Space Sunday: Mars,the Moon and space hotels

It has been some time since my last Mars Science Laboratory (MSL) rover report, so it’s time to play catch up with Curiosity, and take a look at what is happening with Opportunity.

For the last 16 months, Curiosity been engaged is studying “Vera Rubin Ridge”. Originally seen as a measn for the rover to traverse from one area of interest on “Mount Sharp” to another, the ridge became a point of interest itself when the rover imaged a rock formation that could fill a gap in the science team’s knowledge about the mound’s formation.

At the time the rock formation was noticed, engineers had been in the process of trying to overcome a issue with the rover’s drill that had prevented its use for several months. A potential work-around had been tested on Earth, so investigation of the rock formation offered the opportunity to test the updated drilling approach. Curiosity was therefore ordered to reverse course in the hope the tests would be successful and a sample of the rock could be gathered.

While successful, this was actually complicated – the issue with the drill feed mechanism also meant that the usual means of sorting samples post extraction had to be abandoned in favour of a new approach. However, the initial success meant Curiosity could resume drill-based sample gathering and analysis, marking the start of period of exploration around the ridge area – albeit it one interrupted by the 2018 global dust storm. In December 2018, this work concluded with the rover collecting its 19th overall sample on Mars, at a location on the ridge called “Rock Hall”.

Since then, the rover has been completing its work on the ridge, which included taking a “selfie” on January 15th, comprising 57 individual images taken with the Mars Hand Lens Imager (MAHLI) camera on the end of its robotic arm. At the ed of January, Curiosity said farewell to “Vera Rubin Ridge”, resuming its traverse southward towards the “clay bearing unit” it was originally heading to when it stopped at the ridge in September 2017.

The January 2019 “selfie” taken by Curiosity Sol 2291 at the “Rock Hall” drill site, located on “Vera Rubin Ridge”. Note parts of the robot arm have been removed from the completed image due to the fact it would appear in multiple locations in the completed image. Credit: NASA/JPL / MSSS.

At the same time, the science team for the rover released a paper revealing a new mystery about “Mount Sharp” and showing how instruments aboard the rover were re-purposed to allow it to be made.

As I’ve previously reported, previous studies of “Mount Sharp”- more correctly called Aeolis Mons, the 5 km (3 mi) high mound at the centre of the crater – suggested it was formed over two billions years, the result of repeated flooding of the crater laying down bands of sedimentary deposits, some of which were blown away by wind action, others of which settled. Over the millennia, these layers were sculpted by wind action within the crater, until only the central mound was left.

However, this type of water-induced layering should have resulted in the lower slopes of Mount Sharp being heavily compressed; but measurements of the local gravity environment of the terrain Curiosity has been driving over in its ascent up “Mount Sharp”, indicate the layers of the lower slopes are less dense than thought, meaning it is relatively porous. This indicates they were not buried under successive layers as had been thought, and thus some other process must have given rise to the mound.

The measurements were obtained by re-purposing the accelerometers Curiosity uses as a part of its driving / navigation system. Normally, these are used to determine its location and the direction it is facing with enormous precision. But, through a subtle piece of reprogramming, engineers were able to turn them into a gravimeter, allowing Curiosity to measure local gravity every time it stopped driving, and with massively greater precision than can be achieved from orbit.

An image captured by NASA’s Mars Reconnaissance Orbiter (MRO) overlaid with part of Curiosity’s path, including the Bagnold dunes in Gale Crater and up the slopes of Mount Sharp via the Murray Formation. Credit: NASA/JPL

Given the results tend to dispel the idea that water action was primarily responsible for filling the crater with sediments subsequently added to and shaped by wind action, it’s been proposed that “Mount Sharp” has been formed almost entirely as a result of Aeolian (wind-driven) sedimentation. This would leave the layers forming the mound a lot less dense in comparison to layers laid down and built up as a result of water action and settling.

However, this doesn’t entirely explain why the mount was formed, and further study is required before it can be said with certainty that wind played the core part in building and sculpting “Mount Sharp”. In the meantime, the re-purposing of Curiosity’s accelerometers is another example of the flexibility found within NASA’s robot explorers, as Ashwin Vasavada, Curiosity’s project scientist, noted in response to the new information.

There are still many questions about how Mount Sharp developed, but this paper adds an important piece to the puzzle. I’m thrilled that creative scientists and engineers are still finding innovative ways to make new scientific discoveries with the rover.

– Ashwin Vasavada, Curiosity’s project scientist.

New Plan to Contact Opportunity

It is now seven months since communications with NASA’s other operational Mars rover, Opportunity, was lost as a result of the planet girdling dust storm that ran from late May until around the end of July 2018, and which forced the rover to go into a power saving safe mode as there were insufficient sunlight for its solar cells to recharge its batteries.

In late August, ith the skies over Opportunity clearing of dust, NASA initiated an attempt to nudge “Oppy” into trying to resume contact with mission control using what is called the “sweep and beep” method. This involved sending a series of wake up commands throughout the day, then listening for the “beep” signal that would indicated “Oppy” had received the signal and was once again awaiting commands, allowing attempts at recovery to commence.  Unfortunately, this has not been the case.

NASA’s MER rover Opportunity (MER-B) arrived on Mars in January 2004. Contact was lost in June 2018 as a result of a major dust storm on the planet. Since August 2018, attempts to re-establish communications with the rover have been unsuccessful. Credit: NASA/JPL

Originally, it had been intended that if no response was received in  45-day period, NASA would switch to a purely passive means of listening out for “Oppy” in the hope the rover might send a message. But on January 25th, 2019, the space agency indicated they would be taking a different tack.

The new approach means that the “sweep and beep” approach will be continued, but slightly differently. In order to account for the possibility that Opportunity has both and off-kilter clock and both of its primary X-band communications systems, the outward commands designed to nudge a simple “beep” response from the rover will be replace by a command for it to switch away from using its primary communications system(s) to it secondary, the hope being that it would allow the rover to respond, and enable a more detail assessment of Opportunity’s condition to be made.

This effort is expected to continue for “several weeks” before NASA will again reassess the likelihood of re-establishing contact with the rover. However, a new threat is in the offing for Opportunity as winter starts to settle in the hemisphere where it is operating; if its solar panels are not working efficiently, the exceptionally low winter temperatures could damage it beyond recovery.

Continue reading “Space Sunday: Mars,the Moon and space hotels”

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Space Sunday: planet 9, Ultima Thule and space vehicles

It has been thought that Planet Nine, if it exists, might equal Neptune in size, and orbits the Sun 200 times further away than Earth. However, another new study casts possible doubt on its existence. Credit: Caltech / R. Hurt

I’ve written a lot about Planet Nine, the mysterious, yet-to-be-discovered world thought to be orbiting far out in the hinterlands of the solar system, and potentially responsible for the odd orbits of a number of bodies in the Kuiper Belt (referred to as Kuiper Belt Objects, or KBOs). Most recently – in June 2018 – I noted that one field of research suggested that while gravity could be responsible for the eccentric orbits seen with many KBOs, it might not have anything to do with the presence of another planet.

Now a new study – Shepherding In A Self-Gravitating Disk Of Trans-Neptunian Objects – further casts doubt on – but does not eliminate – the need for any planetary object being responsible for the odd orbits of Sedna and the other unusual KBOs. In it Professor Jihad Touma, from the American University of Beirut, and Antranik Sefilian, a PhD student in Cambridge’s Department of Applied Mathematics and Theoretical Physics, suggest a disc of icy material could be the cause.

The eccentric orbits of six TNO thought to have been caused by the influence of the still-to-be-discovered Planet Nine. Some 30 such objects have been discovered, one of which – “The Goblin” – has an orbit extending 2,300 AU out from the Sun. However, a new study suggests that a massive disc of icy material surrounding the Sun at great distance could be responsible for shunting the TNOs into their odd orbits. Credit: Caltech / R Hurt

The attraction for there being a planet responsible for teasing these objects into the odd orbits is that over the last 15 years, some 30 Trans-Neptunal Objects (TNOs) have been discovered in highly-elliptical orbits, all of which would appear to a large planetary object having some form of influence on them. However, despite extensive attempts to locate this mysterious body, possibly the size of Neptune, it has remained elusive – possibly because it doesn’t exist.

The Planet Nine hypothesis is a fascinating one, but if the hypothesised ninth planet exists, it has so far avoided detection. We wanted to see whether there could be another, less dramatic and perhaps more natural, cause for the unusual orbits we see in some TNOs. We thought, rather than allowing for a ninth planet, and then worry about its formation and unusual orbit, why not simply account for the gravity of small objects constituting a disc beyond the orbit of Neptune and see what it does for us?

– study co-author Antranik Sefilian

Instead, he and Touma modelled the full spatial dynamics of TNOs, taking into consideration the influence of the known giant outer planets in the solar system and a massive, extended disc of material beyond Neptune. Their results suggest that such a large – if yet-to-be-discovered – disc of material were to be orbiting the Sun at a great distance, it could give rise to TNOs occupying highly elliptical and exaggerated orbits around the Sun. In addition, they were able to model mass ranges and shapes for the icy disc and demonstrate how gradual shifts in its precession rate, could give rise to the wilder orbits seen with the 30+ eccentric TNOs.

If you remove planet nine from the model and instead allow for lots of small objects scattered across a wide area, collective attractions between those objects could just as easily account for the eccentric orbits we see in some TNOs.

– study co-author Antranik Sefilian

However, there is a problem with the theory – or two issues at this point in time. The first is that, like Planet Nine itself, it’s one things developing a computer model that demonstrates of a disc of distant material can influence TNOs and drive them into strange orbits, it is quite another to physically find it. The second is that attempts thus far made to estimate the mass of icy objects beyond Neptune have only added up to about one-tenth the mass of Earth – which is far too little to have any significant influence over TNOs. Part of the problem here is that as we’re inside the disc and looking out at it, it is incredible hard to sport the material that might be a part of it – something which Sefilian and Touma acknowledge.

Hubble images of other solar systems with massive debris discs surrounding the star. Image Credit: By NASA/ESA, R. Soummer, Ann Feild (STScI)

But there is more than enough evidence found around other solar systems to suggest extended discs of icy material are actually quite commonplace, and so one could well by surrounding our own.  What’s required is a longer, more considered look and the space around us – something that may well take time. And even then, Touma and Sefilian acknowledge that while their study suggests there is no need for any mystery planet, the hunt for Planet Nine shouldn’t be entirely abandoned; it might be that both it and a distant icy disc of objects might be responsible for the “rogue” TNO orbits far outside the plane of the ecliptic.

New Horizons Returns Best View Yet of Ultima Thule

On January 25th, 2019 NASA and John Hopkins University revealed the most stunning picture of Ultima Thule thus far returned by the New Horizons mission as it flew by the Kuiper Belt object (KBO) on January 1st, 2019.
Obtained with the wide-angle Multicolor Visible Imaging Camera (MVIC) the image was captured when New Horizons was just 7 minutes from its point of closest approach to the KBO, and just 6,700 km (4,200 mi) from it.  With an original resolution of 440 feet (135 meters) per pixel, the image was stored in the spacecraft’s data memory and transmitted to Earth on January 18th/19th, where it went through a process designed to sharpen the image and enhance fine detail.

Ultima Thule from a distance of 6,700 kilometres, January 1st, 2019. Credit: NASA / JHU/APL / SwRI

The oblique lighting of this image reveals new topographic details along the terminator, near the top. These details include numerous small pits up to about 0.7 km (0.4 mi) in diameter. The large circular feature, about 7 km (4 mi) across on the smaller of the two lobes, also appears to be a deep depression. It’s currently unclear whether these pits are impact craters or features resulting from other processes, such as “collapse pits” or the ancient venting of volatile materials.

This new image is starting to reveal differences in the geologic character of the two lobes of Ultima Thule, and is presenting us with new mysteries as well. Over the next month there will be better colour and better resolution images that we hope will help unravel the many mysteries of Ultima Thule.

– Alan Stern, New Horizons Principal Investigator

Continue reading “Space Sunday: planet 9, Ultima Thule and space vehicles”

Space Sunday: of the Moon and exoplanets

The 2019 “Super Blood Wolf Moon” – where to see it. Credit: timeanddate.com

The night of January 20th/21st, 2019 marks the only total lunar eclipse visible from the Americas this year – one which also includes Europe and parts of Africa (for those willing to either stay up or get up very early).

Dubbed by some a “Super Blood Wolf Moon”, the eclipse is somewhat unique in that it brings together three lunar events. “Super” refers to the fact that the Moon’s orbit around Earth is not circular but an ellipse. It varies from 362,600 km (225,300 mi) to 405,400 km (251,900 mi) on average. This means that at perigee, the Moon can look up to 30% “brighter” than it does at apogee, and is thus a “supermoon”.

“Blood” is derived from the fact that during an eclipse, the Earth lies between the Sun and the Moon, and the Earth’s atmosphere naturally absorbs more of the blue and green wavelengths, thus leaving more of the red wavelength to strike the surface of the Moon, giving it a bloody hue. A “wolf moon” refers to the first full Moon of January – which is winter in the northern hemisphere and the time when wolf howls were most often heard in the wild.

The entire January 20th/21st eclipse will be visible from start to end from all of both North and South America, and from the UK, Ireland, Portugal, Norway and parts of Sweden and northern Russia. Elsewhere in Europe, the eclipse, including totality – when the Earth’s shadow fully covers the Moon – will be visible across Western Europe, but elements of the entire event – such as of the part of penumbral phase or parts of the partial and total phases.

Eclipse visibility. via timeanddate.com

A timetable of the principal points in the eclipse is provided below.

Event UTC / GMT EST PST
Penumbral Eclipse begins 21 Jan, 02:36:29 20 Jan, 21:36:29 20 Jan, 18:36:29
Partial Eclipse begins 21 Jan, 03:33:54 20 Jan, 22:33:54 20 Jan, 19:33:54
Full Eclipse begins 21 Jan, 04:41:17 20 Jan, 23:41:17 20 Jan, 20:41:17
Maximum Eclipse 21 Jan, 05:12:14 21 Jan, 00:12:14 20 Jan, 21:12:14
Full Eclipse ends 21 Jan, 05:43:15 21 Jan, 00:43:15 20 Jan, 21:43:15
Partial Eclipse ends 21 Jan, 06:50:39 21 Jan, 01:50:39 20 Jan, 22:50:39
Penumbral Eclipse ends 21 Jan, 07:48:02 21 Jan, 02:48:02 20 Jan, 23:48:02

If you cannot view the eclipse directly, there are a number of other ways it can be seen and tracked:

For a Brief Time, There Was Life on the Moon

The LME container seen on Earth, prior to installation in the Chang’e 4 lander. Credit: Chongqing University

On January 14th, 2019, the China National Space Administration confirmed that, albeit briefly, there was life on the Moon.

Admittedly, the life in question was not alien or natural to the Moon, and had been placed there by the Chinese themselves, but it was still a major milestone in the Chang’e 4 mission and China’s lunar aspirations. At its heart is an experiment referred to at the Lunar Micro Ecosystem (LME).

A 2.6 kg (5.7 lb) sealed stainless-steel cylinder containing bioscience test loads, LME designed to test whether Earth plants and organisms can grow in the harsh conditions and reduced gravity on the lunar surface. It includes six types of organisms: cotton seed, potato, rapeseed, Arabidopsis thaliana (a flowering plant), as well as yeast and fruit fly eggs.

The unit has environmental systems keep the container hospitable and Earth-like, except for the low Lunar gravity, low temperatures and radiation. It had been hoped that together, the mix of fly eggs and plants would form a simple synergy: the eggs would hatch with the larvae producing carbon dioxide to assist with plant growth, with the plants producing oxygen (and food) for the fly larvae to progress to flies; the yeast would then help with regulating the carbon dioxide and oxygen. This type of research into developing closed ecological systems is seen as a means of helping to develop biological life support systems for long duration space missions in orbit, on the Moon and to other planets.

Within a few hours after landing on January 3rd, 2019, the biosphere’s temperature was adjusted to 24°C and the seeds were watered. The cotton seed was the first to sprout, as seen in images recorded on January 7th, 2019, that were included in the report issued by CNSA. It was also indicated that the rapeseed and potato seeds had also sprouted and were growing well as of Saturday, January 12th, although no photos were included in the report. It’s not clear what happened with the other seed or the fruit fly eggs.

Image taken from inside the LME on January 7th, 2019 showing the first cotton seed sprouting. Credit: CNSA/Chongqing University

The celebrations on the success of the project were short-lived however, with the onset of the lunar night. In the region Chang’e 4 occupies on the far side of the Moon, temperatures started to fall rapidly at the end of the two-week lunar day, and as the LME chamber does not have any heating systems, it was reported on January 16th that the sprouts had died due to the cold, and the experiment is now regarded as being “over”.

Despite this, the Chinese believe they learned enough from LME to be of use in designing future tests to determine how terrestrial organisms fair in a sealed and pressurized lunar environment.

Continue reading “Space Sunday: of the Moon and exoplanets”

Space Sunday: stainless steel, rovers and explorers

The Starship Hopper under construction at the SpaceX facility at Boca Chica, South Texas. Credit: Austin Barnard/Bloomberg

On Friday, January 11th, 2019, Elon Musk tweeted the first official image of the completed Starship Hopper, the new SpaceX vehicle intended to be an atmospheric test vehicle for the company’s massive Starship vehicle that forms the upper stage of what used to be called the Big Falcon Rocket, the huge lunch system SpaceX is developing.

The vehicle has been under construction at the SpaceX test facility at Boca Chica since December 2018, with the work, surprisingly, being carried out in the open, allows passers-by to photograph and film the work and post to assorted social media, causing something of a stir.

Hopper is not as large as the operational Starship vehicle will be (it is around 40 m / 130 ft tall, compared to Starship’s 52 m / 169 ft height). However, it is the same diameter (9 metres / 29 ft) and highlights the “radical” redesign of the vehicle, such as its more “retro” rocket ship look, and redesigned tail fins (which also double as its landing legs).

The completed Hopper (l) compared to a computer rendering of the vehicle (r), released on January 5th, 2019 by SpaceX CEO Elon Musk. Credit: SpaceX / Elon Musk

The vehicle is intended to be self-powered, using its own engines to fly to altitude, before making a controller descent and landing in the same manner as the full-sized vehicle. In this, its function mimics that of the SpaceX Grasshopper – a specially designed Falcon 9 first stage the company flew in order to learn about the handling characteristics of a Falcon 9 first stage attempting to make a controlled landing after a launch. Flights will initially be to low altitudes, then increase in height.

While Musk’s tweets indicated assembly of the vehicle was finished, further work is required to replace the temporary motors fitted to the vehicle with the flight-capable, methane-fuelled Raptor engines that will power it during ascent and descent. By the time the engines are fitted, the tail fins will have been fitted with shock absorbers to protect the vehicle against the impact of landings, and landing pads.

The “wrinkled” look to the vehicle’s hull is the result of the hull sections being made from a type of stainless-steel alloy which it is believed will be withstand atmospheric entry without the need for complex (and heavier) surface layering, such as reinforced carbon-carbon. Musk has indicated that the skin of the actual Starship will be smooth, and the vehicle will have “a smoothly curving nose section” (and windows).

In terms of the full size vehicle, the first of these is currently being fabricated, together with its booster stage – now simply called “Super Heavy”. Musk has indicated these could be ready as early as June 2019. Once operational, there will likely to be three versions of Starship:

  • The long-duration spacecraft capable of carrying passengers and /or cargo to interplanetary destinations such as the Moon and Mars, to LEO, or between destinations on Earth.
  • A propellant tanker design to refuel other spacecraft – notably the passenger vehicle – whilst in low-Earth orbit.
  • A satellite delivery spacecraft with a large cargo bay and forward door, capable of placing both satellites and other payloads in Earth orbit, or recover items for return to Earth.

The accelerated pace of Starship / Super Heavy development is in keeping with Musk’s goal of flying Japanese billionaire Yusaku Maezawa and an entourage of artists around the moon and back in the mid-2020s. However, it comes at something of a cost. On the same day as Musk tweeted about the Hopper, SpaceX announced it would be laying-off around 10% of its current workforce, some 600 people, as it refocuses efforts on its new launch system and its broadband satellite system.

To continue delivering for our customers and to succeed in developing interplanetary spacecraft and a global space-based Internet, SpaceX must become a leaner company. “Either of these developments, even when attempted separately, have bankrupted other organisations. This means we must part ways with some talented and hard-working members of our team.

– Official SpaceX announcement

To further provide revenue, the company is also mid-way through a US $500 million funding round.

A Steampunk Explorer?

It sounds like something out of a Steampunk novel, but a collaboration between a private space company and the University of Central Florida has shown that a vehicle sent to the asteroids could explore them “indefinitely” using  steam power to propel itself from asteroid to asteroid.

Honeybee Robotics, based in California, and the University of Central Florida (UCF) have developed a vehicle they called World Is Not Enough (WINE), capable of extracting water from asteroids or other planetary bodies, which it then uses as steam to propel itself to its next mining target. This effectively means it – or a vehicle like it – could become capable of indefinite self-refuelling and explore somewhere like the asteroid belt for decades.

By using steam rather than fuel, the World Is Not Enough (WINE) spacecraft prototype can theoretically explore “forever,” as long as water and sufficiently low gravity is present. Credit: University of Central Florida

UCF planetary research scientist Phil Metzger performed extensive computer modelling and simulations over three years in order to show the feasibility of steam propulsion, with the university developing simulated asteroid material that could be used as a feedstock. This work allowed Honeybee Robotics to build the microwave oven sized prototype, with Florida-based Embry-Riddle Aeronautical University providing the steam-powered rocket motors. The complete system was demonstrated for the first time on December 31st, 2018.

It’s awesome. WINE successfully mined the soil, made rocket propellant, and launched itself on a jet of steam extracted from the simulant. We could potentially use this technology to hop on the Moon, Ceres, Europa, Titan, Pluto, the poles of Mercury, asteroids—anywhere there is water and sufficiently low gravity.

– Phil Metzger, UFC, on the WINE prototype demonstration

One of the biggest constraints on robotic missions is the amount of fuel they can carry for manoeuvring. Being able to generate its own rocket propellant in the form of steam frees a vehicle from this constraint. All that is required is a suitable feedstock (and there is ice aplenty to be found throughout the solar system) and electrical energy, which could be supplied via solar panels or a small nuclear RTG “battery”.

Funding for the project has thus far been supported by the NASA Small Business Technology Transfer programme, intended to foster collaboration between universities and small businesses in the development of marketable commercial products. UFC and Honeybee are now seeking partners to continue development of the system.

Continue reading “Space Sunday: stainless steel, rovers and explorers”

Space Sunday: Ultima Thule and Chang’e 4

An artist’s impression of how the surface of Ultima Thule might look, based on the images and data returned by New Horizons thus far. Credit: NASA

We set a record. Never before has a spacecraft explored anything so far away. Think of it. We’re a billion miles farther than Pluto [and] Just like with Pluto, we could not be happier. What you’re seeing is the first contact binary ever explored by spacecraft: two completely separate objects that are now joined together.

– Alan Stern, New Horizons principal investigator

The astronomical year got off to a flying start on January 1st, 2019 when NASA’ New Horizons vehicle – the same craft that flew by Pluto and Charon and their attendant moons in 2015 – shot past (486958) 2014 MU69, a trans-Neptunian Object (TNO) residing in the Kuiper belt. A relatively tiny object, and dubbed Ultima Thule, it wasn’t even known about when the New Horizons mission launched in January 2006.

As I noted in my previous Space Sunday report, Kuiper Belt objects are of particular interest to planetary astronomers and scientists as they represent the oldest near-pristine material in the solar system, and so could contain many secrets, from how rocky planets formed through to the origins of life. Ultima Thule itself has been of particular interest because data gathered from the Hubble Space Telescope (HST) suggested it might be a binary object due to its apparent brightness fluctuating, suggesting two bodies orbiting one another. However, as New Horizons slipped into the final days leading up to the fly-by, it seemed to report no variance’s in the light reflected by the object.

The space craft reached its point of closest approach to Ultima Thule at 05:33 UT on the morning of January 1st, 2019. However, the nature of the approach, coupled with the huge distance between Earth and the vehicle meant that the first images and data wouldn’t be received for several hours after the probe has passed the object (it takes over 6 hours for radio signals to reach Earth from the vehicle), so at the time of closest approach, scientists and the public had to make do with the images received in the 24 hours preceding it.

Left: a composite image of Ultima Thule taken by New Horizons on December 31st. 2018, at a distance of approx. 1.2 million km revealing the object to most likely be a “contact binary”. Right: a sketch showing the estimated rotation axis of the object relative to New Horizons, helping to explain when no variances in brightness were recorded ahead of the encounter. Credit: NASA / JHU APL / SwRI; James Tuttle Keane

These images, captured while New Horizons was still more than 1 million kilometres (635,000 mi) from Ultima Thule, were enough to confirm that, rather than being either a single elongated object (as suggested by the lack of variance in brightness the probe was recording) or two objects orbiting one another, Ultima Thule is in fact a “contact binary” – objects conjoined after gently colliding with one another, to form a shape initially referred to as a “bowling pin” (this latter changed to “dirty snowman” as clearer images were received). They also revealed why New Horizons wasn’t seeing any brightness variations: whereas Hubble was seeing Ultima Thule from more of an “end on” angle (like a bottle tumbling through the air towards you), New Horizons was approach it more-or-less along its axis of rotation (like standing in front of a slowly turning propeller), so it was always reflecting the same amount of light.

The initial images led members of the New Horizons mission team to call Ultima Thule the “first ever” contact binary object to be explored. However, this might be disputed; the nucleus of comet 67P/Churyumov–Gerasimenko, as seen by ESA’s Rosetta mission, as has two lobes connected by a narrow “neck” region which could mark it as a contact binary.

This first colour photo of Ultima Thule reveals its red colour as seen by New Horizons spacecraft from a distance of 137,000 km (85,000 mi), captured on January 1st, 2019, shortly ahead of the point of closest approach. From left to right: an enhanced colour image, a higher-resolution black and white image, and a composite combining both into a more detailed view. Credit: NASA / JHU APL / SwRI

Nevertheless, there is still something magical about the way the two lobes came together – as a member of the New Horizons team put it, the bump of them joining would have been so gentle, had it been caused by a car bumping your own, it wouldn’t result in any real damage. The lobes themselves are of unequal size; at 19 km (12 mi) across, the larger has been dubbed “Ultima”, while the smaller lobe has been dubbed “Thule”, and is 14 km (9 mi) across. Combined, these give the object an overall length of some 33 km (21 mi). That they came together so gently has already been seen as a confirmation of the pebble accretion theory of planetary formation.

The exterior of both lobes is probably a mix of water, methane and nitrogen ices, doubtless mixed with other elements  / minerals, and the reddish hue revealed in the colour images thus far returned is likely the result of the irradiation of ices on its surface – a process witnessed on Pluto. However, it will not until photographs taken much closer to the object – notably those at closest approach, a mere 3,500 km (2,200 mi) – are received in mid-February, that we’ll have a clear view of the object’s topography.

Following the fly-by, the images received by mission control were taken at distances between 137,000 km (85,000 mi) and 28,000 km (18,000 mi) from the object, and part of the initial data transfer. In all, some 7 Gb of data was gathered, but due to the complexities involved, it will take 20 months for all of it to be received on Earth. In fact, at the time this article was written, and due to the passage of the Sun between the spacecraft and Earth, data transfer has been suspended for five days (January 5th through 10th, 2019) to prevent data loss due to solar interference. Even so, the images that have been received have been enough to not only reveal some of Ultima Thule’s secrets, but to also create new mysteries about it.

Alan Stern, the principal investigator for New Horizons, high-fives Alice Bowman, the mission operations manager at JHU APL, after controllers received a transmission from the spacecraft confirming a successful fly-by of Ultima Thule on January 1st, 2019. Credit: NASA / Bill Ingalls

One of these mysteries is that computer modelling suggests that given the way the two lobes came together, Ultima Thule should have a rate of spin to complete one revolution every 3 or 4 hours. However, data from New Horizons indicates it is spinning far slower: one revolution every 15 hours. So something must have slowed it down – the question is, what?

The most obvious explanation would be the gravitational influence of nearby objects – say two or three small moons orbiting Ultima Thule. However, due to the risk of collision, the space around Ultima Thule was surveyed well ahead of the fly-by, and astronomers are convinced there is nothing orbiting it either beyond 800 km (500 mi) or closer than 160 km (100 mi) – although that does leave a fairly large sphere of space between the two which may yet reveal one or more objects. More will be known on this in late January, when data on New Horizons’ own studies of the space around Ultima Thule should be received by mission control.

Continue reading “Space Sunday: Ultima Thule and Chang’e 4”

Space Sunday: Ultima Thule, Dream Chaser and capsule leaks

An artist’s impression of New Horizons passing Ultima Thule on January 1st, 2019. Credit: Adrian Mann/All About Space

On July 14th, 2015, NASA’s New Horizons vehicle, the front-end of the mission of the same name, made its closest flyby of Pluto and Charon (see Perfectly Pluto for more). Before, during and after the point of closest approach, the vehicle gathered huge amounts of data about Pluto, Charon and their attendant moonlets. Much of the data is still being studied, but in the years since the encounter, New Horizons has revolutionised our thinking about dwarf planets.

Since that time, the space vehicle has been travelling on out into the solar system at a speed of around 49,600 km/h (31,000 mph), and almost as soon as the Pluto flyby had been completed, with New Horizons still having plenty of power thanks to its nuclear batteries, astronomers started looking along its route for a possible follow-up target for examination.

After due consideration of options, a suitable target was selected. officially designated (486958) 2014 MU69, the object is a trans-Neptunian body located in the Kuiper belt. Of an elongated, shape, it is estimated to be around 30 km (18.75 mi), and might be a binary system of objects orbiting one another, although this is currently in doubt.

Discovered by astronomers using the Hubble Space Telescope in June 2014, just over a year before New Horizons reached Pluto, the object was unofficially dubbed “Ultima Thule” (Thule, in Greek and Roman literature, being the farthest north you could go, and “Ultima” being used to indicate “beyond”).  It was selected because of its relative proximity to the probe’s projected course out through the Kuiper belt, allowing it to be reached with minimal course corrections using the probe’s orientation thrusters.

The New Horizons journey. Credit: JHU/APL

The Kuiper belt is a massive ring of stellar objects surrounding the solar system between 30 and 55 AU distance (1 AU – astronomical unit –  being the average distance between the Sun and Earth). It is often regarded as the “outer edge” of our solar system, but the truth is, the solar system extends much, much further. Pluto and Charon are themselves Trans-Neptunian objects within the Kuiper belt.

The region – which might be described more as a doughnut than a belt – contains tens of thousands of objects (with more being discovered on almost a weekly basis). However, such is the volume of space they occupy, most are separated from one another by at least the distance separating Earth from the Sun. They are of great interest to astronomers, as they represent pristine material dating back to the very birth of the solar system, so studying them could tell us a lot more about the place in which we live.

The [Kuiper] belt is analogous to the solar system’s attic. It’s an ancient region, very far from the sun, which has been preserved in a deep freeze. It’s the equivalent of an archaeological dig into the history and formation of the planets. So, scientifically it’s a gold mine, and by going there with a spacecraft and observing KBOs up close, like we’ll be doing with Ultima, we hope to learn a lot about how the early formation stages of the planets took place.

– Alan Stern, New Horizons principal investigator

However, New Horizons won’t have long to study Ultima Thule in detail. If all goes well, the vehicle will blaze past the object on New Year’s Day 2019, at 05:33 GMT), travelling far too fast to slow down. At its closest approach, the probe will be some 3,540 km (2,200 mi) from Ultima Thule, which will appear about as large to it as the full Moon does to observers on Earth. As currently takes 6 hours and 8 minutes for a signal to reach Earth from New Horizons, it means that – as with its Pluto encounter – the probe will be working on an automated basis and pre-programmed commands throughout the encounter.

Simulation of anticipated images the LORRI camera aboard New Horizons vehicle will capture during the close approach to Ultima Thule

Even so, astronomers around the world are eagerly awaiting the encounter, as very little in known about Ultima Thule, and what New Horizions has apparently discovered as it approaches this tiny rock – it is too small to even classify as a dwarf planet – has already piqued interest.

What we know of the trans-Neptunian region is that it’s the leftover remnants of the objects that didn’t make it into being planets. These little rocky and icy worlds were formed in the initial disc of material around the sun, the ones that never grew up into being planets in their own right. Since then, they’ve been sculpted by changes in the orbital positions of the giant planets, particularly Neptune. What we see there today are materials from that initial disc. Some of them are familiar, like water ice and rock, but some of them are unfamiliar, like kitchen cleaning chemicals you have under your sink, in solid form

– Michele Bannister, Outer Solar System Origins Survey, Queen’s University, Belfast

As noted earlier, it had been believed, from data gathered by Hubble, that Ultima Thule was an elongated, possibly binary, object. However, on December 20th, 2018, the New Horizons team reported that the light measured from 2014 MU69 is constant, as would be expected from a spherical body. This disparity between Hubble’s finding and those of New Horizons have yet to be explained.

One issue with the flyby has been the partial US Government shut-down that started on December 22nd, 2018, and which has impacted some of NASA’s public outreach feeds. To compensate, the Applied Physics Laboratory, responsible for designing and building New Horizons, and part of John Hopkins University, has taken over mission briefings and will provide live updates via the JHUAPL YouTube page for flyby events on Monday, December 31st 2018, and Tuesday January 1st, 2019. You can see a full schedule here.

Continue reading “Space Sunday: Ultima Thule, Dream Chaser and capsule leaks”