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.
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.
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
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.
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,”
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.
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!”
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 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.
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.