Tag: ISS

Space Sunday: minerals, ice, rockets and capsules

Posted on by Inara Pey

CuriosityNASA’s Curiosity rover has resumed its long, slow climb up the slopes of “Mount Sharp”, the 5 km high mound abutting the central impact peak of Gale Crater on Mars.

For the last few months, the rover has been easing its way over what is called the “Murray Formation”, a transitional layer marking the separation points between the materials deposited over the aeons to create the gigantic mound, and the material considered to be common to the crater floor. Named in honour of the late co-founder of The Planetary Society, Bruce Murray, the formation comprises a number of different land forms, which the rover has been gradually examining.

On June 4th, 2016, Curiosity collected its latest set of drilling samples – the 11th and 12th it has gathered since arriving on Mars – on the “Naukluft Plateau”, a further region of sandstone within the Murray Formation, similar to the area dubbed the “Stimson Formation”, where the rover collected samples in 2015.

The Murray formation extends about 200 metres (650ft) up the side of "Mount Sharp". Starting at the "Pahrump Hills" below "Murray Buttes" in late 2014, Curiosity is about one fifth of the way across the region, spending extended periods examined various features within the formation. Credit: NASA JPL
The Murray formation extends about 200 metres (650ft) up the side of “Mount Sharp”. Starting at the “Pahrump Hills” below “Murray Buttes” in late 2014, Curiosity is about one fifth of the way across the region, spending extended periods examined various features within the formation. Credit: NASA JPL

The aim is to carry out comparative geology between the two sites to determine whether or not their formation is related. The “Stimson Formation” sandstone strongly suggested it has been laid down by wind after the core slopes of “Mount Sharp” had been laid down by sedimentary processes the result of Gale Crater once being home to s huge lake, but which had then been subjected to fracturing by the passage of water. These bands of fractured sandstone have become more prevalent as the rover has continued up through the “Murray Formation”, so it is hoped that by obtaining samples from “Naukluft Plateau”, the science team will gain further understanding of precisely what part water played in the evolution of the slopes of “Mount Sharp” after the lake waters had receded.

The HiRise imaging system on the Mars Reconnaissance Orbiter (MRO) captured the the Mars Science Laboratory rover Curiosity on the Naukluft Plateau in May 2016 (credit: NASA/JPL / University of Arizona)
The HiRise imaging system on the Mars Reconnaissance Orbiter (MRO) captured the Mars Science Laboratory rover Curiosity on the Naukluft Plateau in May 2016 Credit: NASA/JPL / University of Arizona

Since completing the drilling operations, Curiosity has turned south, and is now climbing the mound “head on”, rather than gradually zig-zagging its way upwards.

The MSL rover has also provided geologists with another surprise. In mid-2015, the rover collected samples from a rock dubbed “Buckskin”. Reviewing the analysis of the minerals in the samples, as discovered by Curiosity’s on-board laboratory suite, scientists have found significant amounts of a silica mineral called tridymite.

“On Earth, tridymite is formed at high temperatures in an explosive process called silicic volcanism. Mount St. Helens, the active volcano in Washington State, and the Satsuma-Iwojima volcano in Japan are examples of such volcanoes,” said Richard Morris, a NASA planetary scientist at Johnson Space Centre. “The tridymite in the Buckskin sample is thought to have been incorporated into “Lake Gale”  mudstone as sediment from erosion of silicic volcanic rocks.”

The find is significant because although volcanism did once take place on Mars, it has never been thought of as being silicic volcanism, which is far more violent that the kind of volcanism associated with the formation of the great shield volcanoes of the Tharsis Bulge and other regions of Mars. So this discovery means geologists may have to re-think the volcanic period of Mars’ early history.

China Launches Long March 7

Saturday, June 25th saw the inaugural launch of China’s Long March 7 booster, a vehicle I wrote about back in April 2016. The launch was also the first from China’s fourth and newest space launch facility, the Wenchang Satellite Launch Centre, located on Hainan Island, the country’s southernmost point.

The Long March 7 is a core component to China’s evolving space ambitions. Classified as a medium lift vehicle, it can carry around 13.5 tonnes to low Earth orbit (LEO), it will operate alongside China’s upcoming heavy lift launcher, the Long March 5. This craft will be capable of lifting around the same payload mass directly to geosynchronous orbit, and around 25 tonnes to LEO. Both vehicles will play a lead role in China’s plans to expand her explorations of the Moon, establish a permanent space station in Earth orbit by 2022, and reach Mars with automated missions.

China's Long March 5 (l) and Long March 7 (r) next generation launch vehicles
China’s Long March 7 (right) launched on it inaugural flight on Saturday, June 25th. The bigger Long March 5 (left) is due to launch later in 2016. Credit: China state media

The inaugural launch of the Long March 7 took place at noon GMT on Saturday, June 25th (20:00 local time). It carried a Yuanzheng 1A upper stage and a scale model of China’s next generation crewed orbital vehicle into an orbit of 200 km (120 mi) by 394 km (244 mi) as confirmed by US tracking networks.

Yuanzheng is an automated “space tug” China has used numerous times to deliver payloads to their orbits, and is capable of re-using its engine multiple times. It is most often used to boost China’s communications satellites into higher orbits.

The sub-scale capsule was used to carry out an atmospheric re-entry test to gather data which will be use to further refine and improve the re-entry vehicle which will form a part of China’s replacement for its ageing, Soyuz-inspired Shenzhou crew vehicle. This unit returned to Earth, landing in a desert in Inner Mongolia on Sunday, June 26th, after orbiting the planet 13 times. Also aboard the vehicle was a “cubesat” mission to test a navigation system, and a prototype refuelling system.

Continue reading “Space Sunday: minerals, ice, rockets and capsules” →

Advertisements

Space Sunday: Martian tsunamis, Indian space planes, Chinese telescopes

Posted on by Inara Pey
Mars as seen from 80 million km (50 million mi): a Hubble Space Telescope image of Mars captured during opposition on May 12th, 2016. Coincidentally, the Arabia Terra, one of the subjects in the report below, is the dark area in the centre of the image,
Mars as seen from 80 million km (50 million mi): a Hubble Space Telescope image of Mars captured during opposition on May 12th, 2016. Coincidentally, the Arabia Terra, one of the subjects in the report below, is the dark area in the centre of the image, together with Xanthe Terra. Cryse Planitia (Plain of Gold) is in the lower part of the light-coloured circular area dipping into the dark mass of Arabia and Xanthe Terra. North is to the top of the image, south to the bottom. Credit: NASA / ESA

It has long been believed that Mars once had oceans which covered most of the northern hemisphere lowlands about 3.4 billion years ago. Radar mapping from orbit has revealed layers of water-borne sediment similar to those found on Earth’s ocean floors, sitting on top of a layer of volcanic rock. In addition, there is strong evidence for an ancient shoreline and coastal areas around the rim of the ocean. The problem is, the evidence for the coastal areas is far from complete, leading to one of Mars’ many mysteries: if the lowlands were once home to a vast ocean, where did the shoreline go?

Alexis Rodriguez of the Planetary Science Institute in Tucson Arizona believes a study she and her colleagues have been carrying out may hold the key: sections of the Martian coastline may have been washed away as a result of massive tsunamis. And when I say huge – I mean waves towering some 120 metres (400ft) into the air.

The northern hemisphere of Mars when it was once home to an world-circling ocean, 3.4 billion years ago
The northern hemisphere of Mars when it was once home to an world-circling ocean, 3.4 billion years ago

The time of the Martian ocean coincides when the end of the period known as the Late Heavy Bombardment, when the planets of the inner solar system were subject to a disproportionately large number of asteroid impacts. Rodriguez and her colleagues have suggested that two particularly large meteoroids smashed into the northern hemisphere during this period, driving the tsunamis and reshaping the ancient shoreline.

The focus of the study is a region on Mars where the Arabia Terra upland region meets the lower-lying Chryse Planitia, and which should form a part of the ancient shoreline. Within it, Rodriguez and her team have identified two separate geological formations which may have been created by two separate tsunami events.

In this image
This set of images show the region where Arabia Terra flows down to Chryse Planitia. In figure A, the red line denotes the original ancient shoreline of the region. The grey area below and to the left of it denotes depositions believed to be the result of the first tsunami, together with outflow channels carved by the receding flood (blue arrows). The black line indicates the much younger shoreline of the region at the time of the second impact, which saw the formation of icy lobes in the region, and the embaying of features by slurry and material deposit by the receding waters. Images B and C focus on the coastal areas of deposition and embayment. Image created by Esri’s ArcGIS® 10.3 software

The older of the two looks every bit like a coastal region struck by a huge wave which deposited boulders over 10 metres across. As the water then receded back into the ocean, it cut large backwash channels through its debris and boulder field, depositing large amounts of surface material back into the ocean. Then, several million years later, the second impact took place.

This later event came at a time when Mars was effectively entering an ice age, and caused not so much massive tidal waves, but huge ice slurries which spread across the landscape, much of it freezing out, forming lobes of ice. The material which did make it back into the ocean also “embayed” older features there, partially burying them in the slurry.

Radar imaging has revealed subsurface large lobes of icy deposits along the outwash plains and channels in the Arabia Teraa / Chryse Planitia abutment, indicative of the study's suggestion that some of the material deposited after the second tsunami event froze out before it could flow back to the ancient sea
Radar imaging has revealed subsurface large lobes of icy deposits along the outwash plains and channels in the Arabia Teraa / Chryse Planitia abutment, indicative of the study’s suggestion that some of the material deposited after the second tsunami event froze out before it could flow back to the ancient sea

The study isn’t conclusive, but does offer up some strong supporting evidence. Rodriguez and her team are the first to admit more research is required before the tsunami hypothesis might be confirmed or refuted. They are now examining other areas where the ancient coastline is “missing” to see if they exhibit similar evidence for tsunami events.

Continue reading “Space Sunday: Martian tsunamis, Indian space planes, Chinese telescopes” →

Space Sunday: naming a (dwarf) planet and weather watching on Mars

Posted on by Inara Pey
A revised infographic of the six largest dwarf planets, showing 2007 OR10's revised 3rd place
A revised infographic of the six largest dwarf planets, showing 2007 OR10’s revised 3rd place

While opinions may be in a state of flux over what constitutes a dwarf planet – the recent discoveries around Pluto’s interaction with the solar wind once again highlighting the debate, the fact remains that there are a fair few to be found in the solar system, with the largest five, as traditionally listed in descending order of volume, being: Pluto, Eris, Haumea, Makemake and … 2007 OR10.

These worlds are so small and so far away – in relative terms – that gathering data on them without actually paying them a visit, as we’ve done with Pluto, isn’t easy. In the case of 2007 OR10, this lack of information means it has been left without a name, only a designation related to its year of discovery.

An artist's conception of 2007 OR10. Astronomers suspect that its rosy color is due to the presence of irradiated methane. Credit: NASA
An artist’s conception of 2007 OR10. Astronomers suspect that its rosy color is due to the presence of irradiated methane. Credit: NASA

However, all this might now be changing after data gathered by the Kepler observatory (about which I’ve written in recent Space Sunday reports) has helped reveal the dwarf planet – which orbits the Sun once every 547.5 years – is actually the third largest such body beyond the orbit of Neptune, sitting behind Pluto and Eris, and thus it could be a lot more interesting than first thought.

Up until now, it had been thought 2007 OR10 was about 1280 km (795 mi) in diameter. However, such is the sensitivity of Kepler’s instruments in measuring light variations whilst seeking extra-solar planets orbiting nearby stars, that the observatory has been able to precisely measure variations in the brightness of this unusually dark little world. These measurements, combined with data obtained from the Herschel Space Observatory, suggest that 2007 OR10 is around 1535 km (955 mi) in diameter, or about 255 km (160 mi) larger than previously thought.

2007 OR10The upshot of this is the dwarf planet is liable to be a far more interesting place than previously thought, potentially covered in volatile ices of methane, carbon monoxide and nitrogen, and may even be somewhat active as a result of its interaction with the solar wind. It also means that it is really overdue for a decent name.

According to convention, the honour of naming it goes to the planet’s discoverers, in this case Meg Schwamb, Mike Brown and David Rabinowitz. They discovered it in 2007 during a search for distant bodies in the Solar System. In fact, Mike Brown has already suggested a name: Snow White, in recognition of the planet’s ice surface composition.

However, this hasn’t stopped suggestions rolling in from the general public – up to and including, “Dwarfy McDwarfface”, in recognition of the recent public voting on the name for the UK’s new polar research ship.

I have to admit that – and indifference to Mike Brown’s suggestion, which doesn’t take into account 2007 OR10’s likely rusty complexion – my personal favourite suggestion has to be that from Greenwood Space Travel Supply Co (shown above right), which puts forward a very strong case for the name of this little world.  I’m also wearing my Dwarf Planet Pride Day badge with … pride!

Two Years of Weather Reporting on Mars

NASA’s Curiosity rover has completed its second year on Mars – its second Martian year, that is; August 2016 will actually mark the end of its fourth Earth year of operations in Gale Crater. This milestone is important, as it means that the rover has been able to accumulate data on two full cycles of Martian seasons and weather.

Gathering data over so long a period helps distinguish seasonal effects from sporadic events. For example, a large spike in methane in the local atmosphere during the first southern-hemisphere autumn in Gale Crater was not repeated the second autumn; it was an episodic release, albeit still unexplained. However, the rover’s measurements do suggest that much subtler changes in the background methane concentration may follow a seasonal pattern; while measurements of temperature, pressure, ultraviolet light reaching the surface and the scant water vapour in the air at Gale Crater show strong, repeated seasonal changes.

Monitoring the modern atmosphere, weather and climate fulfils a MSL mission goal, supplementing the better-known investigations of conditions billions of years ago. Back then, Gale Crater had lakes and groundwater that could have been good habitats for microbes, if Mars has ever had any. Today, though dry and much less hospitable, environmental factors are still dynamic.

Curiosity’s Rover Environmental Monitoring Station (REMS), supplied by Spain’s Centro de Astrobiología, has measured air temperatures from 15.9o C (60.5o F) on a summer afternoon, to -100o C (-148o F) on a winter night.

Comparing temperatures at Mars’ Gale Crater (lower set of bars) to temperatures in Los Angeles. It shows key differences both in how much colder the Martian site is throughout the year, and also how much greater the difference between daily highs and lows. Mars has only about one one-hundredth as much atmosphere as Earth, and without that thick blanket of atmosphere the air temperature around Curiosity usually plummets by more than  55o C (100o F) between the afternoon high and the overnight low.

Continue reading “Space Sunday: naming a (dwarf) planet and weather watching on Mars” →

Space Sunday: BEAM and Kepler, Europa and comets

Posted on by Inara Pey
Euorpa's icy, mineral-stained surface as imaged by NASA's Galileo mission - see bwlow (credit: NASA / JPL)
Euorpa’s icy, mineral-stained surface as imaged by NASA’s Galileo mission – see below (credit: NASA / JPL)

In my last Space Sunday article, I covered the arrival of the BEAM inflatable module at the International Space Station, and the concerns for NASA’s Kepler “planet hunter” space observatory. As there’s been further news on both of these, I thought I’d start this Space Sunday with a quick round-up on them, starting with Kepler.

The Kepler observatory, located some 121 million kilometres (75 million miles) “behind” Earth as both orbit the Sun, has been engaged in a 7-year mission to try to locate planets – particularly possible Earth-type planets – orbiting other stars. As I reported last time around, despite one major setback which called a halt to the observatory’s primary mission in 2012, Kepler has been a remarkably successful mission, catalogue some 4,000 potential planets orbiting other suns, with over 1,000 subsequently confirmed as planets.

However, on April 7th, Kepler reported to mission managers that it has entered Emergency Mode – a status indicating a critical problem has occurred, causing the observatory to shut down all science operations and other systems, and was utilising its supplies of valuable propellant to maintain its orientation so it could communicate with Earth, rather than using its electric reaction wheels, powered by sunlight.

Keler 425b - the first Earth-like planet to be found orbiting within its sun's habitable zone
Keler 425b – the first Earth-like planet to be found orbiting within its sun’s habitable zone (credit: NASA)

Over the next several days, mission engineers were able to upload instructions to Kepler so that it could position itself in a “point rest state” where communications could be maintained without eating into further propellant reserves. Following this, a long, slow data download commenced, which allowed engineers to fully understand the extent of the problem – but not the cause. However, this has been enough for a path to recovery to be determined.

Kpler: being nursed back to health from 121 million km away
Kpler: being nursed back to health from 121 million km away (credit: NASA)

Since April 12th, commands have been sent to the observatory instructing it to bring it non-critical systems back on-line one at a time, monitoring responses as it did so. With each system successfully restored, Kepler has been gradually coming to life whilst eliminating potential causes of the original problem. There is still a way to go, but mission managers are now reasonably confident Kepler can be restored to a fully operational status.

“The recovery started slowly and carefully, as we initially merely tried to understand the situation and recover the systems least likely to have been the cause,” said Kepler programme manager Charlie Sobeck on April 14th. “Over the last day and a half, we’ve begun to turn the corner, by powering on more suspect components. With just one more to go, I expect that we will soon be on the home stretch and picking up speed towards returning to normal science operations.”

Meanwhile, BEAM – the Bigelow Expandable Activity Module – an inflatable prototype habitat module which arrived at the International Space Station on April 10th – was extracted from its ferry vehicle, the uncrewed Dragon resupply vehicle, on Saturday April 16th, and successfully secured against the airlock node of one of the station’s modules.

the extraction and relocation were undertaken remotely, using the space station’s robot arm commanded from Earth to lift the BEAM unit, still in its compact “flight” configuration just 2.4 metres (8ft) in length and 2.1 metres (7ft) diameter, from the unpressurised section of the Dragon cargo vehicle and then position it against the US Tranquillity Module of the space station, where it was secured by astronauts Tim Kopra and Jeff Williams.

Space station commander Tim Kopra took this photograph of the BEAM unit, in its compact state, being moved towards the Tranquillity module by the station's robot arm, ready for it to be secured against one of the station's airlocks
Space station commander Tim Kopra took this photograph of the BEAM unit, in its compact state, being moved towards the Tranquillity module (seen on the left, directly under the robot arm) by the station’s robot arm, ready for it to be secured against one of the station’s airlocks (credit: NASA / Tim Kopra)

The module is not due to be inflated until early May, when it will increase in size to some 4m x 3.5m (13ft x 10.5ft) and provide some 16 cubic metres (565 cubic ft) of working space. It will be equipped with monitoring equipment  to investigate how well it protects against solar radiation, space debris and contamination over a 12-18 month period. During this time, ISS crew members will enter the unit 3 or 4 times a year to collect deployment dynamics sensor data, perform microbial surface sampling, conduct periodic change-out of the radiation area monitors, and inspect the general condition of the module.

BEAM-animation
Animation showing the manoeuvre to position BEAM against the Tranquillity module

Continue reading “Space Sunday: BEAM and Kepler, Europa and comets” →

Space Sunday: Of Odysseys, rockets, inflatables and exoplanets

Posted on by Inara Pey
Mars Odyssey: 15 years since launch and still going strong
Mars Odyssey: 15 years since launch and still going strong

Fifteen years ago, on April 7th, 2001, NASA launched their Odyssey mission to Mars. Since then, this orbital vehicle, whilst often overlooking in favour of its younger companions, Mars Express from Europe and NASA’s Mars Reconnaissance Orbiter, has done much to revolutionise our understanding of Mars.

Named for 2001: A Space Odyssey, the seminal science-fiction novel by Arthur C. Clarke, Odyssey arrived in orbit around Mars in October 2001. In doing so, not only did it overcome the failures of the 1999 Mars Climate Orbiter and Mars Polar Lander missions, it almost immediately scored its own major success: one suite of instruments found evidence for water ice close to the surface in large areas of Mars – as significant finding which has since gone on to shape much of our thinking about what lies within the Martian crust.

In 2010, Odyssey provided the highest-resolution (at that time) global map of Mars, stitched together from 21,000 images returned by the Thermal Emission Imaging System (THEMIS). Prior to that, in 2008 Odyssey spotted evidence of salt deposits across about 200 places in the south of Mars. NASA considers these areas to be signs of where abundant water used to sit. Scientists theorized the deposits could come from groundwater, which evaporated and left deposits of mineral behind. While in 2007, Odyssey imaged what appeared to be massive cave mouths on the surface of Mars.

THEMIS confirmed the openings – each between 100 to 250 meters (328 to 820 feet) across – were either vertical shafts running into the Martian crust or possibly openings leading to cavernous spaces beneath the surface. Dubbed the “seven Sisters” the openings were discovered on the flank of Arsia Mons, one of the gigantic Tharsis volcanoes, prompting speculation that they might be the collapsed roofs of lava tunnels within the volcano’s slopes.

A 2007 THEMIS image from Mars Odyssey showing entrances to possible Martian caves, dubbed the "seven sisters." Clockwise from upper-left: Dena, Chloe, Wendy, Annie, Abbey, Nikki and Jeanne. Arrows signify direction of solar illumination (I) and direction of North (N) - Credit: GE Cushing, TN Titus, JJ Wynne, USGS, USGS, Northern Arizona University, and PR Christensen of Arizona State University
A 2007 THEMIS image from Mars Odyssey showing entrances to possible Martian caves, dubbed the “seven sisters.” Clockwise from upper-left: Dena, Chloe, Wendy, Annie, Abbey, Nikki and Jeanne. Arrows signify direction of solar illumination (I) and direction of North (N) – Credit: GE Cushing, TN Titus, JJ Wynne, USGS, USGS, Northern Arizona University, and PR Christensen of Arizona State University

The vehicle has also operated in concert with the Mars Reconnaissance Orbiter in support of surface missions, including both the Curiosity and Opportunity rovers. As well as acting as a communications relay for such missions, Odyssey has been able to add context to the rovers’ work by providing thermal and other images which have helped science teams better understand the environments in which the rovers are operating. Nor does it end there. Odyssey has also been a careful observer of the Martian weather.

As each year on Mars lasts around 26 months, Odyssey has observed the planet through more than six Martian years. These observations have revealed some seasonal patterns that repeat each year and other seasonal events, such as large dust storms, which differ significantly from year to year.

A 2001 false colour map of Mars made from data gathered by Odyssey's gamma ray spectrometer reveals the widespread distribution of hydrogen-enriched soil on Mars (in blue), the result of sub-surface ice deposits
A 2001 false colour map of Mars made from data gathered by Odyssey’s gamma ray spectrometer reveals the widespread distribution of hydrogen-enriched soil on Mars (in blue), the result of sub-surface ice deposits

In just this past year, Odyssey’s orbit has put the spacecraft in position to observe Mars in early morning light. Previously, the spacecraft flew over ground that was either in afternoon lighting or pre-dawn darkness. The new orbit enables studies of morning clouds and fogs and comparison of ground temperatures in the morning to temperatures of the same sites in the afternoon and pre-dawn, again helping to increase our understanding of the various atmospheric mechanisms operating on the planet.

With 15 years under its belt, Odyssey continued to work hard around Mars and shows no sign of stopping. So, happy anniversary, Odyssey!

On Land and Sea

Hard on the heels of Blue Origin’s third successful launch and recovery of their sub-orbital New Shephard capsule and propulsion module during a test flight, Elon Musk’s SpaceX has achieved what had been eluding them:  launching a Falcon 9 rocket with a payload bound for the International Space Station and then landing the first stage of the rocket on a platform at sea.

The success comes after four prior attempted to land the first stage of the booster at sea – part of SpaceX’s efforts to develop a semi-reusable system to reduce overall launch costs – all ended with the booster crashing into the floating landing platform, or toppling over post touch-down.

The Falcon 9 1.1 furst stage of CRS-8 stands tall on the the drone ship following its landing on April 8th, 2016
The Falcon 9 1.1 furst stage of CRS-8 stands tall on the drone ship Of Course I Still Love You, following its landing on April 8th, 2016 (credit: SpaceX)

The April 8th launch, officially titled CRS-8, lifted-off from Cape Canaveral Air Force Station, Florida, at 8:53 GMT. After separating from the second stage of the rocket, which carrying the Dragon cargo craft up to orbit, the first stage of the booster performed a series of three burns  to slow it down and boost it back towards the landing platform – referred to as an autonomous drone ship – that was keeping station downrange of the launch site. Eight and a half minutes after the launch, the first stage made a vertical descent over the platform, re-firing its main engines to slow itself as the landing legs deployed from along the side of the rocket’s body, and it eased into a gentle touch-down.

After the landing, crew boarded the platform to weld the rocket’s landing pads to the deck as a precaution against it toppling over while the platform was being towed back to port. Current plans call for the platform to undergo examination and testing at Kennedy Space Centre to ensure no structural damage occurred during the landing, before it is refurbished for a further at-sea landing, possibly in June 2016. The Falcon booster stage will  also undergo post-flight examination prior to being refurbished for a future launch.

Continue reading “Space Sunday: Of Odysseys, rockets, inflatables and exoplanets” →

Space Sunday: of ice and salts, aurorae, and mountains

Posted on by Inara Pey
A true colour image returned by the Dawn space probe of one of the bright "spots" in Occator crater on Ceres, revealing what might be a cryo-volcano
A true colour image returned by the Dawn space probe of one of the bright “spots” in Occator crater on Ceres, revealing what might be a cryovolcano (credit:NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / PSI)

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.

A false-colour image showing the main peak in Occator crater with the small bright spots off to the right
A false-colour image showing the main peak in Occator crater with the small bright spots off to the right (credit:NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / PSI)

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.

A false colour elliptical map of Ceres showing that Occator (just right of centre) is not the only bright spot on the tiny planetoid others, mostly associated with young (around 70-150 million years old) craters
A false colour elliptical map of Ceres showing that Occator (just right of centre) is not the only bright spot on the tiny planetoid others, mostly associated with young (around 70-150 million years old) craters (credit:NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / PSI)

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.

Long exposure photograph shows the trail of the Atlas V launch vehicle as it carries the Cygnus OA6 vehicle "Rick Husband" into orbit on March 22nd, 2016. In the foreground is the world famous Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Centre (credit: Alex Polimeni / Spaceflight Now)
Long exposure photograph shows the trail of the Atlas V launch vehicle as it carries the Cygnus OA6 vehicle “Rick Husband” into orbit on March 22nd, 2016. In the foreground is the world-famous Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Centre (credit: Alex Polimeni / Spaceflight Now)

Continue reading “Space Sunday: of ice and salts, aurorae, and mountains” →