Tag: Astronomy

Space Sunday: Jovian Moons, and lunar aspirations

Posted on by Inara Pey
A volcanic eruption on Io, the innermost of Jupiter’s four Galilean moons, as witnessed by NASA’s Galileo spacecraft during the multi-year mission of the same name exploration the system. Credit: NASA

We’re probably all familiar with the concept of some Moons within our solar system  – notably Saturn’s Enceladus, and Jupiter’s Europa, Ganymede and Callisto – potentially being completely encompassed by a liquid water (or at least a slushy) ocean under their surfaces. But how about a moon being almost completely encompassed by an ocean of hot volcanic magma just a few kilometres under its surface?

That’s the proposal contained within a new paper written under the auspices of NASA’s Jet Propulsion Laboratory, and based on an analysis of data obtained by the Jovial Infrared Auroral Mapper (JIRAM) instrument aboard NASA’s Juno mission in reference to Io, the innermost of the four Galilean moons of Jupiter.

Of course, we’ve long known that Io, a moon slightly larger than our own, is the most volcanic place in the solar system. More than 400 active volcanoes have been identified since we first witnessed one erupting in 1979, courtesy of NASA’s by Voyager 1 in 1979, and the Juno mission has imaged no fewer than 266 actively erupting during its periodic fly-bys of Io as it studies Jupiter and its moons. The overall driving force behind these volcanoes is tidal flexing deep within Io’s core and mantle, the results of the moon being in a constant state of flux thanks to the gravitational influences of (most particularly) Jupiter to one side and the three other Galilean satellites on the other.

The comparative sizes of the Moon and Io, together with that of Earth to scale. Credit: full Moon – Gregory H. Revera; true colour image of Io – NASA/JPL; Earth: NASA / Apollo 17

However, there has always been something of a question as to how these volcanoes might – or might not – be related and directly powered. Here on Earth, volcanism usually occurs as a result of decompression melting within the asthenosphere – the upper limits of the mantle directly under the lithosphere/crust comprising solid and partially-melted rock. This gives rise to magma, which is then forced upwards through the lithosphere as localised volcanic eruptions. This was long held to be the case with Io, with scientists believing its volcanoes, like the majority on Earth, were driven by the upwelling of individual magma flows.

But during the Galileo spacecraft’s observations of Io between 1995 and 2003, the data gave tantalising hints that Io’s volcanism could be the result of a somewhat different process, but it has taken the unique capabilities of the Juno spacecraft to confirm this to be the case. By gathering extensive thermal and infrared imaging of Io’s mantle, the JIRAM instrument has been able to put together a comprehensive view of the upper layers of Io’s mantle, revealing that far from being a layer mix of solid and partially melted rock, Io’s asthenospheric region is entirely molten in nature.

In other words, lying just below Io’s lithosphere (roughly 12-40 km thick) is a moon-girdling ocean of magma, some 50 km thick, with a mean temperature of some 1,200ºC, and which powers all of Io’s active volcanoes.

The structure of Io as likely confirmed by data obtained by the JIRAM instrument aboard the Juno spacecraft. Credit: Kelvinsong

This may not sound exciting in the scheme of things, but it further demonstrates the uniqueness and complexity to be found within the Jovian system.

A further example of this can be found with Io’s big brother, Ganymede. The third of the Galilean moons in terms of distance from Jupiter, Ganymede is not only the biggest of the Galilean moons orbiting Jupiter, it is the biggest and most massive natural satellite in the solar system. In fact, if it were orbiting the Sun rather than Jupiter, it would be classified as a planet, being even larger than Mercury.

Ganymede, like its smaller siblings around Jupiter – and the rocky planets of the inner solar system – is a complex place enjoying a complicated relationship with its parent; one which shares near-similarities with Earth’s relationship to the Sun.

Much has long been known about Ganymede as a result of observations made from Earth – such as via the Hubble Space Telescope – and by the various missions which have flown past or orbited Jupiter. These have helped us confirm that Ganymede has a sufficiently warm interior to support a global liquid water ocean beneath its crust, an ocean larger by volume than all of Earth’s combined.

The comparative sizes of the Moon and Io, together with that of Earth to scale. Credit: full Moon – Gregory H. Revera; true colour image of Ganymede – NASA/JPL; Earth: NASA / Apollo 17

We’ve also been able to (largely) confirm the presence of a tenuous atmosphere of oxygen and CO2, which seems to be particularly concentrated around the northern and southern latitudes, likely constrained by the interaction between Ganymede’s weak magnetic field and the far more powerful magnetic field generated by Jupiter – the predominant O2 content of the atmosphere is thought to be the result of water vapour escaping the moon’s interior being spilt by the radiation carried down over the poles by the magnetic field interaction.

It is this interaction between radiation, magnetic fields and the surface of Ganymede which have been part of the focus of a study made of the moon using instruments on the James Webb Space Telescope (JWST), and which was recently published.

Ganymede’s surface is dominated by two types of terrain: bright, icy features with grooves, covering about two-thirds of Ganymede’s surface, and older, well-cratered and darker regions )on places scored by asteroid impacts of the moon’s more “recent” past, which could not be confused with the brighter terrain) . The two terrain types are not differentiated in terms of their location on Ganymede’s surface, they are instead intermingled, with the lighter terrain cutting swathes across the darker terrain.

Ganymede, showing its dominant types of terrain. The dark cratered regions, and the brighter, icy regions with grooved terrain. The white radial lines are the results of impacts with the moon and not directly related to the terrain types. Credit: NOAA

Some of these brighter swathes – notably those around the Polar Regions – carry strong evidence of water ice, which appears to have been exposed by (in the words of the study) “the combination of micro-meteoroid gardening, excavating the ice, and ion irradiation”.

In other words, over the millennia, dust and material has been caught within the interactions between the two magnetic fields, smashing into the moon’s surface to expose the underlying water ice, allowing it to be irradiated by plasma also carried by the inflowing magnetic field, causing some of it to escape as water vapour which has been either further irradiated and broken down (thus giving rise to the accumulation of the tenuous, O2-rich atmosphere near the surface), or re-accreting as easily-identified water ice on the surface rock.

Whilst the two magnetic fields interact around Ganymede’s poles and along the moon’s “trailing edge” as it orbits Jupiter in a very similar manner to the interaction between Earth’s magnetic field and that of the Sun over our own poles, the spectral properties seen along the moon’s ”leading edge” in its orbit suggest that there is a far more complex, and yet to be understood interaction taking place between the magnetic fields of planet and satellite. Solving this mystery might require time – and some assistance in the form of the European Space Agency’s Jupiter Icy Moons Explorer (JUICE) mission launched in April 2023, and due to reach the Jovian system in 2031, where it will likely uncover more surprises about both Ganymede and Europa.

Continue reading “Space Sunday: Jovian Moons, and lunar aspirations” →

Space Sunday: 3D printing for space, and asteroids

Posted on by Inara Pey
A RAMFIRE rocket engine nozzle performs a hot fire test at NASA’s Marshall Space Centre, demonstrating the viability of 3D printed, aluminium rocket nozzles. Credit: NASA

3D printing may be a relatively new technology, but it is one that is revolutionising may sectors of industry and commerce – and that includes space exploration. I’ve already covered the work of Relatively Space to manufacture and operate the world’s first 3D printed rocket systems in the form of the (now retired after it maiden launch failure) Terran 1, and the highly ambitious, semi-reusable Tarran R. However, NASA has actually been charting the potential for 3D printing in space and on Earth for almost a decade.

As an example of this; the first 3D printing system installed on the ISS arrived in 2014. It was a modest affair primarily designed to research whether or not practical, plastic-based 3D printing could be used in the microgravity of space. As the analysis of the printed parts demonstrated, there were no weaknesses or deficiencies in their construction when compared to identical items produced on Earth using the same process. Thus, the initial project was expanded to encompass the production of usable items – a wrench, plastic brackets, parts of an antenna system, for example – using a variety of industrial-grade plastic filaments.

ESA astronaut Samantha Cristoforetti using the 3D Printer aboard the ISS. Credit: NASA

The capability was then enhanced with the arrival of ReFabricator – a system which could take plastics used on the ISS and recycle them into plastic filament for use by the printer, with Recycler later adding the ability to do the same with other “waste” materials on the station.

In 2023, the European Space Agency and Airbus Industries went a stage further with Metal3D, a printer capable of producing metal and alloy parts for use on the ISS. It is part of a broader project to develop in-situ orbital and lunar 3D printing systems capable of manufacturing everything from replacement parts to entire assemblies such as radiation shields, vehicle trusses, etc. ESA plan to use an enhanced Metal3D system to use lunar regolith as its raw material in the production of equipment and components.

Meanwhile, NASA has also been busy on Earth with a range of 3D printing projects and studies, one of which  – RAMFIRE – which earlier in the year had its (quite literal) baptism of fire.

Standing for the Reactive Additive Manufacturing for the Fourth Industrial Revolution,  RAMFIRE is a unique process which combines an entirely new aluminium alloy called 6061-RAM and 3D printing to create rocket nozzles for space vehicles. To understand why it is potentially so revolutionary, three points need to be understood:

  • As a rule, aluminium is a poor choice for rocket engine (and particularly engine nozzle) construction as it has a rather nasty habit of melting when exposed to high temperatures – such as those generated by a rocket engine nozzle.
  • While aluminium can be strengthened to withstand higher temperatures through the use of additives, the additives themselves can make it susceptible to cracking and microfractures if the aluminium has to be wield to itself or other items as is again required in the production of rocket nozzles.
  • At the same time, being able to print an entire engine nozzle as a single unit and in aluminium, has the potential of both greatly simplifying the process of rocket engine production (as the nozzle now comprises a single part, rather than up to 1,000 individual parts as is currently the case, and for the engine to be significantly lighter without any reduction in thrust, allowing for a potentially large payload to be carried.

Using 6061-RAM with a 3D printing process developed in partnership with Colorado-based Elementum 3D, NASA has been able to produce single-piece aluminium rocket nozzles which, by a combination of the additives used in the alloy and a series of special cooling channels printed into the nozzles, both withstand the heat of combustion in their chambers and also passively cool themselves in the process.

Over the summer period, two small-scale RAMFIRE nozzles were put through their paces at NASA’s Marshall Space Centre in a series of hot fire tests, the results of which were published by NASA on October 16th. The nozzles were tested using two cryogenic propellant mixes – liquid oxygen and liquid hydrogen in one batch of tests, and liquid oxygen and liquid methane in the other. It had been anticipated the nozzles would manage a pressure of up to 625 psi in their chambers, and run for a handful of minutes apiece. As it turned out, they functioned above the anticipated pressure without damage and racked up a cumulative burn time of almost 10 minutes.

This level of burn time and pressure is well in excess of the major requirement for such engine nozzles: within cargo transports carrying payloads to the surface of the Moon and landing them safely, bore lifting off again for the return trip to Earth to collect more cargo. However, the technology being developed by NASA and Elementum 3D has the potential to be used in a wide range of space vehicle applications, from propellant tank manufacture through to providing a means to provide very lightweight, thrust-efficient aerospike engines, one of the holy grails of space transportation systems.

The 6061-RAM2 aluminium and its associated 3D printing process also has the potential to produce other items required by spacecraft. The above is a demonstrator for a single-piece printed propellant tank, complete with the same cooling channels to help keep cryogenic propellants cold. The result is a lightweight single-piece tank structure with primary side walls just 1.5 mm thick.  Credit: NASA

There is still further R&D to go with RAMFIRE, but NASA and Elementum 3D are already looking at licensing 6061-RAM and the printing process to commercial organisations interested in adapting it for use in their space-based efforts  – and possibly further afield in aerospace research sectors.

Continue reading “Space Sunday: 3D printing for space, and asteroids” →

Space Sunday: Psyche and an eclipse

Posted on by Inara Pey
An artist’s impression of the Psyche mission spacecraft observing and mapping the asteroid 16 Psyche. Credit: NASA

Asteroids have been something of a focus for Space Sunday of late, and they’re going to be again this week. Or at least, one is: 16 Psyche, as this is the target for a NASA mission which, if all goes according to plan, will launch from Kennedy Space Centre on October 12th, 2023.

16 Psyche was discovered by the Italian astronomer Annibale de Gasparis on 17th March 1852, and is named for the ancient Greek goddess of the soul. It has a shape consistent with that of a Jacobi ellipsoid, and measures some 278 km x 238 km x 171 km as it orbits the Sun between Mars and Jupiter once every 4.9 years at an average distance of 437 million km (2.92 AU). It is also the 16th minor planet to be found in the solar system by order of discovery (hence the 16 in its name).

What 16 Psyche might look like. Credit NASA

But what makes 16 Psyche a subject for detailed study is the fact that it is the largest and most massive M-class asteroid – a class of asteroids which appear to contain higher concentrations of metal phases (e.g. iron-nickel) than others within the asteroid belt – yet discovered in the solar system. So massive in fact, that it was long theorised that it was the exposed core of a protoplanet.  These are bodies thought to have been created during the early history of the solar system from the collision and coalescing of planetismals, and which may have gone on to play a role in the formation of the inner planets of the solar system (in fact, for a time in the early 20th century, the coalescing of planetismals into protoplanets and protoplanets into planets was thought to be the process by which all planets were created, an idea long since proven incorrect; planetary formation is far more complex than things bumping into one another and gluing themselves together).

Thus, it is also possible that whilst a protoplanet, 16 Psyche evolved along lines which had nothing to do with planetary formation; thus, studying it might either help in our understanding of planetary formation and / or enable us to more fully understand the unique processes at work within these tiny (in terms to their relationship with planets) bodies, and the mechanisms which ultimate gave rise to their form and nature. Most intriguingly, a mission to 16 Psyche might even point to a different story as to how objects in the solar system formed.

What we do know about 16 Psyche’s surface details, based on observations via the European Southern Observatory’s Very Large Telescope in the Atacama Desert, Chile. Credit: ESO

Hence the upcoming NASA mission and spacecraft which bear the asteroid’s name. First proposed in February 2015 by Arizona State University, the idea was awarded a US $13 million grant under the agency’s ongoing Discovery Programme to allow the basic concept to be fully evaluated and the initial design for the spacecraft determined. As a result of this, the mission was officially adopted into the Discovery Programme at the start of 2017 with a budget capped at $1 billion.

At that time, the mission was targeting a later 2023 launch date; but such was the confidence in the vehicle’s development cycle that this was revised to a July 2022 launch opportunity. This would allow for a much faster mission, drastically reducing the transit time to 16 Psyche, allowing the spacecraft to reach it in 2026, rather than 2029 as would be the case with a 2023 launch. Unfortunately, COVID-19 intervened to delay the construction and testing of the spacecraft, forcing NASA to push the launch date back to October 5th, 2023. Then in September 2023, this was delayed a further week to allow time for adjustments made to the operational parameters for the spacecraft’s cold gas thrusters (used to orient the craft when manoeuvring) to be properly checked and verified.

Psyche (as in the spacecraft) will commence its journey atop a SpaceX Falcon Heavy rocket due to lift off from Pad 39A, Kennedy Space Centre, Florida at 14:16 UTC on October 12th. Once the craft has separated from the Falcon Heavy’s upper stage, it will deploy its massive solar arrays – a span totalling 25 metres and 7.3 metres across at its widest. Capable of generating 21 kilowatts of electricity whilst in the vicinity of Earth (which will decrease over distance to between 2.3-2.4 kilowatts when the spacecraft is orbiting 16 Psyche), these panels will not only provide electrical power to Psyche’s instruments, but will also power the vehicle’s primary propulsion system.

A US SPT-140 Hall-effect thruster being tested at NASA’s Jet Propulsion Laboratory. Credit: NASA/Caltech

This comes in the form of four Hall-effect SPT-140 thrusters which will be used individually rather than collectively during the cruise stages of the mission, to both propel the spacecraft to its destination and slow it for orbital insertion around 16 Psyche. Each thruster uses some of the electricity generated by the solar panels to generate an electromagnetic field, which is in turn used to direct and accelerate a stream of inert xenon gas ions, expelling it as an exhaust mass to propel the craft.

The force of this exhaust is not huge – it’s about equal to that felt when holding an AA battery on the palm of the hand – but the key thing is, it can do so for weeks, and with a tiny amount of fuel, allowing for a constant acceleration, reducing the transit time to the asteroid compared to conventional meaning of transit (i.e. using momentum imparted by the launch vehicle coupled with multiple planetary flybys) and at a fraction of the propellent load (1 tonne or 10%)  that would be required if conventional chemical motors were to be used.

Even so, the journey to 16 Psyche will still the 2.6 tonne spacecraft take 5 years 10 months. The first part will be a 2-year, 7-month outward spiral around the Sun so the spacecraft can perform a flyby of Mars in May 2026. This will allow it to both accelerate and swing itself onto a trajectory which crosses that of 16 Psyche in 2029, allowing the vehicle to slow itself into an initial orbit around the asteroid in August of that year.

During the initial part of the outward cruise, the spacecraft will be used to demonstration a potential new deep space communications technology – DSOC (“dee-sock”), the Deep Space Optical Communications system. This is a laser-based system which, if it works as planned, will increase communications performance and efficiency between Earth and a spacecraft in deep space by between 10 and 100 times, simply because of the removal of signal attenuation compared to radio signals and the greater bandwidth / throughput rates lasers can provide. DSOC will initially be tested through the first 12 months of the mission and, subject to results, the demonstration may be extended into the second year of the vehicle’s cruise phase, allowing the capability to be tested over distances of up to 2.5 AU.

On arrival at 16 Psyche, the spacecraft will enter the first of five orbital regimes (one if which it will use twice) in order to thoroughly map and study the asteroid. In particular, these will attempt to probe any magnetic field the asteroid might have (the presence of such a field would greatly lend itself to the idea the asteroid is in fact the core or partial core of a protoplanet). They will also enable the craft to completely map the surface of 16 Psyche and determine its surface composition and properties.

Orbit Duration Inclination Period Duration Mission
A 92 days 90º 32.8 hours 700 km Magnetic field characterization and preliminary mapping
B(1) 92 days 90º 11.6 hours 303 km Topography and magnetic field characterization
D 100 days 160º 3.6 hours 75 km Determining the chemical composition of the surface
C 100 days 90º 7.2 hours 190 km Gravity investigations and Magnetic field observations
B(2) 100 days 90º 11.6 hours 303 km Topography and magnetic field characterization
Psyche orbital operations at 16 Psyche, 2029-2031. Credit: NASA

Given the nature of the spacecraft and allowing for its overall condition towards the end of the primary mission, it is possible that the Psyche mission could be extended beyond this initial 21-month period.

The launch of the Psyche mission will be broadcast by NASA TV, and can be watched via the link / preview below.

October 2023 Annular Eclipse

On Saturday, October 14th, 2023, nearly one billion people across the United States and the northern countries of South America will be able to watch an annular eclipse of the Sun (or at least a partial eclipse) – as the Moon crosses the Sun’s face as seen from Earth the last solar eclipse for 2023.

Annular solar eclipse seen from Chiayi in southern Taiwan on June 21st, 2020. Credit: Alberto Buzzola

An annular eclipse difference from a total eclipse in that the Sun is never completely hidden by the Moon. In the case of October 14th, this will be because  the Moon will be 4.5 days past apogee (the point where it is  farthest from Earth, and so the tip of its umbral shadow cone misses Earth by around 19,200 kilometres, so the disk of the Moon will appear too small to completely cover the Sun; around 48% of the Sun’s diameter remains visible all around the Moon’s disk, creating what can sometime be a spectacular “ring of fire”.

Those able to see an annular eclipse in the United States are located along a line commencing in Oregon and passing directly through Nevada, Utah, New Mexico  and Texas whilst touch the northeast of California and Arizona and the southwest of Colorado. In South America, the line of the eclipse passes through Mexico Nicaragua, Columbia and northernmost Brazil and touches on Costa Rica, Panama and Venezuela. Further afield, people will see a partial eclipse.

Track and times of the October 2023 annular eclipse across the United States (track across South America shown inset). Credit: NASA Scientific Visualization Studio

However, for those wishing to track the event, NASA’s 2023 Eclipse Explorer offers an interactive map detailing when and where the eclipse will be visible, including the path and duration of annularity (the areas from which the ‘ring of fire’ can be seen), allowing users to dive into the eclipse viewing experience like never before. Both the Time And Date and Virtual Telescope will be livestreaming the eclipse around the globe, as will Slooh via their You Tube Channel.

Of course, if you live along the line of the eclipse, you can always view it live. If you opt to do so (assuming the whether is clear), then remember: never look directly at the Sun either and especially through a telescope or binoculars or camera – don’t even use ordinary sunglasses. To view the eclipse safely you must use solar filters at all times on any optical equipment you are using to observe the Sun and / or wear solar eclipse glasses, regardless of whether your location will experience a partial solar eclipse or an annular solar eclipse. Serious eye damage and even blindness can result if you do not otherwise.

Also, don’t expect things to go really dark in the manner of a total eclipse or to be able to witness the Sun’s corona: that ring of the Sun’s disk peeping around the Moon may be small, but it is still bright enough to prevent that. But it will still be a spectacular event to see, and enthusiasts will go to whatever section of the eclipse track is most easily accessible for them in order to witness it.

Space Sunday: happy 65th, NASA!

Posted on by Inara Pey
The NACA and NASA “meatball” logos. Credit: NASA

On October 1st, 1958 the National Aeronautics and Space Administration officially commenced operations, just two months after then-President Dwight D. Eisenhower signed the US National Aeronautics and Space Act into law.

NASA’s birth essentially arose out of what would become known as the “Sputnik crisis”. In October 1957 Russia launched Sputnik 1, the world’s first artificial satellite. Worse, just a month later, they launched Sputnik 2, which not only carried a living animal into orbit (the dog Laika, doomed to expire in orbit as the technology did not exist for the craft to re-enter the atmosphere and land safely), it demonstrated Russia had a launch system vehicle could be used relatively rapidly. This put US space launch efforts – activities largely split between the three branches of the military – into something of a tailspin, with the realisation that any civilian / science space programme could not be reliant on competing military programmes.

To this end, it was decided to place military space development under the auspices of a new agency within the US Department of Defense: the Advanced Research Projects Agency (ARPA – now the Defence Advanced Research Projects Agency, or DARPA), which was also charged with managing all aspects of emerging technologies research as they related to military use. Meanwhile, civilian space research would be placed in the hands of a new agency, with the National Advisory Committee for Aeronautics (NACA) charged with coming up with a structure for that organisation.

A replica of Sputnik-3 on display at the U. S. S. R. Industrial Exhibition, 1958, held in Moscow. The 4-metre long, 1.3 tonne spacecraft was 100 times the mass of its American counterpart, Explorer-1, and its launch and that of the earlier Sputnik-1 and Sputnik0–2 missions did much to speed the creation of NASA. Credit: Pathé News

Further haste was given to the need to determine the best direction of the US civilian space programme in May 1958, when Russia launched Sputnik-3 to mark the International Geophysical Year. Massing 1.3 tonnes, or 100 times that of the US satellite launched 3 months earlier with the same goal, Sputnik-3 demonstrated Russia had a payload to orbit capability well beyond anything within the United States, and a technical capability to fly large suites of science instruments on a single vehicle (12 instruments in the case of Sptnik-3).

In being instructed to study options for a new civilian space agency, the NACA was uniquely placed. Founded in 1915, it had (at that time) been at the forefront of aviation development in the United States for more than forty years, and following the end of the Second World War, it had become increasingly involved in aerospace research. For example, NACA was responsible for the initial design concept of what would become the X-15 hypersonic aircraft after developing and flying a number of supersonic craft during the early 1950s, and worked with the US Air Force to develop the vehicle from 1954 through until the establishment of NASA in October 1958.

A 1952 photograph of the NACA High Speed Test Force at Edwards Air Force Base during flights of the Douglas D-558-2 Skyrocket, the first aircraft to exceed Mach 2.0 (November 1953). Credit: Armstrong Photo Gallery.

After due consideration, NACA submitted a report and after reading it, James Killian, the then-chair of the Science Advisory Committee realised that NACA was not only well-placed to recommend what form the new space agency should take, it was ideally placed to become the foundation of the new organisation, informing Eisenhower via a memorandum the to Eisenhower stating the new agency should be formed out of a “strengthened and re-designated NACA, a going Federal research agency with 7,500 employees and $300 million worth of facilities” and which could expand its role “with a minimum of delay”. His suggestion was accepted and incorporated into the National Aeronautics and Space Act.

As a result of the decision to transition NACA into NASA, the new agency was able to hit the ground running, gaining three major research centres – Langley Aeronautical Laboratory, Ames Aeronautical Laboratory, and Lewis Flight Propulsion Laboratory, and the NACA budget and staff. In the months immediately following NASA’s establishment, those elements of the US Army and US Navy trying to build and operate orbital rocket systems were transitioned over to the new agency (including the US Army team utilising Wernher von Braun and other former German rocket engineers), together with the California Institute of Technology’s Jet Propulsion Laboratory, which has become world-famous as the developmental and mission operations centre for the majority of NASA’s robotic deep space missions.

As a part of its very first research activities, NASA took over the hypersonic X-15 programme mentioned above, overseeing all 199 flights of that craft along with the US Air Force. At that time NASA came into existence, the NACA and the USAF had been collaborating on the idea of extending the X-15 into an orbit-capable vehicle to be launched vehicle a family of modified missiles, thus allowing the US to gain valuable insight into the design requirements and operating nature of space-capable aircraft, which were even at that time being seen as the future of manned spaceflight.

Conceptual illustrations of the X-15B orbital vehicle with various launch options, and (r) the X-20 Dyna-Soar. Credit: Mark Wade

In particular, the USAF was keen to gather data to help with a  concept for a multi-role “space glider” which would evolved into the X-20 Dyna-Soar project of the early 1960s (although this was ultimately cancelled in 1963). However, NASA’s new leadership preferred a more cautious approach to putting men in space, determining primates should be flown first and recovered for post-flight study. Therefore, the X-15B concept, with its need for a skilled pilot at the controls, was rules out in favour of the less capable but easier to fly Mercury capsule. Thus was NASA’s manned spaceflight programme born.

Today, whilst still a relatively small organisation in terms of manpower when it comes of federal agencies (the Federal Aviation Administration, for example, numbers 48,000 employees to NASA’s 18,000), and with a modest budget (less than US $26 billion from the US mandatory federal budget of US $4.1 trillion – which admittedly and conversely is still around 4.5 times more than the FAA’s), NASA is an incredibly diverse and far-reaching organisation.

NASA’s rarely-noted administration headquarters at 300 E Street SW, Washington DC. Credit: NASA (1997)

Not only does it manage all of America’s civilian space activities through ten major research and operations centres across the United States (as well as numerous smaller facilities and centres), it continues to carry out wide-ranging aeronautical research and development in what is a continuance of the cutting-edge work started by the NACA more than 100 years ago.

In addition, NASA is involved in R&D and operations across many disciplines and areas of research, including communications; vehicle and transportation safety; environmental monitoring (climate and weather in partnership with the National Oceanic and Atmospheric Administration (NOAA); pollution control, environmental management, global land use, deforestation monitoring, agricultural monitoring, etc (much in partnership with the US Geological Survey, or USGS); research into alterative and sustainable energy systems; nuclear research; multiple avenues of general science research as they pertain to the planet and to healthcare; and in promoting education, science, mathematics and the harnessing of technology through a range of STEM initiatives in the US and around the world.

So, happy anniversary NASA. You may be at retirement age in human terms – but here’s to many more!

Updates

OSIRIS-REx Samples

Previously on Space Sunday (as they say on TV shows) NASA’s ORISIS-REx mission returned to Earth samples captured from 101955 Bennu, a carbonaceous near-Earth asteroid. As we left that story, the sealed capsule containing the estimated 250 grams of material was pending a transfer to NASA’s Johnson Space Centre (JSC), Texas.

The first glove box unit at the ARES facility, JSC, purpose-built to handle the disassembly of the ORISIS-REx sample return capsule so that the samples of asteroid Bennu it contains can be removed for examination and analysis. Credit: NASA / Robert Markowitz

That transfer occurred on Tuesday, September 26th, 2023, with the sample capsule being airlifted from the US Army’s Dugway Proving Ground in Utah, some 31 kilometres from where it landed, to Ellington Field Joint Reserve Base near Houston, Texas. From here the special transpiration container with the capsule inside was move by road to the Astromaterials Research and Exploration Science (ARES) centre at JSC.

ARES is home to the world’s largest collection of “astromaterials” (samples returned from space), and is usually the first US centre to examine such samples brought to Earth by US space missions. As such, it is the ideal permanent home for the OSIRIS-REx samples, and will be the centre that carries out an initial sample analysis and then divvy it up for distribution to research centres around the world and to museums.

How it should have gone – the OSIRIS-REx TAGSAM “touch-and-go” mechanism recovering samples from the surface of asteroid 101955 Bennu in 2020. As it turned out, the asteroid’s surface was so brittle, the sample head and arm smashed through it to a depth of around 50cm.

Continue reading “Space Sunday: happy 65th, NASA!” →

Space Sunday: the return of OSIRIS-REx

Posted on by Inara Pey
The OSIRIS-REx Sample Return Capsule (SRC) in the landing zone at UTTR, September 24th, 2023. Credit: NASA TV

On September 8th, 2016 at 23:05 UTC, an Atlas V 411 rocket lifted-off from Space Launch Complex (SLC) 41, Cape Canaveral Air Force Station (now Space Force Station). Launched by United Launch Alliance (ULA), the rocket carried aloft NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx), an ambitious mission to study a carbonaceous near-Earth asteroid and obtain as large a sample of material as possible for a return to Earth.

More recently, on September 24th, 2023, the mission achieved its goal, returning an estimated 250 grams of material – four times the minimum amount scientists hoped to obtain at the start of the mission – from the 500m diameter asteroid 101955 Bennu. It is not the first mission to return a sample of material from an asteroid; Japan holds that record with its Hayabusa and Hayabusa-2 missions. The first rendezvoused with asteroid 25143 Itokawa in 2005, the second with asteroid 162173 Ryugu in 2018; however, given both these missions returns a total sample cache of under 6 grams, OSIRIS-REx is the most successful to date.

A ULA Atlas 5 launches OSIRIS-REx on its way to a rendezvous with asteroid Bennu

Over the intervening seven years since its launch and return, OSIRIS-REx completed a round-trip journey of some 6.4 billion kilometres. Along the way it performed a fly-by of Earth some 12 months after launch, allowing it to enter an orbit around the Sun from which it could intercept Bennu. This passage around the Sun allowed OSIRIS-REx to past through the Earth-Sun Lagrange L4 position, where it performed a search for a class of near-Earth objects known as Earth-Trojan asteroids. Whilst no previously unknown asteroids were located during the 11-day survey in February 2018, the exercise yielded valuable data on vehicle manoeuvring for the kind of precise imaging required on reaching Bennu.

As it approached OSIRIS-REx Bennu in late 2018, OSIRIS-REx was able to observe Jupiter, adding to his science mission, prior to entering an initial orbit at the start of December 2018. It then spent most of the month generally characterising the asteroid, detecting hydrated minerals in the form of clay across the asteroid’s surface, suggesting it was once a part of a larger object rich with frozen water, offering a further pointer to how life-forming minerals and water may have been carried to Earth and the inner planets.

On December 31st, 2018 OSIRIS REx closed to just 1.75 km above Bennu’s surface, allowing it commence an extensive remote mapping and sensing mission which allowed the science team to identify potential areas which might be suitable for gathering one or more samples. In reaching that altitude, OSIRIS-REx set a new record for the closest distance any spacecraft has orbited a celestial object, beating ESA’s Rosetta mission’s orbit of 7 km around the comet 67P/Churyumov–Gerasimenko.

In all, 14 months were spent carefully surveying Bennu, allowing for potential sample-gathering sites to be identified, with the spacecraft closing to just 1 km above the asteroid, breaking its own record and allowing a final survey of the four preliminary landing sites so a final selection could be made. In the end, a site dubbed “Nightingale”, a fairly open shallow depression on the asteroid’s surface, was selected, and the mission moved to the rehearsal phase.

Image sequence showing the rotation of Bennu, imaged by OSIRIS-REx at a distance of around 80 km. Credit: NASA Goddard

In order to collect samples, OSIRIS-REx had to make physical contact with the asteroid in a “touch and go” (TAG) manoeuvre. This would see the spacecraft deploy a robot arm underneath itself. Called the Touch-And-Go Sample Arm Mechanism or TAGSAM, this spring-loaded arm carried a camera system and, on its end, a sample gathering system. The craft would then use its thrusters to gently push itself down towards Bennu, bringing the sample head into contact with the asteroid’s surface.

At this point, several things would happen in rapid succession: the springs in the arm would absorb the spacecraft’s motion, allowing it to maintain contact for a second or two as a jet of inert nitrogen would be directed at the surface under the sample head in order to blast material up into it while Velcro-like rings on the end of the head would snag dust particles and the like. Then, as the springs in the arm recoiled under the mass of the spacecraft and very gently push it back away from the asteroid, allowing a Mylar cap to close over the sample head, trapping whatever had been captured inside the head. Finally, once the spacecraft was sufficiently clear of the asteroid – 40m or so -, OSIRIS-REx would fire its thrusters an position itself back in orbit a few hundred metres above the asteroid, where the sample gathering operation could be assessed for success and from which, if required, a further attempt made to grab material.

A computer simulation of OSIRIS-REx making contact with asteroid Bennu. Credit: NASA

All of this was obviously quite complex – and due to the the delay in communications between vehicle and Earth, had to be carried out entirely autonomously. Hence the rehearsal phase of the mission. These were carried out in April and August 2020, with the first bringing the craft to within 65 metres of the sample site and the second stopping just 40 metres above it. Both saw the craft go through all phases of the TAG operation, sans actually touching the asteroid, with a small burst from the thrusters substituting from the recoil of the TAGSAM springs to push it away from the asteroid once more. Both rehearsals were flawless and paved the way for the first – and only, as it turned out – sample gathering attempt.

Continue reading “Space Sunday: the return of OSIRIS-REx” →

Space Sunday: hycean worlds and seeking signs of life

Posted on by Inara Pey
An artist’s impression of the (potentially) hycean world K2-18b. Credit: NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University)

“Hycean world” may not be a term familiar to many. It refers to a type of hot, water-covered planet with a hydrogen atmosphere – “hycean” being a portmanteau from HYdrogen and oCEAN – sitting somewhere between Earth and Neptune in size, and which could be promising candidates for harbouring life, as they would be naturally warm and wet. However, there is a slight wrinkle in this theory: up until now, hycean planets have been purely hypothetical – although several contenders for the title have been identified.

One such contender is K2-18b, an exoplanet 124 light years away. It sits within the habitable zone of a relatively mild-mannered red dwarf star called K2-18 (and also EPIC 201912552), located within the constellation of Leo when viewed from Earth. First discovered by the Kepler mission in 2015, K2-18b is referred to as a “super Earth” because it is around 3 times the size and 9 times the mass of Earth, but smaller than Neptune (3.9 times the size and 17 times the mass of Earth).

From the start, it was known that K2-18b had an atmosphere dominated by hydrogen. Studies also showed that while it orbits in close proximity to its parent star, taking just 33 terrestrial days to complete an orbit – such is the star’s low energy output (just 2.3% that of the Sun), K2-18b receives a very similar amount of solar energy to the Earth: 1.22kW per square metre compared to our own average of 1.36kW per square metre. This means the planet likely has a global temperature range of between averages of −23°C at the poles and +27°C in the tropics, making it potentially ideal for hosting liquid water.

A hypothetical example of composition of an exoplanet’s atmosphere obtained during a transit, when the light from the star passes through the atmosphere of the planet to be captured by an observatory’s spectrograph, allowing it to be broken down and the elements within the planet’s atmosphere identified. Credit: NASA, ESA, CSA, STScI, Joseph Olmsted (STScI)

In 2019, the Hubble Space Telescope (HST) found evidence that water vapour is present in K2-18b’s atmosphere, further edging it towards hycean status. However, the jury has remained out on the matter. The HST observations of 2019, for example, appeared to also find traces of ammonia and hydrocarbons – two elements which should not exist if there is also a large amount of liquid water present (as it would absorb them). Further, a 2021 study suggested that if K2-18b is tidally locked with its star (that is, always keeping the same side facing towards the star, which given their proximity to own another would seem likely), then any water on the sunward side of the planet would likely be in a supercritical state, making any form of liquid ocean impossible.

However, using the Near Infrared Spectrograph (NEARSpec) and Near-Infrared Imager and Slitless Spectrograph (NIRISS) detectors on the James Webb Space Telescope (JWST) a team of astronomers from the UK and USA are attempting to build a comprehensive – if not yet complete – view of K2-18b’s atmospheric spectra. Their initial findings have been published in a new paper, and suggest that K2-18b might yet prove to be a hycean planet.

In particular, the paper confirms that HST did find water vapour in K2-18b’s atmosphere, it was wrong about the presence of ammonia and hydrocarbons; the team having found no trace of either – although they have found both methane and carbon dioxide in the atmosphere, both of which also lean themselves to a potential for the planet having a liquid ocean.

The chemical composition of K2-18b’s atmosphere. Credit: NASA, CSA, ESA, R. Crawford (STScI), J. Olmsted (STScI), Science: N. Madhusudhan (Cambridge University)

More interestingly, the team also appear to have detected dimethyl sulphide, (CH3)2S – DMS for short. This is potentially a critical discovery, and so far as we know, DMS is the result of a wholly organic process: marine life and plankton giving vent to flatulence. If this is as true for K2-18b as for Earth, then the case for that planet having a liquid water ocean becomes pretty clear.

However, a note of caution needs to be struck here. As the researchers themselves make clear, the signal for DMS within K2-18b’s atmosphere is only 2 sigma. While this equates to a 98% confidence level in the instruments on JWST having correctly identified it, the results nevertheless fall far short of the 5 sigma (over 99.9% confidence) required by science to indicate the instruments have correctly identified the presence of a particular element within the atmosphere of another world. As such, further examinations of K2-18b’s atmosphere need to be made to see if that 5 sigma level can be achieved – or if the DMS traces fade away to nothing.

And even if the DMS readings prove to be correct, it again doesn’t automatically mean the planet is home to life. Whilst the sole cause for DMS here on Earth is that of marine life farts, the same may not be true for other places in the galaxy; it might yet be show the some strange geological or chemical cause might be responsible for its presence. Nevertheless, the data thus far obtained by JWST do suggest that K2-18b could be a warm, naturally wet planet – and potentially points the way to other such worlds existing within the galaxy.

Are Pollutants a way to find Industrial Civilisations?

Using the transit method of analysing the atmosphere of a planet, as with the case of K2-18b above, is one of the best ways we have at our disposal to determine its potential to support life. However, it might also be the means of detecting technological life itself – as pointed out by an international team led by Canadian–American astronomer and planetary scientist Sara Seager.

As we’re only too aware, humanity has developed a nasty habit of buggering up Earth’s atmosphere with pollutants. Some of these have very clear spectral signatures and cannot be produced in quantity by natural means. As such, looking for them elsewhere might be indicative of the worlds where they are found being home to industrial civilisations.

Analysing the atmospheres of exoplanets through the transit method for signs of pollutants / inorganic elements in large qualities might indicate the presence of an industrial civilisation. Credit: sciencing.com

Take sulphur hexafluoride (SF6) and nitrogen trifluoride (NF3), as Seager and colleagues suggest. These are two inorganic greenhouse gases (NF3 for example, is 17,000 times more effective at warming the atmosphere than CO2). Both are artificially created, and are used by a number of modern industries. What’s more, they have very distinctive spectral signatures and very long half-lives; as such they have the potential to make ideal “technosignatures” if they were to be detected in the atmosphere of an exoplanet.

Of course, this also requires that any extra-solar civilisation follows something of a similar development path as we are on, but it is an intriguing idea. In fact, and as Seager and her team note, whilst fluorine might be the 13th most abundant element on Earth, very little of it occurs naturally in any form; most of it is produced (and used) in industrial processes. So again, should the analysis of an exoplanet’s atmosphere reveal multiple fluorine elements, there’s a fair chance (again using Earth as a model) they might point to a technological civilisation being present.

Resuming the Hunt for “Planet Nine” – Or Its Economy Sized Version

I’ve covered the conundrum of Planet Nine – the Neptune-sized planet some believed to be orbiting the Sun at an average distance of around 460 AU and responsible for chucking a number of Kuiper Belt Objects (KBOs) into highly unusual orbits of their own well outside of the plane of the ecliptic – numerous times (see here, here, and here, for more).

Most vigorously proposed and pursued by Mike Brown, a leading planetary astronomer at the California Institute of Technology, it was a contentious idea – most notably because of the small data pool from which Brown and his colleagues drew on to establish the whole idea of “Planet Nine”. It was also one that quickly came into doubt as repeated attempts to locate the mystical world failed to do so and evidence against such a large planet existing continued to mount.

It had been thought that Planet Nine, if it exists, might equal Neptune in size. However, a 2020 study largely pushed this idea out of the window. Now it has been suggested a smaller body – closer to Earth in size – might be lurking far out in the solar system and exerting a possible influence on KBOs / TNOs. Credit: Caltech / R. Hurt

When I last wrote about this situation, back in June 2020, it was to cover the work of Professor Samantha Lawler, an assistant professor of astronomy, University of Regina, Canada. Due in part to her involvement in the Outer Solar System Origins Survey (OSSOS), coupled with models such as the Nice Model (as in the town in France, not “nice”) of planetary migration, she was able to demonstrate the vast majority of eccentric KBOs could be accounted for through purely natural gravitational interaction. Most, that is, but not all; as she noted in her findings, small groups of KBOs remain a outliers, defying explanation for their eccentricities.

Some of the latter lie within a sub-category of KBOs referred to as trans-Neptunian objects (TNOs). These are objects with obits close enough to that of Neptune so as to be directly influenced by its gravity, which forces them into very defined modes of behaviour. However, a small percentage of TNOs (approx. 13% of the total) refuse to show any sign of being under Neptune’s influence, almost as if there is something else acting on them gravitationally and limiting Neptune’s ability to call them to heel; something perhaps like a yet-to-be discovered “Planet Nine”; albeit one on a much smaller scale than previously imagined – its economy-sized version, if you will.

The idea has grown out of unrelated research concerning the early development of the solar system. In running hundreds of simulations on how the solar system may have formed, and the planets – particularly the gas giants – migrated away from the Sun, researchers noted their models repeatedly formed multiple Earth-sized planets in the outer solar system. The exact number varied with each simulation, but they all shared the common fate of either being completely ejected from the solar system thanks to the outward migration of the gas giants, or – in the case of a small handful – being pushed into very distant orbits around the Sun where they have yet to be found.

Most interestingly, the researchers noted that if just one of these small planets – one with a mass around twice that of Earth – were to be pushed into a high inclination orbit – say 45º – and at an average distance of just 200 AU from the Sun, then it could have the potential to exert influence over the recalcitrant TNOs in a manner pretty close to their actually behaviour, and similarly affect other outlier KBOs.

Those behind the study are not proposing that there is a “mini-me” Planet Nine tap dancing its away around the Sun; merely that their work has thrown up some potentially interesting results. Nevertheless, in some quarters it has somewhat reinvigorated the whole idea of a distant planet (or even planets) still awaiting discovery as they make their way slowly around the Sun, and so the hunt may yet resume.