Space Sunday: the Martian tilt and Plutonian clouds

Tethys, Enceladus and Mimas seen above and blow Saturn's rings in a stunning image captured by the NASA / ESA Cassini mission, released on February 22nd, 2016. - are captured in this group photo from NASA's Cassini spacecraft released on Feb. 22. Tethys (660 miles across) appears above the rings, while Enceladus (313 miles across) sits just below center. Mimas (246 miles across) hangs below and to the left of Enceladus. This view looks toward the sunlit side of the rings and was acquired at a distance of approximately 837,000 miles from Enceladus.
Tethys, Enceladus and Mimas seen above and blow Saturn’s rings in a stunning image captured by the NASA / ESA Cassini mission, released on February 22nd, 2016. Tethys, 1056 km (660 mi) in diameter appears above the rings, with  Enceladus, 501 km (313 mi) across, just below them with Mimas, 393.6 km (246 mi) across below and to the left of Enceladus. Looking towards the sunlit side of the rings and was acquired at a distance of approx 1,339,000 km (837,000 mi) from Enceladus (credit: NASA / JPL)

The Sliding Surface of Mars

We’re all familiar with images of the surface of Mars, with the Tharsis volcanoes straddling the equator and the great gash of the Vallis Marineris just to the south. It’s a view seen in many orbital images of the planet, and one thought to have been more-or-less representative of the topography of Mars from the earliest times.

However, new studies by geomorphologists, geophysicists and climatologists led by a team of French scientists, suggest that the surface of the planet underwent a gigantic “tilt” of between 20 to 25 degrees some 3 to 3.5 billion years ago, drastically altering its appearance whilst also offering an explanation for one of the mysteries of Mars.

Mars as we know it today, Arsia Mons, Pavonis Mons, and Ascraeus Mons straddling the equator
Mars as we know it today, Arsia Mons, Pavonis Mons, and Ascraeus Mons straddling the equator, and part of the Tharsis Bulge, with massive Olympus Mons further to the north and west, and the gash of the Vallis Marineris to the south and east

While a process known as variations of obliquity can cause a planet’s axial tilt to shift  over large periods of time (Earth’s axial tilt of 23.4° is decreasing at the rate of about 47 minutes of arc per century, for example), this is not the cause of Mars’ shifting “face”. Rather it is the result of the massive Tharsis Bulge.

The largest volcanic dome in the solar system, Tharsis is a plateau some 5,000 km (3,125 mi) across and around 12 km (7.5 mi) thick, topped by the massive volcanoes of Tharis Montes: Arsia Mons, Pavonis Mons, and Ascraeus Mons. It formed over a period of roughly half a billion to a billion years, commencing around 3.7 billion years ago.

The French research suggests that as the Tharsis Bulge grew as a result of volcanic activity, so it gained considerable mass – perhaps a billion billion tonnes), which caused the crust and mantle of the planet to “slip” around the core, rather like turning the flesh of an apricot around its stone. Thus, Tharsis appears to have “dropped” to the equator from a latitude of around 20 degrees north, completely changing the face of Mars during its first 1 to 1.5 billion years of history – the time at which life might have arisen, if it arose at all.

Mars as it may have appeared around 3.5-3.7 years ago, prior to the Tharsis Bulge forming
Mars as it may have appeared around 3.5-3.7 years ago, prior to the Tharsis Bulge forming (credit: Didier Florentz, Université Paris-Sud)

While such a slippage had previously been suggested, notably through the work of Isamu Matsuyama of the University of Arizona in 2010, the French study is the first to offer definitive geomorphological evidence that this is the case. One of the major outcomes of the work is that it explains why Mars has huge and seemingly anomalous underground reservoirs of water ice located far from the poles. As the mantle and crust shifted, so they carried the frozen land which originally lay over the poles away from them, complete with the subsurface water and ice.

Overall, the study radically alters the generally accepted chronology of Mars, which has Tharsis forming before the before the widespread creation of rivers and water channels on Mars. now it appears that Tharsis formed at a time congruent with the existence of liquid water on Mars and the formation of river valleys and other water features. Thus, the volcanic activity on Tharsis may have actually contributed to the period of liquid stability on the planet.

The Methane Snows and Particle Clouds of Pluto

 enhanced color image is about 2,230 feet (680 meters) per pixel. The image measures approximately 280 miles (450 kilometers) long by 140 miles (225 kilometers) wide. It was obtained by New Horizons at a range of approximately 21,100 miles (33,900 kilometers) from Pluto, about 45 minutes before the spacecraft’s closest approach to Pluto on July 14, 2015.
Captured from a distance of 33,900 km (21,000 mi) from the point of closest approach to Pluto on July 14th, 2015, this New Horizons enhanced colour image reveals the ice-capped mountains of “Cthulhu Regio” in a strip some 450 x 225 km (280 x 140 mi). The image was taken about 45 minutes prior to closest approach (NASA/JPL / DHU?APL / SwRI)

The New Horizons team has discovered a chain of exotic snowcapped mountains stretching across the dark expanse on Pluto informally named “Cthulhu Regio”, one of the minor planet’s more identifiable features, and which stretches almost halfway around Pluto equator, some 3,000 km (1,850 mi) in length and some 750 km (450 mi) across, with one end abutting the ice-covered flats of “Sputnik Planum” I’ve previously written about in my coverage of New Horizons.

The high-resolution images show a mountain range in approximately 420 km ( 260 mi) long, the highest slopes of which are coated with a bright material that contrasts sharply with the dark red of the more usual dark red colouring of the region (thought to be the result of dark tholins, complex molecules initially formed by the reaction of methane and sunlight high in Pluto’s atmosphere, coating much of “Cthulhu Regio”. Scientists believe the white material could be methane which has condensed out of Pluto’s tenuous atmosphere to form ice, coating the peaks, much as ice can condense out of cold air on Earth to form frost. There has even been speculation that the white material is the result of methane ice condensing as “snow” and falling across the peaks.

A New Horizons image of Pluto annotated by astronomer Will Grundy, apparently showing clouds above the planet's limb (faintly arrowed) and passing over a part of "Sputnik Planum" (circled)
A New Horizons image of Pluto annotated by astronomer Will Grundy, apparently showing clouds above the planet’s limb (faintly arrowed) and passing over a part of “Sputnik Planum” (circled) – credit: NASA/JPL / JHU/APL / SwRI

And if snow on Pluto weren’t enough, speculation is growing that it may also have clouds within its thin atmosphere. While nothing has been officially announced by NASA or the New Horizons science team, New Scientist released a series of images on Friday, March 4th, together with extracts of e-mails exchanged between mission team members, in which they discuss the possibly that clouds over Pluto have been imaged by the spacecraft.

“There’s a few fairly localised low-altitude features just above the limb that I’ve drawn lame arrows pointing to,” Lowell Observatory astronomer Will Grundy states in one e-mail, “but also a few bright cloud-like things that seem to be above and cutting across the topography in the circled area,”

A closer look at what appears to be a cloud over the edge of "Sputnik Planum" (credit: NASA/JPL / JHU/APL / SwRI)
A closer look at what appears to be a cloud over the edge of “Sputnik Planum” (credit: NASA/JPL / JHU/APL / SwRI)

That there has been no public comment on the formations coming directly from the scientist studying the New Horizons images and data suggests they are uncertain of precisely what they are seeing. However, if confirmed, these would be the first-ever clouds seen on the dwarf planet, and a further indication that its atmosphere is even more complex than so far thought.

Assuming the images do show clouds, they are likely to be made up of particles of nitrogen ice along with methane and other compounds. But this doesn’t really explain why they are present.

Pluto’s atmosphere is rich in compounds and minerals – such as the tholins mentioned above – which give it is banded layered look, and these particles are constantly falling through the atmosphere, affected by ultraviolet light from the Sun, combining, breaking up, and recombining and they fall. So how and why some might coalesce into clouds within the hazy atmosphere is something of a conundrum.

340 Days and Home Again

US astronaut Scott Kelly returned to Earth on March 1st with comrade Mikhail Kornienko after spending 340 days in orbit – the longest period of time an American has spent in space.

The goal of their year-long expedition on the International Space Station is to better understand  how the human body reacts and adapts to the harsh environment of space in order to better inform current assessments of crew performance and health, and help determine better countermeasures to reduce health and associated risks associated with long-duration space missions.

Scott Kelly (l) and and Mikhail Kornienko (credit: NASA)
Scott Kelly (l) and Mikhail Kornienko (credit: NASA)

While lifted from the Soyuz capsule after landing  (a usual safety precaution to prevent astronauts and cosmonauts falling and injuring themselves as their bodies re-adjust to the full effects of Earth’s gravity), Kelly and Kornienko, together with fellow cosmonaut Sergey Volkov  who was returning to Earth after the more usual 5.5 month rotation aboard the station, were walking and moving with only slight assistance by the time they had completed the helicopter flight from their landing point back to a nearby military base, Kelly happily chewing gum. They then gave a series of press interviews, one of which is embedded below,

The flight is not the longest period of time someone has spent in space; cosmonaut Valeri Polyakov currently holds that record at a whooping 437.7 days in orbit, with Sergei Avdeyev coming in just behind at 379.6 days and Vladimir Titov and Musa Manarov tying in 3rd place with 360 days in orbit apiece. However, this is the first time such a long-duration mission has been undertaken with the availability of a control subject on earth in the form  of Scott Kelly’s identical twin brother, Mark, allowing a comparative study on the genetic effects of spaceflight to be undertaken.

While they may be back on Earth, Kelly, Kornienko and Volkov still have a little part of them flying in space aboard the ISS in the form of Lego figures unveiled by UK astronaut Tim Peake as they departed the space station. Holding the little figures up against the backdrop of Earth’s atmosphere as the Soyuz craft carrying his three crew mates prepared to undock from the ISS, Peake took a photo and said, “Farewell Expedition 46 – an honour and privilege to serve with such great crew mates!”

Tim Peake's Lego figures of Kornienko (l) and Kelly (r) with Volkov in between (credit: ESA / Tim Peake)
Tim Peake’s Lego figures of Kornienko (l) and Kelly (r) with Volkov in between (credit: ESA / Tim Peake)

ESA’s Moon Ambitions

The European Space Agency has unveiled its own ambitions to establish a presence on the Moon, and hopes to engage international support for the project. At a symposium entitled  Moon 2020-2030 – A New Era of Coordinated Human and Robotic Exploration, the agency set out its strategy for developing a permanent presence on the Moon in the form of an international “village” supporting both lunar exploration and science and offering a “gateway” to the rest of the solar system.

The ESA Moon plans raises the hoary old myth that a human presence on the Moon is necessary for any attempt to reach Mars and beyond.
The ESA Moon plans raises the hoary old myth that a human presence on the Moon is necessary for any attempt to reach Mars

The study is intended to put a roadmap to the International Space Exploration Coordinated Group (ISEG) of 14 international space agencies in order to help define the human exploration of the solar system. It is the first major initiative by ESA’s new Director General, Jan Woerner, who has long-held that the Moon should be integral to any follow-on activity taking place after the ISS has ceased operations in the mid-2020s.

There are many reasons for a human (or automated) presence on the Moon, and the ESA study offers some interesting examples of adopting technologies  – such as 3D printing and manufacturing – to help establish such a presence.

The Moon, for example, is a very good blocker of radio “pollution” leaking outwards from the Earth, so locating a radio observatory on the far side of the Moon would shield it totally from that pollution.

There are manufacturing and other benefits which could come from operations n the Moon, and well as an inordinate amount of other science research which could be carried out. But whether a permanent human presence there is actually required has already been called into question: critics have pointed out that much of which is proposed for science could be carried out remotely or tele-robotically, the 2.7 second delay in two-way Earth-moon communications notwithstanding.

Other critics have challenged to study for the way it promotes the Moon as the means of reaching Mars and beyond, an approach which has long been seen as hampering efforts to send humans to Mars rather than aiding them, adding undue costs and complexities into missions would could be far more efficiently and effectively undertaken via direct launches from the surface of the Earth, as advocated in proposals like Mars Direct, the Mars Design Reference Missions, and so on.

The Mars Direct proposal calls for two vehicles to be used. An "Earth Return Vehicle" (l), and a "Mars Hab" (r), used to fly a crew to Mars be form their living / working space for a 500-day mission on the surface. The "Earth Return Vehicle" would fly to Mars ahead of the crew and fuel itself for the return trip using the Sabatier reaction
Mars Direct, proposed in 1996, and enhanced and improved since then, and verified in terms of cost (US $30 billion over 10 years, then US $1 billion per year per mission) by an independent NASA / ESA study in 2003, utilises a direct-from-Earth approach to a Mars mission which both leverages resources available on Mars to reduce mission mass (and cost) by using a technique first discovered in 1913 to produce fuel for the journey home directly from the Martian atmosphere before the first crew has even departed Earth, whilst also offering crews a better level of Earth return redundancy than other direct flight mission proposals

Certainly, inclusion of lunar goals in America’s long-term goals for space exploration have historically lead to issues for NASA, which is attempting to more solidly focus its aims on reaching Mars (although it could do with offering a strategy that is a lot more concrete and realistic than has so far been offered). As such, and all political issues aside as regards willingness and funding, the ESA plan could face a largely uphill battle to gain broader international support.

4 thoughts on “Space Sunday: the Martian tilt and Plutonian clouds

  1. What interesting times we live in! 🙂 I love your ‘space newsletter’ format, condensing the major space news of the past days in a single article, which was most fascinating to read. Cool, I might still be alive when ESA establishes an automated factory on the surface of the Moon 🙂


    1. Thanks, Gwyn :).

      My biggest problem with these posts is what to include and what to leave to one side. This week for example, there was also news about the first Star Trek-style transport of classical physics information (previously only achieved at the quantum level), news on fast radio bursts hinting at a new exotic object beyond our galaxy, the attempts to get NASA’s budget shifted so that it’s not so much a political football (whilst still leaving the door open to it being a political football!). News from China on their robot lunar mission… Hopefully I’ll get to these in upcoming reports :).


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