The science team behind the joint NASA / ESA Dawn mission has released the most stunning high-resolution images yet seen of Ceres, one of the solar system’s three “protoplanets” located in the asteroid belt between the orbits of Mars and Jupiter.
The Dawn spacecraft has been mapping Ceres for also a year, operating at its lowest altitude above the tiny world since December 2015. During the course of the year, the images and data it has returned have, alongside information sent to us about Pluto and Charon by the New Horizons mission, caused planetary scientists to start seriously reconsidering all they thought they understood about minor planetary bodies in the solar system.
However, one thing everyone has been waiting for has been to see high-resolution images of Occator crater and the strange bright spots within it which have been the cause of so much interest and speculation, ever since they were first imaged by the Hubble Space Telescope.
While the vehicle may have commenced its most detailed mapping orbit of Ceres in December, due to the complexities of Dawn’s orbit around the tiny world, it was not until relatively recently that it was able to overfly the 92 km (57 mi) diameter Occator and capture images of what lay within it, and these images were released on March 22nd, as a part of a science briefing given at the 7th annual Lunar and Planetary Science Conference in Texas.
Taken from an altitude of just 385 kilometres (240 miles) above the crater, the images reveal a huge dome-like structure with a dimpled top forming the brightest of the “spots” in Occator. It looks for all the world like a volcano, prompting speculation that it might be what is called a “cryovolcano”. The theory here being that Ceres may contain significant quantities of volatiles (ices), which are gently heated by the dwarf planet’s interior, causing them to erupt through the surface layer, the deposits they leave behind slowly building up the volcano-like dome.
However, this is not he only theory on what might be happening. Spectral observations show that the light patches found in Occator and elsewhere are consistent with a magnesium sulphate called hexahydrite, which resembles Epsom salts here on Earth. Thus, an alternative theory is that impacts in places like Occator expose the salt-rich ices trapped in the crust to the vacuum of space. This causes the ice to sublimate (vaporise), leaving the salt behind.
Commenting on the two the two theories, Ralf Jaumann, planetary scientist and Dawn co-investigator at the German Aerospace Center (DLR) said, “Before Dawn began its intensive observations of Ceres last year, Occator Crater looked to be one large bright area. Now, with the latest close views, we can see complex features that provide new mysteries to investigate. The intricate geometry of the crater interior suggests geologic activity in the recent past, but we will need to complete detailed geologic mapping of the crater in order to test hypotheses for its formation.”
In the interim, NASA has released a new video summarising Dawn’s investigations of Ceres.
Cygnus Rendezvous with ISS
March 22nd saw the latest Orbital ATK Cygnus resupply vehicle lifted-off from Space Launch Complex 41 on Cape Canaveral Air Force Station, Florida in a spectacular night-time launch beneath a full Moon.
The automated vehicle, carrying 3.5 tonnes of supplies and equipment up to the International Space Station, made a flawless ascent into the Florida sky, the clear weather and moonlight offer some extraordinary opportunities for photographers, as shown in the image below, taken by Alex Polimeni for Spaceflight Now.
The Cygnus vehicle, named Rick Husband after the commander of the ill-fated Space Shuttle Orbiter Columbia, who lost his life along with the rest of his crew when that vehicle broke apart whilst re-entering the Earth atmosphere at the end of STS-107, rendezvoused with the ISS on Saturday, March 26th, 2016.
Rather than docking directly with the space station (as is the case with Russian Soyuz vehicles and Progress resupply craft), Cygnus (and the SpaceX Dragon resupply vehicle) slowly manoeuvre alongside the ISS until they are within reach of the station’s robot arm. This is then used to grapple the vehicle and then gently attach it to one of the station’s airlocks.
The arrival of the Cygnus vehicle marks the start of a busy 3-week period of orbital operations at the space station. Already docked at the ISS are the two Soyuz crew-carrying Earth return vehicles, and two Russian Progress resupply vehicles. However, one of the latter will be departing the station in the next few days to make way for another Progress resupply flight – Progress 63, bringing a further 2 tonnes of supplies of equipment to the ISS over the weekend of the 2/3rd April.
Then, if all goes according to plan, a resupply mission flown by SpaceX should be arriving at the space station in the second week of April, with a further 3.5 tonnes of cargo and bringing the total number of craft simultaneous docked at the ISS to six.
There’s no doubting the fact that northern and southern lights, caused by the collisions between gaseous particles in the Earth’s atmosphere with charged particles released from the sun, are beautiful sights. But to see truly astounding aurora, we have to look further afield – all the way out to Jupiter, in fact.
With its massive magnetic field and thick, rich atmosphere, Jupiter is the home of truly stupendous auroral displays, and in 2011 scientists were able to witness one of the grandest of them all, when a massive coronal mass ejection (CME) struck the planet, as reported in a paper published on March 22nd, 2016 in The Journal of Geophysical Research.
A CME is a massive burst of matter and electromagnetic radiation from the Sun. Whilst much slower moving (comparatively speaking) than solar flares, CMEs are immensely powerful. In the case of the 2011 event, so powerful that it actually physically pushed Jupiter’s magnetosphere around 1.6 million km (1 million miles) closer to the planet, producing a spectacular x-ray aurora above the planet’s poles in the process – and NASA’s Chandra X-Ray Observatory was watching, offering us some remarkable images of the auroral displays.
The event allowed scientists to observe how x-rays are created within Jupiter’s atmosphere during these events, and to identify areas of follow-up investigation on the behaviour of the Jovian magnetic field in preparation for the arrival of NASA’s Juno mission, which should enter orbit around Jupiter in July of 2016 on a mission to study magnetosphere, map its magnetic fields and observe Jovian auroras.
China Aggressively Targets Mars
China has confirmed its aggressive target to send a complex, multi-part mission to Mars in 2020 – or 2022, if they miss the 2020 launch window. The mission will comprise an orbiter vehicle, a static lander and an automated rover.
This effectively means China will be integrating two steps into one. For its Moon exploration programme, the Chinese first launched orbiters before attempting – successfully – to soft-land the Chang’e-3 probe on the lunar surface.
The orbiter part of the mission will seek out signs of methane on Mars as well as studying the Martian atmosphere and imaging the surface of the planet. It will also act as a communications relay for the surface lander and rover.
The latter will likely be modelled on the Yutu vehicle China successfully deployed to the Moon in 2013, and may carry a similar range of science instruments – Yutu’s ground-penetrating radar, for example, revealed some intriguing discoveries about the composition and history of the Moon, such as evidence of volcanic floods. However, the rover will have grater automated navigation and operation capabilities, as tele-operation from Earth isn’t possible over the distances involved, due to the time delay in communications.
Given that this will be the first truly interplanetary mission China has undertaken, and which involves some significant challenges the country has never before faced (such as getting the lander / rover through the Martian atmosphere and landing them safely), it really is an ambitious undertaking with an extremely short time frame. However, it is only the tip of the iceberg; China intends to follow the 2020 mission with a sample return mission before 2030, which will be carried out as part of a larger scale programme to explore the solar system by robotic means, much as America, Russia and Europe have been doing.
Tolkien on Titan
As the only known natural satellite to have a thick and complex atmosphere rich in organics, a surface heavy in hydrocarbons, with rivers and lakes of liquid methane, together with weather systems which include methane rain, fog, winds and more, Saturn’s largest moon Titan is a fascinating place, thought to be much like an embryonic Earth before life arose here, only a lot colder.
Now Titan can claim another similarity to Earth: mountains waiting to be climbed by the intrepid. The full extent of Titan’s mountains, which average around 3,000 metres (11,000 ft) high, has been revealed in a new map of the massive moon (Titan is 50% larger than our own Moon) produced by radar data obtained by NASA’s Cassini orbiter.
The mountain ranges are mostly gathered around Titan’s equator, and in a nod to Middle Earth, the International Astronomical Union has officially named many of the ranges after characters and locations from J.R.R. Tolkien’s classic mythology – Teniquetil Montes, Rerir Montes, Angmar Montes, and so on, with elevated highlands also named for characters – Gandalf Colles, Arwen Colles, and Bilbo Colles, for example.
However, this is no idle exercise for the benefit of far-future tourists.The investigation was motivated by a search for active zones within Titan’s crust—places where dynamic forces have shaped the landscape, perhaps in the relatively recent past. By studying them, scientists can gain greater insight into what is going on inside Titan.
On Earth, for example, mountain chains are formed where forces have shoved the surface upward from underneath, the result of Earth’s hot mantle – the layer of liquid rock beneath the planet’s hard rock crust – ebbing and flowing due to forces deep within the planet. It is believed that Titan’s icy crust sits above an ocean of liquid, which is also moving as a result of forces affecting them.
By studying the mountain chains on Titan, science teams hope to better understand what these forces are. Might they only be the result of a heat source deep within Titan’s core? Are the result of tidal forces from Saturn, or related to Titan’s rotation? Or are the mountains indicative that the upper layer of this subsurface ocean slowly freezing out and expanding, pushing the crust above around and crumpling parts of it into mountains and rugged highland terrain?
“There is lot of value in examining the topography of Titan in a broad, global sense,” said Jani Radebaugh, a Cassini radar team associate, “since it tells us about forces acting on the surface from below as well as above,”