Tag Archives: Rosetta

Space Sunday: water on Europa, Rosetta on a comet and Musk on Mars

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)

On Monday, September 26th, after some teasing beforehand, NASA provided an update on the venting of water by Jupiter’s icy moon, Europa.

As I noted in my last Space Sunday report, Europa is covered by shell of water ice, much of it discoloured by mineral deposits and by deep cracks, beneath which it is believed to have a liquid water ocean about 100 km (62.5 miles) deep. The ocean is believed to be made possible by tidal flexing enacted by the massive gravity of Jupiter as well as from the other large Galilean moons. This generates heat within Europa, and this heat stops the water from freezing solid.

In 2012, The Hubble Space Telescope (HST) captured what appeared to be a huge plume of water erupting some 200 kilometres (125 mi) above the surface of Europa, using its Space Telescope Imaging Spectrograph (STIS) instrument. The update offered on September 26th provided information on further plumes, strengthening the case of water existing under the ice crust of Europa in the process – a crust which may be far thinner than thought.

Europa transit illustration. Europa orbits Jupiter every 3 and a half days, and on every orbit it passes in front of Jupiter, raising the possibility of plumes being seen as silhouettes absorbing the background light of Jupiter. Credit: A. Field (Space Telescope Science Institute)

Europa transit illustration. Europa orbits Jupiter every 3 and a half days, and on every orbit it passes in front of Jupiter, raising the possibility of plumes being seen as silhouettes absorbing the background light of Jupiter. Credit: A. Field (Space Telescope Science Institute)

Over a 15-month period, astronomers used Hubble’s STIS to observe Jupiter and Europa in the ultra-violet spectrum. During that time, Europa occulted (passed in front) of Jupiter on 10 separate occasions. The observations were an attempt to examine a possible extended atmosphere around the moon, which is slightly smaller than our own. However, on three of the passes, astronomers witnessed what appeared to be plumes of water erupting from the surface – and in pretty much the same location as seen in 2012. Analysis of the plumes revealed they were made up of hydrogen and oxygen consistent with water vapour being broken apart by Jupiter’s radiation in a process known as radiolysis.

The plumes are not constant, but rather flare up intermittently, possibly as a result of the surface ice on Europa flexing in response to the same gravitational influences that are keeping the ocean beneath the ice from freezing out. This suggests that the icy crust is, at least around the region where the plumes are occurring, thinner than had been thought. This is important, because it could mean that any automated mission sent to Europa could have a fair chance of cutting its way through the ice to deploy a submersible vehicle which could then search for any evidence of life in Europa’s salty ocean – which contains between two and three times as much water as all of Earth’s oceans combined.

The Gentle Crunch: Rosetta Mission Ends

The European Space Agency’s Rosetta spacecraft said farewell on Friday, September 30th, bringing the 12-year mission that bears its name to a close.

Launched in 2004, Rosetta was a daring attempt to rendezvous with a short-period comet, 67P/Churyumov-Gerasimenko, then orbit it and study it as it swept through the inner solar system and around the sun on its (roughly) 6-year obit. The aim was to give us unique insight into cometary behaviour and – more directly – to study one of these tiny lumps of mineral and chemical rich rock “left over” from the solar system’s formation, and thus gain greater understanding as to how things came to be, and perhaps how life itself might have begun.

Rosetta, Europe's mission to unlock the secrets of the early solar system through the study of comet 67p-C/G, and the Philae comet lander (image: European Space Agency)

Rosetta, Europe’s mission to unlock the secrets of the early solar system through the study of comet 67P-C/G, and the Philae comet lander (image: European Space Agency)

Rosetta travelled almost 8 billion km (5 billion miles), including three flybys of Earth and one of Mars, and two asteroid encounters, before finally arriving at 67P/C-G in August 2014. In November of that year, The Philae lander was deployed in the hope of studying the comet from the surface and gathering samples of its material for analysis. Unfortunately, Philae’s anchoring mechanism failed, sending the little lander bouncing across the comet, until it came to rest in a location where it was receiving insufficient sunlight to recharge its batteries. Nevertheless, in the time it did have before its batteries were almost depleted, the washing machine sized lander some 80%+ of its science goals.

Meanwhile, Rosetta studied the comet in the long fall towards the Sun, and carried out an extensive mission of study, analysis and image capture, much of which has completely altered thinking around comets like 67P/C-G. For example, the mission discovered that water within the comet has a different ‘flavour’ to that of Earth’s oceans, suggesting that the impact of such comets with primordial Earth played far less of a role in helping start Earth’s oceans than had been thought.

The final descent: Rosetta’s OSIRIS narrow-angle camera captured this image of Comet 67P/Churyumov-Gerasimenko from an altitude of about 16 km above the surface during the spacecraft’s final descent on September 30, 2016. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

The final descent: Rosetta’s OSIRIS narrow-angle camera captured this image of Comet 67P/C-G from an altitude of about 16 km above the surface, as the spacecraft commenced its final descent on September 29th, 2016. Craggy hills about 614 metres wide rise from a surface smothered in dust redeposited on the comet’s surface after being outgassed during its active phase. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

As the comet became more active during its approach to the Sun, Rosetta found complex organic molecules – amino acid glycine, which is commonly found in proteins, and phosphorus, a key component of DNA and cell membranes – were present in the dust vented by 67P/C-G, reinforcing the idea that the basic building blocks for life may have been delivered to Earth from an early bombardment of such rocks. The mission also confirmed that the comet’s odd shape – two potato-like lobes of different sizes joined at a narrow waist – was the result of a very slow-speed collision very early in the comet’s 4.5 billion-year age.

In all the spacecraft  operated in the harsh environment of the comet for 786 days, made a number of dramatic flybys close to its surface, survived several unexpected outgassings, and made two full recoveries for potentially serious “safe mode” situations. However, all things must inevitably come to an end, and with its manoeuvring propellants almost exhausted, on September 29th, Rosetta set course for a gentle crash landing on 67P/C-G.

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Space Sunday: of Einstein, waves, landers and honours

The LIGO observatory, Hanford, Washington State

The LIGO observatory, Hanford, Washington State (source: LIGO)

Thursday, February 11th saw the announcement of the first direct detection of gravitational waves (not to be confused with “gravity waves”, as some in the media initially took to calling them, but which are something else entirely*), which are ripples in the fabric of space-time whose existence was first proposed by Albert Einstein, in 1916.

The detection came about partly as happenstance, in that the Large Interferometer Gravitational Wave Observatory (LIGO), a world-wide operation established in 1992 and involving 900 scientists from 80 institutions in 15 countries. However, the detectors in use up until recently had failed to provide direct evidence of gravitational waves.

Albert Einstein in 1916, when he was formulating his General Theory of Relativity

Albert Einstein in 1916, when he was formulating his General Theory of Relativity (source: Wikipedia)

Enter the National Science Foundation in the United States.  Over the last five years, they have funded the development and construction of two “Advanced LIGO” detectors, themselves massive feats of technology and engineering, located 3,000 km apart in the United States. One resides Livingston, Louisiana, and the other in Hanford, Washington State.

These detectors started running in February2015, in what was called an “engineering mode”. However, in September 2015 work started on running them up to full operational status when, and completely unexpectedly and within milliseconds of one another, both appeared to detect gravitational passing through them.

The odds of such an event occurring almost precisely at the time when the detectors were starting to do the work for which they have been designed would seem to be – and no pun intended – astronomical. As a result the LIGO investigators wanted to be sure of what had just happened and verify what they had apparently detected; hence why the news was only released on February 11th, 2016, several months after the actual detection had been made.

Since the initial detection, the LIGO teams have deduced the gravitational waves were created by two black holes, each barely 150km across,  but each travelling at around half the speed of light and massing around 30 times as much as our on Sun, spinning around one another and merging together some 1.3 billion light years away. As such, the detection marked two things: the first direct proof of gravitational waves and the conformation of a another theory: that black holes can meet and coalesce to create much larger black holes.

But what are “gravitational waves”, and why are they important?

Predicted over a century ago by Einstein in his theory of general relativity, gravitational waves are at their most basic, ripples in spacetime, generated by the acceleration or deceleration of massive objects in the cosmos. So, for example, if a star goes supernova or two black holes collide or if two super-massive neutron stars orbit closely about one another, they will distort spacetime, creating ripples which propagate outwards from their source, like ripples across the surface of a pond. The problem has been that these ripples are incredibly hard to detect, although the proof that they may well exist has been available since 1974.

It was in that year, two decades after Einstein’s passing, that astronomers at the Arecibo Radio Observatory in Puerto Rico discovered a binary pulsar (two rapidly rotating neutron stars orbiting one another). Over the ensuing years, astronomers measured how the period of the stars’ orbits changed over time. By 1982 it had been determined the stars were getting closer to each other at exactly the rate Einstein’s  of general theory relativity predicted would be required for the generation of gravitational waves. In the 40 years since its discovery, the system has continued to fit so precisely with the theory, and astronomers have had little doubt it is emitting gravitational waves.

The moment of detection: September 14th, 2015

The moment of detection: September 14th, 2015 (source: BBC News)

The LIGO detection however, provides the first direct  evidence of gravitational waves, and with it comes the ability to see the universe in a totally new way.

“It’s like Galileo pointing the telescope for the first time at the sky,” LIGO team member Vassiliki  Kalogera, a professor of physics and astronomy at Northwestern University in Illinois, said. “You’re opening your eyes — in this case, our ears — to a new set of signals from the universe that our previous technologies did not allow us to receive, study and learn from.”

Just as we’re able to study the universe in various wavelengths of light, using them to reveal things we otherwise would not be able to see, so gravitational waves will allow us to see the more of the dynamics in cosmic events which have so far remained hidden from us. We would in theory be able to see precisely what is happening in the heart of a supernova for example, and be able to detect the collisions and mergers of black holes, and more. So gravitational waves offer us a further means to increase our understanding of the cosmos.

(*In case you were wondering, gravity waves are physical perturbations driven by the restoring force of gravity in a planetary environment; that is, they are specific to planetary atmospheres and bodies of water, not cosmological events.)

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Space update: seeking planet X, examining comets and sifting sand

CuriosityNASA’s Curiosity rover has been sampling the sands of the “Namib Dune” the vehicle has been studying / circumnavigating for the last few weeks as it studies an extensive dune field which is slowly making its way down the slopes of “Mount Sharp” on Mars at the rate of about a metre per year.

“Mount Sharp”, more formally called Aeolis Mons, is the huge mound of material gathered against the central impact peak of Gale Crater. It forms the rover’s primary mission target in its quest to better understand conditions on Mars down through the ages, and to look for areas which at some point in the planet’s past, may have had all the right conditions – minerals, chemicals, water, heat, shelter, etc., – which might have allows life to arise.

The dune field on the north-east flank of “Mount Sharp” is of considerable interest to scientist, as it is the first genuine dune field to be studied on another world, and obtaining a clearer understanding of how the Martian wind moves sand could lead to a clearer picture of how big a role the wind plays in depositing concentrations of minerals often associated with water across the planet, and by extension, the behaviour and disposition of liquid water across Mars.

Tracks on a sand dune: this image from Curiosity's front Hazard Avoidance Camera (Hazcam) shows the rover's tracks on the same of "Namib Dune" as it starts sample gathering

Tracks on a sand dune: this image from Curiosity’s front Hazard Avoidance Camera (Hazcam) shows the rover’s tracks on the same of “Namib Dune” as it starts sample gathering

On January 12th, the rover reached a target area for sample gathering dubbed “Gobabeb”, and even this presented a challenge. Curiosity had to manoeuvre up onto the dune, and then turn in place in order to start sample gathering operations. This meant a cautious approach to the location, initially “scuffing” the sand to obtain and indication of its depth and composition (loose firm material). After this the rover gently edged onto the sand and deployed the robot arm to use its small scoop in only its second major sample gathering exercise, which took place on January 14th.

The sand gathered by the operations well be sorted within the CHIMRA system inside the robot arm, which uses a series of sieves to divide the sand grains by coarseness. Once sorted, the samples are delivered to the rover on-board chemical and analysis systems  – ChemMin, the Chemical and Mineralogical laboratory and SAM, the Sample Analysis at Mars suite – for examination.

A second sample of sand was gathered on January 19th, and is currently awaiting processing.

CHIMRA

CHIMRA – the Collection and Handling for In-Situ Martian Rock Analysis device attached to the turret at the end of Curiosity’s robotic arm, processes samples acquired from the built-in scoop (red) and the drill, which is not shown but is also part of the turret. CHIMRA also delivers samples to the analytical lab instruments inside the rover. Two paths to get material into CHIMRA are shown (the scoop delivers material to the location marked at the bottom, and the drill deposits material to the sample transfer tube shown at top). Also marked are the location of the vibration mechanism used to shake the turret and cause the sample to move inside CHIMRA, and the portion box (yellow) from which the material processed through a sieve is delivered to the analytical lab instruments.

Europe Joins Dream Chaser

In my last Space Sunday report, I covered the news that Sierra Nevada Corporation (SNC) will be joining SpaceX and Orbital ATK in supporting US work to delivery supplies to, and remove waste from, the International Space Station.

As a part of a new contract which commences in 2019 and runs until 2024, the expected end of ISS operations, SNC will utilise an unmanned cargo version of its Dream Chaser “mini shuttle”, which is based on a lifting body design, to carry up to 5 tonnes of material to the space station. Now Europe has officially joined SNC as a strategic partner.

The Drem Chaser Cargo, bult by SNC, and the International Berth and Docking Mechanism, to be supplied to SNC for Dream Chaser flights by the European Space Agency

The Dream Chaser Cargo, built by SNC, and the International Berth and Docking Mechanism, to be supplied to SNC for Dream Chaser flights by the European Space Agency

SNC and Europe have been looking at options for Dream Chaser development since SNC lost out to SpaceX and Boeing to supply the crewed version of Dream Chaser to NASA for ferrying crews back and forth between the ISS and US soil. Confirmation that NASA will be using Dream Chaser for the resupply flights means that ESA can nor push ahead with developing an International Berthing and Docking Mechanism (IBDM) for Dream Chaser.

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Space Sunday: the sand dunes of Mars and flying to the ISS

CuriosityThe Mars Science Laboratory rover, Curiosity, continues to climb the flank of “Mount Sharp” (formal name: Aeolis Mons), the giant mount of deposited material occupying the central region of Gale Crater around the original impact peak. For the last three weeks it has been making its way slowly towards the next point of scientific interest and a new challenge – a major field of sand dunes.

Dubbed the “Bagnold Dunes”, the field occupies a region on the north-west flank of “Mount Sharp”, and are referred to as an “active” field as they moving (“migrating” as the scientists prefer to call it) down the slops of the mound at a rate of about one metre per year as a result of both wind action and the fact they are on a slope.

Curiosity has covered about half the distance between its last area of major study and sample gathering and the first of the sand dunes, simply dubbed “Dune 1”. During the drive, the rover has been analysing the samples of rock obtained from its last two drilling excursions  and returning the data to Earth, as well as undertaking studies of the dune field itself in preparation for the upcoming excursion onto the sand-like surface.

While both Curiosity and, before it, the MER rovers Opportunity and Spirit have travelled over very small sand fields and sand ripples on Mars, those excursions have been nothing like the one on which Curiosity  is about to embark; the dunes in this field are huge. “Dune 1”, for example, roughly covers the area of an American football field and is equal in height to a 2-storey building.

"dune 1" in the "Bagnold Dunes", imaged here by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter (MRO) is roughly 300 metres across and as tall as a 2-storey building. The image is in false color, combining information recorded by HiRISE in red, blue-green and infrared frequencies of light.

“dune 1” in the “Bagnold Dunes”, imaged here by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter (MRO) is roughly 300 metres across and as tall as a 2-storey building. The image is in false colour, combining information recorded by HiRISE in red, blue-green and infra-red frequencies of light.

While the rover will not actually be climbing up the dune, it will be traversing the sand-like material from which it is formed and gathering samples using the robot arm scoop. This is liable to be a cautious operation, at least until the mission team are confident about traversing parts of the dune field – when Curiosity has encountered Martian sand in the past, it has not always found favour; wheel slippage and soft surfaces have forced a retreat from some sandy areas the rover has tried to cross.

Study of the dunes will help the science team better interpret the composition of sandstone layers made from dunes that turned into rock long ago, and also understand how wind action my be influencing mineral deposits and accumulation across Mars.

On Earth, the study of sand dune formation and motion, a field pioneered by British military engineer Ralph Bagnold – for whom the Martian dune field is named – did much to further the understanding of mineral movements and transport by wind action.  Understanding how this might occur on Mars is important in identifying how big a role the Marian wind played in depositing concentrations of minerals often associated with water across the planet, as opposed to those minerals accumulating in those areas as a direct consequence of water once having been present.

A mosaic of images taken on September 25th, 2015 (Sol 1,115) captures by the right lens of the rover's Mastcam system. .The view is toward south-south-west and reveals the "Bagnold Dunes" as a dark band across the middle of the image, blending with mesas beyond them

A mosaic of images taken on September 25th, 2015 (Sol 1,115) captures by the right lens of the rover’s Mastcam system. .The view is toward south-south-west and reveals the “Bagnold Dunes” as a dark band across the middle of the image, blending with mesas beyond them

Next NASA Rover to Have its Own Drone?

In January I wrote about ongoing work to develop a helicopter “drone” which could operate in concert with future robot missions to Mars. Now the outgoing director of NASA’s Jet Propulsion Laboratory has indicated the centre would like to see such a vehicle officially included as a part of the Mars 2020 rover package.

Weighing just one kilogramme (2.22 pounds) and with a rotor blade diameter of just over a metre (3.6 feet), the drone would be able to carry a small instrument payload roughly the size of a box of tissues, which would notably include an imaging system. Designed to operate as an advanced “scout”, the drone would make short daily “hops” ahead of, and around the “parent” rover to help identify safe routes through difficult terrain and gather data on possible points of scientific interest which might otherwise be missed and so on.

Since January, JPL has been continuing to refine and improve the concept, and retiring JPL Director Charles Elachi has confirmed that by March 2016, they will have a proof-of-concept design ready to undergo extensive testing in a Mars simulation chamber designed to reproduce the broad atmospheric environment in which such a craft will have to fly. The centre hopes that the trials will help convince NASA management – and Congress – that such a drone would be of significant benefit to the Mars 2020 mission, and pave the way for developing drones which might be used in support of future human missions on the surface of Mars.

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