Category: Space Sunday

Space Sunday: mesas, dunes NEOs, comets and launches

Posted on by Inara Pey
A dramatic look back: in the foreground is the lower slope of one of the "Murray Buttes", in the far distance the tall peaks of Gale Crater's huge rim. One of the final images taken by Curiosity from within the region of the buttes on Thursday, September 8th, the rover's 1,454 sol on Mars. Credit: NASA/JPL / MSSS
A dramatic look back: in the foreground is the lower slope of one of the “Murray Buttes”, in the far distance the tall peaks of Gale Crater’s huge rim. One of a series of images taken by NASA’s Curiosity rover on Thursday, September 8th, the rover’s 1,454 sol on Mars. Credit: NASA/JPL / MSSS

NASA’s Mars Science Laboratory rover, Curiosity, has said “farewell” to “Murray Buttes” in a stunning series of images, as it continues its climb up the slopes of “Mount Sharp”, a massive mound of deposited material located at the central impact peak of Gale Crater.

The mesas of “Murray Buttes” mark the upper extend of the transitional “Murray Formation”, where the material deposited during the earliest centuries of “Mount Sharp’s” formation merge with the rock comprising the crater floor. Curiosity has been passing by the area of the buttes for a little over a month now, carrying out examinations of the rock surface and gathering samples of mudstone for analysis.

Murray Buttes with the faint outlines of Gale Crater beyond, as images on Thursday, September 8th 2016, by NASA's Curiosity rover during its 1m454 sol on Mars. Credit: NASA/JPL / MSSS
“Murray Buttes” with the faint outlines of Gale Crater beyond, as images on Thursday, September 8th 2016, by NASA’s Curiosity rover during its 1,454 sol on Mars. Credit: NASA/JPL / MSSS

Believed to be the eroded remnants of ancient sandstone that originated when winds deposited sand after lower “Mount Sharp” had formed, the buttes rival anything of a similar nature found on Earth in terms of dramatic looks and structure. So much so that while we’re hardly likely to see Clint Eastwood ride his horse around the base of one, they would nevertheless fit neatly into a Sergio Leone western.

Several of the pictures – mosaics of images captured by the rover which have been white-balanced to match typical Earth daylight lighting conditions and then stitched together to offer complete scenes – reveal the deeply layered nature of the sandstone, sandwiched in what is referred to as “cross-bedding”. This indicates that the formations are the result of both wind deposition of material and then wind erosion, further confirming the idea that “Mount Sharp” was initially formed as a formed as a result of Gale Crater once being home to a great lake, before the waters receded and wind action took over.

A closer view of the layered nature of the sandstone deposits forming "Murray Buttes", showing the "cross bedding" of the layers, indicative of the role that wind played in their deposition / formation. This picture comprises a mosaic of images captured by Curiosity rover on Thursday, September 8th, 2016 during its 1,454 sol on Mars. Credit: NASA/JPL / MSSS
A closer view of the layered nature of the sandstone deposits forming “Murray Buttes”, showing the “cross bedding” of the layers, indicative of the role that wind played in their deposition / formation. This picture comprises a mosaic of images captured by Curiosity rover on Thursday, September 8th, 2016 during its 1,454 sol on Mars. Credit: NASA/JPL / MSSS

The images were taken as Curiosity traversed the base of the final butte, where it gathered a final drilling sample on September 9th. On completion of the sample-gathering, the rover will continue farther south and higher up Mount Sharp, leaving these spectacular formations behind.

Curiosity's route up the slopes of "Mount Sharp". Credit: T.Reyes / NASA/JPL
Curiosity’s route up the slopes of “Mount Sharp” – click for full size. Credit: T.Reyes / NASA/JPL

The Sand Dunes of Shangri-La

On September 7th, NASA issued a video showing the latest radar images captured by the Cassini probe of the surface of Saturn’s largest moon, mighty Titan. The data was gathered as the probe swept by the huge moon – which is blanketed by a thick atmosphere and is known to have lakes and rivers of liquid hydrocarbons on its surface – at a distance of some 976 km (607 mi) on July 25th, 2016 – one of the closest passes over the moon the vehicle has ever made.

Because of the moon’s thick atmosphere, conventional camera systems cannot be used to probe Titan’s mysteries, so Cassini uses a radar system to “map” surface features in black-and-white. Of particular interest to mission scientists during the July 25th flyby was a dark patch along Titan’s equator, previously images by the radar system at much greater distances and dubbed “Shangri-La”. And area which revealed itself to be – in part – a region of linear dunes, mostly likely comprised of grains derived from hydrocarbons that have settled out of Titan’s atmosphere, and which have been sculpted by Titan’s surface winds. Scientists can use the dunes to learn about winds, the sands they’re composed of, and highs and lows in the landscape.

Also captured by the radar is an arena dubbed “Xanadu annex”, believed to be an out-thrust of chaotic terrain from a region dubbed “Xanadu” just to the north of “Shangri-La”. First imaged by the Hubble Space Telescope in 1994, just before the Cassini / Huygens mission was launched, “Xanadu” and its annex are thought to be remnants of the moon’s icy crust before it was covered by organic sediments from the atmosphere.

OSIRIS-REx Lifts-off as an Asteroid Sweeps By Earth

On Thursday, September 8th, NASA successfully launched OSIRIS-REx on a 7-year trek to reach asteroid Bennu, where it will gather surface samples and return them to Earth for analysis. The mission, which I previewed in my last Space Sunday report, lifted-off flawlessly from Space Launch Complex 41 at Cape Canaveral Air Force Station at 19:05 EDT, atop its Atlas V booster at the start of a journey which will carry it a total of 7.2 billion kilometres (4.5 billion miles).

The Atlas V booster carrying OSIRIS-REx shortly after lift-off on Thursday, September 8th. Credit: Ken Kremer
The Atlas V booster carrying OSIRIS-REx shortly after lift-off on Thursday, September 8th. Credit: Ken Kremer

Witnessing the launch was principal investigator Dante Lauretta, from the University of Arizona. “I can’t tell you how thrilled I was this evening, thinking of the people who played a part in this,” he said following the launch.

“This represents the hopes and dreams and blood, sweat and tears of thousands of people who have been working on this for years.”

The mission will gather samples from the surface of the asteroid – a remnant from the formation of the solar system – and will also map Bennu’s orbit around the Sun and the influences affecting it.

This is because the asteroid is a near-Earth object (NEO): an asteroid which periodically passes across Earth’s orbit around the Sun, and can come very close to our planet whilst doing so. So close, in fact, that some estimates of Bennu’s future orbit suggest it will collide with Earth towards the end of the next century.

Continue reading “Space Sunday: mesas, dunes NEOs, comets and launches” →

Space Sunday: Jupiter’s poles, signals from space, exploding rockets

Posted on by Inara Pey
Captured at a distance of 78,000 km (48,000 mi) from Jupiter by JunoCam, this image reveals the pale bluish region of Jupiter's north polar region, speckled by hurricane-like cloud formations
Captured at a distance of 78,000 km (48,000 mi) from Jupiter by JunoCam, this image reveals the pale bluish region of Jupiter’s north polar region, speckled by hurricane-like cloud formations. Credit: NASA/JPL / SwRI / MSSS

NASA’s Juno spacecraft has continued to return data and images from its second pass around Jupiter on August 27th, 2016. Images in visible and infra-red light have been received as a part of the data – together with the sound of Jupiter’s “voice”.

Of particular interest are the images of Jupiter’s north pole – which has never been seen by human eyes, and is revealed as being vastly different to the rest of the planet, together with detailed images of the planet’s south pole, only previously briefly seen by the Cassini mission in 2008, whilst en route to Saturn.

“First glimpse of Jupiter’s north pole, and it looks like nothing we have seen or imagined before,” said the Juno mission’s principal investigator Scott Bolton on the release of the most recently received images and data on Friday, September 2nd.

An enhanced view of the north polar hurricane-like clouds images by Juno on August 27th, 2016
An enhanced view of the north polar hurricane-like clouds images by Juno on August 27th, 2016, together with the blue tingle of the polar atmosphere. Credit: NASA/JPL / SwRI / MSSS

“It’s bluer in colour up there than other parts of the planet, and there are a lot of storms. There is no sign of the latitudinal bands or zone and belts that we are used to—this image is hardly recognisable as Jupiter. We’re seeing signs that the clouds have shadows, possibly indicating that the clouds are at a higher altitude than other features.”

All of Juno’s science instruments were active during the flyby,gathering some 6 Mb of data, images and sounds, which was transmitted back to Earth over a period of a day and a half once the space vehicle had moved away from Jupiter once more. Among this data were images from the Italian-built Jovian Infra-red Auroral Mapper (JIRAM), which returned the first ever close-up infra-red images of Jupiter’s massive aurora.

A mosaic of three infra-red images of Jupiter's southern aurora taken some 4 hours after the closest point of the flyby. The images were captured by the Jovian Infra-red Auroral Mapper (JIRAM) camera aboard Juno at wavelengths ranging from 3.3 to 3.6 microns -- the wavelengths of light emitted by excited hydrogen ions
A mosaic of three infra-red images of Jupiter’s southern aurora taken some 4 hours after the closest point of the flyby. The images were captured by the Jovian Infra-red Auroral Mapper (JIRAM) camera aboard Juno
at wavelengths ranging from 3.3 to 3.6 microns — the wavelengths of light emitted by excited hydrogen ions. Credit: NASA/JPL / SwRI / IAPS

“JIRAM is getting under Jupiter’s skin, giving us our first infra-red close-ups of the planet,” said Alberto Adriani, JIRAM co-investigator from Istituto di Astrofisica e Planetologia Spaziali, Rome. “These views of Jupiter’s north and south poles are revealing warm and hot spots that have never been seen before.

“No other instruments, both from Earth or space, have been able to see the southern aurora,” he continued. “Now, with JIRAM, we see that it appears to be very bright and well-structured. The high level of detail in the images will tell us more about the aurora’s morphology and dynamics.”

Juno doesn’t only have eyes, it has ears as well. We’ve known for a long time that Jupiter can be quite “vocal”, and the flyby allowed Juno’s Radio/Plasma Wave Experiment (WAVE) to capture the sound of the planet’s aurorae.

“Jupiter is talking to us in a way only gas-giant worlds can,” said Bill Kurth, co-investigator for WAVE. “We detected the signature emissions of the energetic particles that generate the massive auroras which encircle Jupiter’s north pole. These emissions are the strongest in the solar system. Now we are going to try to figure out where the electrons come from that are generating them.”

Juno is now heading back away from Jupiter on the second of its “long” orbits of the planet. On October 19th, the spacecraft will once again skim over Jupiter’s cloud tops, where it will perform a further braking manoeuvre to reduce its orbital period around the planet to just 14 days.

Did ET Call Us? Mostly Likely Not

The end of August saw  various media outlets a-buzz with news about Russian scientists having detected a “strong” radio signal from deep space, with muttering and speculations about aliens, despite cautionary notes from assorted space-related outlets and organisations.

The signal was actually detected in May 2015 by the RATAN-600 radio telescope in Zelenchukskaya, south-western Russia. At the time, the telescope was conducting a survey of astronomical objects in the framework of the SETI (Search for Extraterrestrial Intelligence) programme. It seemed to come from the general direction of the star HD 164595, a star around 95 light years away which is very similar to our own Sun but about 1.5 billion years older, and known to have at least one planet – a gas giant roughly the mass of Neptune – orbiting it.

News about it reached a wider audience in August when a member of the team behind the survey decided to e-mail data on it to colleagues asking for thoughts on what it might be, and suggesting the region of the sky containing HD 164595 should be monitored for further indications of the signal and possible causes.

The RATAN-600 radio telescope. Credit: Russian Academy of Sciences
The RATAN-600 radio telescope. Credit: Russian Academy of Sciences

This request was picked up by science and technology writer Paul Gilster, who blogged about it on his website Centauri Dreams.  While Gilster clearly stated there was no evidence of the signal being the work of an extra-terrestrial civilisation, he did couch his post in terms of the power requirements and possible technological status of such a civilisation were the signal to prove to be artificial in nature.

The information was also received by the SETI Institute in California. Their senior astronomer, Seth Shostak, estimated that if transmitting  in all directions, the signal would require energy on the order of 10^20 watts – or more energy than the Earth receives from the Sun – making the originating species a Type II civilisation on the Kardashev scale. If directed solely towards Earth,  Shostak estimated the energy requirement would “only” be around 10^13 watts – roughly equivalent to all of the energy used by humanity here on Earth, putting the aliens at a Type I civilisation on the Kardashev scale – that is, equal to or slightly more advanced than we are.

Continue reading “Space Sunday: Jupiter’s poles, signals from space, exploding rockets” →

Space Sunday: exoplanets, dark matter, rovers and recoveries

Posted on by Inara Pey
An artist's impression of Proxima b with Proxima Centauri low on the horizon. The double star above and to the right of it is Alpha Centauri A and B. Credit: ESO
An artist’s impression of Proxima b with Proxima Centauri low on the horizon. The double star above and to the right of it is Alpha Centauri A and B. Credit: ESO

On August 15th, I wrote about rumours that an “Earth-like” planet has been found orbiting our nearest stellar neighbour, Proxima Centauri, 4.25 light years away from our own Sun. The news was first leaked by the German weekly magazine, Der Spiegel, which indicated the discovery had been made by a team at the European Southern Observatory’s (ESO)  La Silla facility – although ESO refused to comment at the time.

However, during a press conference held on August 24th, ESO did confirm the detection of a rocky planet orbiting Proxima Centauri. Dubbed Proxima b, the planet lies within the so-called “Goldilocks” habitable zone around its parent star – the orbit in which conditions are “just right” for the planet to harbour liquid water and offer the kind of conditions in which life might arise.

Comparing Proxima b with Earth. Credit: Space.com
Comparing Proxima b with Earth. Credit: Space.com

The ESO data reveals that Proxima b is orbits its parent star at a distance of roughly 7.5 million km (4.7 million miles), at the edge of the habitable zone, and does so every 11.2 terrestrial days and is about 1.3 times as massive as the Earth. The discovery came about by comparing multiple observations of the star over extended periods using two instruments at La Silla to look for signs of the star “wobbling” in its own spin as a result of planetary gravitational influences. Once identified, ESO called on other observatories around the world to carry out similar observations / comparisons to confirm their findings.

Although the planet lies within the “Goldilocks zone”, just how habitable is it likely to be is still open to question. Stars like Proxima Centauri, which is roughly one-seventh the diameter of our Sun, or just 1.5 times bigger than Jupiter, are volatile in nature, all activity within them entirely convective in nature, giving rise to massive stellar flares. As Proxima-B orbits so close to the star, it is entirely possible that over the aeons, such violent outbursts from Proxima Centauri have stripped away the planet’s atmosphere.

Proxima Cantauri compared with other stellar bodies - and Jupiter (Credit: Space.com)
Proxima Cantauri compared with other stellar bodies – and Jupiter. Credit: Space.com

In addition, the preliminary data from ESO suggests the planet is either tidally locked to Proxima Centauri, or may have a 3:2 orbital resonance (i.e. three rotations for every two orbits) – either of which could make it an inhospitable place for life to gain a toe-hold. The first would leave one side in perpetual daylight and the other in perpetual night, while the second would limit any liquid water on the surface to the tropical zones.

Nevertheless, the discovery of another world in one part of our stellar backyard does raise the question of what NASA’s upcoming TESS mission might find when it starts searching the hundreds of nearby stars for evidence of exoplanets in 2018.

Juno’s Second Pass Over Jupiter

NASA’s Juno space craft made a second successful close sweep over the cloud-tops of Jupiter on Saturday, August 27th to complete its first full orbit around the planet. Speeding over the planet at a velocity of 208,000 km/h (130,000 mph) relative to Jupiter, Juno passed just 2,400 km (2,600 miles) above the cloud tops before heading back out into space, where it will again slowly decelerate under the influence of Jupiter’s immense gravity over the next 27 days, before it once again swing back towards the gas giant.

“Early post-flyby telemetry indicates that everything worked as planned and Juno is firing on all cylinders,” said Rick Nybakken, Juno project manager at NASA’s Jet Propulsion Laboratory, as telemetry on the flyby started being received on Earth some 48 mins after the flyby, which occurred at 13:44 UTC.

A twin view of Jupiter captured by Juno on August 23rd, when the spacecraft was some 4.4 million km (2.8 million miles) from the gas giant and approaching Jupiter to complete its first full orbit. On the left is a colour image from JunoCam, on the right an infra-red image Credit: NASA/JPL-Caltech/SwRI/MSSS
A twin view of Jupiter captured by Juno on August 23rd, when the spacecraft was some 4.4 million km (2.8 million miles) from the gas giant and approaching Jupiter to complete its first full orbit. On the left is a colour image from JunoCam, on the right an infra-red image. Credit: NASA/JPL / SwRI / MSSS

All of Juno’s science suite was in operation during the passage over Jupiter’s clouds. However, due to speed at which the gathered data can be returned to Earth, and given it cannot all be relayed in one go or necessarily continuously, it will be a week or more before everything has been transmitted back to Earth. Nevertheless the science team are already excited by the flyby.

“We are getting some intriguing early data returns as we speak,” Scott Bolton, principal investigator of Juno from the Southwest Research Institute, stated. Some of that data included initial images of Jupiter captured as Juno swept towards the planet during the run-up to periapsis. “We are in an orbit nobody has ever been in before, and these images give us a whole new perspective on this gas-giant world,” Bolton added.

Continue reading “Space Sunday: exoplanets, dark matter, rovers and recoveries” →

Space Sunday: Juno, ISS and SLS

Posted on by Inara Pey
July 14th: Jupiter with Io, Europa and Ganymede as seen by Juno after the craft had finished its critical orbital burn to slip into a 53.5 day orbit around the giant planet
July 14th: Jupiter with Io, Europa and Ganymede as seen by Juno after the craft had finished its critical engine burn to slip into a 53.5 day orbit around the giant planet. Juno will once again skim Jupiter’s cloud tops on Saturday, August 27th. Credit: NASA / JPL; SwRI / MSSS

NASA’s Juno mission to Jupiter is swinging back in towards the gas giant, on route to complete the first of some 37 planned polar orbits of the planet between now and February 2018 which are designed to probe the mysteries of the giant planet as never before.

As I reported in early July, the Juno space vehicle arrived at Jupiter on July 4th, where it completed a critical burn of its UK-built Leros-1b engine to ease its way into a highly elliptical orbit around Jupiter after a voyage of 2.8 billion km (1.74 billion miles) and 5 years, during which the craft first looped out past the orbit of Mars before falling back towards Earth to pick up a “gravity assist” to accelerate it on to its rendezvous with Jupiter.

The July 4th braking manoeuvre placed Juno in an orbit which, at its closest to Jupiter, skims just a few thousand kilometres above the planet’s cloud tops, and at its furthest sees Juno over 3 million kilometres from the planet. That first braking manoeuvre was undertaken with the probe’s science systems powered-down as a precautionary measure, and were powered-back up a few days after closest approach.

On August 27th, the vehicle will complete the first of these 53.5-day during “long” orbits, once again passing to within 4,200 km (2,600 mi) of Jupiter’s cloud tops at the equator, after arcing down over the planet’s north pole – and this time, all of the science instruments will remain operational, including JunoCam, the vehicle’s imaging system.

JunoCam has actually be in continuous operation in ” marble movie” mode since July 11th, 2016, capturing 5 full-colour images per hour, watching Jupiter spin from a distance (a sample of this movie is embedded blow – not Jupiter’s spin is greatly speeded-up). However, Jupiter is so small in most of the images  – just 50 pixels across – that these haven’t been a source of interest to the media. As Juno approaches Jupiter on August 27th, however,   the imaging system will switch from “marble movie” mode to gathering images at a higher rate to fully capture the close flyby as the craft passes over Jupiter’s north pole, curls around the planet north-to-south, before heading back out into space once more on the second of its “long” orbits.

JunoCam has a relative narrow field of view, so the images it captures on August 27th will be tightly focus on Jupiter’s clouds, and   not as panoramic as those we’re been accustomed to seeing from the Hubble Space Telescope and from the now defunct Galileo mission. But they should still hopefully prove spectacular.

The next time Juno makes a close approach to Jupiter after this will be on October 19th. At that time, the science instruments will again be powered-off while the craft makes a second orbital burn, this time to reduce its orbit around Jupiter of 53.5 days to just 14 days, allowing the primary science mission to start.

This is intended to improve our understanding of Jupiter’s formation and evolution. The spacecraft will investigate the planet’s origins, interior structure, deep atmosphere and magnetosphere. Juno’s study of Jupiter will help us to understand the history of our own solar system and provide new insight into how planetary systems form and develop in our galaxy and beyond. It will also, for the first time, allow us to “see” below Jupiter’s dense clouds.

Selling the ISS?

This past week, NASA hosted a Journey to Mars showcase, looking at the space agency’s plans for developing the means to send humans to Mars in the 2030s. The actual plans for doing so are still pretty nebulous, but much of in revolves around the current development of the Orion Multi-Purpose Crew Vehicle (MPCV) and its supporting systems (including deep-space habitat modules), and the rocket system which will be used to launch it, the Space Launch System (SLS).

This being the case, the event was hosted at NASA’s Michoud Assembly Facility in New Orleans, where the core stage of the SLS vehicle the Orion MPCV. Included in the event was a trip to see a further test firing of one of the RD25 engines which will power the SLS at launch, and were previously used to power the space shuttle during its ascent to orbit.

However, what particularly grabbed the attention of the media was the announcement that the space agency is looking to sell the International Space Station to a private entity or entities in the mid-2020s, under the understanding that said entity/ies will keep the station active and continue to allow NASA to have access to it.

The move is a bold one. Currently, the ISS is the biggest single component of NASA’s budget, (just over US  $3 billion in 2016 and projected to pass US $4 billion in 2020), and is only funded through until 2024. Thus, selling it to a private concern, could allow NASA to continue to make use of the station for research purposes beyond 2024 without having to meet all of the hefty costs involved in actually operating the station, potentially freeing-up some of the money dedicated for ISS support for use elsewhere.

Quite who would be willing to buy the ISS – both SpaceX and Boeing are apparently on NASA’s list of potential interested parties, although the interest may not be reciprocal – and quite how NASA’s international partners feel about the idea, is unclear.

Continue reading “Space Sunday: Juno, ISS and SLS” →

Space Sunday: exoplanets, greenhouses and meteors

Posted on by Inara Pey
Sunset on an alien world: an artist's impression of sunset on an Earth-like planet orbits our nearest stellar neighbour, Proxima Centauri (seen closest, left), with Alpha Centauri A and B shining in the distance - story below
Suns over an alien world: an artist’s impression of the view from an “Earth-like” planet orbits our nearest stellar neighbour, Proxima Centauri (seen closest, left), with Alpha Centauri A and B shining in the distance – story below. Credit: ESO/L. Calçada

Last week I reported on the latest issue to strike NASA’s Kepler mission to survey other stars for signs of planets orbiting them. On July 28th, during routine communications with the observatory – which is following the Earth around the Sun roughly 121 million kilometres (75 million miles) “behind” the planet – it was discovered the photometer, the camera-like tool used to detect alien planets, had been turned off.

Power was restored to the unit on August 1st, but engineers were still mystified as to why it had turned off in the first place. Communications with the observatory on Thursday, August 11th, confirmed the photometer was still active and Kepler was gathering data, allowing the engineering team to focus on a possible cause for the unit powering off.

The Photometer includes a curved focal plane of 42 charge-coupled devices (CCDs) arranged within 25 individual modules. One of these modules – Module #7 – suffered a power overload in January 2014, disabling it. Most crucially, the failure prompted the photometer unit to power itself off – just as appeared to have happened shortly before July 28th, 2016, suggesting the most recent issue could also be related to the focal plane.

Kepler's focal plane, showing its array of 25 modules, being assembled at Ball Labs prior to Kepler's launch in 2009
Kepler’s focal plane, showing its array of 25 modules, being assembled at Ball Labs prior to Kepler’s launch in 2009

Analysis of the data received following the restoration of power to the photometer reveals that another module, Module #4,  had failed to warm up to the required operating temperature, strongly suggesting it has also failed, and thus triggered the power-down.

As a result, the science and engineering team responsible for the mission have determined that the targets that were assigned to Module #4 will yield no further science results, but this should not impact Kepler’s overall science campaign, which is expected to continue through until 2019, by which time all no-board fuel reserves will have been depleted, and much of Kepler’s work will have been taken over by the James Webb Space Telescope and NASA’s Transiting Exoplanet Survey Satellite (TESS), examined in my previous Space Sunday column.

An “Earth-Type” World Just 4.2 Light Years Away?

Kepler has detected over 4,000 exoplanet candidates, of which around 216 have been shown to be both roughly terrestrial in size and form, and located within the “Goldilocks Zone” (or more formally the circumstellar habitable zone (CHZ) or habitable zone) around their parent star – the region at which planetary conditions could be “just right” for life to arise. Unfortunately, most of these planets are a very long way away. Kepler 425b, for example, regarded as Earth’s (slightly bigger) “cousin”, and the first exoplanet to be confirmed to be orbiting in its star’s habitable zone, is some 1,400 light years away.

However, Kepler is not alone in the hunt for extra-solar planets. Observatories here on Earth are also engaged in the work, both in support of Kepler by undertaking detailed follow-up examinations of candidate stars, and also as part of their own programmes. A recent article in Germany’s Der Spiegel magazine now claims that one of these, the European Southern Observatory’s (ESO)  La Silla faclity, has found an “Earth-like” planet very much closer to home.

Quoting an alleged member of the ESO team, Der Spiegel states the new planet is orbiting Proxima Centauri, our nearest stellar neighbour, a mere 4.25 light years away, and which can be seen in the southern hemisphere night skies. A red dwarf low-mass star roughly one-seventh the diameter of our Sun, or just 1.5 times bigger than Jupiter, it is thought to be gravitationally bound to the Alpha Centauri binary system of stars, frequently the subject of science-fiction stories down through the decades.

The Alpha Centauri system seen through a modest telescope. At the top, slightly left of centre is the Sun-like Alpha Centauri A, to the upper right is the K1 V Alpha Centauri B. The red circle denotes tiny Proxima Centauri
The Alpha Centauri system seen through a modest telescope. At the top, slightly left of centre is the Sun-like Alpha Centauri A, to the upper right is the K1 V Alpha Centauri B. The red circle denotes tiny Proxima Centauri

Given the two primary stars in the Alpha Centauri system are broadly similar to our own Sun  – Alpha Centauri A particularly so – and both are slightly older (around 4.85 billion years), the system has been a frequent subject for study, with the potential for either star to have planetary bodies orbiting it, or given the two stars orbit one another every 79.91 terrestrial years at a distance roughly equivalent to that between the Sun and Uranus, quite possibly around both of them. In fact, two recent papers have suggested two planets orbiting Alpha Centauri B. The first, from 2012, was subsequently dismissed as a spurious data artefact. The  second, from 2015, has yet to be confirmed.

So far, ESO representatives have refused to confirm or deny the Der Spiegel article, or whether an announcement on the matter will be made at the end of August as the magazine claims.  This has been taken by some as tacit confirmation of the discovery, and others that the data – if true – is still being verified. If the latter is the case, some caution at ESO is understandable: the La Silla Observatory was responsible for announcing the 2012 discovery of “Alpha Centauri Bb”, which as noted above, turned out to be a data anomaly.

Some are outright sceptical of the article, pointing out that Proxima Centauri has long been the subject of exoplanet searches by both observatories on Earth and the Hubble Space Telescope, and nary a hint of another other body, large or small, orbiting it has been found.

As a dwarf star – one of the smallest known – Proxima Centauri is also somewhat volatile, with about 88% of the surface active (far more than the Sun’s), and is completely convective, giving rise to massive stellar flares. While this doesn’t out the potential for planets to be orbiting it, the fact that the star’s habitable zone is between 3.5 and 8 million kilometres from its surface, any planet within that zone would be tidally locked to Proxima Centauri, leaving one side in perpetual daylight and the other in perpetual night, with the risk that any atmosphere would be stripped away over the aeons by the stellar flares. So even if the Der Spiegel article is confirmed, it would seem the planet might still be a pretty inhospitable place, even if it is within the Goldilocks zone.

Continue reading “Space Sunday: exoplanets, greenhouses and meteors” →

Space Sunday: of Martian and lunar robots, distant worlds and ET

Posted on by Inara Pey

CuriosityAugust 2016 sees NASA’s Mars Science Laboratory rover Curiosity rack up four (terrestrial) years of operations on the surface of Mars.

The rover marked this anniversary rather quietly, by preparing to take further rock samples, this time from a target dubbed “Marimba”. Once gathered, the samples will be subjected to on-board analysis by Curiosity using the compact laboratory systems contained the rover’s body.

The sampling take place as the rover is engaged in a multi-month ascent of a mudstone geological unit as it continues its climb towards higher and progressively younger geological areas on “Mount Sharp” (more correctly, Aeolis Mons), which will include some rock types not yet explored.

August 2nd, 2016 (Sol 1,418)T: the Navigation Camera (Navcam) on Curiosity's mast images the rover's extended robot arm over a section of the "Marimba" target rock, ready to use the wire brush mounted on the "hand" at the end of the arm in order to scour surface material which otherwise might contaminate and samples gathered from the rock, prior to the rover taking a drilling sample. Credit: NASA/JPL / MSSS
August 2nd, 2016 (Sol 1,418)T: the Navigation Camera (Navcam) on Curiosity’s mast images the rover’s extended robot arm over a section of the “Marimba” target rock, ready to use the wire brush mounted on the “hand” at the end of the arm in order to scour surface material which otherwise might contaminate and samples gathered from the rock, prior to the rover taking a drilling sample. Credit: NASA/JPL / MSSS

In the meantime, examining the samples gathered from “Marimba” will allow a direct comparison with mudstone samples gathered further down the slopes of “Mount Sharp” and from the flatlands of Gale Crater. This will enable scientists to  build a more complete picture of the mineral and chemical  environment the rover is travelling through, and so further understand the general conditions which may have once have existed within the crater.

Goodnight from a Lunar Jade Rabbit

China has finally bid farewell to Yutu (“Jade Rabbit”, named for the companion to the Moon goddess Chang’e), its first lunar robotic explorer, after 31 months of surface operations.

The little solar-powered rover arrived on the lunar surface as part of Chain’s Chang’e 3 lander / rover mission on December 13, 2013, and was deployed from the lander some  7.5 hours after touch-down.

Yutu as imaged from the Chang'e 3 lander (part of the solar pnael from which can be seen in the lower right corner). Credit: National Astronomical Observatories of China
Yutu as imaged from the Chang’e 3 lander (part of the solar panel from which can be seen in the lower right corner). Credit: National Astronomical Observatories of China

However, due to the vast temperature differential experienced between the sunlit and shadowed parts of the rover at the time of the landing, operations didn’t commence until December 21st, when the rover was uniformly lit by the Sun. It’s first activity was to drive part-way around its parent lander and photograph it. After this, the rover travelled some 40 metres (130 ft) from the lander to commence independent science operations studying the lunar surface.

Yutu was designed to operate for just three months and travel up to 10 km (6.2 mi) within an area of 3 square kilometres (1.2 sq mi). Following its expose to the first 14-day long lunar “night”, the rover resumed operations in January 2014. However, as the second lunar night period approached (lasting 14 terrestrial days), the rover suffered a glitch in its drive mechanisms, leaving it susceptible to the harsh cold of the night-time, and on February 12th, following its second Lunar night, the rover was declared lost … only to resume communications with Earth within 24 hours.

Since that time, although immobilised, the little rover has maintained almost regular contact with Earth, but with each night period taking an increasing tolls on its systems. Even so, its continued survival gained it a huge and loyal following on the Chinese micro-blogging site, Weibo, where in a leaf firmly pulled from NASA’s book of social media engagement, Yutu had a first-person account.

It was via that social media account that Yutu’s final demise was announced, as if from the rover itself, on August 2nd 2016:

This time it really is goodnight. There are still many questions I would like answers to, but I’m the rabbit that has seen the most stars. The Moon has prepared a long dream for me, I don’t know what it will be like – will I be a Mars explorer, or be sent back to Earth?

The message gained a huge response from the rover’s 600,000 followers, and the Chinese space agency officially confirmed the rover had “died”, on Wednesday, August 3rd.

Continue reading “Space Sunday: of Martian and lunar robots, distant worlds and ET” →