Posted on by Abby Cessna

What are the Sizes of the Planets?

Size of the planets compared.

It is often difficult to grasp just how large the planets actually are. There are a number of ways to measure a planet, including diameter, volume, and surface area.

Mercury is the smallest planet in our Solar System since Pluto was demoted to a dwarf planet. It has a diameter of 4,879 km, and a surface area of 17.48 x 107 km2, which is only about 11% of Earth’s surface area. Mercury’s volume is even smaller in comparison at 6.083 x 1010 km3, which is only 5.4% the volume of Earth.

Venus is similar in size to Earth, which earned it the title of Earth’s twin. Venus has a diameter of 12,100 km and a surface area of 4.6 x 108 km2. These measurements are 95% and 90% of Earth’s diameter and surface area respectively. With a volume of 9.38 x 1011 km3, Venus’ volume is 86% of  Earth’s.

Earth has a diameter of 12,742 km and a surface area of 5.1 x 108 km2. Its volume of 1.08 x 1012 km3 gives the planet the largest volume of any of the terrestrial planets.

Mars is also a small planet, the second smallest in our Solar System. Mars’ diameter is 6,792 km, only about 53% of Earth’s diameter. At only 28% of Earth’s surface area, Mars has a very small surface area of 1.45 x 108 km2. Mars’ volume of 1.63 x 1011 km3 is only 15% of Earth’s volume.

All of the gas giants are larger in size than the four inner planets. Jupiter is the largest planet in our Solar System. It has a diameter of 143,000 km, which is more than 11 times the size of Earth’s diameter. The numbers only get larger from there. Jupiter has a surface area of 6.22 x 1010 km2. That is 122 times greater than Earth’s surface area. Jupiter’s volume of 1.43 x 1015 km3 is an incredible number. You can fit 1321 Earths inside Jupiter.

Saturn is the second largest planet in our Solar System. It has a diameter of 120,536 km across the equator, and a surface area of 4.27 x 1010 km2. With a volume of 8.27 x 1014 km3, Saturn can hold 764 Earths inside.

Uranus has a diameter of 51,118 km and a surface area of 8.1 x 109 km2. Although Uranus is much smaller than Jupiter, it is still large. With a volume of 6.83 x 1013 km3, you could fit 63 Earths inside the gas giant.

Neptune is slightly smaller than Uranus, but still very large. The planet has a diameter of 49,500 km. You could fit 57.7 Earths inside Neptune, which has a volume of 6.25 x1013 km3.  Neptune has a surface area of 7.64 x 109 km2, which is 15 times Earth’s surface area.

We have written many interesting articles about the Solar Planets here at Universe Today. Here’s tWhat are the Different Masses of the Planets?, What Is The Atmosphere Like On Other Planets?, What is the Average Surface Temperatures of the Planets? and What are the Diameters of the Planets?

For more information, check out this website to learn all about the planets and this page from NASA to learn about the planets.

Astronomy Cast has an episode on each of the planets including Mercury.

Posted on by Abby Cessna

Weight on Other Planets

Planets and other objects in our Solar System. Credit: NASA.

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Many children, and even adults, dream of visiting other planets and wonder what it would be like to stand on another planet. For one thing, your weight would be different on another planet, depending on a number of factors including the mass of the planet and how far you are away from the center of the planet.

Before we start, it’s important to understand that the kilogram is actually a measurement of your mass. And your mass doesn’t change when you go anywhere in the Universe and experience different amounts of gravity. Your weight is best measured in newtons. But since your bathroom doesn’t measure your weight in newtons, we’ll use kilograms. This is what your bathroom scale would say if you stepped on another world.

Mercury is the smallest planet in our Solar System, but it is dense. Because Mercury is so small, it has very little gravity. If you weighed 68 kg on Earth, you would only weigh 25.7 kg on Mercury. 

Venus is very close to Earth in size and mass. Venus’ mass is roughly 90% of the mass of the Earth. Thus, it is no surprise that someone would weigh a similar amount on Venus. Someone who weighed 68 kg on Earth would weigh 61.6 kg on Venus.

Mars is quite a bit smaller than Earth with only 11% of our planet’s mass. Mars is larger than Mercury, but it is not as dense as the smaller planet. If you weighed 68 kg on Earth then you would weigh 25.6 kg on Mars. Since Pluto was demoted to a dwarf planet, Mars became the planet where you would weigh the least.

Jupiter is the largest planet in our Solar System with the most mass. Because of Jupiter’s mass, you would weigh more on that planet than on any other one in our Solar System. If you weighed 68 kg on Earth then you would weigh 160.7 kg on Jupiter, over twice your normal weight. That is if you could actually stand on Jupiter’s surface, which is impossible because it is a gas giant, and gas giants do not have solid surfaces.

Saturn is a gas giant best known for its planetary rings system. It is also the second biggest planet in our Solar System. Despite its mass though, the planet has a very low density and a lower gravity than Earth. If you weighed 68 kg on Earth, you would weigh 72.3 kg on Saturn.

Uranus is a gas giant without a solid surface. Although Uranus is larger in size than Neptune, it has less mass and therefore less gravity. You would only weigh 60.4 kg on Uranus, if you weighed 68 kg on Earth.

Neptune, the last planet in our Solar System, is a gas giant. If you weighed 68 kg on Earth, then you would weigh 76.5 kg on Neptune if you could stand on the planet’s surface.

Although the Moon is not a planet, it is one of the few objects that astronauts have actually visited. Because the Moon is so small, it has a low density and low gravity. If you weighed 68 kg on Earth, then you would only weigh 11.2 kg on the Moon.

Universe Today has a number of articles to check out including weight on the moon and mass of the planets.

If you are looking for more information then determine your weight on other planets and facts about the planets.

Astronomy Cast has an episode on gravity.

Posted on by Nancy Atkinson

Crew Emerges from Simulated Mars Mission

The Mars 500 crew at the halfway point of their mission. Credit: ESA

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Six crewmembers emerged from 105 days of isolation on Tuesday, completing a simulated Mars mission. This experiment was the first phase of the Mars 500 program to help understand the psychological and medical aspects of long spaceflights. “We have successfully completed our mission,” said crew member Oliver Knickel. “This is a big accomplishment that I am very proud of. I hope that the scientific data we have provided over the last months will help to make a mission to Mars possible.”
 
The simulated mission began on March 31 of this year. Inside the isolation facility in Moscow, Russia the crew participated in a range of scenarios as if they really were traveling to the Red Planet – including launch, the outward journey, arrival, transfer to and from the Martian surface, simulated emergencies, and finally the long journey home.

All communications with anyone outside the facility had a delay of up to 20 minutes each way, just as a real mission to Mars would have. The only thing missing was microgravity during the simulated flight and one-third of Earth’s gravity during the simulated time on Mars. Plus, of course, the crew never faced any of the real dangers of launch, spaceflight, landing or living on a planet hostile to human life.

The crew includes Knickel, a mechanical engineer in the German army, Cyrille Fournier, an airline pilot from France and four Russians: cosmonauts Sergei Ryazansky (commander) and Oleg Artemyev, Alexei Baranov, a medical doctor, and Alexei Shpakov, a sports physiologist.

An external view of the Module for Mars 500 Image Credit: ESA
An external view of the Module for Mars 500 Image Credit: ESA

The crew grew some of their own food to supplement the usual space-style pre-packaged meals. Any spare time was spent reading, watching films and playing music and games together.
 
 
“We had an outstanding team spirit throughout the entire 105 days,” said Cyrille Fournier. “Living for that long in a confined environment can only work if the crew is really getting along with each other. The crew is the crucial key to mission success, which became very evident to me during the 105 days.”
 
This initial 105-day study is the precursor to a complete simulation of a fully-fledged mission to Mars and back due to start in early 2010. That exercise will see another six-member crew sealed in the same chamber to experience a complete 520-day Mars mission.

Source: ESA

Posted on by Nancy Atkinson

Going to Mars Together

Mars. Credit: NASA

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From the “this makes complete sense” department: NASA and ESA have established an initiative to make future explorations of Mars a joint venture. The ESA Director of Science and Robotic Exploration, David Southwood, met with NASA’s Associate Administrator for Science, Ed Weiler at the end of June and created the Mars Exploration Joint Initiative (MEJI) that will provide a framework for the two agencies to define and implement their scientific, programmatic and technological goals at Mars. The initiative includes launch opportunities in 2016, 2018 and 2020, with landers and orbiters conducting astrobiological, geological, geophysical and other high-priority investigations, leading up to a sample return mission in the 2020s.

Both NASA and ESA have been reassessing their Mars exploration programs, and Weiller revealed at a press conference last year (when it was announced that the Mars Science Laboratory would be delayed) that NASA and ESA would seek to work together. But now it is official.

The two space agencies will be working together to plan future missions. A joint architecture review team will be established to assist the agencies in planning the mission portfolios. As plans develop, they will be reviewed by ESA member states for approval and by the US National Academy of Sciences.

Source: ESA

Posted on by Abby Cessna

Discovery of the Planets

Sir William Herschel

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We actually only know the exact date of when a few of the planets were discovered. Five of the planets, not including Earth, have been known to exist for thousands of years  – Mercury, Mars, Venus, Jupiter, and Saturn. The Ancient Greeks and Romans wrote about the planets many centuries ago. Because the planets look like stars to the naked eye, that is where the term planets comes from. Because the planets move in the sky, they were termed wandering stars. The term planet comes from the Greek word for wanderer, “planetes.” Many ancient people thought that the planets were gods, so they gave them the names of their gods. All of the planets, except Earth have names of Roman deities.

The other three planets – Uranus, Neptune, and Pluto – were not discovered until at least the 1700’s. Pluto is no longer a planet since it was reclassified as a dwarf planet in 2006. It was known as the ninth planet for 70 years though, so its discovery will be included here. Uranus was discovered in 1781 by the famous astronomer Sir William Herschel, although that was not the first sighting of it. The planet had been sighted as early as 1690 by the English astronomer John Flamsteed. It was also sighted by Pierre Lemonier in the mid 1700’s. Sir Herschel at first thought that Uranus was a comet, but he noticed the irregularities early on and compared it to a planet in his notes.

Because Neptune cannot be seen without the help of a telescope, it was not discovered until after 1610, when Galileo created the telescope. Alexis Bouvard, a mathematician, saw that another planet had to be affecting Uranus’ orbit, so astronomers started looking for it. Two astronomers, John Couch Adams and Urbain Le Verrier, discovered Neptune independently or rather made the calculations and determined where Neptune could be found. The planet turned out to be 1° from Verrier’s calculations and 12° from Adams’. There was a dispute between France and England over who discovered the new planet because Adams and Verrier are from England and France respectively.

Pluto was the last planet discovered, although that distinction returned to Neptune when Pluto was reclassified as a dwarf planet. Pluto was discovered in 1930 by the astronomer Clyde Tombaugh. Many people had been searching for a ninth planet – the elusive planet X – for quite a while. Since Pluto was discovered near the calculated location of planet X, they thought the two planets were one and the same. Later, astronomers realized that there was no such planet X.

Universe Today has a number of articles on the planets including who discovered Neptune and the planets of our Solar System.

Check out these other articles including mathematical discovery of the planets and the planets.

Astronomy Cast has episodes on all of the planets including Mercury.

Posted on by Abby Cessna

Names of the Planets

Planets and other objects in our Solar System. Credit: NASA.

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You may recognize the names of the planets from your high school literature course or a history class. That is because many of the planets were first discovered by ancient civilizations, and so planets are named after their gods.

The Romans named Mercury after the messenger of the gods because it appears to move so quickly.

Venus was named after the Roman goddess of love because of its shining presence. The planet is the brightest object in the sky beside the Moon and the Sun. A number of other cultures also named Venus after their own gods or goddesses of love and war.

Earth is the only planet not named after a god. The name is based on Germanic and Old English words for “ground.”

Mars was named after the Roman god of war because of its red color, which reminded people of blood. Other civilizations also had names for the planet based on its color. The Egyptians called it “Her Desher,” which means “the red one.”

Jupiter was named after the king of the gods – Zeus by the Greeks and Jupiter by the Romans. Ancient civilizations most likely named this planet after the most powerful god because of its size. Jupiter is the largest and most massive planet in our Solar System.

Saturn was named after the father of the king of gods as well as being the god of agriculture and harvest. In mythology, Saturn had taken the position of king of the gods from his own father, Uranus, and then Jupiter overthrew him. Saturn is the last planet that can be seen from Earth without the aid of a telescope.

Uranus was not discovered until 1781 by Sir William Herschel, so it was not necessarily going to be named after a Roman god. In fact, Herschel named the planet “Georgium Sidus” in honor of George III who was King of England at the time. Others called the planet Herschel in honor of the astronomer who had discovered it. The name Uranus, which is the name of the Roman god who is the father of Jupiter, was suggested by the astronomer Johann Bode. That name was widely accepted in the mid 1800’s, and it fit in with the other planets, which all had names from mythology.

Neptune had been observed by a number of astronomers, but they believed it was a star. Two people, John Couch Adams and Urban Le Verrier, calculated the planet’s location. Johann Galle, the astronomer who discovered the planet using Verrier’s calculations, wanted to name the planet after Verrier. Many astronomers objected though, so it was named after Neptune the Roman god of the sea. The name was very fitting because the planet is a bright sea blue.

Universe Today has a number of articles on the planets including facts about the planets and the planets of the solar system.

If you are looking for more information on the planets take a look at the planets and interesting facts about the planets.

Astronomy Cast has episodes on all of the planets, so start with Mercury.

Posted on by Nancy Atkinson

Perchlorates and Water Make for Potential Habitable Environment on Mars

This mosaic assembled from Phoenix images show the spacecraft's three landing legs. Splotches of Martian material on the landing leg strut at left could be liquid saline-water. Click for larger version on Spaceflightnow. com Credit: Kenneth Kremer, Marco Di Lorenzo, NASA/JPL/UA/Max Planck Institute and Spaceflightnow.com. Used by permission

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Scientists say that the Arctic region studied by Phoenix lander may be a favorable environment for microbes. Just-right chemistry and periods where thin films of liquid water form on the surface could make for a habitable setting. “Not only did we find water ice, as expected, but the soil chemistry and minerals we observed lead us to believe this site had a wetter and warmer climate in the recent past — the last few million years — and could again in the future,” said Phoenix Principal Investigator Peter Smith of the University of Arizona, Tucson.

The Phoenix science team released four papers today after spending months interpreting the data returned by the lander during its 5-month mission.

The most surprising finding was perchlorate in the Martian soil. This Phoenix finding caps a growing emphasis on the planet’s chemistry, said Michael Hecht of from the Jet Propulsion Laboratory, who led a paper about Phoenix’s soluble-chemistry findings.

“The study of Mars is in transition from a follow-the-water stage to a follow-the-chemistry stage,” Hecht said. “With perchlorate, for example, we see links to atmospheric humidity, soil moisture, a possible energy source for microbes, even a possible resource for humans.”

Perchlorate, which strongly attracts water, makes up a few tenths of a percent of the composition in all three soil samples analyzed by Phoenix’s wet chemistry laboratory. It could pull humidity from the Martian air. At higher concentrations, it might combine with water as a brine that stays liquid at Martian surface temperatures. Some microbes on Earth use perchlorate as food. Human explorers might find it useful as rocket fuel or for generating oxygen.

Close up shows splashes of material on lander leg strut. Image: Kenneth Kremer, Marco Di Lorenzo, NASA/JPL/UA/Max Planck Institute. Used by permission.
Close up shows splashes of material on lander leg strut. Image: Kenneth Kremer, Marco Di Lorenzo, NASA/JPL/UA/Max Planck Institute. Used by permission.

A paper about Phoenix water studies, led by Smith, cites clues supporting an interpretation that the soil has had films of liquid water in the recent past. The evidence for water and potential nutrients “implies that this region could have previously met the criteria for habitability” during portions of continuing climate cycles, these authors conclude.

Phoenix dug down with its scoop and found ice just under the surface of Mars. “We wanted to know the origin of the ice,” Smith said. “It could have been the remnant of a larger polar ice cap that shrank; could have been a frozen ocean; could have been a snowfall frozen into the ground. The most likely theory is that water vapor from the atmosphere slowly diffused into the surface and froze at the level where the temperature matches the frost point. We expected that was probably the source of the ice, but some of what we found was surprising.”

Evidence that the ice in the area sometimes thaws enough to moisten the soil comes from finding calcium carbonate in soil heated in the lander’s analytic ovens or mixed with acid in the wet chemistry laboratory. Another paper from a team led by University of Arizona’s William Boynton report that the amount of calcium carbonate “is most consistent with formation in the past by the interaction of atmospheric carbon dioxide with liquid films of water on particle surfaces.”

This mosaic of images from the Surface Stereo Imager camera on NASA's Phoenix Mars Lander shows several trenches dug by Phoenix, plus a corner of the spacecraft's deck and the Martian arctic plain stretching to the horizon. Image Credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University
This mosaic of images from the Surface Stereo Imager camera on NASA's Phoenix Mars Lander shows several trenches dug by Phoenix, plus a corner of the spacecraft's deck and the Martian arctic plain stretching to the horizon. Image Credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University

The new reports leave unsettled whether soil samples scooped up by Phoenix contained any carbon-based organic compounds. The perchlorate could have broken down simple organic compounds during heating of soil samples in the ovens, preventing clear detection.

The heating in ovens did not drive off any water vapor at temperatures lower than 295 degrees Celsius (563 degrees Fahrenheit), indicating the soil held no water adhering to soil particles. Climate cycles resulting from changes in the tilt and orbit of Mars on scales of hundreds of thousands of years or more could explain why effects of moist soil are present.

Phoenix launched in August 2007and landed in May, 2008. Phoenix ended communications in November 2008 as the approach of Martian winter depleted energy from the lander’s solar panels.

Sources: JPL, EurekAlert, Spaceflightnow.com

Posted on by Nancy Atkinson

Test-Bed Rover is Now Stuck — Which is a Good Thing!

With a slope of about 10 degrees and a pointy rock under the test rover's belly, this sandbox setup at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is ready for engineers to use the test rover to assess possible moves for getting Mars rover Spirit out of a patch of loose Martian soil. Credit: JPL

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Engineers at the Jet Propulsion Laboratory have intentionally driven their engineering rover into soft soil in a sandbox testbed, to simulate how the Spirit rover is stuck on Mars. And they did a good job of it, too, as the test rover, called SSTB1, is stuck, as well, with its wheels spinning and going nowhere. The science team has confirmed a rock on Mars, underneath Spirit is touching the underside of the rover, so engineers have placed a similar looking rock in the test sandbox, as seen above.

“We want to experiment with different extraction techniques down here on Earth before we actually do them for real on Mars,” said John Callas, project manager for the Mars rovers. “Our expectation is that it will some time to get Spirit out, so we will be able to get a better feel for that here in this facility to see how well the techniques work and how long it will take for them to work.”

The rover team spent several days of preparing a sloped area of soft, fine soil to simulate Spirit’s current sandtrap on Mars. On June 30 they maneuvered the test rover around, driving the wheels to the loose soil where the rover would sink and slide to the side, with a slope of about 10 degrees, as engineers believe Spirit has done on Mars.

You can follow the work being done to free Spirit from her predicament at the Free Spirit website. JPL regularly posts updates and videos showing what the rover teams are doing, and currently you can see a movie of how the test rover was driven in the sandbox to get stuck.

A test rover rolls off a plywood surface into a prepared bed of soft soil. Credit: JPL
A test rover rolls off a plywood surface into a prepared bed of soft soil. Credit: JPL

There are actually two test vehicles, and the folks at UnmannedSpaceflight.com have a page explaining the differences, as well as other FAQs about the attempts to free Spirit. The one being use for this current test, SSTB1 is a full size replica of the MER vehicles, but it has a few differences such as no solar panels, and a few other minor missing parts. It has the same mass as the ones on Mars, which means it has a higher weight on Earth than the MERs have on Mars.

The other test rover, SSTB Lite, is a stripped down vehicle with same wheel size, actuators and suspension system, but has other major components missing which gives it a weight on Earth that is similar to the weight of MER on Mars. However, when the Opportunity rover was stuck a couple of years in the Purgatory dune, engineers found that SSTB1 behaved more similarly to the MER vehicles, possibly because both the SSTB1 and the soil were subject to the same gravity vector.

Mosaic of the area around Home Plate where Spirit remains stuck was made especially for Spaceflight Now (Used by permission). Credit: Kenneth Kremer, Marco DiLorenzo, NASA/JPL/Cornell/Spaceflight Now. Click for larger image.
Mosaic of the area around Home Plate where Spirit remains stuck was made especially for Spaceflight Now (Used by permission). Credit: Kenneth Kremer, Marco DiLorenzo, NASA/JPL/Cornell/Spaceflight Now. Click for larger image.

So, just where is Spirit on Mars? Take a look at this great image created by Ken Kremer and Marco DeLorenzo of UnmannedSpaceflight.com, showing Spirit’s current location. It shows smooth area in the foreground, that concealed slippery water related sulfate material where rover became stuck. Once free, Spirit will drive to area near the unusually capped hill ahead designated Von Braun to sample water related evidence there. Let’s hope the engineer’s work here on Earth will “Free Spirit” and enable explorations of Von Braun, and beyond.

Caption for mosaic above: Mosaic of the area around Home Plate where Spirit remains stuck was made especially for Spaceflight Now (Used by permission). Credit: Kenneth Kremer, Marco DiLorenzo, NASA/JPL/Cornell/Spaceflight Now. Click the picture for a larger image.

Sources: “Free Spirit” website, Unmanned Spaceflight, Spaceflightnow.com

Posted on by Nancy Atkinson

Landforms Indicate “Recent” Warm Weather on Mars

Retrogressive scarps with cuspate niches, long branching spurs and associated fluvial-like tributary channels. Credit:NASA/JPL/UofA

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Remember the polygon-shaped landforms at Mars north polar region that the Phoenix lander studied? The polygons are produced by seasonal expansion and contraction of ground ice, and these shapes have been found in other regions on Mars as well. New studies of images from the HiRISE camera on the Mars Reconnaissance Orbiter indicates that the Martian surface near the equator experienced freeze-thaw cycles as recently as 2 million years ago. This means Mars had significantly warmer weather in its recent past, and has not been locked in permafrost conditions for billions of years as had been previously thought.

The HiRISE images show polygon-patterned surfaces, branched channels, blocky debris and mound/cone structures.

Dr. Matthew Balme, from The Open University, made the new discovery by studying detailed images of equatorial landforms that formed by melting of ice-rich soils, such as the polygons, branched channels, blocky debris and mound/cone structures. These are all found in an outflow channel, thought to have been active as recently as 2 million to 8 million years ago. Since the landforms exist within, and cut across, the pre-existing features of the channel, this suggests that they, too, were created within this timeframe.

Full resolution view of domed polygons from HiRISE. Credit: NASA/JPL/U of A
Full resolution view of domed polygons from HiRISE. Credit: NASA/JPL/U of A

All of these features are similar to landforms on Earth typical of areas where permafrost terrain is melting.

“The features of this terrain were previously interpreted to be the result of volcanic processes,” said Balme. “The amazingly detailed images from HiRISE show that the features are instead caused by the expansion and contraction of ice, and by thawing of ice-rich ground. This all suggests a very different climate to what we see today.”

This also means as the shorter the time period since the last warm weather on the planet, the better the chance that any organisms that may have lived in warmer times are still alive under the planet’s surface.

“These observations demonstrate not only that there was ice near the Martian equator in the last few million years, but also that the ice melted to form liquid water and then refroze,” said Balme. “And this probably happened for many cycles. Given that liquid water seems to be essential for life, these kinds of environments could be a great place to look for evidence of past life on Mars.”

Source: STFC

Posted on by Nancy Atkinson

Rover Update With Video

Image from Spirit's front hazcam from sol 1940. Credit: NASA/JPL

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Here’s a rover update: Spirit remains stuck in her location on the west side of Home Plate, and work continues at JPL for testing on how to extract the rover from being embedded in soft soil. A rock may be underneath Spirit, keeping her from moving, but more images are being taken by the microscopic camera at the end of the robotic arm to try and determine exactly what is going on under and around the rover. But with a boosted power supply, Spirit has also been busy making scientific observations of her surroundings. And one more thing, which would be extremely fun, rover driver Scott Maxwell hinted on Twitter that Spirit has so much power now from a recent wind event that cleared off her solar panels that she may attempt to make overnight observations. So stay tuned for PANCAM images of the Martian night sky!

Enjoy this video update on the Mars Exploration rovers by another rover driver, Ashley Stroupe.

As of Sol 1932 (June 9, 2009), Spirit’s solar array energy production is at 828 watt-hours. Total odometry remains at 7,729.93 meters (4.80 miles).

Meanwhile over on the other side of the planet, Opportunity continues to drive south on the way to Endeavour crater. On Sol 1906 (June 4, 2009), the rover completed a 69-meter (266-foot) drive due south. Elevated actuator currents with the right-front wheel continue to cause concern. On Sol 1910 (June 8, 2009), the planned drive stopped early because a multi-wheel current limit threshold was exceeded. A diagnostic maneuver on the next sol was successful indicating the cause on the previous sol was due to the elevated right-front wheel motor currents.

The view from Opportunity on sol 1912. Credit: NASA/JPL
The view from Opportunity on sol 1912. Credit: NASA/JPL



A long, backward drive was performed on Sol 1912 (June 10, 2009). Driving backwards is one technique to mitigate the elevated wheel currents. However, wheel currents continued to be elevated after that 72-meter (236-foot) drive. Further resting of the rover’s actuators is being considered.

The plan ahead includes opening the shroud of the miniature thermal emission spectrometer (Mini-TES) to expose the instrument’s dust-contaminated elevation mirror to the environment. This is an attempt to allow the wind environment to clean dust off the mirror.

As of Sol 1912 (June 10, 2009), Opportunity’s solar array energy production is 431 watt-hours. Opportunity’s total odometry is 16,569.05 meters (10.3 miles).