Tag Archives: planetary science

Study: Mars’ meandering canyons formed under ice

A new study comparing Mars’ meandering canyons with those found in the Arctic regions on Earth suggests that the Martian valleys were formed by water melting under large ice sheets, not flowing water on the surface.

A large number of the valley networks scarring the surface of Mars were carved by water melting beneath glacial ice, not by free-flowing rivers as previously thought, according to new research published in Nature Geoscience. The findings effectively throw cold water on the dominant “warm and wet ancient Mars” hypothesis, which postulates that rivers, rainfall and oceans once existed on the red planet.

To reach this conclusion, lead author and postdoctoral research scholar Anna Grau Galofre of Arizona State University’s School of Earth and Space Exploration developed and used new techniques to examine thousands of Martian valleys. She and her co-authors also compared the Martian valleys to the subglacial channels in the Canadian Arctic Archipelago and uncovered striking similarities. The western edge of the Devon ice cap on the Canadian Arctic Archipelago.

I have noted previously on Behind the Black my sense that the planetary science community was beginning to shift away from the hypothesis of flowing liquid surface water on Mars as an explanation for the planet’s riverlike and oceanlike features to some form or ice/glacial activity. For a half century the scientists have tried and failed to come up with some scenario that could allow water to flow on the surface in Mars’ cold climate and thin atmosphere.

Ice or glacial activity rather than flowing liquid water might solve this problem, and today’s paper is a push in this direction.

Rover update: Curiosity pauses to drill

Curiosity's entire journey so far in Gale Crater

Overview map of Curiosity's recent travels

The artist’s oblique drawing above, as well as the map to the right, provide some context as to Curiosity’s present location and its entire journey in Gale Crater. For the overall context of Curiosity’s travels, see my March 2016 post, Pinpointing Curiosity’s location in Gale Crater. For all rover updates since then through May 2020, go here.

Since my last update on July 7, 2020, Curiosity has quickly moved a considerable distance to the east, as planned, skirting the large sand field to the south in its journey to the best path upward onto Mt. Sharp. The science team however has detoured away from their planned route, shown in red on the map, heading downhill a bit in order to find one last good location in the clay unit to drill. They are at that location now and are presently scouting for the best drilling spot.

About a week ago, before heading downhill, they had stopped to take a set of new images of Curiosity’s wheels. » Read more

A shadowed ice patch on Mars

A shadowed ice patch on Mars
Click for full image.

Cool image time! The evidence coming back from Mars in the past two decades has increasingly suggested that there is a lot of water in that planet’s mid- and high latitudes. In the mid-latitudes the evidence suggests that ice is locked in a lot of buried and inactive glaciers that were laid down during periods when the planet’s rotational tilt, its obliquity, was greater so that the annual seasons were more extreme. During those times the mid-latitudes were colder than the poles, and water was being transferred from the poles to those mid-latitudes.

The image to the right appears to be more such evidence. Taken on March 21, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and cropped and brightened by me to bring out the important details, it shows what looks to be a distinct patch of ice on the south-facing slope of the rim of a large crater. Since this crater is in the southern mid-latitudes (34 degrees south), that south-facing slope generally gets much less sunlight, even in the summer, so any remaining buried glacial ice on that slope will linger for a longer period.

Think of the lingering ice and snow patches on shadowed locations on Earth. Because the Sun does not directly shine on them, they will be the last patches to melt away.

What I think is likely important about this patch are the exposed layers along its edge. These are the spots that are melting first, as they are where the ice is exposed, unprotected by a layer of dust and debris. It is also here that we have a window into that geological history. Even at this resolution you can see that the ice was laid down in layers, meaning that it contains evidence of those repeated climate cycles produced by Mars’ shifts in obliquity.

Those layers even seem to show the same sharp and sudden change from brighter and dirtier layers, as seen in the layers of the north pole ice cap, that occurred about 4.5 million years ago.

How tantalizing. The entire climate history of Mars is sitting there for us to decipher. We need only drill a few core samples and voila! the pieces of that history will start to fall into place.

A relaxed crater on Mars

A relaxed crater on Mars
Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, shows what the science team for the high resolution camera on Mars Reconnaissance Orbiter (MRO) call a “Relaxed Crater.” This particular image was taken in July 2014. A more recent photo was taken in March 2020 to create a stereo pair, but because this older image shows more of the crater I decided to highlight it.

The crater is considered relaxed because it is very shallow and appears as if, after impact, some process caused the interior to in-fill with material even as the rim became less pronounced and degraded (as explained in this paper [pdf]). The process could have involved either molten magma or melted ice. As this crater is located in the northern highlands to the southwest of Erebus Mountains, in a region that research has consistently suggested has a great deal of ice just below the surface, the latter seems likely. This assumption is further reinforced in that the crater is also located in the mid-latitudes where scientists have found a lot of craters they think are filled with buried glaciers. This certainly seems the case here.
» Read more

Scientists better constrain time frame of Mars’ active dynamo

Using data from the MAVEN orbiter, scientists have now constrained the time frame when Mars’ dynamo was active and producing a global magnetic field, between 3.7 and 4.5 billion years ago.

Magnetism in certain rocks on Mars’ surface indicate that the Martian dynamo was active between 4.3 and 4.2 billion years ago, but the absence of magnetism over three large basins – Hellas, Argyre, and Isidis – that formed 3.9 billion years ago has led most scientists to believe the dynamo was inactive by that time.

Mittelholz’s team analyzed new data from NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) orbiter and found clear evidence of a magnetic field coming from the Lucus Planum lava flow that formed about 3.7 billion years ago – much later than at other areas studied.

There is of course a lot of uncertainty here.

Curiosity and other Mars orbiters threatened by budget cuts

The proposed budget for NASA in the Trump administrations 2021 budget request to Congress includes significant budget cuts to both Curiosity and several Mars orbiters needed to act as relay communications satellites.

The White House’s 2021 federal budget request allocates just $40 million to the mission, a decrease of 20% from the rover’s current funding. And that current funding is 13% less than Curiosity got in the previous year, said Curiosity project scientist Ashwin Vasavada, of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

If the 2021 request is passed by Congress as-is, Curiosity’s operations would have to be scaled back considerably. Running the mission with just $40 million in 2021 would leave unused about 40% of the science team’s capability and 40% of the rover’s power output, which comes from a radioisotope thermoelectric generator (RTG), Vasavada said.

In addition, the proposed budget will require a 50% reduction in imaging by Mars Reconnaissance Orbiter, the end to the Mars Odyssey orbiter, and a significant but unspecified reduction in the use of the MAVEN orbiter.

I reported these facts back in March but there is no harm in noting them again.

The question is not whether there should be cuts at NASA. Considering the overall federal debt and annual budget deficit, NASA’s budget should be cut. The question is what to cut. The planetary program, probably NASA’s most successful program, is certainly not the program to cut. Instead, the Trump administration should be cutting the waste and badly run programs, like SLS, that spend billions and accomplish nothing.

If Congress and Trump did this, they could cut NASA’s total budget and still have plenty left over for the commercial manned program — including going to the Moon — and also increase the budget to the planetary program. I’ve been saying this since 2011, and nothing has happened in the past decade to change that conclusion.

Triple impact on Moon

Impact craters Messier and Messier A on the Moon

Cool image time! A new image release from Lunar Reconnaissance Orbiter (LRO) takes a look at the impact process that created the crater Messier and its neighbor crater Messier A. The photo to the right, cropped to post here, shows both craters.

Take a close look at Messier A. It is actually a double crater itself. From the release:

Messier A crater, located in Mare Fecunditatis, presents an interesting puzzle. The main crater is beautifully preserved, with a solidified pond of impact melt resting in its floor. But there is another impact crater beneath and just to the west of Messier A. This more subdued and degraded impact crater clearly formed first.

Did these three craters happen as separate events. According to the data, it appears no. Instead, they might have all been part of a single rain of asteroids, all occurring in seconds.
» Read more

In the midst of Mars’ volcano country

lava channel
Click for full image.

Cool image time! While the rest of the world is entirely focused on panic and disease, I am going to go on with my life. The photo to the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on December 26, 2019. I suspected this channel was lava, and when I asked Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center in Arizona, he confirmed my suspicion.

Yes, that surface appears to be lava–it is part of the Elysium plains, which have many geologically-young lava flows. It’s likely that the channel is a lava channel, and the surrounding plains may be from an earlier stage of the same eruption.

The entire surface of the channel and the surrounding plains appear very fresh, mostly because of their smoothness and lack of many craters. You can also see what looks like a recent impact (the small dark splotch near the left edge about two-thirds from the top).

The fresh and smooth look of Elysium Planitia generally has led scientists to conclude that much of this region is formed from lava flows, some relatively recently. Thus, this particular lava channel is smack dab in the middle of Mars’ volcano country, quite vast and extensive. The context map below illustrates this.
» Read more

Quick fading of a Martian impact crater

Fresh impact crater on Mars, in 2010
Click for full image.

The same impact, four Martian years later.
Click for full image.

Cool image time! Though it seems that no one is really interested in anything but the Wuhan virus and the attempt by our corrupt politicians to use it to gain power, I think that life requires more from us than politics and panic. Thus, I am going to keep posting pure science and cool images.

The two photos to the right were taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) almost ten years apart. They were both posted as captioned images, the first in 2010, the second on March 19, 2020 to illustrate the remarkable fading of a fresh impact’s dark ejecta, in only about four Martian years.

The March 19, 2020 captioned image included an animation to illustrate the change. I prefer putting the two images side-by-side. Either way, the change is striking. As planetary scientist Alfred McEwen noted in his caption, “the dark material has faded into the background, while the new 6.3-meter diameter crater persists.”

Wind and dust storms probably acted to wipe out the dark material, but the process did not take that long, and last year’s global dust storm was not a major factor, since much of the dark material was already gone in this July 2012 image.

The crater itself is located in Arcadia Planitia, just west of the Erebus Mountains, the very region in the northern lowlands that SpaceX has made its primary candidate landing site for its Starship rocket, partly because the terrain is flat which makes landing easy, and partly because there is amply evidence that these lowlands have lots of ice just below the surface. And the full image for the 2019 photo reinforces this conclusion. Much of the rougher ground south of the impact appears to be the partially sublimated surface of an ice block.

So, while this region will provide an easy smooth landing site and plenty of water for the first human arrivals, those humans will also have to contend with a planet without a thick atmosphere to protect them from most meteorites. Rare as these events are, they happen more often because of Mars’ location closer to the asteroid belt, and they hit the surface far more frequently.

Wednesday at the non-existent Lunar & Planetary Science Conference

The Moon's south pole

My virtual coverage of the cancelled 51st annual Lunar & Planetary Science conference continues today with a review of the abstracts of presentations that were planned for today, but unfortunately will never be presented.

As a side note, the social shutdown being imposed on America due to the panic over COVID-19 has some side benefits, as has been noted in a bunch of stories today. Not only will this possibly destroy the power the left has on college campuses as universities quickly shift to online courses, it will also likely put an end to the endless science conferences that are usually paid for by U.S. tax dollars. (That cost includes not just the expense of the conference, but the fees and transportation costs of the participants, almost all of whom get the money from either their government job or through research grants from the government.)

Anyway, for good or ill, the virus shut down the planetary conference in Texas this week, forcing me to post these daily summaries based not on real presentations where I would have interviewed the scientists and gotten some questions answered, but on their abstracts placed on line beforehand. Today, the three big subjects were the south pole of the Moon (as shown in the map above from one abstract [pdf], produced by one instrument on Lunar Reconnaissance Orbiter [LRO]), the Martian environment, and Titan. I will take them it that order.
» Read more

Tuesday at the non-existent Lunar & Planetary Science Conference

Boulder on Bennu with changes in layered texture changes

Today was supposed to have been the second day of the week-long 51st annual Lunar & Planetary Conference, sadly cancelled due to fear of the Wuhan virus. As I had planned to attend, I am now spending each day this week reviewing the abstracts of the planned presentations, and giving my readers a review of what scientists had hoped to present. Because I am not in the room with these scientists, however, I cannot quickly get answers to any questions I might have, so for these daily reports my reporting must be more superficial than I would like.

On this day the most significant reports came from scientists working on the probes to the asteroids Bennu and Ryugu as well as the probes to the Moon. The image to right for example is from one abstract [pdf] that studied the texture differences found fourteen boulders on Bennu. The arrows point to the contacts between the different textures, suggesting the existence of layers. Such layers could not have been created on Bennu. Instead, these rocks must have formed on a parent body large enough and existing long enough for such geological processes to take place. At some point that parent body was hit, flinging debris into space that eventually reassembled into the rubble pile of boulders that is Bennu.

Other abstracts from scientists from both the Hayabusa-2 mission to Ryugu and the OSIRIS-REx mission to Bennu covered a whole range of topics:
» Read more

Martian dust devil tracks come and go

The changing surface of dunes on Mars
Click for full image.

Earlier image of the same dunes
Click for full image.

Cool image time! To understand what created the vastly strange and alien Martian surface, it will be necessary for scientists to monitor that surface closely for decades, if not centuries. To the right is one small example. Taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) and rotated, cropped, and reduced to post here, it shows a dune field inside a crater in the southern cratered highlands of Mars. Craters have been found to be great traps for dust and sand on Mars. Once the material is blown inside, the winds are not strong enough to lift the material out above the surrounding rims. Thus you often get giant dunes inside craters, as we see here.

What makes this location of interest to planetary scientists is the changing surface of these dunes. They have been monitoring the location since 2009. In 2013, the MRO science team released a captioned photograph, the second image to the right, also rotated, cropped, and reduced by me to match the same area in the top image. In that caption planetary scientist Corwin Atwood-Stone of the Lunar and Planetary Laboratory in Arizona wrote,

This area was previously imaged in August 2009, about two Mars years ago, and in that image dust devil tracks were also visible. However the tracks visible now are completely different from the earlier ones. This tells us that there has been at least one dust storm since then to erase the old tracks, and lots of dust devil activity to create the new ones.

Since then the MRO science team has taken repeated images of this location to monitor how the dust devil tracks change, as well as monitor possible changes to the dunes themselves, including avalanches. The newest image above shows the result of the global dust storm last year. It wiped out the dust devil tracks entirely.

The newer image was entitled, “Monitor Dune Avalanche Slopes,” but I couldn’t find any examples. Based on published research, I am sure there is something there, even if I couldn’t find them. Maybe my readers have a better eye than I.

The upcoming very busy planetary probe season

The next few months are going to be very busy and exciting for the planetary science community. Seven different probes will be either flying past or landing on four different solar system objects, with interesting events happening every few weeks:

  • September 21: One of Hayabusa-2’s mini-landers, Minerva-II-1, will land on the asteroid Ryugu
  • October 3: Another Hayabusa-2 mini-lander, MASCOT, will land on Ryugu
  • Late October: Hayabusa-2 itself will land and grab a sample of Ryugu
  • November 26: The U.S. lander InSight will land on Mars.
  • December 3: OSIRIS-REx will arrive at the asteroid Bennu.
  • December: Chang’e-4 will land on the Moon’s far side.
  • January 1: New Horizons will fly past the Kuiper Belt object Ultima Thule.

In addition, another Hayabusa-2 mini-lander will also land on Ryugu, sometime after Hayabusa-2’s landing. Moreover, as OSIRIS-REx and New Horizons approach their targets we shall see daily new and increasingly sharper images of both Bennu and Ultima Thule, prior to their arrival.

I expect from September to January there will be many many very cool images coming from space, on almost a daily basis.

Lunar landers/rovers for sale!

Moon Express, one of the five finalists trying to win the Google Lunar X-Prize (GLXP) before it expires at the end of this year, announced today its long range plans, focused on building low cost lunar landers rovers, and sample return missions that could be purchased and launched for a tenth the cost of a typical government mission.

The GLXP mission won’t be the last lunar voyage for Moon Express, if all goes according to plan. Its deal with Rocket Lab covers up to five launches, and Moon Express wants at least two more to occur in the next few years, Richards revealed during a news conference today.

The first post-GLXP mission, scheduled to launch in 2019, will set up a robotic research outpost near the lunar south pole and prospect for water and other resources. Then, in 2020, Moon Express will launch the first commercial lunar sample-return mission. That effort, Richards said, should prove out the company’s technologies and its business model, which is centered around creating low-cost access to the moon’s surface for a variety of customers. The core piece of hardware to make all of that happen is a single-engine lander called the MX-1, which will launch on the GLXP flight. Moon Express aims to mass-produce the MX-1, sell it as a stand-alone lunar explorer and have it serve as a building block for three larger, more capable spacecraft — the MX-2, the MX-5 and the MX-9, Richards said today.

The MX-2 combines two MX-1s into a single package, boosting the MX-1’s payload capacity in Earth-moon space and potentially enabling missions to Venus or the moons of Mars. As their names suggest, the MX-5 and MX-9 incorporate five engines and nine engines, respectively, and broaden the exploration envelope even further, Richards said. All of these spacecraft will be available in orbiter, lander and deep-space variations, and the MX-5 and MX-9 vehicles will also come in a sample-return configuration.

Moon Express has not revealed how much it will charge for any of these spacecraft. However, company representatives have said that, together, the MX-1 and Electron can deliver a lunar mission for less than $10 million (that’s “cost,” not retail). Electron flights currently sell for about $5.5 million apiece, putting the lander’s raw cost at $4.5 million or less.

Essentially, they are taking the revolution in satellite technology that is making everything smaller and cheaper and applying it to planetary exploration. They are then offering this technology as a very cheap and fast option for scientists and governments. Based on these numbers, a mission to the Moon could cost a customer less than $20 million, which is nothing compared to a typical NASA mission. Even India’s Mars Orbiter was several times more expensive than this.

While I consider NASA’s planetary program second to none, and one of the best things it does, Moon Express is demonstrating, as has SpaceX with launch services, that private enterprise, if given the chance, can do it better.

Cubesats to the planets!

Link here. The article is a good detailed overview of the many upcoming planetary missions that are using small and relatively inexpensive cubesats as either part of their mission, or are the mission itself.

This trend also partly explains the number of new rocket companies like Rocket Lab and Firefly Space Systems that are developing small rockets aimed at launching cubesats. These companies have recognized a growing demand, and are trying to serve it. As the article notes,

Lifts are so hard to come by that the first interplanetary CubeSat — NASA’s twin INSPIRE mini-spacecraft, intended to test key technology for future missions — has been waiting for almost two years. “We still have to find a ride,” says Anthony Freeman, who manages the Innovation Foundry at NASA’s Jet Propulsion Laboratory in Pasadena, California.

Our limited understanding of the Martian climate through time

The uncertainty of science: Annual Reviews periodically publishes papers providing a detailed scientific review of the present state of knowledge in a variety of fields. They do this by collecting the papers in volumes focused on general areas of research, such as Astronomy and Astrophysics, Plant Biology, and even Sociology.

Today I received the announcement of the publication of the 44th volume of the Annual Review of Earth and Planetary Sciences, listing the volume’s table of contents. While there were many interesting papers on a variety of planetary subjects that interested me (“The climate of Titan,” “Impacts of Climate Change on the Collapse of Lowland Maya Civilization,” and “The Lakes and Seas of Titan”), one paper in particular, entitled “The climate of early Mars”, intrigued me enough after reading the abstract to download it and read it in its entirely. (As a science journalist I have free access to the full text of these papers. While the abstract is free to all, if you wish to read the full text you need to either buy it, or visit a university library that subscribes to each particular series.)

As a review I found the paper quite fascinating. It provided an excellent overview of our present understanding of Mars’s climate history, information that is especially useful to me in reporting on the results from the various Martian orbiters and rovers, as it gives me a wider context and allows me to better understand and analyze each press announcement. This in turn allows me to distinguish between a real discovery of some importance and a garbage press release that is really nothing more than a sales pitch for more funding.

The bottom line of this paper however is this: We know without doubt, based on a lot of geological evidence, that approximately 3 to 4 billion years ago liquid water existed on the Martian surface, leaving behind complex valley drainage networks similar to those created by flowing water on Earth. In addition, the data from the rovers has also found evidence, clays and other minerals, that could only have formed if water once flowed on the surface. What we don’t know is how that liquid water could have existed. The data so far does not provide any clear mechanism for warming the climate enough as well as producing a thick enough atmosphere to allow liquid water to flow. To quote the paper:

In summary, no single mechanism is currently accepted as the cause of anomalous warming events on early Mars.

The data also suggests that an ocean on Mars was unlikely, though not impossible. Instead, it appears that if any warming events occurred to produce liquid water, they were temporary and short-lived. What caused those warming events, however, remains a scientific mystery.

The paper also made clear once again the complexity of climate science, and how difficult it is to develop climate models that explain the geological evidence, not just on Mars, but on Earth as well. As the paper also noted, “Just like the climate of Earth today, the ancient climate of Mars was probably complex, with multiple factors contributing to the mean surface temperature.” And like the climate of Earth, many of those multiple factors remain uncertain and poorly understood. It will be many years before we really understand how Mars got to be the way it is.

Likely, to figure it out we will have to go there ourselves and poke around with our own hands.

Juno closing in on Jupiter

Jupiter from Juno

On Friday the Juno science team released a new image of Jupiter taken by the spacecraft from about 6.8 million miles away.

The reduced resolution image on the right is cropped but with the colors enhanced to bring out the four Galilean moons, Ganymede, Callisto, Europa, and Io. The website notes that “Juno is approaching over Jupiter’s north pole, affording the spacecraft a unique perspective on the Jovian system. Previous missions that imaged Jupiter on approach saw the system from much lower latitudes, closer to the planet’s equator.”

Rendezvous and orbital insertion happens on July 4.

To save money, NASA management has shut down a troubled program to build a more efficient plutonium power supply for its deep space missions.

To save money, NASA management has shut down a troubled program to build a more efficient plutonium power supply for its deep space missions.

The cancelled ASRGs would have generated electrical power from the expansion of gas warmed by the radioactive decay of plutonium-238. NASA says that the devices have the same power output as its current generation of Multi-Mission Radioactive Thermoelectric Generators (MMRTG) but use four times less plutonium-238, a scarce resource. One MMRTG with 4.8 kilograms of plutonium is currently powering the Curiosity rover on Mars.

The United States has less than 40 kilograms of plutonium-238 left, but the DOE restarted production this year. Green says he is confident that the DOE will be producing plutonium-238 at a rate of 1.5 kilograms per year by 2019. He says that the stockpiled plutonium-238, along with the new supply, will be enough to send another planned rover to Mars in 2020 and to complete other missions in the 2020s – without any need for the extra efficiency of the ASRGs.

The ASRG program had been a year and a half behind schedule and had had its management team replaced at one point.

Russia heads for Mars

Russia heads for Mars: a detailed look at the Phobos/Grunt sample return mission, set to launch on November 8.

I really wish the Russians good luck with this project. Not only would it herald their return to planetary science since the fall of the Soviet Union, success here would break their long string of failures to the red planet. Though their unmanned planetary program had some remarkable achievements during the Soviet era, of the 19 missions they flew to Mars in the 1960s, 1970s, and 1980s, all were failures, producing almost no useful data.

A NASA senior review of all planetary missions?

Here’s a tidbit I just spotted on the EPOXI (formerly Deep Impact) status website, buried in a November 1, 2011 update::

Meanwhile, NASA has decided that there will be a senior review of all operating planetary exploration missions. That will likely include a review of the status of the Deep Impact Flyby spacecraft to determine whether an additional extended mission should be approved. Decisions will not occur until early 2012.

Though Deep Impact is still a functioning spacecraft in orbit around the sun, up until this notice I had not heard of any plans to use it again after its flyby of Comet Hartley-2 in 2010. However, there is no reason its cameras could not be used for astronomy, though unfortunately its high resolution camera has a focus problem which prevents it from taking the sharpest images.

However, the timing of this review of planetary missions, combined with the story last week that the Obama administration might end all funding for future planetary missions, is intriguing. I wonder if they are tied together in some way. That the notice above says the decision will be made in “early 2012” — the moment when the Obama administration will unveil its 2012 federal budget recommendations — strongly suggests that they are linked.

Could that the administration be thinking it can salvage the bad press it will receive for shutting down all future planetary missions by spending a small amount on extending missions already in space? Or is this planetary review another indication that the rumors are true and the administration plans to end the planetary science program entirely?

Unfortunately, I am speculating here, without any real information. Stay tuned to find out.

A summary of Messenger’s first six months in orbit around Mercury

A summary of Messenger’s first six months in orbit around Mercury.

Though packed with lots of results, this strikes me as the most interesting discovery so far:

Orbital data reveal that Mercury’s magnetic field is offset far to the north of the planet’s center, by nearly 20% of Mercury’s radius. Relative to the planet’s size, this offset is much more than in any other planet, and accounting for it will pose a challenge to theoretical explanations of the field. . . . This finding has several implications for other aspects of Mercury, says Anderson, who co-authored several of the presentations in the MESSENGER session. “This means that the magnetic field in the southern hemisphere should be a lot weaker than it is in the north. At the north geographic pole, the magnetic field should be about 3.5 times stronger than it is at the south geographic pole.

The rover Opportunity as seen from Mars orbit

Opportunity on Endeavour Crater rim

The image to the right was taken by Mars Reconnaissance Orbiter, with the white arrow showing the Mars rover Opportunity perched on the rim of Endeavour Crater.

The rover’s scientists hope that the rocks found on the crater rim, dredged up from deep below when the crater impact occurred, will be the oldest rocks so far touched on the Martian surface, and thus give them a peek at ancient Martian geology.

Video from Dawn

NASA has released an update summarizing what scientists have found since Dawn went into orbit around Vesta in July. The video below, compiled from images Dawn has taken, gives a nice visual overview. The most interesting big feature, understated by the video, is the series of grooves that appear to encircle the asteroid’s equator. To my eye it almost looks like Vesta was once two asteroids that got merged into one, with these grooves indicating the weld point.

The direct link to the video can be found here.

Embedded video from

NASA Jet Propulsion Laboratory California Institute of Technology

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