Space Sunday: life’s building blocks, black holes and moles

A dramatic plume sprays water ice and vapour from the south polar region of Saturn’s moon Enceladus. It’s known that these plumes contain organic material, and now have been shown to contain the possible precursors to the building block of life. Credit: NASA/JPL / Space Science Institute

Saturn’s moon Enceladus is one of several icy worlds within the solar system that likely harbour a vast ocean beneath its icy crust. We know this because the Cassini mission spotted geysers of vapour bursting out from its south polar region. Following daring passes through these plumes, rising hundreds of kilometres from Enceladus, the spacecraft was able to obtain samples that confirmed they comprised water vapour.

As I’ve noted in past Space Sunday articles, it is believed the vapour originates from a vast ocean under the moon’s ice, and that this ocean is kept liquid as a result of Enceladus being constantly “flexed” by the gravities of Saturn and its other moons, flexing that both causes the ridges and fractures seen on Enceladus’s surface and generates frictional heat deep within the Moon’s core. These heat could both keep the subsurface ocean liquid and also cause hydrothermal vents on the ocean floor. Such vents on Earth are sources of chemical energy and elements such as carbon, nitrogen, hydrogen and oxygen – the essential building blocks of life, and it has been suggested this could be the same on Enceladus.

An artist’s impression of the interior of Enceladus, showing the rocky core, ocean and icy crust. The geysers imaged by Cassini in the moon’s southern hemisphere are also show. Credit: NASA/JPL

2018, an international team based in Germany studying the data gathered by Cassini found the geyser plumes contained a range of organics. Now, as revealed in the October issue of The Monthly Notices of the Royal Astronomical Society. that same team have taken their studies further, finding evidence of organic compounds that could be the precursors to the actual building blocks of life. What’s more, these compounds are condensed within icy grains containing oxygen and nitrogen that are ejected any the geysers. On Earth, similar combinations of these compounds take part in the chemical reactions that form amino acids, core essential building blocks for life as we know it.

More excitingly, these reactions could be driven by the heat generated by hydrothermal vents, and on Earth, the oldest fossilised lifeforms have been found around such vents on the ocean floor, leading to the theory that they are the places where life first emerged on the planet.

If the conditions are right, these molecules coming from the deep ocean of Enceladus could be on the same reaction pathway as we see here on Earth. We don’t yet know if amino acids are needed for life beyond Earth, but finding the molecules that form amino acids is an important piece of the puzzle.

– Nozair Khawaja,  study, lead Free University of Berlin

In this illustration, you can see the organic compounds combining with the icy grains in the plumes emitted by Enceladus. Credit: NASA/JPL

Here we are finding smaller and soluble organic building blocks — potential precursors for amino acids and other ingredients required for life on Earth.

– Jon Hillier, study co-author.

That these basic compounds have been found in material released by Enceladus does not automatically mean that life is forming in its deep ocean, but their discovery does point to the potential of amino acids being formed beyond Earth, which could have significant import with regard to the search for life in the universe.

Currently – and as I’ve again reported – both NASA and ESA are planning mission to Jupiter’s moon Europa, another moon with the potential of having a warm, liquid water ocean under its mantle of ice. These discoveries with Enceladus point to it also being worthy of further and detailed study. NASA has mulled such a mission in 2015 and 2017 – the Enceladus Life Finder (ELF) – but it has yet to receive funding.

ELF is designed to orbit Saturn and make repeated passes through the geyser plumes of Enceladus in order to locate any biosignatures and biomolecules that might be present in the vapours. It is also intended to measure amino acids, and analyse fatty acids or methane (CH4) that may be within the plumes found in the plumes and that might be produced by living organisms.  These latest result may cause NASA to give the mission further consideration.

Could “Planet Nine” Actually be a Black Hole?

Planet Nine, the mysterious, yet-to-be-discovered world thought to be orbiting far out in the hinterlands of the solar system, and potentially responsible for the odd orbits of a number of bodies in the Kuiper Belt, is something I’ve written about numerous times in this column.

In my last piece on the subject, I noted a paper that suggested that gravity created by a large disc of dust and icy material orbiting well beyond the Sun might be largely responsible for the odd orbits of these trans-Neptunian Objects (TNOs). Now another paper suggests that if it is gravity responsible, it could actually be due to a black hole lurking on the fringes of the solar system.

Computer modelling showing how a possible large planetary body (“Planet Nine”, also “Planet X” and other names) could account for the eccentric orbits of several TNOs. Now a new paper suggests an ancient black hole might be responsible.  Credit: Caltech / R Hurt

The black hole in question is a primordial black hole (PBH), a hypothetical class of small black holes thought to have emerged soon after the Big Bang as a result of density fluctuations in the very early universe. It is believed that most PBHs have likely evaporated, but some with sufficient mass could still exist, wandering the galaxy, although none have thus far been directly observed.

In their paper, astronomers Jakub Scholtz and James Unwin suggest that a wandering PBH might have strayed close enough to our solar system to have been caught by the Sun’s gravity to orbit it at a distance between 300 and 1,000 AU. They note that there are certain similarities between the estimated mass of the object responsible for giving rise to the eccentric TNO orbits and that found in an excess in microlensing events.

Their hypothesis is that a PBH of around five Earth masses may have been captured by the Sun’s gravity – that’s well within the mass range hypothesised for Planet Nine. But finding it if it exists, will be problematic: a PBH of around 5 Earth masses would likely have a diameter of 5 cm (2 in), and have a Hawking temperature of approximately 0.004 K – making it colder than the cosmic microwave background (CMB) and thus exceptionally hard to detect.

The hypothesis is controversial, as Scholtz and Unwin note. However, they also suggest a way in which the idea could be proven or eliminated from consideration. PBHs are They propose a search for annihilation signals from the dark matter halo of the PBH. If it is annihilating, the halo would provide a powerful and localised signal offering a mix of X-rays, gamma-rays and other high-energy cosmic rays. If such a source were to be detected and found to be moving, it could be indicative of a local PBH.

Insight: of Moles and Marsquakes

Since the end of February 2019, NASA has been wrestling with an issue with an instrument carried to Mars by its InSight lander.

The instrument in question is the “mole”, a self-hammering heat probe designed to burrow  up to 5 metres (16 ft) in order to record the amount of heat escaping from the planet’s interior, helping scientists determine more about Mars. Officially called the Heat Flow and Physical Properties Package (HP3). It was placed on the surface of Mars not long after InSight arrived on the planet at the end of 2018 (for more on the mission, see: Insight on InSight, InSight, MarCO and privately to the Moon and InSight, space and interstellar space).

In order to burrow, HP3 requires friction from surrounding soil; without it, the recoil from the self-hammering action causes it to simply bounce in place – which is what has been happening. It is thought that the “mole” has struck loose sub-surface material, denying it the friction it needs. Nor can it be raised: while the probe is connected to its base unit by a cable, it is not designed to be retracted.

InSight’s robot arm is used to move the main housing of the HP3 experiment to expose the “mole” in readiness to try to use the scoop at the end of the arm to apply pressure to the probe / collapse the rim of the hole around the “mole” to give it sufficient frictional contact to allow it to start moving again. Credit: NASA/JPL

Numerous attempts have been made to try to get the probe moving again without success. For the last several months, the mission team have been attempting to use the scoop on the end of lander’s robot arm to try to collapse the opening of the mole’s hole in the hope the material pushed into it will compact and provide the needed frictional grip for the probe. However, in order not to be influenced by any shadow cast by the lander, HP3 had to be positioned well clear of the vehicle, limiting the amount of pressure it could apply in order to try to collapse the hole.

Instead, engineers now intend to use the scoop to apply pressure directly against the probe, pushing it against the side of its  hole. The hope is that this will give the probe sufficient purchase, allowing it to move past the looser material that is causing problems. If this fails, an attempt will be made to try to use the lip of the scoop to drag material into the hole before again pressing the bottom of the scope against the probe in the hope the combination of the added material in the hole and the pressure of scoop will provide the friction the probe needs.

An image from the camera on InSight’s robot arm as an attempt is made to collapse the wall of the hole around the HP3 instrument. Credit: NASA/JPL

In the meantime, the other experiment InSight placed on the surface of Mars, the Seismic Experiment for Interior Structure (SEIS), designed to make precise measurements of quakes and other internal activity within the planet, has been functioning perfectly. It has detected 21 confirmed Marsquakes since it was deployed on December 19th, 2018.

The quakes are not much more than subtle rumbles to our ears, but they reveal a lot about the interior of Mars, including the fact that the Martian crust is a little like the Earth and a little like the Moon, with a lean towards the Moon. While cracks on both the Earth and the Moon can result from quakes, those on Earth tend to get filled with water and other material. However, on the Moon, they remain open and exposed, allowing them to act as sounding bells so that while the sound of a quake on Earth is rapidly lost, on the Moon it can persist for a minute or more – and the same is true on Mars.

NASA recently released a number of recordings of the Marsquakes detected by InSight. Their frequency is normally far too low for human hearing, so the reocrings speed them up, giving Mars a voice. The one below was picked up on May 22nd 2019 mission Sol 173) and registered as a magnitude 3.7 quake.

It’s been exciting, especially in the beginning, hearing the first vibrations from the lander. You’re hearing what’s really happening on Mars as InSight sits on the open landscape.

– Constantinos Charalambous, InSight science team member, Imperial College, London

Space Pictures of the Week

Witnessing an Eclipse by Drone

On 2nd July, 2019 a total eclipse of the Sun was visible from South America. Miguel Claro, a professional photographer and science communicator and his girlfriend Apolónia Rodrigues flew from Portugal to Chile witness the event after Apolónia had the idea of filming the event using a drone. Where she flew the drone, equipped with a camera, Miguel took still images of the view from the ground around their position, then edited both the video footage and pictures together to create a dramatic 2 minute film.

China’s New Capsule System

In May 2018, I wrote China’s next generation of crewed capsule vehicles (see: Kepler, China, and a voyage to the Sun); now the Chinese have officially revealed photographs of one of the new capsule variants.

Resembling the Boeing CRT-100 Starliner that will be used to transport to and from the International Space Station, the Chinese vehicle will carry a crew of 4 or 5. It comprises a reusable capsule, supported by a service module unit that will provide power, energy and propulsion for the crew unit.

The prototype (?) new Chinese crew capsule and service module under construction. Credit: CAST

The Service module is said to be in two classes: a smaller unit capable of orbital flights and with an approximate mass of 14 tonnes with the capsule, and a large unit, designed for deep space missions such as going to the Moon (a stated goal for China) and with a mass of around 20 tonnes when combined with the capsule. It was this large Service Module featured in the images released by the China Academy of Space Technology (CAST).