Category: Space Sunday

July 1^st, 2023 saw the launch of a new space telescope – the European Space Agency’s (ESA’s) Euclid – on one of the most intriguing space missions yet started.

Classified as a M(edium)-class mission within ESA’s Cosmic Vision campaign, Euclid was originally to have been launched via Russian Soyuz ST-B; however, following Russia’s invasion of Ukraine, ESA ended all partnerships with Roscosmos, the Russian space agency, and the mission was  – with NASA’s assistance – shifted to using a SpaceX Falcon 9 rocket launching out of NASA’s Kennedy Space Centre (KSC), Florida.

Following a flawless launch from Pad 39A, KSC at 15:12 UTC, the booster lifted the observatory to orbit, the second stage of the rocket successfully sending it on its way towards the Earth-Sun L₂ Lagrange point, with the telescope will commence observations, in a 30-day gentle transit. Along the way, the instruments and systems on the spacecraft will be powered-up and go through check-out procedures so as to be ready for commissioning as the craft arrives at the  L₂ position.

For those unfamiliar with the term, the  L₂ position is one of five points of equilibrium for small-mass objects under the gravitational influence of two massive orbiting bodies (points where the gravitational influences of the larger bodies effectively “cancel one another out”). Also known as libration points, they are: the L₁ position sitting between both bodies, but nearer the smaller than the larger; L₂, located on the opposite side of the smaller body relative to the larger; L₃, located on the opposite side of the larger body relative to the smaller; and L₄ leading the smaller of the two in it orbit around the larger, and L₅ trailing.

Those familiar with the Lagrange points will likely recognise the L₂ position as being the focal point for the James Web Space Telescope (JWST) in its journey around the Sun. On arrival, Euclid will enter a similar 1-million km wide elliptical orbit around the L₂ position in a manner which will prevent it ever falling into Earth’s shadow. once in place, the 1.4 billion Euro spacecraft will spend a nominal 6 years within this orbit using a combination of a visible light camera and a near-infrared spectrometer/photometer in an attempt to gain a better understanding of dark energy and dark matter.

Sometimes (often in bad science-fiction) conflated as the same thing, dark matter and dark energy are two different entities. In simple terms, dark matter is a hypothetical form of matter with a physical mass, and thought to account for the so-called “missing mass” of the universe (some 85% of its expected mass). The “dark” of the name refers to the fact that it does not absorb, reflect, or emit electromagnetic radiation, making it extremely difficult to defect. However, various gravitational effects which can be observed can only take place if there is more matter involved than can be detected – thus implying dark matter’s existence.

Dark energy, however, is an unknown form of energy which was first suggested in 2011. Up until that point, it had been believed that the expansion of the universe – the result of the big bang – was slowing imperceptibly down through the aeons, the result of the gravitational mass of the billions of galaxies within it gradually overcoming the momentum imparted to them by the big bang. However, careful analysis of the measurement of numerous supernovae suggest that the expansion of the universe is actually accelerating – which could only be due to some unknown force acting on all the galaxies. Thus, the concept of dark (again meaning hard / impossible to directly detect) energy was born, a force potentially responsible for as much as 68% of the total energy contained with in the present-day observable universe.

To try to better pin down both dark matter and dark energy, Euclid will use its instruments to chart some 2 billion galaxies across one third of the night sky relative to Earth, capturing light that has taken up to 10 billion of the universe’s 13.8 billion-year lifespan to reach us. In doing so, it will measure their shape and the degree of red shift evident, whilst also using the effects of gravitational lensing on some to reveal more data about them. From this, it is hoped that astrophysicists might be able to construct a model to explain how the universe is expanding which might both explain the nature and force of dark energy and potentially offer clues as to the actual nature of dark matter – the mass of which must be having some impact on dark energy as it pushes a the galaxies.

However, this is going to take time; from the start of operations in a couple of months, it will take the Euclid team 2 years to gather sufficient data  which can start to be meaningfully analysed. After that, it will take four years of gather additional data which might be used to refine and improve the initial analyses, and offer up at least some answers.

Urine is a Key to Mars

If humans are to travel to and from Mars, there are a number of issues which need to be addressed, among them the issue of drinking water for the 6-9 month trips to / from Mars (assuming the use of chemical propulsion).

One of these is how to supply the crew with water. NASA state that trained astronauts required 4.4 litres of water per day for drinking, food preparation, hygiene and cleaning. For a crew of four going to Mars that’s between 3.16 and 4.75 tonnes of payload mass alone (+ reserves for emergencies on top of that). While that mass might also be used to supplement a vehicle’s radiation shielding, the fact remains that carrying large amounts of water is just so much deadweight compared to other, more efficient means of providing radiation protection (such as Kevlar and high density polyethylene, or HDPE). To make water efficient, it needs to be recycled.

This is already the case on the International Space Station (ISS). As a part of the Environmental Control and Life Support System (ECLSS), the US / International element of the ISS has long been able to supply recycle water back into usable drinking water (the Russian segments of the station rely more heavily on resupply from Earth for water, as the Russian saw this as the easier solution to developing efficient and space-taking recycling systems).

Within the US ECLSS are two water recycling systems – the primary Water Purification Assembly (WPA), which literally plucks water out of the station’s atmosphere in the form of condensate, sweat, exhale water molecules, water drops escaping during food processing and other acts, and water used for hygiene, and the Urine Processor Assembly, a subset of the WPA, which does exactly was that name suggests.

However, both systems have always been limited in their efficiency (the UPA to just 85% of all urine being recycled to a state where it is properly purified water). But over the last several years, various improvements have been made to the systems, raising their overall efficiency to 93.5%. In particular, urine recycling efficiency was raised to 87% through improvements in 2019/2020 and by cycling the semi-clean water through the primary WPA system to produce purified water suitable for drinking. However, a sticking point remained urine brine – a mix of water and body chemicals which could not be put through the WPA, but was simply tanked and disposed of.

Now water can even be extracted from that brine for recycling, thanks to a new addition to the ECLSS recently installed on the ISS and which has been undergoing evaluation. Called the Brine Processor Assembly (BPA), it is a combination of filter membranes and a heating system. The former traps the chemicals in the brine whilst allowing the water through. The water is then heated by the elements in the unit, forming a humid air flow which is then fed to the WPA, where the water is extracted alongside that gathered from other humid air captured by the WPA, and purified for re-use.

The result: up to 98% of all water consumed or used on the international segments of the ISS can now be recycled – an additional 4.5% compared to pre-BPA amounts. This is significant because NASA has always seen a 98% water recycling capability as a break-point for long duration space operations. It doesn’t eliminate the need for some measure of reserve supplies – but it drastically reduces the additional mass of water that might otherwise need to be carried, bringing the potential for crewed missions to Mars a little step closer to being practical.

Continue reading “Space Sunday: a “dark” mission, recycling water and a round-up” →

Even as Europe’s Jupiter Icy Moons Explorer (Juice) is commencing its long trek to the Jovian system in order to study Ganymede, Callisto, and Europa, three of Jupiter’s Galilean moons, more is being learned about Europa and its far more distant “cousin”, Enceladus, as the latter orbits Saturn.

In the case of Europa, the findings of a new study suggest that it may have formed somewhat differently than has long been thought, and that it may actually be less subject to deep heating and volcanism that has been thought – potentially decreasing the chances for it to harbour subsurface oceans and possible life.

As has been mentioned numerous times in this column, Europa is of fascination because it is covered in an icy shell which appears to cover a liquid water ocean, churning over a rocky mantle and kept liquid due to a combination of internal heat radiating out from the Moon’s molten core and the gravitational “push/pull” inflicted on it by both Jupiter and other three Galilean moons, which give rise to heating through subsea volcanism and hydrothermal vents (which might also pump the ocean full of biologically useful molecules).

However, Kevin Trinh, a planetary scientist at Arizona State University (ASU), and his follow researchers suggest that Europa may have formed a lot slower than previously assumed, and somewhat differently to how it is generally assumed planets and small moons form, and that even now, it may not have a fully-formed core – possibly a result of its distance from the Sun.

The accepted theory for the formation of solid planets and moons is that as they coalesced out of ice, dirty, rocks, etc., and were compressed under increasing gravity – assisted by the Sun’s heat – underwent melting, the heavier filling into the centre of the planet / moon to form the core, with the “middleweight” rocks forming a semi-liquid, hot mantle, and the outermost becoming the brittle crust.

But given its size and distance from the Sun, Europa may never have reached the stage of the heaviest elements separating out of its mantle to for the core – or that it is still going through the process, but at a much slower rate and assisted by the gravitational flexing imposed on it by the other large Jovian moons and Jupiter itself.

This doesn’t mean the moon doesn’t have an ocean – Trinh and his colleagues believe the evidence for the ocean is too great to deny –, but rather its formation was different to previously thought, and may have been the result of a metamorphic process, which continues to power it today. In short, the rocks of the mantle were naturally hydrated (that is, contain water and oxygen), as the interior heat increased, it caused the water and oxygen to be released, forming the ocean and its icy shell.

For most worlds in the solar system we tend to think of their internal structure as being set shortly after they finish forming. This work is very exciting because it reframes Europa as a world whose interior has been slowly evolving over its whole lifetime. This opens doors for future research to understand how these changes might be observed in the Europa we see today.

– Carver Bierson, ASU’s School Of Earth and Space Exploration.

Just how far along the formation of a core might be, assuming this ASU study is correct, is an unknown. The study suggests that the core started to form billions of years after Europa’s formation, and that full differentiation has yet to occur.

If the theory is correct, it has some significant implications for Europa as a possible abode of life. As noted above, the traditional view is that the moon has had a hot, molten core which could, thanks to the gravitational flexing by Jupiter and the other large Jovian moons, power subsea volcanism and venting sufficient to create hotspots of life in the ocean depths. Without such a fully-formed core, however, it is unlikely that such is the case. But this does not mean that Europa is necessarily lifeless.

It could be that the heat within the rocky mantle – again driven by gravitational flexing – could lead to a more uniform heating of the sea floor, allowing for life to be more widespread around Europa and feeding on the minerals and chemicals released by the hydration process.  However, the flipside to this is that such heating could equally leave much – if not all – of the ocean little more than an icy slush, either limiting any life to a very narrow band of heated water very close to the sea floor, or frozen out in the slush.

In the meantime, while Enceladus is even further from the Sun and a lot smaller than Europa – but the evidence for it having a subsurface ocean is more compelling. The southern polar area has long been subject to out gassing material into space – material which is known to be contributing to the growth of Saturn’s E-ring.

The out gassing was first imaged by NASA’s Voyager 2 vehicle in the 1980s and again by the joint European-NASA Cassini mission, which saw the Cassini spacecraft actually pass through some of the plume of material several times, confirming the presence of water vapour and other minerals, all of which are almost contributing to the tiny moon having a very tenuous atmosphere.

Data on the plumes gathered by Cassini have been the subject of extensive studies since they were gathered, revealing that do contain very simple organic molecules and even molecular hydrogen and silica. All of this indicates that chemical reactions between water and warm rock are occurring on the seafloor under Enceladus’ ocean, most likely around hydrothermal vents.

For the last 5 years, a team of scientists at Freie Universität Berlin, have been studying data from a number of sources – Cassini and Earth-based observations – relating to the materials found within Saturn’s E-ring, which, as noted, is at least in part made up of material ejected from Enceladus in an attempt to both better understand the composition of the ring and its relationship with material coming from the moon. What they’ve found has come as a surprise to many planetary scientists: phosphorus.

The importance here is that phosphorus is the rarest of six elements which life here on Earth utilises in various forms – such as combining it with sugars to form a skeleton to DNA molecules and also helps repair and maintain cell membranes. What’s more, the concentrations of the mineral within the plumes are about 500 times greater than the highest known concentrations in Earth’s oceans. While the phosphorus has been detected within Saturn’s E-ring rather than within the plumes rising from Enceladus, its discovery nevertheless is seen as offering “the strictest requirement of habitability” within the moon’s ocean, given that Enceladus is blasting material into the E-ring at the rate of 360 litres per second.

A 2018 study involving Enceladus’s ocean and the likely minerals in might contain had drawn the conclusion that any phosphorus concentrations on the moon would have been depleted in the moon’s oceans a long time ago, and thus unavailable for potential life. However, in reviewing the new findings, the team behind the 2018 study have stated their findings have now been overturned.

In particular, the Freie team also identified the presence of  orthophosphate within the phosphates of the E-ring. This is the only form of phosphorus that living organisms can absorb and use as a source of growth. This suggests that not only are phosphates “readily available” in Enceladus’ oceans, it is in forms simple life can make use off to help in its development. Coupled with the fact that the oceans of Enceladus are likely warm and rich in a broad range of minerals and chemical elements, further raises the potential for the moon to harbour microbial life. This had already led to renewed calls for a dedicated mission to the little moon for a more direct investigation.

Continue reading “Space Sunday: of Earth and moons” →