that allow us to explore for
    previous water
  • Chose two sites on opposites sides of the planet
  • Gusev Crater Possible site of an ancient lake
  • Meridiani Planum Large Hematite deposits seen
    from orbit

6
Landing Sites
7
Gusev Landing Site (Spirit)
8
Meridiani Site (Opportunity)
9
Meridiani Landing Site
10
Getting There
  • Three general stages
  • Launch (Nail biting)
  • Cruise (Boring)
  • Entry Landing (Nails re-grown over six months
    to bite again)

11
Launch
  • Each rover had narrow launch windows to arrive at
    their destinations (3 weeks)
  • Spirit (launched June 10th 2003) on a Delta-II
  • Opportunity (launched July 7th 2003) on a
    Delta-IIH
  • Opportunitys later launch date put Mars further
    away hence more energy needed to get there

12
Cruise
  • Long, cold, and dark (7 months)

13
Entry Landing
  • Takes about 6 minutes to reach ground
  • Enters at 12000 mph and reaches temperatures of
    1500K
  • Bounces and rolls for up to a km
  • See Movie

14
The Rover
  • Each rover is 185 kg and roughly the size of a
    small go-kart with a five foot mast
  • Solar panels provide a maximum of 140 W at noon
    (cf 16 W on Sojourner)
  • Nominal battery recharge lifetime of 90 sols
    (recently upgraded to 180 sols)
  • Can travel upwards of 40 m a sol

15
The Rover
16
Instruments
  • PANCAM (Panoramic Camera)
  • Pair of high-res CCDs on top of mast
  • Allows 3D imaging of surroundings
  • Used to scan for interesting sites to visit

Bonneville crater (current site of Spirit Rover)
17
Instruments cont.
  • Microscopic Imager (MI)
  • A microscope with a CCD attached to the end
    (opposite of what we are used to)
  • Attached to Rover arm (1 of 4 instruments)
  • Provides detailed images of rock and soil
    surfaces
  • Determines size and shape of grains and pebbles

18
Instruments cont.
  • Miniature Thermal Emission Spectrometer
    (Mini-TES)
  • Infrared spectrograph mounted in the mast
  • Scanning mirror sends light down mast, looks
    where Pancam looks
  • Used to determine mineral composition from a
    distance
  • Particularly looking for minerals formed by water
    action

19
Instruments cont.
  • Mossbauer Spectrometer (MS)
  • Sensor mounted on rover arm.
  • Takes 12 hours to perform a single measurement
  • Used to study mineral composition of rocks close
    up
  • Particularly looking at iron rich minerals, if
    hydrated might be from water action

20
Instruments cont.
  • Alpha Particle X-ray Spectrometer (APXS)
  • Sensor mounted on rover arm
  • Used to study emission from rocks
  • Can yield information about composition,
    formation, and weathering
  • Usually makes measurements at night (avoid solar
    background?)

21
Instruments cont.
  • Rock Abrasion Tool (RAT)
  • Mounted on rover arm
  • Diamond grinding wheels capable of digging a 45mm
    diameter hole 5mm deep in 2 hours
  • Used to expose fresh rock surfaces for study
  • Important to look at un-weathered rock

22
Instruments cont.
  • Magnet Arrays (MA)
  • Three sets of magnets rover arm, front of rover,
    and rover top
  • Used to study air-born magnetic dust
  • The freeze-dried remains of water created
    minerals?

23
Instruments cont.
  • Calibration Targets
  • Each instrument has internal calibrators
  • Pancams is unique it is a working sundial!
  • Children designed the artwork on the surface
  • Says Mars in sixteen languages
  • Original idea by Bill Nye (Yes, the Science Guy)

24
Instruments cont.
25
Typical Rover Day
  • Wake up with Sun
  • Perform tasks (spectra integrations, imaging, or
    roving)
  • Take naps (power downs to allow solar panels to
    recharge batteries)
  • More science
  • Power down for the night, also do long MS or APXS
    integrations overnight

26
Science with Spirit
  • After rolling off the lander Spirit went to the
    rock dubbed Adirondack
  • Found olivine, a mineral that doesnt weather
    well
  • Soil very sticky, evidence of a lot of salts

27
Science with Spirit
  • Just as Spirit begins investigating Adirondack it
    ceases communication
  • Turned out to be a problem with the flash memory
  • Files built up in flash memory causing the rover
    to continuously reboot
  • Took 10 days to recover sufficiently to continue
    science operations

28
Science with Spirit
  • Moved on from Adirondack and dug a hole with its
    front left wheel
  • More sticky soil found
  • Evidence that soil has expanded and contracted
    repeatedly
  • Caused by heating/cooling, freezing/ thawing, or
    salty liquid rising/falling

MI image of area before hole was dug
29
Science with Spirit
  • Next moved on to new rock Humphrey
  • 3/5/04 Spirit too finds evidence of water
  • Scratched Humphrey with RAT to reveal bright salt
    crystals

30
Science with Spirit
  • Humphrey is a volcanic rock with bright crystal
    structures
  • Implies water flowed through it
  • Either water came with magma that formed it or it
    was submerged later on
  • Much less than the water reported from Opportunity

MI image of scratched Humphrey
31
Science with Spirit
  • Approaching a crater within Gusev, Bonneville
  • Currently exploring the crater rim
  • Took image of Earth from Mars (A first from the
    surface of any other planet)

32
Science with Opportunity
  • Experience with Spirit allows Opportunity to get
    off its lander in 7 days (cf 12 w/Spirit)
  • Landed in a small crater with layered bedrock
    nearby!
  • Bedrock is only 8m away and is 0.5m tall

33
Science with Opportunity
  • Rolls off lander and examines soil
  • Finds spherical grains could be impact,
    volcanic, or water action in origin

34
Science with Opportunity
  • Next drives up to Opportunity Ledge to survey
    it for more detailed study later
  • MI finds similar spherical grains (blueberries)
    embedded in the rock
  • Spends 2 weeks surveying

35
Science with Opportunity
  • Press silence from NASA on rovers between 2/26
    and 3/2
  • Then they announce definitive evidence that this
    rock on Mars was once soaked in liquid water for
    long amounts of time
  • Investigation centered on the rock El Capitan

36
Science with Opportunity
  • Many lines of evidence intersect
  • The blueberries are uniformly spread through the
    rock, not layered.
  • Highest concentrations of salt compounds ever
    found on Mars (particularly sulfur)
  • Hydrated iron mineral jarosite found
  • Wavy structures in the rock suggest water action
  • Vugs cavities left behind when salt crystals
    deposited in rock either erode of dissolve in
    less salty water

37
Science with Opportunity
Pancam image of Last Chance. The rippling
structures are too small to have been formed by
wind therefore moving water is the only other
explanation
38
Science with Opportunity
  • Vugs in El Capitan

39
Science with Opportunity
  • After spending 2-3 weeks near El Capitan
    Opportunity moves on
  • Observes Solar eclipses by both of Mars moons,
    Phobos and Deimos, with Pancam

40
Science with Opportunity
  • Just after leaving the lander surveyed the crater
    with Mini-TES to look for Hematite (red high,
    blue low
  • Now testing soil samples in areas abundant in
    hematite
  • Hematite most commonly forms on Earth in liquid
    water

41
Science with Opportunity
  • Last week took Mossbauer spectrum of the
    blueberries
  • Found to have a large percentage of hematite!
  • Yet another confirmation of the water soaked
    hypothesis

42
The Future of Spirit
  • Continue to explore rim of Bonneville crater
  • Currently digging in the martian soil and
    studying the rocks around the crater rim

43
The Future of Opportunity
  • Explore nearby hematite deposits
  • Head out onto the hematite rich plain towards
    large crater Endurance (720m)

44
The Future of Opportunity
45
Lifetime of the Rovers
  • Initially capped at 90 sols
  • Recently extended to 180 sols because of greater
    than expected performance and less dust settling
    on the solar panels
  • Spirit in Sol 80 and Opportunity in Sol 59
  • We can expect 3-5 months of more productive
    returns from these rovers
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