Category: Space Sunday

Space Sunday: ISS – 20 years of living in space

Posted on by Inara Pey
The International Space Station seen from the space shuttle Atlantis, May 23rd, 2010. The vertical gold / maroon panels are the solar panels for generating power; the white horizontal panels are the radiators for removing excess heat from the station. Credit: NASA

On October 21st, 2000, a Soyuz vehicle lifted-off from the Baikonur Cosmodrome in Kazakhstan en route for the fledgling International Space Station ISS, carrying two cosmonauts and an American astronaut. Sergei Krikalev, Yuri Gidzenko and William Shepherd were not the first people to visit the ISS, but when Soyuz TM-31docked with the station on November 2nd, they became the first official crew to live and work aboard it, and their arrival marked the start of 20 years of continuous occupation of the station.

At the time of the arrival of the Expedition 1 crew, the ISS was a small affair, the Russian-built Zarya propulsion, attitude control, communications and electrical power distribution module, launched in 1998; the American Unity module, intended to link future US and international modules on the station with the Russian units, delivered by the shuttle Endeavour in 1998; and the Russian Zvezda, which rendezvoused and docked with the station in July 2000.

The primary role of the Expedition 1 crew was to commission the ISS and its systems and to oversee the initial expansion of the station, with the assistance of two space shuttle flights. The first of these delivered the additional solar arrays to power the station, elements of the “keel” of the station (the Integrated Truss Structure), and the second the US Destiny research module. However, the work wasn’t all construction related: the three men also started the station’s long-running science programme that continues through to today. They also caused a slight controversy as they started work.

The ISS at the time of Expedition-1 crew. On the left is the Soyuz TM-31 vehicle the crew flew to the station aboard, docked against the Russian Zvezda module. In the middle is the Zarya module, the first module launched, and the US Destiny module to the right. This image was captured by the crew of STS-97 aboard the shuttle Endeavour, December 2000. Credit: NASA

The idea of a US space station has started to come together in the 1980s under the project title Space Station Freedom. This was later revised to Space Station Alpha before finally becoming the International Space Station following the signing of a US / Russian agreement to build a joint orbital facility. However, the “Alpha” name stuck with many at NASA, including Expedition 1 commander Shepherd, who insisted on using it – much to the consternation of Russian officials, who felt they had had the first space station in Salyut and Mir, so the new station was at best “Beta” (or better yet in their eyes, Mir -2).

Once aboard the station, and with the agreement of Krikalev and Gidzenko, Shepherd insisted on using “Alpha” as the station’s radio call sign, stating it was easier to say than “International Space Station” or “ISS”. Despite the annoyance on the part of Russia, “Alpha” continued to be used by the Expedition 1 crew, resulting in it being adopted as the station’s official radio call-sign.

As well as playing hosts to three space shuttle missions – the third of which delivered the Expedition-2 crew -, Shepherd Krikalev and Gidzenko also oversaw the start of re-supply missions using the Russian Progress vehicles (essentially fully automated Soyuz vehicles) capable of delivering around 2.4 tonnes of supplies and fuel to the ISS.

Following Expedition-1, the initial crews visiting the ISS were exclusively made up of Russian cosmonauts and American astronauts, with each crew spending, on average, 5-6 months on the station. It was not until June 2006 that the first international crew member boarded the ISS in the form of German astronaut Thomas Reiter. He was followed in 2008 by Frenchman Léopold Eyharts and Japan’s Koichi Wakata in 2009 (Wakata actually served a total of 5 Expedition crew rotations: 18, 19, 20 (all back-to-back and continuous) and 38 and 39 (again back-to-back). After this, crews routinely included one or more non-American / Russian astronaut.

The men who started it all: Sergei Krikalev, William Shepherd (centre) and Yuri Gidzenko: the Expedition-1 crew. Credit: Roscosmos

In the 20 years since Expedition-1, 240 individuals have made 395 flights to the ISS (including 7 “space tourists”) – a number that represents 43%of all human flights into space. In that time, the space station has grown from those initial three units to a total of 16 permanent pressurised modules, numerous unpressurised pallets and work stations, and one commercial unit, the Bigelow Expandable Activity Module (BEAM), an inflatable unit, currently configured as a storage space.

Outside of the Zarya, Zvezda, Unity and Destiny modules, the ISS comprises the following pressurised modules:

  • For science: the Columbus European module (added February 2008); the Japanese Kibō module (which, with its unpressurised work platform is the largest crewed elements of the ISS, added between 2008 and 2009); the Russian Rassvet module (now primarily used for storage, added May 2010).
  • Airlock / docking: the US Quest Joint Airlock, supporting EVAs using either US or Russian space suits (added July 2001); the Russian Pirs and Poisk airlock / docking modules (added September 2001 and November 2009, respectively, and connected to the Zvezda module); the US International Docking Adapters 2 and 3 (IDA-1 was lost in a Falcon 9 launch failure), delivered in 2016 and 2019 respectively.
  • Other modules: the US Harmony “hub node” connecting the European and Japanese science modules to the US Destiny module (added 2007); the European Tranquillity life-support and environmental module (added November 2009); the Leonardo European multi-purpose module (added February 2011) and the European Copula module, with its seven large windows (added in 2010).

Together, the pressurised modules of the ISS offer a volume of living / working space equitable to that of a 747 airliner. The overall mass of the ISS, including the Truss, and all unpressurised / external elements is approximately 425 tonnes.

Nor is this all: four more Russian modules are awaiting launch to the ISS: the Nauka Multipurpose Laboratory Module (MLM). Delayed since 2007, it is currently slated for a 2021 launch, but this may yet be cancelled as the warranties on several of the module’s system expire in later 2021; the Prichal “docking bell”, primarily intended to provide docking for two further power modules (SPM-1 and SPM-2) and for Soyuz  / Progress docking. Prichal is slated for launch in late 2021, and the two SPM units in 2024.

Further commercial elements are also due to be added  in the form of the Bishop Airlock Module, designed for the launch of cubesats from the station (and awaiting launch before the end of 2020), and the Axiom commercial node, due to be added in 2024.

The 2 decades of ISS operations has seen the amount of equipment deployed in the station increase. This is the console for operating one of the station’s 2 robot arms (located in the US Destiny module) which has become surrounded by a plethora of laptops and monitors that help monitor EVA operations. Credit: NASA

The living spaces on the ISS can support up to 6 crew at a time, although the standard crew complement outside of rotation periods, when two crews are operating side-by-side, has tended to be 3 (even when the shuttle was still operational). With the arrival of the SpaceX Crew Dragon and the Boeing Starliner, crews can now increase to 4-6, depending on requirements.

However, we’re not talking glitzy, hi-tech living. Despite its volume, the ISS is cramped; personal space is limited to a couple of cubic metres (mostly used to hang an astronaut’s sleeping bag), and “free” space has become increasingly overcrowded with the passing years as more and more equipment has been packed into the various modules.

The first Japanese astronaut to work aboard the ISS, Koichi Wakata, attempts to get some sleep during his fifth Expedition crew rotation (Expedition-39), which saw him take command of the ISS in 2014. Credit: NASA / JAXA

The lack of gravity means that almost any surface can be used as a floor, ceiling or wall, depending on a person’s orientation. However, to try to keep a general sense of orientation within the Russian modules, surfaces facing towards Earth are considered “down” and are coloured olive green; surfaces pointing away from Earth are considered “up”, and are painted beige. Perpendicular surfaces between them flow from the one colour to the other as you look “up” or “down”.

Doe to the lack of personal space, almost any “free” space on the structural walls / ceilings / floors of the various modules tend to become the home of personal and other mementos. One area of the Zvezda module, for example, has been turned into a corner for expressions of the Russian orthodox faith, and another a shrine to Russian heroes of space flight and discovery from Tsiolkovsky to Gagarin.

The two most popular areas of the station are the Harmony module, with its communal dining area, which is also used to celebrate birthdays, anniversaries, holidays, etc., and the European Copula, due to its unparalleled views out of its windows. Overall, however, life on the ISS is described as, “noisy, smelly [if your sinuses clear, as they are usually blocked due to the lack of gravity], dirty and awash with everything from human skin and floating globs of sweat [crew are expected to undertake around 2 hours of physical exercise a day] to the pencil you misplaced yesterday and which is now floating around in the air currents between modules,” with the noise being noted as the biggest issue.

The scientific range of the ISS has been, and remains, extensive. Human and life sciences space research includes the effects of long-term space exposure on the human body, testing medical systems and procedures specifically aimed towards supporting long-duration space missions (e.g. to Mars and back), zero-ego production of pharmaceuticals to help with ailments on Earth (the lack of gravity allows compounds to be mixed that would otherwise naturally separate). The broader aspects of life sciences have included the growth of unique protein crystals, and the evolution, development, growth and internal processes of plants and animals.

A second major area of research has been materials science.  This has included the production of unique materials (again made possible due to the lack or gravity) or materials with a greater purity than can be achieved on Earth; energy production and clean energy alternatives. Astronomy and Earth sciences have formed a third leg of ISS science, with the former encompassing wide-ranging stellar and solar studies such as the impact of cosmic rays and the solar wind on out atmosphere, solar observations, research into dark matter, etc. Earth sciences have included climate change studies, monitoring ice melt, global pollution (including world-wide emissions of carbon gases and aerosols, etc.

The fourth aspect of ISS research is education and cultural outreach. This includes teaching and lecturing from orbit, working with Earth-based students by carrying out their experiments, etc. An amateur radio programme gives students from around the world the opportunity to contact the ISS and talk about science, technology, mathematics and engineering with the crew.

Research is split between the various science modules on the station, with some providing unique environments / facilities for specific research fields, others sharing larger research projects. The science programme can additionally be extended or supplemented through equipment and experiments carried up to the ISS via crewed and uncrewed vehicles.

The ISS in 2012: A – Zvezda; B – Zarya; C – Unity; D – Tranquillity; E – Quest; F – Destiny (under truss); G- Harmony; H – Kibō (with external experiments pallet); I – Columbus. Not visible: Rassvet and Leonardo. 1 – Soyuz vehicles; 2 – radiators; 3 – Integrated Truss; 4 – solar arrays. Credit: image – NASA / Roscosmos

Operating the ISS has not been easy.  It is subject to numerous international agreements, has required the involvement of some 17 nations over the years (although Brazil has officially withdrawn from the programme), with 15 nations being original signatories to the ISS Intergovernmental Agreement. A total of 25 individual space agencies and centres around the world have a hand in managing ISS operations from the ground, with Russia and America providing the primary mission control centres and staff. These two countries are also responsible for carrying all crew to / from the station, and for the core missions to keep the station supplied with consumables, fuel, equipment, etc., although Japan also provides re-supply missions as well (as did the Europeans until their Automated Transfer Vehicle (ATV) programme came to an end).

Given the number of nations involved, there have inevitably been tensions from time-to-time, with perhaps the most famous being in 2009, when a disagreement between America and Russia resulted in Russian mission managers banning US personnel from using the toilets in the Russian modules and forbidding their cosmonauts from using toilets in the US modules!

Outside of odd bouts of tension on the ground, the main challenges in operating the ISS tend to be space-based. Several parts of the station are now ageing (the Zvezda module, whilst launched in 2000, was actually built in the 1980s, for example), so maintenance of the station, inside and out, accounts for a significant about of operational time. Stress on the structure as a whole means that there are often minor pressure / atmosphere leaks – which can be exacerbated by impacts with dust and tiny particles of debris, some of which can grow to be quite serious (but not life-threatening).  There’s also the growing risk of collision with large pieces of orbital debris.

However, despite all this, the ISS today continues to be at the forefront of human space research, and can form an essential platform for research into crewed missions to Mars. It is estimated to cost US $7.5 million per crew member per day to operate the station – which, while expensive, is still less than half the anticipated cost set in 2000. Thanks to the US Senate and House finally giving approach, US funding for the station means it can now continue operating through to 2030.

Space Sunday: water on the the Moon; asteroids & comets

Posted on by Inara Pey
The Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint US / German programme, Credit: NASA

Earlier in October, NASA teased the world with news of a special announcement concerning the Moon, using social media to announce the fact … they would be making an announcement on Monday, October 26th.

The announcement of the announcement led to a lot of speculation (and a lot of ribbing at NASA’s expense) with some correctly identifying the fact that the news would have something to do with the Stratospheric Observatory for Infrared Astronomy (SOFIA), the world’s largest flying telescope. This is a joint NASA / DLR (German space agency) venture that flies a German-built 2.5m diameter reflecting telescope aboard a short-bodied 747 SP operated by NASA.

Flying at 12 km above the ground, and so well above the worst of the distorting effect of the Earth’s atmosphere and capable of 10-hour observation sorties, SOFIA is almost as capable as space-based telescopes of a similar nature (having around 85% of the infra-red capability of a similarly-sized space telescope), whilst offering fair easier and lower-priced maintenance, upgrade and general operational costs. In addition, the range of the 747 aircraft means that SOFIA can operate over almost any location on Earth and so be available for almost any observational requirements than fall without the telescope’s capabilities.

The German-built telescope on the Sofia aircraft during flight tests. The “spots” around and on the open telescope bay door are airflow indicators to help with monitoring air passing over the open door. Credit: NASA

When finally made public, the announcement – which was billed as being related to NASA’s current plans to return humans to the Moon, Project Artemis -, proved to be that SOFIA has detected water molecules on the sunlit surfaces of the Moon.

Whilst an important discovery, marking a further increase in the presence of water on the Moon (which we’ve known about since 2009), it is important to offer a measure of context to the discovery: this is about water molecules bound within the regolith (surface material) of the Moon, not actual water ice, as was confirmed in 2018 for many of the permanently shadowed and very cold craters of the Moon’s south polar regions.

In particular, SOFIA detected the infra-red signature for water molecules within the crater Clavius (perhaps most famous for being the location of the lunar administrative base in 2001: A Space Odyssey).  Located in the southern highlands at 58.4°S 14.4°W, Clavius is one of the oldest formations on the lunar surface, believed to have formed some 4 billion years ago; it is some 230 km across and some 3.5 km deep.

Clavius crater as seen via the Johannes Kepler Observatory, Linz, Austria, 2004. North is towards the top of this image. Credit: H. Raab

That water molecules may be widely present in lunar regolith had been long suspected. However, previous estimates as to how much might be present had been hampered by the fact that previous studies could not clear differentiate between the presence of water molecules (H2O) and hydroxyl (OH). During extended observations of Clavius, utilising  a special instrument, the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST), the airborne observatory was able to detect water molecules at around 100 to 400 parts per million in a cubic metre of regolith.

To put this in proportion, this means that SOFIA detected the equivalent of one third of a litre of water trapped in a cubic metre of lunar surface material – which is actually a lot.  If the SoFIA findings hold true for all of the surface material within the sunlit parts of the Moon, it means there a potentially a lot of water to be had;  but whether or not it is actually accessible or have any significant bearing on human activities on the Moon is open to debate. Certainly, it is unlikely to have any significant impact on America’s Project Artemis, despite claims otherwise.

Simply put, the water molecules detected within Clavius are most likely bound in glass beads that resulted from micrometeoroid impacts. As such, it is nowhere near as potentially accessible as the water ice in the south polar region craters, and it is going to need relatively intensive processing in order to be properly extracted and turned into usable water – and the kind of heavy engineering required to achieve this at scale isn’t going to be available for use on the Moon any time soon, and may not even been cost-effective even when it is.

Clavius crater as seen by NASA’s Lunar Reconnaissance Orbiter (launched in 2009 and still operational). Note that is this image, north is at the bottom. Credit: NASA

Nevertheless, the discovery is important for our understanding of the Moon and our longer-term exploration of the lunar surface. It might also mean a new lease of life for SOFIA. whilst not mentioned in the release, NASA had sought to quietly terminate the 10-year-old telescope in 2021, citing it’s “lack of scientific output”.

Continue reading “Space Sunday: water on the the Moon; asteroids & comets” →

Space Sunday: asteroid sampling & starship building

Posted on by Inara Pey
Kissing an asteroid: the sample head of TAGSAM, the sample gathering mechanism on NASA’s OSIRIS-REx makes contact with asteroid Bennu on October 20th, 2020. Credit: NASA

In my previous Space Sunday update, I covered the (then) upcoming attempt by NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) to snag samples of material from the surface of asteroid 101955 Bennu, a carbonaceous near-Earth asteroid.

The attempt was successfully made on Tuesday, October 20th – although just how successful it was did not become apparent until a few days later, when mission engineers realised they now had a slight problem.

The mission required OSIRIS-REx slowly descended from its close-in altitude of 770m, a sample gathering called TAGSAM (Touch-And-Go Sample Acquisition Mechanism) extended beneath it. This was intended to make very brief contact with the surface of Bennu, absorbing the spacecraft’s momentum in springs, and allowing it to fire a nitrogen jet to blast material up from the asteroid some of which would hopefully be caught in the arm’s sampler head, prior to the arm “pushing off” from Bennu once more, allowing OSIRIS-REx to gently back away to a point where it could examine what it has gathered.

OSIRIS-REx: the sample-gathering operation. Credit: NASA

The entire operation was scheduled to take some 4.5 hours from start to back-away and parking. The event was live-streamed, but due to the current distance between Earth and Bennu, those on Earth were witnessing events 18.5 minutes after they had actually occurred. This also meant the entire operation was carried out autonomously, the software controlling it having been previously uploaded to the satellite.

OSIRIS-REx, following Bennu’s rotation about its axis, struck the asteroid a metre one metre away from its intended contact point, which lay within a shallow crater on Bennu that has been christened “Nightingale”. It remained in contact with the surface for 6 seconds – very slightly longer than had been anticipated.

The moment of contact for TAGSAM – and of actually smashing through the surface material on Bennu (film speeded up). Credit: NASA

Whilst there was a camera on the robot arm recording the operation, the footage could not immediately be sent back to Earth. Instead, mission controllers relied on the telemetry OSIRIS-REx did immediately transmit back to Earth. This revealed that everything had apparently gone as planned: TAGSAM made contact, the gas was fired and regolith (surface material blasted upwards. The telemetry then confirmed OSIRSIS-REx was backing away from the asteroid towards the point where analysis of the amount of captured material could be carried out.

This was transcendental. I can’t believe we actually pulled this off. The spacecraft did everything it was supposed to do. Even though we have some work ahead of us to determine the outcome of the event, this was a major accomplishment for the team. I look forward to analysing the data to determine the mass of sample collected.

– OSIRIS-REx Principal Investigator Dante Lauretta

Then came the first of the surprises.  When the video footage captured by the TAGSAM arm camera was received and processed (above right) on October 21st, it revealed that the sample head hadn’t so much touched the surface of Bennu as smashed straight through it to an estimated depth of almost 50 centimetres – and in doing so, had pulverized a rock roughly 20 cm across which, when first viewed in the footage, caused the mission team to worry it might prevent sample gathering and damage the sample head.

The next step in the operation was to analyse the state of the sample head once TAGSAM had been returned to its stowed position against the spacecraft. To do this, one of the star tracker cameras used for navigation was tasked to capture an image of the sample head. When this was returned to Earth, mission staff had a second surprise: the sample head was “leaking” material.

Following the sample gathering operation, a Mylar diaphragm should have rotated over the opening of the sample head to seal any material gathered inside it – but the star tracker camera revealed this had failed to sit correctly, and a small cloud of material was forming around the sample head as it persistently “leaked” out. Given the force of the contact with Bennu, the mission team realised that, rather than just collecting 60 grams of material, the sample head had likely been filled to capacity, preventing the Mylar cover from correctly sealing it.

A small but growing cloud of material gathers around the TAGSAM sample head on OSIRIS-REx following a sample gathering operation that likely overfilled the sample containment area, preventing a Mylar diaphragm (the white semi-circle, visible in the middle of the circular sample head) from sealing the cavity. Credit: NASA

With material slowly but steadily escaping, the decision was been taken to cancel the attempt to estimate the amount of material gathered, and instead move to transferring the sample head to the Sample-Return Capsule (SAC). This is the unit that will return the sample to Earth when OSIRIS-REx return here in 2023. As the SAC is sealable, moving the sample head there as soon as possible – in this case, October 27th – will ensure the remaining material from Bennu is preserved.

In the meantime, and while OSIRIS-REx cannot start on its return to Earth until March 2021, the decision has been made not to return the vehicle to a low-level “hover” orbiting Bennu, but to instead allowing it to continue away from the asteroid at around 44 metres per hour until it reaches a more extended orbital position.

Continue reading “Space Sunday: asteroid sampling & starship building” →

Space Sunday: OSIRSIS-REx: sampling an asteroid

Posted on by Inara Pey
An artist’s impression of NASA’s OSIRIS-REx above the asteroid Bennu,with Earth added in the background for dramatic effect. Credit: NASA Goddard

After a period of delay, NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) is due to attempt the collection of a 60 gram (2.1 oz) sample from the surface of 101955 Bennu, a carbonaceous near-Earth asteroid, on Tuesday, October 20th.

Originally scheduled for August 2020, the attempt to gather the sample requires the space craft to slowly descend to within “touching” distance of the asteroid using a robotic arm. If successful, the sample gathering will open the door for OSISRIS-REx to complete the remainder of its mission before making its way back to Earth where the sample can be analysed.

Launched in September 2016, OSIRIS-REx is one of two such asteroid sample return missions currently in progress, the other being Japan’s Haybusha 2 mission (the original Hayabusha mission also returned samples from an asteroid – but they only amounted to around 1 milligram of material).

Having been launched well ahead of OSIRIS-REx, Hayabusha 2 is actually on its way back to Earth from asteroid 162173 Ryugu, with which it rendezvoused in June 2018. It spent 18 months surveying the asteroid, depositing four micro-rovers on its surface before gathering samples blown off of the asteroid by the force of a kinetic impactor (think bullet), allowing it to collect a mix of surface and sub-surface material. Currently, Hayabusha 2 will deliver its cargo back to Earth during a fly-by on December 6th, 2020, after which it may be tasked with a further sample return mission.

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

OSIRIS-REx reached it’s target, Bennu, at the very end of December 2018 and has spent most of the intervening time studying the asteroid in detail. Both Bennu and Ryugu are of interest to scientists for a number of reasons: they are both part of a class of asteroids that are believed to have been around since the formation of the solar system, and so they could help us learn more about that period.

Both are also in the Apollo asteroid group, meaning they routinely cross Earth’s orbit, and thus present a potential collision risk, and at 1 km diameter for Ryugu and just under 1/2 a km for Bennu, an impact from either would not be a Good Thing for Earth. So, another reason for sampling them is to determine their composition (and by extension, allow us to draw conclusions about the composition of other large Apollo asteroids) that may help make a determination of how to deal with them should that threat of impact become real (in fact, there is a chance that Bennu in particular might impact Earth between 2175 and 2199).

Finally, samples from both might offer clues as to how life-forming materials reached the surface of Earth.

Bennu has proven particularly intriguing for scientists. For one thing, it has proven to be entirely unlike anything that had been anticipated; rather than being relative smooth, with crater pits and sand-like regolith (surface material), Bennu revealed it is a boulder-strewn place with rocks in places comparable to mountains relative to its size, many of them placed so closely together, any attempt to gather samples near them would like result in a loss of the vehicle. This required a more extensive survey to determine potential sample sites, with five initially being identified, before these were narrowed to two, the primary, Nightingale, and a back-up.

This image, captured by OSIRIS-REx shows the Nightingale sample gathering crater surrounded by large boulders. The silhouette of the spacecraft (which is about the size of a van – excluding the solar panels and has a mass of just over 2 tonnes) added for comparison. Credit: NASA Goddard

The asteroid also demonstrated it can emit plumes of material from within itself when in the “warm” part of its 1.2 year orbit around the Sun. However, one of the most surprising discoveries was the identification of six bright boulders on the asteroid’s surface which, when subjected to spectroscopic analysis, revealed themselves to be of the same materials as boulders on Vesta, the second-largest asteroid in the solar system, surveyed by the NASA / ESA Dawn mission.

It’s believed that the presence of these rocks indicates that Bennu started life as part of a larger body – an asteroid or planetesimal – within the asteroid belt beyond Mars, where it was in collision with a fragment of Vesta, depositing material from the latter on its surface. That event, or another similar collision, led to a “catastrophic disruption” within Bennu’s parent, creating Bennu itself and sending it on its way into the inner solar system to be caught in an orbit much closer to the Sun.

The asteroid has also revealed itself to be particularly rich in carbon-bearing material, which can tell us how much water it may have contained (and how much might still be present as sub-surface ice). What is particularly interesting here is that many of the boulders on Bennu contain mineral veins composed of carbonate – which on Earth often precipitates from hydrothermal systems that contain both water and carbon dioxide. Some of these rocks are located around the Nightingale sample  recovery area. The presence of such carbonate strongly suggests that Bennu’s parent body, whether asteroid or small planetary body,was likely hydrothermally active. This has in turn given rise to the prospect that any sample returned by OSIRIS-REx might contain organic material.

Continue reading “Space Sunday: OSIRSIS-REx: sampling an asteroid” →

Space Sunday: flares and flights

Posted on by Inara Pey
Solar flares and coronal mass ejections have the potential to be massively disruptive, but fortunately, the Sun is of a nature that they are unlikely to be directly harmful to life on Earth on their own. Credit: NASA

As I noted a couple of weeks prior to this article (see: Space Sunday: 3D printed rockets; pi for a planet and solar cycles), our Sun is now entering its 25th (in terms of when formal record-keeping began) cycle of activity. Over the next few years it will become increasingly active with sun spot, flares and their associated events, reaching a peak in about 2025/26, before things once again start to settle down in the second half of this 11-year cycle.

Such events have the potential to interfere with modern life on Earth, particularly in disruption electronic and electrical systems, and present a very real radiation threat to astronauts. Fortunately, however, the Sun is mild-aged and so even its wilder outbursts are not now as bad as they could be, and a number of factors have to line up in order for them to directly affect us on this planet (as happened with the Carrington Event of 1859). Which is not to say we’re entirely safe: the Sun could decide to throw a particularly violent tantrum when Earth happens to be in (for us) the wrong place.

Solar activity is important, as it offers insight for the potential for life forming on other worlds. Take M-class red dwarf stars, for example. They are the most populous class of star in the galaxy, and many have been found to harbour planets (the TRAPPIST-1 system being the most famous) some of which occupying the so-called habitable zone around these stars that should make them good candidates for harbouring life.


It has been known for some time that solar flares can impact the atmospheres of exoplanets, as shown in this ESA video. The new study shows they can do much more

However, such is their size, M-class stars can host solar eruptions that can be 10,000 times more violent that the “average” solar event (flare + coronal mass ejection, or CME) experienced by the Sun and because of the convective nature of such small stars, they are more the norm than the exception. As the normal light / heat output from these stars a much lower than the Sun’s, any planets around them must orbit correspondingly close to the star than is the case within our own solar system. This means that they are potentially more prone to being impacted by these massive super flares, up to and including physically ripping away their atmospheres over time, raising the question as to just how this might affect their surface conditions and habitability for life as we know it.

A study of almost 30 of these M-dwarf stars just published in the Astrophysical Journal reveals that overall such super flares extremely limit the potential for anything but the hardiest micro-organism – although their presence early in a star’s life could actually initially help give life on a planet a helping kick-start,

The study used two sources to study the flaring of some 27 M-dwarf stars: NASA’s TESS “planet hunter” satellite, and the Evryscope Telescope array located at the Cerro Tololo Inter-American Observatory in Chile and operated UNC-Chapel Hill, North Carolina, USA. Both the telescope array and TESS were tasked with observing the candidate stars at the same time, allowing any flare activity on them to be simultaneously recorded.

Solar flares can be accompanied by coronal mass ejections (CMEs) that see huge amounts of the sun’s surface ejected into space as plasmas and electro-magnetic radiation that can massively impact planets. In this image, a CME is clearly visible as a disk is used to block out that of the Sun as is it imaged by the ESA / NASA SOHO mission. Credit: ESA / NASA

As a super flare – which could last up to 15 minutes – occurred, measurements were taken every 2 minutes, generating a temperature profile for the flare from start to finish. This revealed a strong, if complicated, correlation between the overall temperature output of a super flare and the amount of deadly ultra-violet radiation it contained. In turn, this allowed the team to conclude that it is extremely likely that planets in close proximity to these stars will receive so much UV radiation, they are unlikely to support the survival all but the hardiest of micro-organism.

The report also notes that in particular, such super flares would likely quickly wreck any protective ozone layer that may form within a planet’s atmosphere, further limiting the development of life – but that conversely, they may initially be required to help impact ozone formation, in order to allow sufficient radiation to reach the surface of a planet in order to power pre-biotic chemistry that in turn may kick-start living processes.

The team behind the study point out that their data is a relatively fine sampling thus far, and more work is needed. They also note that the super flares captured in the study can be classified as “classic” – an event rising to single peak in terms of radiation, temperature, and outburst in a similar manner to our own solar flares – and “complex”: a solar flare that essentially “pulses” with multiple peaks of energy. The cause of these “complex” super flares is unknown, although they appear to be in the majority based on the sample recorded. The fact that they “pulse” with output means that their physical impact on planetary atmospheres is also liable to more complicated than a direct cause / effect correlation seen with “classic” flares.

Even so, the findings open up a new avenue of study for understanding the potential habitability of exoplanets close to M-dwarf stars, and the result have already tended to correlate a 2018 study that suggests the planet found orbiting our nearest stellar neighbour, Proxima Centauri is unlikely to be life-bearing due to it being impacted by similar super flares.

Spaceflight Round-Up

Crew-1 Delayed

NASA Crew-1: Shannon Walker, Victor Glover and Mike Hopkins, and Soichi Noguchi. Credit: NASA

The first operational flight of the SpaceX Crew Dragon to the International space Station has been delayed.

The flight, which will carry a crew of four – NASA astronauts Shannon Walker, Victor Glover and Mike Hopkins, and JAXA astronaut Soichi Noguchi – to the ISS, had been scheduled to lift-off from Kennedy Space Centre on October 31st. However, on October 10th, NASA announced the flight will be held over until at least mid-November.

No formal reason for the delay has been given;  however the scrubbing of a Falcon 9 launch just 2 seconds before lift-off is being seen as a possible cause. That launch, on October 2nd, of a GPS 3 satellite, was aborted due to what Elon Musk, SpaceX CEO described as an “unexpected pressure rise in the turbomachinery gas generator.”  It has yet to be rescheduled.

The first stage units of both that rocket and the one for the Crew-1 flight have never previously flown, so some have theorised the delay to Crew-1 is to give time for SpaceX to evaluate the problem and ensure it is not something endemic to newer Falcon 9 boosters. Certainly, the GPS 3 launch scrub didn’t prevent SpaceX from launching a further batch of its Starlink Internet satellites using a previously-flown Falcon 9 first stage.

Continue reading “Space Sunday: flares and flights” →

Space Sunday: supernovas, weird planets and warnings

Posted on by Inara Pey
The crab nebula: the remnants of a supernova that occurred some 6,500 light years from Earth, and was first recorded by Chinese astronomer in 1054. This is a composite picture made up of 24 images captured by the Hubble Space Telescope in December 1999 and early 2000. Credit: NASA / ESA

Life on our planet faces many threats. Cosmically speaking, the three biggest threats life on Earth faces, are solar flares an coronal mass ejections, Earth-crossing asteroids, and locate supernova events – the violent explosions of stars as they die.

Of these three, Earth-crossing asteroids tend to get the most attention, as they are regarded as the most immediate n terms of potential threat and what we can actually do to actually mitigate that threat if we’re given enough warning. Solar activity is a risk, but fortunately, when even at the peak of its cycle, our middle-aged Sun is rarely viciously violent, and when it does get angry, it’s rare that Earth is directly in the path of an lash-out – although as I noted in my previous Space Sunday article, we have recently come close.

Supernovas are also a mixed bag – we certainly can’t stop them, and if one occurs that is sufficiently violent and close enough to us, then we could be in a spot of bother no matter where we are in our orbit around the Sun. If close enough, supernovas of Type 1a or Type II could go so far as to be extinction level events (ELEs). Fortunately, in order to do so, such a supernova would have to occur in a fairly massive star that’s within a few hundred light years of us – and there are precious few of those. And if if one did explode as a supernova, that are all so far away, we’d see them long before we’d feel the effects.

Take Betelgeuse for example, a star that has caused much speculation among some due to its recent behaviour. Even if we witness the light of its supernova explosion tomorrow, it would be another 100,000 years for the “hard” radiation of the explosion’s cosmic rays to reach us.

But what of smaller stars – white dwarfs – that are also given to going out with a supernova bang? There are a couple on our neighbourhood, but they are nowhere near that stage in their lives, nd by the time they are, we’ll pretty much be beyond the distance from them at which they could do us a mischief.

While supernovae – the violent explosions of certain types of large star at the end of their lives – can leave richly colours clouds of gas and material, like the Veil Nebula seen here, some 2,400 light years away (and some of the earliest of which go on to be the birthplaces of new stars), this is not always the case. Some can leave “bubbles” in interstellar space, regions with very little material in them at all. Credit: NASA / ESA

So, does that mean supernova are not a threat? No; leaving ELEs aside, a local supernova could still trigger long-term havoc with things like the Earth’s climate. In  fact, a new study indirectly points to this possibly being the case around 2-3 million years ago, when the Earth was subjected to the effects of a nearby supernova.

The basic evidence for this comes from concentrations of 60Fe, an iron isotope, found in deep ocean sedimentary rock layers called the ferromanganese crusts. What is significant about this is that 60Fe doesn’t naturally occur here, but is a by-product of supernova events, thus leading some to conclude the remnants of such an explosion once washed over us. However, it has also been pointed out that 60Fe can also be synthesised by AGB stars as they approach the end of their lives without ever going supernova, so it is possible the deposits found on the ocean beds were purely the result of distant interaction with one or more AGB stars far back in the time of Earth’s youth.

Because of this ambiguity, a team from the Technical University of Munich gathered several dozen ferromanganese crust samples from four widely separated  locations on the floor of the Pacific ocean and at depths of between 1.6 km and 5.1 km beneath the ocean surface. They subjected all of these samples to extensive analysis to see if they could find traces of other elements that could be tied to either  a supernova or the output of an AGB star. And they were successful, finding concentrations of the manganese isotope 53Mn. This is significant as this isotope doesn’t naturally occur on Earth, nor is it a product of AGB stars – but it is a product of supernova explosions.

Not a slice of chocolate cake but a slice of a sample of the ferromanganese crust layers drawn from the floor of the Pacific Ocean and shown to contain isotopes that were most likely created by a supernova event.Credit: Dominik Koll / Technical University of Munich

Further, the team’s analysis of both the 53Mn and 60Fe concentrations revealed that both are present in similar amounts and the same ratios throughout all of the samples studied. This suggests that both were present in the Earth’s biosphere at the same time, and were deposited on the ocean floor in  similar quantities over the same period of time, again pointing to them having a common origin in a supernova event. What’s more, because 60Fe has a half-live of 2.6 million years before it decays into nickel, said supernova  could not have occurred more than about 2.5 million years ago.

In addition, the concentrations of both isotopes proved sufficient for the team to estimate the like size of the star the caused the supernova: between 11 and 25 times the size of our Sun. That’s of a sufficient size for the supernova to create what’s as called a “bubble” or “cavity” in space:  a  region that appears to be almost completely  devoid of matter. Interestingly, for the last 7-10 million years, our solar system has been travelling through just such a “bubble”, called the Local Cavity. It is believed to have formed as a result of number of supernova events that occurred between 20 and 10 million years ago – which creates an interesting overlap with the idea of a supernova affecting Earth some 2.5 million years ago.

2.5 million years ago also marks the start of the of Pleistocene period, a time of considerable climate change that saw repeated cycle of ice ages that in turn saw dramatic shifts in the flora and fauna, with multiple mini extinction events, This cycle then repeated in the late Pleistocene through early Holocene (11,700 years ago), and the planet started to warm up again, leading to further cycles of extinction (notably those mammals that had developed to level in the cold, like the woolly mammoth).

What triggered that sudden cooling is unknown, but while the Munich study doesn’t point it it directly, it has been shown that severe interference by cosmic rays can cause dramatic shifts in climate, particularly towards the colder extremes. So again, the time link between that ancient supernova evidenced in the ferromanganese crusts of the seabed  and rise of the ice ages of the Pleistocene is interesting.

Climate change during the early Pleistocene period – possibly the result of atmospheric interference by the supernova – may have given rise to the glaciation periods that occurred throughout that time. These in turn spurred the evolution of species such as the woolly mammoth, the European  Cave Lion and woolly rhino (both to the right of the painting above), all of which became extinction as Earth’s climate once ago changed over the late Pleistocene  and into the Holocene, with some extinctions (such as the mammoth) likely accelerated by over-hunting by primitive humans. Image: painting by Mauricio Antón, “What Killed the Woolly Mammoth?”

Starship SN8 Set for Pressure Tests

The core hull of the SpaceX Starship prototype SN8 was moved to the test stand during the pas week to undergo tank pressure tests. Fitted with the aft aerodynamic flaps that will help the vehicle “skydive” through the atmosphere, but sans the upper section, nose cone and forward aerodynamic surfaces, and currently without motors, the core section was due to undergo a pressure test as this article was being written.

Starship prototype SN8 with aft aerodynamic surfaces in their folded configuration sitting on the test stand at the SpaceX Boca Chica facilities. Its flight to 15 km altitude should take place in the next couple of weeks. Credit: RGV Aerial Photography

This test involves the tanks within the section being filled to operating pressures with inert liquid nitrogen. A hydraulic ram under the stand the exerts pressure on the base of the structure to simulate the stresses the three Raptor engines that power the vehicle will place on the structure in order to verify its fitness for flight.

Should this test be successful, SN8 will have the upper sections added, and its engines mounted. It will then go through further tests, including actual fuelling and a static firing of it motors. Once all these tests have been completed, the vehicle will be ready for its 15 km high “hop”, which is likely to take place before the end of the month.

At the same time as SN8 is undergoing its tests, prototype SN9 is also being readied for its first flight.

Continue reading “Space Sunday: supernovas, weird planets and warnings” →