NASA's Mars Exploration Rover Mission (MER) is an ongoing robotic space mission involving two rovers, Spirit and Opportunity, exploring the planet Mars. It began in 2003 with the sending of the two rovers—MER-A Spirit and MER-B Opportunity—to explore the Martian surface and geology.
Objectives
The scientific objectives of the Mars Exploration Rover mission are to:
- Search for and characterize a variety of rocks and soils that hold clues to past water activity. In particular, samples sought include those that have minerals deposited by water-related processes such as precipitation, evaporation, sedimentary cementation, or hydrothermal activity.
- Determine the distribution and composition of minerals, rocks, and soils surrounding the landing sites.
- Determine what geologic processes have shaped the local terrain and influenced the chemistry. Such processes could include water or wind erosion, sedimentation, hydrothermal mechanisms, volcanism, and cratering.
- Perform calibration and validation of surface observations made by Mars Reconnaissance Orbiter instruments. This will help determine the accuracy and effectiveness of various instruments that survey Martian geology from orbit.
- Search for iron-containing minerals, and to identify and quantify relative amounts of specific mineral types that contain water or were formed in water, such as iron-bearing carbonates.
- Characterize the mineralogy and textures of rocks and soils to determine the processes that created them.
- Search for geological clues to the environmental conditions that existed when liquid water was present.
- Assess whether those environments were conducive to life.
During the next two decades, NASA will conduct several missions to
address whether life ever existed on Mars. The search begins with
determining whether the Martian environment was ever suitable for life.
Life, as humans understand it, requires water, hence the history of
water on Mars is critical to finding out if the Martian environment was
ever conducive to life. Although the Mars Exploration Rovers do not have
the ability to detect life directly, they offer important information
on the habitability of the environment in the planet's history
History
The probes were launched June and July 2003 and landed January 2004 in widely separated equatorial places on Mars.
On January 21, 2004, the Deep Space Network lost contact with Spirit,
for reasons originally thought to be related to
a thunderstorm over Australia. The rover transmitted a message with no
data, but later that day missed another communications session with
the Mars Global Surveyor. The next day, JPL received a beep from the
rover, indicating that it was in fault mode. On January 23, the flight
team succeeded in making the rover send. The fault was believed to have
been caused by an error in the rover's flash memory subsystem. The rover
did not perform any scientific activities for ten days, while engineers
updated its software and ran tests. The problem was corrected by
reformatting Spirit's flash memory and using a software patch to avoid memory overload; Opportunity was also upgraded with the patch as a precaution. Spirit returned to full scientific operations by February 5.
On March 23, 2004, a news conference was held announcing "major
discoveries" of evidence of past liquid water on the Martian surface. A
delegation of scientists showed pictures and data revealing a stratified
pattern and cross bedding in the rocks of the outcrop inside a crater
in Meridiani Planum, landing site of MER-B, Opportunity. This
suggested that water once flowed in the region. The irregular
distribution of chlorine and bromine also suggests that the place was
once the shoreline of a salty sea, now evaporated.
On April 8, 2004, NASA announced that it was extending the mission life
of the rovers from three to eight months. It immediately provided
additional funding of US $15 million through September, and $2.8 million
per month for continuing operations. Later that month, Opportunity arrived
at Endurance crater, taking about five days to drive the 200 meters.
NASA announced on September 22 that it was extending the mission life of
the rovers for another six months. Opportunity was to leave Endurance crater, visit its discarded heat shield, and proceed to Victoria crater. Spirit was to attempt to climb to the top of the Columbia Hills.
With the two rovers still functioning well, NASA later announced another 18 month extension of the mission to September 2006. Opportunitywas to visit the "Etched Terrain" and Spirit was to climb a rocky slope toward the top of Husband Hill. On August 21, 2005, Spirit reached the summit of Husband Hill after 581 sols and a journey of 4.81 kilometers (2.99 mi).
Spirit celebrated its one Martian year anniversary (669 sols or 687 Earth days) on November 20, 2005. Opportunity celebrated
its anniversary on December 12, 2005. At the beginning of the mission,
it was expected that the rovers would not survive much longer than 90
Martian days. The Columbia Hills were "just a dream", according to rover
driver Chris Leger. Spirit explored the semicircular rock
formation known as Home Plate. It is a layered rock outcrop that puzzles
and excites scientists. It is thought that its rocks are explosive
volcanic deposits, though other possibilities exist, including impact
deposits or sediment borne by wind or water.
Spirit's front right wheel ceased working on March 13, 2006,
while the rover was moving itself to McCool Hill. Its drivers attempted
to drag the dead wheel behind Spirit, but this only worked until
reaching an impassable sandy area on the lower slopes. Drivers directed Spirit to
a smaller sloped feature, dubbed "Low Ridge Haven", where it spent the
long Martian winter, waiting for spring and increased solar power levels
suitable for driving. That September, Opportunity reached the
rim of Victoria crater, and Spaceflight Now reported that NASA had
extended mission for the two rovers through September 2007. On February
6, 2007, Opportunity became the first spacecraft to traverse ten kilometers (10,000 meters) on the surface of Mars.
Opportunity was poised to enter Victoria Crater from its perch on
the rim of Duck Bay on June 28, 2007, but due to extensive dust storms,
it was delayed until the dust had cleared and power returned to safe
levels. Two months later, Spirit and Opportunity resumed
driving after hunkering down during raging dust storms that limited
solar power to a level that nearly caused the permanent failure of both
rovers.
On October 1, 2007, both Spirit and Opportunity entered
their fifth mission extension that extended operations into
2009, allowing the rovers to have spent five years exploring the Martian
surface, pending their continued survival.
On August 26, 2008, Opportunity began its three-day climb out of Victoria crater amidst concerns that power spikes, similar to those seen on Spirit before
the failure of its right-front wheel, might prevent it from ever being
able to leave the crater if a wheel failed. Project scientist Bruce
Banerdt also said, "We've done everything we entered Victoria Crater to
do and more." Opportunity will return to the plains in order to
characterize Meridiani Planum's vast diversity of rocks—some of which
may have been blasted out of craters such as Victoria. The rover had
been exploring Victoria Crater since September 11, 2007. As of January
2009, the two rovers had collectively sent back 250,000 images and
traveled over 21 kilometers (13 mi).
After driving about 3.2 kilometers (2.0 mi) since it left Victoria crater, Opportunity first
saw the rim of Endeavour crater on March 7, 2009. It passed the 10-mile
mark (16 kilometers) along the way on sol 1897.Meanwhile, at Gusev
crater, Spirit was dug in deep into the Martian sand, much as Opportunity was at Purgatory Dune in 2005.
On January 3 and January 24, 2010, Spirit and Opportunity marked six years on Mars, respectively. On January 26, NASA announced that Spirit will be used as a stationary research platform after several months of unsuccessful attempts to free the rover from soft sand.
NASA announced on March 24, 2010, that Opportunity, which has an
estimated remaining drive distance of 12 km to Endeavour Crater, has
traveled over 20 km since the start of its mission. Each rover was
designed with a mission driving distance goal of just 600 meters.One
week later, they announced that Spirit may have gone into hibernation for the Martian winter and might not wake up again for months.
On September 8, 2010, it was announced that Opportunity had reached the halfway point of the 19-kilometer journey between Victoria crater and Endeavour crater.
On May 24, 2011, NASA announced that it will cease attempts to contact Spirit,
which has been stuck in a sand trap for two years. The last successful
communication with the rover was on March 22, 2010. The final
transmission to the rover was on May 25, 2011.
Design and construction
Spirit (and its twin, Opportunity)
are six-wheeled, solar-powered robots standing 1.5 m (4.9 ft) high,
2.3 m (7.5 ft) wide and 1.6 m (5.2 ft) long and weighing 180 kg
(400 lb). Six wheels on arocker-bogie system enable mobility over rough
terrain. Each wheel has its own motor. The vehicle is steered at front
and rear and is designed to operate safely at tilts of up to 30 degrees.
Maximum speed is 50 mm/s (2 in/s);0.18 km/h, although average speed is
about 10 mm/s (0.4 in/s). Both Spirit and Opportunity have
pieces of the fallen World Trade Center's metal on them which were
"turned into shields to protect cables on the drilling mechanisms".
Solar
arrays generate about 140 watts for up to four hours per Martian day
(sol) while rechargeable lithium ion batteries store energy for use at
night. Spirit's onboard computer uses a 20 MHz RAD6000 CPU with
128 MB of DRAM, 3 MB of EEPROM, and 256 MB of flash memory. The
rover's operating temperature ranges from −40 °C to +40 °C (−40 °F to
104 °F) andradioisotope heater units provide a base level of heating,
assisted by electrical heaters when necessary. A gold film and a layer
of silica aerogel provide insulation.
Communications
depends on an omnidirectional low-gain antenna communicating at a low
data rate and a steerable high-gain antenna, both in direct contact with
Earth. A low gain antenna is also used to relay data to spacecraft
orbiting Mars.
Fixed science instruments include
- Panoramic Camera (Pancam) – examines the texture, color, mineralogy, and structure of the local terrain.
- Navigation Camera (Navcam) – monochrome with a higher field of view but lower resolution, for navigation and driving.
- Miniature Thermal Emission Spectrometer (Mini-TES) – identifies promising rocks and soils for closer examination, and determines the processes that formed them.
The rover arm holds the following instruments
- Mössbauer spectrometer (MB) MIMOS II – used for close-up investigations of the mineralogy of iron-bearing rocks and soils.
- Alpha particle X-ray spectrometer (APXS) – close-up analysis of the abundances of elements that make up rocks and soils.
- Magnets – for collecting magnetic dust particles.
- Microscopic Imager (MI) – obtains close-up, high-resolution images of rocks and soils.
- Rock Abrasion Tool (RAT) – exposes fresh material for examination by instruments on board.
The cameras produce 1024-pixel by 1024-pixel images, the data is compressed, stored, and transmitted later.
- MER - A Spirit
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| The launch patch for Spirit, featuring Marvin the Martian |
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| Artist's conception of rover on Mars |
Spirit, MER-A (Mars Exploration Rover – A), active from 2004 to 2010. It was one of two rovers of NASA's ongoing Mars Exploration Rover Mission. It landed successfully on Mars at 04:35 Ground UTC on January 4, 2004, three weeks before its twin, Opportunity (MER-B), landed on the other side of the planet. Its name was chosen through a NASA-sponsored student essay competition. The rover became stuck in late 2009, and its last communication with Earth was sent on March 22, 2010.
The
rover completed its planned 90-sol mission. Aided by cleaning
events that resulted in higher power from its solar panels, Spirit went
on to function effectively over twenty times longer than NASA planners
expected following mission completion. Spirit also logged 7.73 km
(4.8 mi) of driving instead of the planned 600 m (0.4 mi), allowing more
extensive geological analysis of Martian rocks and planetary surface
features. Initial scientific results from the first phase of the mission
(the 90-sol prime mission) were published in a special issue of the
journal Science.
On
May 1, 2009 (5 years, 3 months, 27 Earth days after landing; 21.6 times
the planned mission duration), Spirit became stuck in soft soil. This
was not the first of the mission's "embedding events" and for the
following eight months NASA carefully analyzed the situation, running
Earth-based theoretical and practical simulations, and finally
programming the rover to make extrication drives in an attempt to free
itself. These efforts continued until January 26, 2010 when NASA
officials announced that the rover was likely irrecoverably obstructed
by its location in soft soil, though it continued to perform scientific research from its current location.
The rover
continued in a stationary science platform role until communication with
Spirit stopped on sol 2210 (March 22, 2010). JPL continued to attempt
to regain contact until May 24, 2011, when NASA announced that efforts
to communicate with the unresponsive rover had ended. A formal farewell
was planned at NASA headquarters after the Memorial Day holiday and was
televised on NASA TV.
Mission overview
The primary surface mission for Spirit was planned to last at least 90 sols. The mission received several extensions and lasted about 2,208 sols. On August 11, 2007, Spirit obtained
the second longest operational duration on the surface of Mars for a
lander or rover at 1282 Sols, one Sol longer than the Viking 2 lander.
Viking 2 was powered by a nuclear cell whereas Spirit is powered by solar arrays. Until Opportunity overtook
it on May 19, 2010, the Mars probe with longest operational period
was Viking 1 which lasted for 2245 Sols on the surface of Mars. On March
22, 2010, Spirit sent its last communication, thus falling just
over a month short of surpassing Viking 1's operational record. An
archive of weekly updates on the rover's status can be found at the Spirit Update Archive.
Spirit's total odometry as of March 22, 2010 (sol 2210) is 7,730.50 meters (4.80 mi).
- MER - B Opportunity
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| The launch patch for Opportunity, featuring Duck Dodgers (Daffy Duck). |
Opportunity, MER-B (Mars Exploration Rover – B),
is a robotic rover on the planet Mars, active since 2004. Launched
from Earth on July 7, 2003, it landed on Meridiani Planum on January 25,
2004 at 05:05 Ground UTC (about 13:
15 local time). This was three weeks after its twin Spirit (MER-A),
also part of NASA's Mars Exploration Rover Mission, touched down on the
other side of the planet. Its twin became immobile in 2009 and in 2010
ceased communications, but MER-B is still active as of 2012, having
already exceeded its planned duration of activity thirty times over.
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| Opportunity in April 2003 (Before Launch) |
Mission highlights include completion of the 90 Sol (90 Martian days) mission, discovery of an extramartian meteorite (Meridiani Planum),
and over two years studying Victoria crater. It survived dust-storms in
2007 and reached Endeavour crater in 2011, which has been described as
the equivalent of a "second landing site". After conducting stationary
science in the bleak winter months, it began moving again in May 2012.
Mission overview
The primary surface mission for Opportunity was planned to last
90 sols. The mission has received several extensions and has been
operating for 3125 days since landing. An archive of weekly updates on
the rover's status can be found at the OpportunityUpdate Archive.
From its initial landing, by chance, into an impact crater amidst an otherwise generally flat plain,Opportunity has
successfully investigated soil and rock samples and taken panoramic
photos of its landing site. Its sampling allowed NASA scientists to make
hypotheses concerning the presence of hematite and past presence of
water on the surface of Mars. Following this, it was directed to travel
across the surface of Mars to investigate another crater site,Endurance
crater, which it investigated from June – December 2004. Subsequently, Opportunity examined
the impact site of its own heat shield and discovered an
intact meteorite, now known as Heat Shield Rock, on the surface of Mars.
From late April 2005 to early June of that year, Opportunity was
perilously lodged in a sand dune, with several wheels buried in the
sand. Over a six week period Earth-based physical simulations were
performed to decide how best to extract the rover from its position
without risking a permanent immobilization of the valuable vehicle.
Successful maneuvering a few centimeters at a time eventually freed the
rover, which resumed its travels.
Opportunity was directed to proceed in a southerly direction
to Erebus crater, a large, shallow, partially buried crater and a
stopover on the way south towards Victoria crater, between October 2005
and March 2006. It experienced some mechanical problems with its robotic
arm.
In late September 2006, Opportunity reached Victoria crater and explored along the rim in a clockwise direction. In June 2007 it returned to Duck Bay, its original arrival point; in September 2007 it entered the crater to begin a detailed study. In August 2008, Opportunity left Victoria crater for Endeavour crater, which it reached on August 9, 2011.
Opportunity's total odometry as of July 24, 2012 (sol 3022) is 34,633.40 meters (21.52 mi).
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SOURCE: Wikipedia & NASA
By:Agas
By:Agas
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