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.
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.
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.
A time-lapse image of a fuel tank for the Relativity Terran-1 rocket being constructed using 3D printing techniques. Credit: @thesheetztweetz
Not too many years ago, the only organisations that were seen as being able to operate space launch systems were governments, notably the United States, Russia, Japan, China and India, although France has a long track record of launch vehicle development, while nations like the UK have also dipped a toe or two into the waters.
However, over the last 20 years, we’ve seen a major paradigm shift with launcher development that has seen much of it move away from government-sponsored development and purely into private hands (although actual launch contracts awarded by governments can oft help grease the wheels of commerce for these companies).
The most obvious commercial launch vehicle developers have frequently been mentioned in these pages: SpaceX, Blue Origin, United Launch Alliance, Northrop Grumman, and so on (note I’m deliberately avoiding certain names such as Arianespace, because while they are the oldest commercial launch provider in the world, they don’t actually develop the rockets they launch; and the big boys of Boeing and Lockheed Martin, as outside of their involvement in ULA, they are focused on government-funded launch vehicle development).
However, there are many, smaller commercial companies that are involved in launch vehicle development and operation. Two of the more interesting of these are Rocket Lab, which I have mentioned in these pages in the past, and Relativity Space.
Founded in 2006, Rocket Lab is the mini-me SpaceX of small payload launchers. Established by its current CEO, New Zealander Peter Beck, the company originally operated in Auckland, New Zealand, but now is primarily headquartered in the United States as a US company (the New Zealand arm being a wholly owned subsidiary).
The Electron rocket with Rocket Labs’ CEO, New Zealander Peter Beck
Rocket Lab operates the Electron Rocket, flying commercial payloads of up to 300 kg to low Earth orbit (LEO) or up to 200 kg to a sun synchronous orbit (SSO). A two-stage vehicle, Electron uses the electric pump-fed Rutherford rocket motor in both stages, making it the first launch system to use an electric pump system to deliver fuel to the engines.
Currently an expendable launch system, Rocket Lab plan to follow in the footsteps of SpaceX and make the first stage of Electron reusable, although they will not be using a propulsive landing system like SpaceX, but will use parachutes / a parafoil. In addition, the company plans to start providing customers with an optional third stage for the vehicle that can provide a “kick” to motor payloads can use to circularise their orbits.
Up until the time of writing, the company has only launched out of a purpose-built facility on the Mahia Peninsula on New Zealand’s North Island, where it has a 30-year licence to launch rockets every 72 hours. To help with this, the facility offers two launch pad complexes; however, the real ability to meet such a high rate of launches (assuming Rocket Lab grows the customer list it needs to warrant such a fast launch rate) is in the rocket fabrication and assembly process.
The extensive use of composites in the fabrication of both the Electron rocket and its motors means that Rocket Lab can fabricate and assemble a launch vehicle every seven days. Credit: Rocket Lab
Thanks to the high use of composite throughout the Electron and its motors which accounts for around 95% of parts in both, Rocket Lab has been able to develop a fully automated and very flexible fabrication facility that can produce all the composite parts for the single launch vehicle in just 12 hours. This in turn allows the company to assemble and test a new rocket every seven days.
Starting in 2020 – and potentially in the next couple of weeks – Rocket Lab will commence launch operations from the Mid-Atlantic Regional Spaceport, Wallops Island, Virginia, USA (located at the southern end of NASA’s Wallops Flight Facility). Should it go ahead, the UK’s proposed Sutherland Spaceport, Scotland, may also become a base of operations for Rocket Lab, offering launches alongside the UK’s Orbex, a company a small-scale, reusable launcher capable of delivering up to 150 kg to a 500 km SSO.
Through the long grass – an Electron Rocket undergoing static tests at Rocket Lab’s new launch facilities at the Mid-Atlantic Regional Spaceport, Wallops Island, Virginia, USA. Credit: Rocket Lab
As well as the commercial launch capabilities, Rocket Lab has also been developing its own satellite system – Photon – which the company has indicated could also be used as a carrier vehicle for small interplanetary science missions.
In this, CEO Peter Beck has long been a proponent of exploring Venus, and has been contemplating sending a small mission that planet for the last two years – something he believes Rocket Lab could achieve for as little as US $30 million, utilising Electron as the launcher and Photon as the ferry vehicle, delivering a small science probe massing around 37 kg to Venus. With the discovery of phosphine in the planet’s atmosphere (see Space Sunday: phosphine on Venus, test flights and Jupiter), Beck has indicated Rocket Lab may well accelerate these plans.
Rocket Lab has also developed is own satellite – Photon – which it is considering as the carrier for a small science mission to Venus in the wake of the discovery of phosphine in the planet’s atmosphere. Credit: Rocket Lab
Venus, the second planet out from the Sun and roughly the same size of Earth, is well known for being the prime example of a runaway greenhouse effect. Shrouded in dense, toxic clouds that hide its barren surface from view, the planet has an average surface temperature 464°C, its dense, carbon-dioxide dominant (96%) atmosphere places an average pressure on that surface around 92 times the mean pressure at sea level here on Earth – or roughly the same pressure as exerted by the sea at a depth of 900 metres (3,000 ft).
Yet, as I’ve recently reported (see: Space Sunday: Venus’ transformation, SLS and an asteroid), there is evidence to suggest that Venus started life as a warm, wet planet with liquid water seas of its own, only to be started on the road to becoming the hothouse we know today thanks to Jupiter’s wandering influence.
However, if this theory is correct, and Venus was once warm and wet, the question of whether it was sufficiently so to give rise to the earliest forms of basic life becomes a very real one – as does what might have happened to that life as the planet started its long transformation in the superheated, super pressurised world we see today.
Did the changing conditions simply wipe out any microbes that may have arisen there, or did those microbes themselves have been transformed, moving to the upper reaches of the Venusian atmosphere where they could survive on the heat from both the Sun and rising from through the planet’s atmosphere without necessarily being dry roasted, while drawing on the minerals and chemicals also floating within the high-altitude clouds?
The idea of entirely atmosphere-borne forms of life on planets like Venus and Jupiter is not new, but this past week, the potential for some form of organic activity on Venus became a lot more real with the detection of a compound this is usually the off-shoot of organic processes within the mid-levels of the Venusian cloud layers.
Phosphine is a colourless, flammable, very toxic gas compound made up of one phosphorus and three hydrogen atoms (PH₃). It is most commonly produced by organic life forms, thus its presence within the atmosphere of Venus raises the tantalizing possibility that something is alive in that atmosphere – although it should be noted, it can also be created artificially.
The detection of phosphine in Venus’ atmosphere was made by an international team using two different telescopes in different parts of the world. The team, led by astronomers working out of Cardiff University in the UK, first identified the compound using the James Clark Maxwell Telescope (JMCT), located in Hawaii. They then turned to the Atacama Large Millimetre/sub millimetre Array (ALMA) in Chile, equipped with more sensitive detectors than JCMT, to confirm their findings.
The James Clark Maxwell telescope, Hawaii. Credit: Will Montgomerie/EAO/JCMT
It’s important to note that while the phosphine has been identified, the team responsible for identifying it are not jumping to the conclusion it means there is life within the Venusian atmosphere. While – in our experience – it is generally the result of organic interactions, it can be produced in the laboratory, as noted, through chemical interactions – and Venus is a veritable chemical hothouse.
What is surprising is the amount of phosphine calculated to be in the cloud layer: roughly 20 parts per billion. While a comparatively tiny amount, it is astonishing to planetary astronomers because it’s long been assumed that if any phosphorus existed in Venus’ atmosphere, it would long ago have bonded with oxygen atoms, of which there are a lot around Venus, albeit the majority being bound within the dominant carbon dioxide.
Following their discovery the team, led by Jane Greaves of Cardiff University and ideo Sagawa at Kyoto Sangyo University, Japan, sought potentially natural means for the formation of phosphine around Venus. These included things such as chemical reactions in the atmosphere driven by strong sunlight or lightning, or the interaction of chemicals coming from volcanic activity, or delivered by meteorites. However, none of these mechanisms could account for the volume of phosphine Venus appears to have.
Even so, this doesn’t necessarily mean that the phosphine is the result of tiny Venuisan organisms; as the team note, it could be the result of as yet unknown photochemistry or geochemistry mechanisms within the planet’s atmosphere or the planet itself.
Although we concluded that known chemical processes cannot produce enough phosphine, there remains the possibility that some hitherto unknown abiotic process exists on Venus. We have a lot of homework to do before reaching an exotic conclusion, including re-observation of Venus to verify the present result itself.
– Study member Ideo Sagawa
Obviously, to determine whether or not biotic or abiotic processes are responsible for the phosphine, further study – preferably close-up – of Venus’ atmosphere is required. Although further Earth-based observations from Earth can help confirm the volume of phosphine within the planet’s atmosphere, satellites orbiting Venus will offer a far more complete picture, simply because they can study the planet in detail over the course of years, building up a complete picture of its composition using spectrographic analysis.
Two Venus missions – VERITAS, the Venus Emissivity, Radio Science, InSAR, Topography, And Spectroscopy orbit and DAVINCI+, an atmospheric penetrator, are already being considered by NASA as planetary missions among missions to other destinations, with one of this group of proposals due to be selected in April 2021. Either could help sniff out the phosphine and potentially help identify its cause. Japan’s Akatsuki orbiter may also help in further studies of phosphine around Venus.
The private company Rocket Lab has been developing plans to mount its own mission to Venus for some time, using their Electron rocket, which has been operating since 2018, and their new Photon upper stage, which made its début in august 2020. Rocket Lab founder and CEO Peter Beck believes that Venus has been undervalued as a place for stud (although there have been some 30 fly, orbital and lander missions since 1962).
Courtesy of the Ivan Allen College of Liberal Arts, Georgia Tech
The Moon and Mars are very different places, but for the last 40 years, the idea of sending humans to Mars has been tied very closely to the idea of a return to the Moon. However, whether this point of view has helped or hindered either a return to the Moon with a human presence or the goal of sending humans to Mars is highly debatable.
In 1989, for example, NASA was challenged to develop a plan to get humans back to the Moon and then on to Mars. Much was made of the idea that the former was necessary because it would ultimately make the means to reach the latter easier and cheaper; however, the blueprint NASA eventually proposed for achieving both a return to the Moon and the onwards exploration of Mars – called the Space Exploration Initiative – required a 30-year time frame to complete and a bill of US $450 billion – or more in comparable terms, than the United States spent on World War 2. Result: any idea of going to the Moon or Mars was quietly pushed aside in favour of just building the International Space Station.
Much of this plan cited the idea that the Moon could be used to form a “cheaper” launch venue for reaching Mars and elsewhere in the solar system, with materials gathered from the surface of the Moon making it “cheaper” to build and test the required hardware needed to reach Mars, whilst the lunar environment could offer the means of testing technologies needed in the attempt to reach Mars such as landing systems, use of local resources. Similar claims were made in the early 2000s with NASA’s Vision for Space Exploration, which similarly ended up pushed to one side on the grounds and time frame.
In actual fact, when things like the amount of energy required to launch humans to the Moon and to launch them to Mars, there is actually very little difference – in fact, when you take into consideration the energy needed to slow a mission into lunar orbit, the energy needed to land it on the Moon, and the energy to re-launch from the Moon to reach Mars, and going to Mars via the Moon actually becomes more expensive in terms of your energy budget – particularly when you consider that regardless of whether they go directly to Mars or via the Moon, all crews will commence their mission directly from Earth. And when you add in all the costs and complexities involved in developing a lunar launch capability – fabrication facilities for vehicle production, development of fuel depots and so on – then the bill for going to Mars via the Moon starts to outstrip the bill for going to Mars directly from Earth.
This point was pretty much demonstrated in the 1990s by aerospace engineers Robert Zubrin and David Baker. Following that US $450 billion bill, they looked at how humans to realistically and cost-effectively be taken to Mars and back safely. Their work resulted in the Mars Direct mission proposal which, in 1996, would have cost around US $10 billion for the first mission and then $1 billion per mission thereafter, with two launches taking place every 2 years.
One of the unique aspects of Mars Direct was the idea of sending the Earth Return Vehicle (ERV) to Mars 2 years ahead of the crew, with the crew following in the “hab” – a combined spacecraft and home. Credit: Mars Society UK
While there were issues with the Mars Direct proposal (for example: the small number of crew – just 4 people – in the original profile, and a certain cavalier attitude towards cosmic radiation exposure), it offered a “lifeboat” option for getting a crew back to Earth, and it held up to scrutiny as a practical means to reaching Mars within a 10-12 year development cycle. So much so, in fact, that it became the basis for a generation of NASA Mars mission proposals (the Design Reference Missions), and former NASA Administrator Michael Griffin pushed the agency into starting work on the development of the Ares launch vehicles identified as being required for the Mars Direct proposal, under what became known as the Constellation programme (although ultimately, Constellation was cancelled after just one flight of an Ares 1 booster to make way for the Space Launch System).
In terms of technology development, the Moon is also of questionable benefit in terms of missions to Mars. Much has been made of testing landing systems for use on Mars through missions to the Moon, but the fact is, such tests are of limited value: the Moon has little practical atmosphere, ergo, there’s no means to test atmospheric entry systems. A lunar landing also requires an entirely propulsive means of slowing a vehicle and bringing it to a safe landing. However, the tenuous Martian atmosphere allows for aerobraking as both the demands of atmospheric entry and immediately afterwards. It also allows the use of a certain degree of aerodynamic flight capabilities and – potentially and depending on the mass of the landing vehicle – the use of parachute braking systems in addition to propulsive means of slowing and landing.
The atmosphere of Mars readily lends itself to ISRU – in-situ resource utilisation, than allows a 19th century process, the Sabatier Reaction, to generate water, methane and oxygen, using just a small amount of hydrogen feedstock carried to Mars by the ERV. Credit: Orange Dot Productions / Inara Pey
Similarly, while there is plenty of scope for in-situ resource utilisation on both the Moon and Mars – the production of fuel stocks, air and water, for example – the fact that Mars has an atmosphere that can be used in the production of these elements, whilst on the Moon they must be obtained through processing the regolith, again means the respective technologies needed for doing so on Mars are very different to those needed on the Moon.
So does this mean the idea of using the Moon as a proving ground for going to Mars is a complete misnomer? Not entirely. There are opportunities for testing technologies and procedures that will be required on Mars through a human presence on the Moon – but they do need to be put into perspective. And this is pretty much the findings that have come out of the annual Humans to Mars summit organised by Explore Mars and held virtually at the start of September 2020.
In particular, the summit noted that currently, we only have two data points for human activities in gravity environments: hear on Earth, and the micro gravity environment of Earth orbit. Therefore, even though the Moon’s gravity is half that of Mars, it would still provide a vital data point on things like muscle atrophy and bone calcification, cardiovascular impact, etc., allowing scientists gain greater information on how the human body adapts to a range of gravity environments over extended periods.
Also, things like basic rover systems for use on Mars could be practically tested on the Moon, because when all is said and down, engineers estimate that the requirements for a pressurised rover vehicle intended for use on Mars are around 70-80% the same as those for a pressurised rover intended for use on the Moon. The Moon also offers the potential for testing automated systems that could play a significant role on Mars: such and guidance systems for landings, self-deploying base stations, etc.
Pressurised rovers designed for use on Mars have much in common with similar vehicles intended for use on the Moon. Therefore, it makes sense for technologies for the former be tested / employed on the latter – something that also helps lower development and operating costs. Image credit: JAXA / Toyota
Crew activities could also benefit from lunar operations – although here, caution should again be exercised. For example, the summit identified the use of the Lunar Orbital Platform-Gateway (LOP-G) as a means of simulating transit flights to / from Mars to study the physical / psychological / practical challenges of 6-7 month transit times – but frankly, work like this could be carried out just as effectively from Earth orbit. However, options for providing greater protection against cosmic and solar radiation could benefit enormously from lunar-based testing.
Overall, the idea of integrating lunar and Mars mission requirements – where there are natural and genuine cross-overs – could ultimately assist humanity’s move from going back to the Moon to moving onwards to Mars than might be the case in viewing them as separate goals. But in order for this to work, how using the Moon to genuinely assist in undertaking human mission to Mars needs to be clearly understood and stated. The report from the Humans to Mars summit, although it does contain one or two questionable assertions, is nevertheless a positive step towards doing so.
NEOs: One Reason Why Amateur Astronomers are Important
There’s been a lot of late about near-Earth objects (NEOs) – asteroid that can come close to Earth in their orbits and so present a risk of striking Earth at some point. For example, on August 31st, I wrote about this over-excitement around 2018 VP₁ despite the fact it can never present a significant threat (see Space Sunday: Venus’ transformation, SLS and an asteroid).
However, on September 10th, 2020, a much larger asteroid crossed Earth’s orbit, and served as a reminder that there are sizeable bodies out there we have yet to find and which could represent a serious threat – and the importance of amateur astronomers in finding them.
2020 QU6, measuring roughly a kilometre across, passed by Earth at a distance of 40 million kilometres. That’s far enough away for it not to be classified as a near miss, although its orbit is still being assessed to see if it might become a future threat. Certainly, given its size, 2020 QU6 is substantial enough to cause a massive level of devastation were it to make contact. However, what is of key interest here is that, just two weeks prior to its passage past the Earth it was entirely unknown.
The negative image in which Leonardo Amaral identified NEO 2020 QU6. Credit: Leonardo Amaral
Despite its size, 2020 QU6 was not stopped until August 27th, 2020, when amateur astronomer Leonardo Amaral, working at the Campo dos Amarais observatory in Brazil, observed it for the first time. A keen asteroid hunter,Leonard identified the asteroid using equipment he had obtained via a 2019 grant from the Planetary Society that allowed him to significantly upgrade his equipment. In this, he is part of a global network of amateur astronomers the Planetary Society support in the work hunting down asteroids that might pose a threat to Earth.
Thus, his discovery of 2020 QU6 both underlines the importance of amateur astronomers in the finding and tracking of NEOs – particularly given that the major space agencies believe they’ve thus far only identified around 90% of large NEOs that pose a very significant threat to Earth should they collide with us. Leonardo’s work also highlights the importance of amateur astronomers operating in the southern hemisphere, where the larger agencies carrying out similar work don’t have such a pronounced presence as they do in the northern hemisphere., so there is a greater reliance on professional and amateur astronomers. This in a particularly valid point to remember, because knowing there could still be several hundred objects of 1 km or larger routinely crossing the orbit of Earth that we’re completely unaware of is a little unsettling.
Inara Pey: Living in a Modemworld 