New Arecibo Radar Images Show Comet Responsible for Camelopardalids is an Icy, Cratered Mini World

Radar images of Comet 209P/LINEAR taken from May 23 through May 27, 2014. The Earth is at the bottom of these images: the “side view” is a result of the radar imaging method. Several features are visible on the comet, perhaps ridges or cliffs. This is only the fifth comet nucleus imaged by Arecibo in the last 16 years, and the most detailed. Resolution in the vertical direction is 7.5 meters (25 feet) per pixel. Image credit: Arecibo Observatory/NASA/Ellen Howell.

When Comet 209P/LINEAR — the comet that brought us the Camelopardalids meteor shower last weekend – was first discovered in February of 2004, astronomers initially thought it was an asteroid. However, subsequent images of the objects showed it had a tail, and so it was reclassified as a comet. Now, new images taken by the Arecibo Observatory planetary radar system reveal Comet 209P/LINEAR has complex surface features that will require more analysis to fully interpret. This mini world seems to be filled with ridges and cliffs along with its icy surface.

“This is the highest resolution radar image we have obtained of a comet nucleus,” said Dr. Ellen Howell from the Universities Space Research Association, who led the observations of the comet at Arecibo, located in Puerto Rico.

The Arecibo Observatory is taking advantage of the approaching close pass of Earth by Comet 209P/LINEAR, taking these new radar images which confirm this comet to be about 2.4 by 3 km kilometers (1.5 x 1.8 miles) in size and elongated in shape. Earlier optical observations suggested this size range, but now these radar observations are the first direct measurement of the nucleus dimensions.

Radar images of Comet 209P/LINEAR taken from May 23 through May 27, 2014. The Earth is at the bottom of these images: the “side view” is a result of the radar imaging method. Several features are visible on the comet, perhaps ridges or cliffs. This is only the fifth comet nucleus imaged by Arecibo in the last 16 years, and the most detailed. Resolution in the vertical direction is 7.5 meters (25 feet) per pixel.  Image credit: Arecibo Observatory/NASA/Ellen Howell
Radar images of Comet 209P/LINEAR taken from May 23 through May 27, 2014. The Earth is at the bottom of these images: the “side view” is a result of the radar imaging method. Several features are visible on the comet, perhaps ridges or cliffs. This is only the fifth comet nucleus imaged by Arecibo in the last 16 years, and the most detailed. Resolution in the vertical direction is 7.5 meters (25 feet) per pixel. Image credit: Arecibo Observatory/NASA/Ellen Howell

Comets very rarely come this close to Earth, but don’t worry: Comet 209P/LINEAR is not coming close enough to cause any problems or concerns.

“Comet 209P/LINEAR has no chance of hitting Earth,” said data analyst Alessondra Springmann from Arecibo. “It comes no closer than 8.3 million kilometers (5.2 million miles) to Earth, safely passing our planet.”

But this relatively close pass makes this an extraordinary opportunity to get images of the surface. As Dr. Howell noted, these observations of are some of the most detailed. Just six comet nuclei have been imaged by spacecraft, and a wide variety of surface features and structures have been observed on these icy objects.

“We are being cautious,” Howell told Universe Today. “Radar images are not regular “spatial” images, and one can easily be misled by treating them as a regular picture. But proper analysis will take weeks or months, not minutes. What these radar images show is certainly not ordinary, but we don’t really have anything to compare to. The image looks different than asteroids we have imaged, but I don’t know what is due to surface feature differences and what might be scattering differences by the surface material.”

Comets have a central nucleus made of ice, dust, and rocks, and a coma of dust and gas. Two tails, one made of ions and one of dust, form in the direction pointing away from the sun.

Other comets seen by Arecibo radar include 103P/Hartley 2 and 8P/Tuttle, and 73P/Schwassmann-Wachmann 3.

Radar images of Comet 209P/LINEAR taken from May 23 through May 27, 2014. The Earth is at the bottom of these images: the “side view” is a result of the radar imaging method. Several features are visible on the comet, perhaps ridges or cliffs. This is only the fifth comet nucleus imaged by Arecibo in the last 16 years, and the most detailed. Resolution in the vertical direction is 7.5 meters (25 feet) per pixel.  Image credit: Arecibo Observatory/NASA/Ellen Howell
Radar images of Comet 209P/LINEAR taken from May 23 through May 27, 2014. The Earth is at the bottom of these images: the “side view” is a result of the radar imaging method. Several features are visible on the comet, perhaps ridges or cliffs. This is only the fifth comet nucleus imaged by Arecibo in the last 16 years, and the most detailed. Resolution in the vertical direction is 7.5 meters (25 feet) per pixel. Image credit: Arecibo Observatory/NASA/Ellen Howell

Unlike long period comets Hale-Bopp and the late Comet ISON that swing around the Sun once every few thousand years or few million years, Comet 209P/LINEAR visits our neighborhood frequently, coming ‘round every 5.09 years. However, it will not be close enough to Earth again for radar imaging any time in the next 100 years.

With a rotation period of approximately 11 hours as determined by Carl Hergenrother at the University of Arizona using the 1.8 meter VATT telescope, this comet is one of the many Jupiter family comets, which orbit the Sun twice for every time Jupiter orbits once.

It was discovered by the Lincoln Laboratory Near-Earth Asteroid Research (LINEAR) automated sky survey.

The Arecibo Observatory, located in Puerto Rico, is home to the world’s largest and most sensitive single-dish radio telescope at 305 meters (1000feet) across. This facility dedicates hundreds of hours a year of its telescope time to improving our knowledge of near-Earth asteroids and comets.

Dr. Howell specializes in studying comets and asteroids using radar, as well as passive radio and infrared spectroscopy techniques to determine the surface and coma properties of small solar system bodies. She was assisted in these observations of Comet 209P/LINEAR by Michael Nolan, Patrick Taylor, Alessondra Springmann, Linda Ford, and Luisa Zambrano.

Arecibo Observatory, and the complementary Goldstone Solar System Radar in California run by NASA’s Jet Propulsion Laboratory, are both observing comet 209P/LINEAR during its pass by Earth in May. These radar facilities are unique among telescopes on Earth for their ability to resolve features on comets and asteroids, while most optical telescopes on the ground would see these cosmic neighbors simply as unresolved points of light.

For more images and information on Comet 209P/LINEAR, see the Arecibo Observatory’s planetary radar page.

The Arecibo Observatory is operated by SRI International under a cooperative agreement with the National Science Foundation, and in alliance with the Sistema Universitario Ana G. Méndez-Universidad Metropolitana and the Universities Space Research Association. The Arecibo Planetary Radar program is supported by NASA’s Near Earth Object Observation program.

Planetary Scientist Colin Pillinger Dies

British planetary scientist Colin Pillinger with the Beagle 2 lander.

British planetary scientist Colin Pillinger has passed away. Pillinger, age 70, was best known as leading the 2003 attempt to land the Beagle 2 spacecraft on Mars, part of the European Space Agency’s Mars Express mission.

His family said in a statement: “It is with profound sadness that we are telling friends and colleagues that Colin, whilst sitting in the garden yesterday afternoon, suffered a severe brain hemorrhage resulting in a deep coma. He died peacefully this afternoon at Addenbrooke’s hospital, Cambridge, without regaining consciousness … We ask that all respect our privacy at this devastating and unbelievable time.”

While the Beagle 2 spacecraft failed and likely crashed on Mars, the mission was notable because it was the first time an individual researcher had sent their own vessel into space and the first British-built interplanetary spacecraft. However, a lack of funding meant the Beagle 2 project always struggled. The spacecraft did launch, but all contact with Beagle 2 was lost after its separation from the Mars Express spacecraft, just six days before atmospheric entry.

However, the BBC noted that the mission was “a turning point in bringing together the space science and industrial communities in the UK – which didn’t used to speak with one voice. Beagle-2 wasn’t built in Colin’s backyard: it was the product of UK brains and hard-work in many companies and universities.”

You can read more about Pillager’s career and achievements at the BBC and the International Business Times.

Oh, the Places We’ve Been: 21 Spacecraft Trajectories Plotted in One Picture

One image from an infographic showing trajectories of 21 different unmanned spacecraft. Click for full image. Credit: Kevin Gill.

Want to know the orbital paths where different spacecraft have traveled and where they are now? A great new infographic put together by Kevin Gill is a visualization of where 21 different unmanned spacecraft have traveled through the Solar System. “The spacecraft data and planet orbital data is derived from NASA/JPL Horizons ephemeris,” said Gill on G+. “The image was rendered using a modified version of my Orbit Viewer WebGL application and put into infographic form using Photoshop. Body and spacecraft positions are as of December 15, 2013.”

By the way, Kevin’s orbit viewer is really fun to play with!

See the full infographic below or on Kevin’s website here:

Paths range from the earliest vector data available, typically just following launch, to either the latest data available or December 15, 2013, whichever is earlier.

“Originally intended as an animation, my browser was not too amused with the quantity of data being thrown at it,” Kevin said via G+. “In the new year, given sufficient demand, I may optimize the modeling and animation algorithms and either produce the animation or release it as a distinct WebGL visualization.”

We certainly look forward to that!

Three different views of our Solar System and the paths of unmanned spacecraft trajectories from their launches to Dec. 15, 2013. Credit: Kevin Gill.
Three different views of our Solar System and the paths of unmanned spacecraft trajectories from their launches to Dec. 15, 2013. Credit: Kevin Gill.

Mercury’s Surface is Full of Sulfur

The southern portion of Mercury’s Vivaldi basin and outlying rugged terrain

Named for the 17th-century Venetian composer, the southern half of Mercury’s Vivaldi basin is seen in this image acquired on August 26 by NASA’s MESSENGER spacecraft. The 213-km (132-mile) -wide crater’s smooth floor is contrasted by the incredibly rugged terrain beyond its outermost ring — a result of the ejected material that was flung out from the impact site and emphasized by the low angle of illumination.

The floor of the crater remained relatively smooth due to molten material that erupted in the wake of the impact event, flooding the basin.

Recent findings from the MESSENGER mission have revealed variations in Mercury’s surface composition due to volcanism that occurred at different times, as well as a surprising concentration of elements like magnesium and sulfur — much more so than any of the other terrestrial planets.

In results to be published in the Journal of Geophysical Research, scientists report that Mercury’s volcanic smooth plains differ in composition from older surrounding terrains. The older terrain has higher ratios of magnesium to silicon, sulfur to silicon, and calcium to silicon, but lower ratios of aluminum to silicon, suggesting that the smooth plains material erupted from a magma source that was chemically different from the source of the material in the older regions, according to Shoshana Weider of the Carnegie Institution of Washington, the lead author on the paper.

Mercury’s surface was also found to be high in magnesium and sulfur-enriched minerals.

“None of the other terrestrial planets have such high levels of sulfur. We are seeing about ten times the amount of sulfur than on Earth and Mars,” Weider said. “In terms of magnesium, we do have some materials on Earth that are high in magnesium. They tend to be ancient volcanic rocks that formed from very hot lavas. So this composition on Mercury tells us that eruptions of high-temperature lavas might have formed these high-magnesium materials.”

Read: MESSENGER Reveals Mercury’s Colors

The data was gathered with MESSENGER’s X-Ray Spectrometer (XRS) — one of two instruments designed to measure the abundances of many key elements in the top 2mm of Mercury’s crust. XRS detects emissions from elements in the 1-10 kiloelectron-volt (keV) range – specifically, magnesium, aluminum, silicon, sulfur, calcium, titanium, and iron.

Read more on the MESSENGER mission site here.

Inset image: A global mosaic of Mercury from MESSENGER (2011). Image credits: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Planetary Bake Sale and Car Wash to Support Exploration of the Solar System

Would you support a car wash or bake sale for planetary science?


Across the country, planetary scientists and students are planning for an upcoming bake sale and car wash on June 9, 2012. The event is in response to the 21% proposed budget cuts to planetary exploration, and while the volunteer bakers and washers will take donations, the main idea is to get the word out to the general public about the proposed budget slashing, and to ask people to send letters to their representatives. “Take Social Action and Participate,” says the event website. “Help Protect the NASA Planetary Budget from Cuts!”

The event was organized by Alan Stern, Principal Investigator of the New Horizons mission and former Associate Administrator of NASA’s Science Mission Directorate. There are several institutions across the US who already have events planned, (see here for planned events) and Stern is hoping for more events to be added. There’s even a ‘cookbook’ of ideas and instructions for how to host an event.

The event is supported by the Division for Planetary Sciences (DPS) of the American Astronomical Society, the world’s largest professional association of planetary scientists, which urges Congress to support and fund a vigorous planetary science program as recommended by the National Research Council. “We strongly believe that the robotic exploration of the solar system resonates with the American people; it is something that NASA needs to be doing and doing exceptionally well, and it is something the American people will support even in tight budget times,” the DPS said in a statement.

At the Lunar and Planetary Science Conference in March, Steve Squyres, Principal Investigator of the Mars Exploration Rovers and chair of the recent National Research Council (NRC) Decadal Survey for planetary science, said that for the planetary science budget to be restored, it would be crucial for the scientific community to respond in a unified fashion. “I’ve spent a lot of time looking at the budget, and as bad as it looks, they are looking for reasons to cut even further. There just is not enough money. What we just cannot do, we can’t give anyone reasons to cut even further. There are people looking to do that. We must respond as a unified voice.”

This bake sale and carwash is an attempt to have a unified voice across the country of showing how devastating the cuts would be for the future of NASA’s overall vision. President Obama has stated he will see astronauts on Mars in his lifetime, so the plan to put the Mars program essentially on hold is perplexing.

Additionally, the job losses and “institutional knowledge” losses would be devastating. “A 20% budget cut will likely equal 20% loss of jobs,” one commenter from the audience at the LPSC NASA Night event said. “People who land missions on Mars will lose their jobs, and when we get to the stage of landing humans on Mars, those with the know-how won’t be there.”

Check out the National Planetary Exploration Car Wash & Bake Sale website to see how you can support planetary science.

Can NASA’s Planetary Science Budget Be Saved?

NASA’s new Associate Administrator for the Science Mission Directorate, John Grunsfeld, speaking the Lunar and Planetary Science Conference on March 19, 2012. Credit: John Blackwell/USRA


“Flat is the new up,” said NASA’s new Associate Administrator for the Science Mission Directorate, John Grunsfeld, attempting to bring a bit of levity to the outlook for NASA’s proposed 2013 budget. Grunsfeld was speaking to a shellshocked community that will be taking the biggest hit in the NASA budget decrease: planetary scientists attending the Lunar and Planetary Science Conference this week in The Woodlands, Texas. There weren’t many jokes or laughs during Grunsfeld’s talk; nor from Jim Green, NASA’s Planetary Science Division Director. Both gave short remarks and then answered questions from the audience at “NASA Night,” the annual NASA Headquarters briefing event at LPSC.

“I wish I had a good succinct answer that this was punitive for overruns on the Mars Science Lab or JWST (James Webb Space Telescope), but this is not a Pavlovian system,” said Grunsfeld. “It comes down to tough trades: do we cut across the board, or do we pick some area? Sadly, it was decided that planetary science was the area.”

President Obama’s proposed FY 2013 budget would eliminate $300 million from the agency’s Planetary Sciences Division, a 21% cut from the $1.5 billion it received for 2012.

“We essentially lost the ability to create new missions,” Grunsfeld said.

Sitting among the people who, because of this proposed budget “whacking” (as Grunsfeld called it), will likely lose jobs or see their life’s work delayed or canceled, it was hard not to believe that this particular budgetary decision is wrong in every way possible. NASA would be slashing what many believe is the space agency’s most successful program.

“A 20% budget cut will likely equal 20% loss of jobs,” one commenter from the audience said. “People who land missions on Mars will lose their jobs, and when we get to the stage of landing humans on Mars, those with the know-how won’t be there.”

President Obama has stated he will see astronauts on Mars in his lifetime, so the plan to put the Mars program essentially on hold is extremely short-sighted, if not ironic.

“What a lot of people don’t realize is these cuts will most deeply impact the youth in our field,” wrote Dr. Pamela Gay in her StarStryder blog. “Many senior people who normally can find funding for themselves and a small fleet of postdocs and students will now just be funding themselves. It’s hard. It’s ugly. Especially when we work so hard to get people to get educations in this field.”

Planetary scientist Jim Bell, who is also President of The Planetary Society, along with Bill Nye, TPS’s Executive Director, both gave impassioned pleas for everyone – and especially for Grunsfeld and Green – to “fight back” against the cuts and request a review of “the largest crisis facing Planetary Science.”

Grunsfeld said he and Green are there to fight for the scientists and the missions. “Jim (Green) could have thrown his badge on the table (in response to the budget proposal), but he decided to stay and fight,” Grunsfeld said. He offered hope by reminding everyone how in 2004 when he was NASA’s chief scientist, the decision was made to not do the final repair mission to Hubble. That decision was eventually reversed. “History tends to repeat itself,” he said.

Jim Green, NASA’s Planetary Science Division Director speaking at the Lunar and Planetary Science Conference on March 19, 2012. Credit: John Blackwell/USRA.

Grunsfeld and Green both stressed how the scientists — and anyone in attendance or watching the webcast of the event — should spread the word to the general public about the importance of planetary science and also about contacting their congress-people – the ones who make the final decision about the budget.

“Without question, we must keep our eye on the ball this year,” Green said. “Our top priority for the Planetary Science Division this year is to make the landing of the Curiosity rover a success. Tell everyone about this, relate this to your neighbor. We should not let this opportunity go by without relaying it to our stakeholders, the general public. This is such an important event, and a success will compel this nation to invest more in planetary science.”

But yet, NASA’s Education and Public Outreach budget has been cut from $136 million in FY12 to $100 million in the FY13 request.

The ExoMars program. Credit: ESA

One of the most perplexing issues about the budget cuts is how NASA’s involvement in future international Mars missions, an orbiter and lander called ExoMars — with instruments and science teams already selected for parts of the mission — would be cancelled. This leaves the international partners in the lurch, damages NASA’s reputation among the international science community and puts in doubt the possibility of any future collaboration.

Yet, Green said in his talk that NASA needs to “deliver on our international commitment,” and NASA officials often tout the incredible success of the international cooperation of the International Space Station – saying it is a model for future international missions.

NASA Administrator Charlie Bolden has asked the Science Mission Directorate and Grunsfeld to reformulate an agency-wide Mars exploration strategy, where they are now suggesting a smaller, US-only Mars mission in 2018.

But could a smaller mission be less expensive and offer anywhere near the amount of science that could have been attained with the joint ExoMars mission?

“Can we recapture the Mars program?” Grunsfeld asked. “We’re not just going to look at 2018 mission but a much larger Mars program. It will be an enormous amount of work, not new analysis, but compiling inputs you (the scientists) have made in the past, and where we are in the science to see what kind of path forward makes sense.”

Grusnfeld and Green also suggested a future melding of science and human spaceflight-related missions as a way to get more funding for Mars missions. But when asked by Universe Today for an example of a “dream” Mars science mission within a scenario of a human spaceflight precursor, neither could come up with a really enticing idea.

However, Grunsfeld said science at NASA would stand to benefit from developments in human exploration and space technology. “It might be a bit of a stretch, but imagine what kind of planetary mission you could launch with a 70 metric ton launch capability,” he said, referring to the Space Launch System’s big rocket that is in the preliminary stages of being developed for future human mission to either an asteroid, the Moon or Mars.

One piece of good news: Green announced that the GRAIL mission has already received a mission extension, as well as MESSENGER, which was announced earlier. Still hanging in the balance are extended missions such as for Kepler and MER, the decisions on which will be made by this summer, Green said.

The outlook for the start-up of production of Pu-238 is not brilliant – and for any future outer planet mission, this is crucial for power for the spacecraft, and ultimately, for science. The Department of Energy did not receive any funding for a re-start, so it looks as though NASA may have to go it alone and pay the entire costs of start-up and reproduction.

Surely, it was a tough situation for Green and Grunsfeld to be in, especially for Grunsfeld – a true scientist, astronaut and ‘Hubble Hugger’ who just started his new job at NASA HQ in January. “I’m trying to look at big picture. I come from an environment where I’ve loved the partnership between humans and science. When NASA has done well overall, science has done well. So we are in tough times, and NASA needs to have a cohesive vision.”

So, it may come down to grassroots support for NASA to possibly change the current of action. While the administration proposes a budget, but it’s Congress that actually enacts the budget and appropriates the money, so anyone who is passionate on this subject needs to contact their representatives.

Inspired by Neil de Grasse Tyson’s recent suggestion during testimony to Congress (see video below) that NASA should receive a full penny on the dollar of the national budget ($37.5 Billion) instead of less than half a cent at the $17.7 billion now proposed, a student named John Zeller has started a website, Penny4NASA., which offers templates for letters to Congress, petitions on and more.

The Planetary Society is also mounting a campaign to restore the science funding to NASA.

We’ll add more links to ways to support science and planetary missions as they come in.

New ESA Images Reveal Volcanic History of Mars

Tharsis Tholus towers 8 km above the surrounding terrain. Its base stretches 155 x 125 km. What makes Tharsis Tholus unusual is its extremely battered condition. Image Credit: ESA/DLR/FU Berlin (G. Neukum)


Earlier this week, The European Space Agency released new Mars images taken by instruments aboard the Mars Express spacecraft. The images show details of Tharsis Tholus, which appears to be a very large and extinct volcano that has been battered and deformed over time.

On Earth, Tharsis Tholus would be a towering giant of a volcano, looming 8 km above the surrounding terrain, with a base of roughly 155 x 125 km. Despite its size, Tharsis Tholus is just an average run-of-the-mill volcano on Mars. That being said, it isn’t the size of Tharsis Tholus that makes it interesting to scientists – what makes the remnants of this volcano stand out is its extremely battered condition.

What does the battered condition of Tharsis Tholus mean to planetary scientists studying Mars?

Details shown in the image above by the HRSC high-resolution stereo camera on ESA’s Mars Express spacecraft reveal signs of dramatic events which have significantly altered the volcanic region of Tharsis Tholus. Two (or more) large sections have collapsed around its eastern and western regions in the past several billion years, leaving signs of erosion and faulting.

One main feature of Tharsis Tholus that stands out is the volcanic caldera in its center. The caldera is nearly circular, roughly 30 km across and ringed by faults that have allowed the floor of the caldera to subside by nearly 3km. Planetary scientists believe the volcano emptied its magma chamber during eruptions. Once the magma chamber had emptied its lava onto the surface, the chamber roof became unstable under its own weight and collapsed, forming the large caldera.

This image was created using a Digital Terrain Model (DTM) obtained from the High Resolution Stereo Camera on ESA’s Mars Express spacecraft. Elevation data from the DTM is colour coded: purple indicates the lowest lying regions and beige the highest. Image Credit: ESA/DLR/FU Berlin (G. Neukum)

This month is a very busy month for Mars exploration. Russia’s recently launched (and in distress) Phobos mission (Mission coverage at: has a mission goal of returning a sample from Mars’ moon, Phobos, along with “piggyback” missions by China and the Planetary Society.

NASA’s plans to launch the Mars Science Laboratory on November 25th (Coverage at: MSL consists of the “Curiosity” rover and will be performing experiments designed to detect organic molecules, which may help detect signs of past or present life on Mars.

This month also marks the end of the “Mars500” mission, which ended on Friday (coverage at: when the participants opened their hatch for the first time since June 2010. During the past 520 days, the participants were working in a simulated spacecraft environment in Moscow.

Learn more about Mars Express at:

Source: ESA Press Release

Opportunity Rover Heads for Spirit Point to Honor Dead Martian Sister; Science Team Tributes

Spirit’s last panoramic from Mars was taken during February 2010 before her death. Featured on Astronomy Picture of the Day (APOD) on 30 May 2011. Spirit’s final panoramic picture show from Mars was snapped on Sol 2175 in February 2010 before entering hibernation mode in March 2010 just prior to the onset of her 4th Martian winter. Spirit was just 500 feet from her next science target - dubbed Von Braun – center of the mosaic. The Columbia Hills form the backdrop to the mosaic from Spirits final resting place. Spirit never awoke. NASA ceased all communications attempts with Spirit on May 25, 2011. Credit: Mosaic by Marco De Lorenzo and Ken Kremer, images NASA/JPL/Cornell University.


Scientists leading NASA’s Mars rover team have selected “Spirit Point” as the name for the spot where the “Opportunity” Mars rover will arrive at her next destination – Endeavour Crater. The site was named in honor of the death of the “Spirit” Mars Exploration Rover, which NASA recently declared has ceased all communications with Earth.

Spirit’s passing comes after more than six highly productive years roving the surface of the red planet as humankind’s surrogate. NASA concluded the last attempt to communicate with Spirit in a transmission on May 25, 2011.

“First landfall at Endeavour will be at the southern end of Cape York [at Spirit Point],” Steve Squyres told me. Squyres of Cornell University, Ithaca, N.Y., is principal investigator for the rovers.
Read tributes from the Spirit rover science team below.

In memory of Spirit, the last panorama she snapped on Sol 2175 in February 2010 was featured on Astronomy Picture of the Day (APOD) on May 30, 2011 and is the lead image here. The photo mosaic was created by Marco Di Lorenzo and Ken Kremer and shows some of the last scenes that Spirit ever photographed.

Spirit approaches von Braun mound in April 2009
This mosaic of images was collected on Sol 1869 in April 2009 as Spirit approached a mysterious circular volcanic mound known as Von Braun, at left. Foreground at center, left ahead shows where Spirit became stuck in a concealed sand trap of slippery, water related sulfate minerals lying adjacent to the eroded volcanic plateau named Home Plate. Columbia Hills in the background.
Mosaic Credit: Kenneth Kremer/Marco Di Lorenzo/NASA/JPL/Cornell

Endeavour’s massive rim consists of a series of ridges. Cape York is a 400 foot wide (120 meters) rim fragment at the western edge of Endeavour. Opportunity should reach “Spirit Point” before the end of this year, 2011.

“Spirit Point” was chosen as the site at Endeavour to commemorate the scientific achievements of Opportunity’s twin sister “Spirit”. Endeavour Crater was determined to be Opportunity’s long term destination nearly three ago after she departed the environs of Victoria crater.

“The Initial exploration plan will be decided when we get closer. The [science] priorities will depend on what we find,” Squyres added.

Since August 2008, the blistering pace of Opportunity’s long overland trek of about 11 miles (18 kilometers) has brought the golf cart sized robot to within about 2 miles (3 kilometers) of the rim of the humongous Endeavour crater – some 14 miles (22 kilometers) in diameter. Endeavour is more than 20 times wider than Victoria crater and by far the largest feature the Opportunity will ever explore – see route maps below.

This oblique view with moderate vertical exaggeration shows the portion of the rim of Endeavour crater given the informal name "Spirit Point." This is the location where the team operating NASA's Mars Exploration Rover Opportunity plans to drive the rover to its arrival at the Endeavour rim. As of mid-June 2011, Opportunity was about 2 miles away from the rim of Endeavour. Credit: NASA/JPL-Caltech/Univ. of Arizona

“Spirit achieved far more than we ever could have hoped when we designed her,” according to Squyres in a NASA statement. “This name will be a reminder that we need to keep pushing as hard as we can to make new discoveries with Opportunity. The exploration of Spirit Point is the next major goal for us to strive for.”

The imaging team of Marco Di Lorenzo and Ken Kremer created a series of Spirit photomosaics from publically available images to illustrate the location and hazardous nature of Spirits final resting place – which fortuitously turned out to be a scientific goldmine revealing new insights into the flow of liquid water on Mars billions of years ago.

Mosaic of microscopic images of Spirit’s underbelly on Sol 1925 in June 2009
Mosaic shows predicament of being stuck at Troy with wheels buried in the sulfate-rich Martian soil. This false color mosaic has been enhanced and stretched to bring out additional details about the surrounding terrain and embedded wheels and distinctly shows a pointy rock perhaps in contact with the underbelly.
Mosaic Credit: Marco Di Lorenzo/ Kenneth Kremer/NASA/JPL/Cornell

The western rim of Endeavour possesses geological deposits far older than any Opportunity has investigated before and which may feature environmental conditions that were more conducive to the potential formation of ancient Martian life forms.

Spirits last transmissions to Earth took place in March 2010, before she entered hibernation mode due to ebbing solar power and succumbed to the likely damaging effects of her 4th Martian winter.

Spirit was closing in on her next science target, a mysterious volcanic feature named Von Braun, when she became mired in a sand trap named “Troy” on the outskirts of the eroded volcano named “Home Plate, just about 500 feet away. See our mosaics.

Spirit embedded at sand trap in February 2010 on Sol 2174
Numerous attempts by the rover team failed to extricate Spirit from the sand trap at Troy in which she became mired in May 2009 on the western edge of Home Plate. Mosaic shows last robotic arm maneuver before hibernation and above bright toned soil containing hydrated sulfates. Mosaic Credit: Marco Di Lorenzo/ Kenneth Kremer/ NASA/JPL/Cornell

Unable to escape and absent of sufficient power to run critical survival heaters, Spirit experienced temperatures colder than ever before that probably crippled fragile electronics components and connections and prevented further communications – although no one knows for sure.

NASA’s twin rovers Spirit and Opportunity have been exploring the Martian terrain on opposite sides of the red planet since the dynamic duo successfully landed over 7 years ago in January 2004.

Both robots were expected to last just three months but have accumulated a vast bonus time of exploration and discovery in numerous extended mission phases.

*** Several top members of the rover science team kindly provided me some comments (below) to sum up Spirits achievements and legacy and what’s ahead for Opportunity at Endeavour.

Ray Arvidson of Washington University, St Louis, Deputy Principal Investigator for the rovers:

“Spirit’s last communication with Earth was in March 2010 as the southern hemisphere winter season began to set in, the sun was low on the horizon, and the rover presumably stopped communicating to use all available solar power to charge the batteries.

Von Braun was one of the two destinations Spirit was traveling to when the rover became embedded in soft sands in the valley to the west of Home Plate.

Von Braun is a conically-shaped hill to the south of Home Plate, Inner Basin, Columbia Hills. Goddard is an oval-shaped shallow depression to the west of von Braun and was the second area to be visited by Spirit. Both von Braun and Goddard are suspected to be volcanic features.

Spirit is the brightest spot in this image taken on 31 March 2011 from Mars orbit. Spirit is gleaming in the sun beside Home Plate inside Gusev Crater. The solar panels are not covered by an optically thick layer of dust. Spirit last communicated on 22 March 2010. Credit: NASA/JPL/UA

During Spirit’s six year and two month mission the vehicle acquired remote sensing and in-situ observations that conclusively demonstrated that the ancient Columbia Hills in Gusev Crater expose materials that have been altered in water-related environments, including ground water corrosion and generation of sulfate and opaline minerals in volcanic steam vents and perhaps hydrothermal pools.

Together with its sister rover, Opportunity, the Mars Exploration Rover Mission, was designed to “follow the water” and return data that would allow us to test the hypothesis that water was at and near the surface during previous epochs.

Opportunity is still exploring the evidence in Meridiani for ancient shallow lakes and is on the way to outcrops on the rim of Endeavour crater, a ~20 km wide crater that exposes the old Noachian crust that shows evidence from orbital data for hydrated clay minerals.

These two rovers have performed far beyond expectations, unveiled the early, wet history of Mars, and have made an enormous scientific return on investment.”

Steve Squyres of Cornell University, Ithaca, N.Y., Principal Investigator for the rovers:
“Our best hope for hearing from Spirit was last fall. When that didn’t happen, we began a long, careful process of trying every possible approach to re-establishing contact. But it slowly became clear that it was unlikely, and I personally got used to the idea that Spirit’s mission was probably over several months ago.

Once that right front wheel failed, Spirit’s days were numbered in that kind of terrain. It wouldn’t have made any difference if we had tried to move Spirit sooner. We were very lucky to have survived as long as we did.

One of the lessons learned is to try to keep the wheels from failing.

It’s very sad to lose Spirit. But two things have softened the blow. First we’ve had a long time to get used to the idea. Second, even though Spirit is dead, she died an honorable death. If we’d lost her early in the mission, before she accomplished so much, it would have been much harder. But she accomplished so much more than any of us expected, the sadness is very much tempered with satisfaction and pride.

The big scientific accomplishments are the silica deposits at Home Plate, the carbonates at Comanche, and all the evidence for hydrothermal systems and explosive volcanism. What we’ve learned is that early Mars at Spirit’s site was a hot, violent place, with hot springs, steam vents, and volcanic explosions. It was extraordinarily different from the Mars of today.

Opportunity is heading at high speed for the rim of Endeavour Crater. First landfall will be at the southern end of Cape York. She should be there in not too many more months.

It hasn’t yet been decided where Opportunity will attempt to climb up Endeavour… we’ll see when we get there.

The phyllosilicates are a high priority, but the top priority depends on what we find.

The yellow line on this map shows where NASA's Mars Rover Opportunity has driven from the place where it landed in January 2004 -- inside Eagle crater, at the upper left end of the track -- to a point about 2.2 miles (3.5 kilometers) away from reaching the rim of Endeavour crater. Credit: NASA/JPL-Caltech/MSSS

I hope Spirits legacy will be the inspiration that people, especially kids, will take away from Spirit’s mission. I have had long, thoughtful conversations about Spirit with kids who have had a rover on Mars as long as they can remember. And my fondest hope for Spirit is that somewhere there are kids who will look at what we did with her, and say to themselves “well, that’s pretty cool… but I bet when I grow up I can do better. That’s what we need for the future of space exploration.

Spirit existed, and did what she did, because of the extraordinary team of engineers and scientists who worked so hard to make it possible. It’s a team that I’m incredibly proud to have been a small part of. Working with them has been quite literally the adventure of a lifetime.”

Jim Bell of Arizona State University, lead scientist for the rovers Pancam stereo panoramic camera:

“It is with a bittersweet sense of both sadness and pride that NASA announced the official end of the mission for the Mars Exploration Rover Spirit.

The Spirit team has seen the end coming since communications were lost with the rover in March 2010. Mission engineers made heroic efforts to reestablish contact. In the end Spirit was conquered by the extremely cold Martian winter and its two broken wheels, which prevented its dusty solar panels from pointing toward the Sun.

But what a mission! Designed to last 90 days, Spirit kept going for more than six years, with the team driving the rover almost 5 miles (8 km) across rocky volcanic plains, climbing rugged ancient hills, and scurrying past giant sand-dune fields. It eventually spent most of the mission near the region known as Home Plate, which is full of layered, hydrated minerals.

Data from the rover enabled dozens of scientific discoveries, but three stand out to me as most important:

Hydrated sulfate and high-silica soils in the Columbia Hills and around Home Plate.
These minerals, and the environment in which they occur (Home Plate is a circular-shaped, finely layered plateau that may be the eroded remains of a volcanic cone or other hydrothermal deposit), tell us that at some point in the past history of Gusev there was liquid water and there were heat sources — two key ingredients needed to consider the area habitable for life as we know it.

Carbonate minerals in some of the rocks within the Columbia Hills.
Carbonates were expected on Mars, if indeed the climate was warmer and wetter in the past. However, their detection has been elusive so far. Indeed, the Spirit team had to work hard to uncover the signature of carbonates years after the rover made the measurements. As the analysis continues the results for Mars in general could be profound.

An incredible diversity of rock types, from all over Mars, that Spirit was able to sample in Gusev crater.
Some of the rocks appear to be from local volcanic lava flows or ash deposits. But others have likely been flung in to the area over time by distant impacts or volcanoes, and a few even appear to be meteorites, flung in from outer space. Spirit’s instruments provided the team with the ability to recognize this amazing diversity, and thus to learn much more about Mars in general, not just Gusev in particular.

Spirit also helped us test an experiment: If we put all the rover’s images out on the Web for everyone in the world to see, in near real-time, would people follow along? They did!

I wonder if, maybe 10 or 15 years from now, I’ll meet some young colleagues who were turned on to space exploration by being able to check out the latest Spirit images from Mars from their classroom, or living room, every day when they were a kid. That would be extremely satisfying — and a great testament to the power of openly sharing data from space exploration missions like Spirit’s.

Meanwhile, Opportunity continues to rove on to city-size Endeavour crater, where orbital measurements have identified, for the first time in either rover’s mission, the signatures of clay minerals in the crater’s rim. Clays are also formed in water, but in less acidic, perhaps more life-friendly water than the sulfates that Opportunity has been mapping thus far.”

Rob Manning, Jet Propulsion laboratory, Pasadena, CA., Mars Rover Spacecraft System Engineering team lead
“Although Opportunity has proven her endurance, Spirit was the one we struggled with the hardest to get what she earned. Suffering from late repair and modification, a blown fuse in her power system and with possibly damaged circuits, she was very late getting out the door and onto the pad in Florida.

Unlike Opportunity, whose Hematite-laden Meridiani destination had been established long before launch, Spirit was launched with a great deal of uncertainty on where she would find herself on Mars. Would it be the flat and safe plains of Elysium? Would the intriguing but rough ancient Gusev crater with what appears to have been an ancient river flowing into a giant but now dry lake?

If Opportunity failed to get on her way to Mars, would her destination become Meridiani? Would Spirit have also been as lucky to find herself bouncing into a tiny rock-outcropped crater as Opportunity had?

Only after the successful launch of Opportunity followed by further successful rocket and airbag tests to confirm that the landing system design would work in the rougher terrain inside Gusev crater allowed us to seal her fate and her permanent home.

She would go Gusev and test the Gusev lake hypothesis. Sadly the surface of Gusev where she came to rest revealed a meteor impact-tilled lake of ancient lava. Any signs of ancient water lake beds and other fantastic discoveries would have to wait until she surmounted many more obstacles including summiting a formidable hill her designers never intended her to attempt.

Spirit, her designers, her builders, her testers, her handlers and I have a lot to be thankful for.

That NASA, the congress and the public were willing to trust us with this daunting feat is perhaps a statement about the persistent spirit of discovery that remains in all of us.

I think that Spirit is alive and well.”

Map mosaic shows 7 Year and 30 Kilometer Long Journey of Opportunity approaching Endeavour Crater. Opportunity is being targeted to Spirit Point on the rim of Endeavour Crater, to honor her now dead sister. Photo mosaic of Santa Maria crater at top right was featured on Astronomy Picture of the Day on 29 January 2011. Mosaic shows Opportunity self portrait at the rim of Santa Maria where she investigated signatures of hydrated mineral deposits.
Mosaic Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Kenneth Kremer