Tag: Astronomy

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

Posted on by Inara Pey
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.

Continue reading “Space Sunday: life’s building blocks, black holes and moles” →

Advertisements

Space Sunday: Venus and getting to the Moon

Posted on by Inara Pey
A new study suggests that less that one billion years ago, Venus had liquid water on its surface and atmospheric conditions similar to Earth’s. Credit: NASA

We’re familiar with the idea that Venus is a very hostile place: it has a thick, carbon-dioxide atmosphere mixed with other deadly gases that is so dense, it would instantly crush you were you to step onto the planet’s surface unprotected, and hot enough to boil you in the same moment as well as burn your skin away due to the presence of sulphuric acid. But for a long time, due to its enveloping clouds, it was believed that Venus could be a tropical paradise – a place of warm seas, lakes and rain forests, kept warm by the Sun whilst also protected from the worst of the heat by those thick clouds.

Now, according to a new study presented on September 20th, 2019 at the Joint Meeting of the European Planetary Science Congress (EPSC-DPS),that view of Venus as a warm, wet – and potentially habitable world. What’s more, but for a potentially massive cataclysmic event / chain of events, Venus might have remained that way through to modern times. The study comes from a team at the NASA Goddard Institute for Space Science (GISS), led by Michael Way and Anthony Del Genio.

The studies uses data gathered by two key NASA missions to Venus: the Pioneer Venus orbiter mission (1978-1992), and the Pioneer Venus Multiprobe mission (1978). The latter delivered four probes into the Venusian atmosphere, none of which were expected to survive impact with the planet’s surface, but instead sought to send their findings to Earth as they descended – although as it turned out, one did survive impact and continued to transmit data on surface conditions for more than an hour.

As oceans on Venus might have appeared. Credit: ittiz

That data was coupled with a 3-D general solar circulation model that accounts for the increase in radiation as the Sun has warmed up over its lifetime and models used to define Earth’s early conditions, enabling the GISS time to develop five simulations to try to determine how surface Venus may have developed happened over time – and all five models produced very similar outcomes.

In essence, the models suggest that around 4 billion years ago, and following a period of rapid cooling after its formation, Venus likely had a primordial atmosphere rich in carbon dioxide, and with liquid water present on the surface. Over a period of around 2 billion years, much of the carbon dioxide settled in a similar manner seen on Earth, becoming subsurface carbonate looked in the planet’s crust. In the process, a nitrogen-rich atmosphere would have been left behind, again potentially not that different to Earth’s.

By about 715 million years ago – and allowing for the planet having a sufficient rotation period (16 Earth days or slower) – conditions would have reached a point where a stable temperature regime ranging between 20°C (68 °F) and 50°C (122 °F) could be maintained, with the models indicating that the planet could have oceans and / or seas and / or lakes varying in depth from about  10 m (30 ft) to a maximum of about 310 m (1000 ft), generating sufficient cloud coverage combined with the planet’s rotation to deflect enough sunlight and prevent the atmosphere from overheating. Further, had nothing further happened, these conditions could have more-or-less survived through to current times.

So what happened? That has yet to be fully determined, but the suggestion is that a series of connected global events came together in what might be regarded as a single cataclysmic re-surfacing of the planet. This is somewhat supported by data gathered by the Magellan probe (1988-1994). The GISS team suggest that this caused a massive outflow of the CO2 previously trapped in the subsurface rock that in turn caused a runaway greenhouse effect that resulted in the hothouse we know today,  where the average surface temperature is 462°C (864°F).

The surface of Venus called Phoebe Regio, as imaged by the Soviet era Venera 13, 1981-1983

Something happened on Venus where a huge amount of gas was released into the atmosphere and couldn’t be re-absorbed by the rocks. On Earth we have some examples of large-scale outgassing, for instance the creation of the Siberian Traps 500 million years ago which is linked to a mass extinction, but nothing on this scale. It completely transformed Venus.

– Michael Way – GISS Venus study joint lead

There are questions that still need to be answered before the models can be shown to be correct, which the GISS team acknowledge by stating further orbital study of Venus is needed. However, if the study’s findings can be shown to be reasonably correct, it could have relevance in the study of exoplanets.

Until now, it has been believed that planets with an atmosphere occupying a similar orbit around their host star would, like Venus, be subject to tremendous atmospheric heating, preventing liquid water or habitable conditions to exist on their surfaces. However, the GISS models now suggest that subject to certain boxes  being ticked, such planets occupying the so-called “Venus zone” around their parent stars could have liquid water present – and might actually be amenable to life.

Artemis and the Moon: Political Football

America is trying to return humans to the Moon by 2024 via a programme called Artemis. It’s an effort that requires funding, clear thinking, co-ordination and agreement. Right now, it would appear as if few of these are proving to be the case.

On the one hand, things do appear to be moving forward. According to a presentation on September 11th, the Lunar Orbital Gateway Platform (LOP-G) is on track. Both the Power and Propulsion Element (PPE -due for launch in 2022) and the Habitation and Logistics Outpost (HALO – due for launched in 2023), as the two core elements of the initial Gateway – remain on track. Even so, doubts have been sewn concerning its relevance, as I’ll come back to in a moment.

An artist’s impression of an unpiloted commercial lander leaving a scaled-back LOP-G for a descent to the surface of the Moon ahead of a 2024 human return to the lunar surface. The LOP-G is the unit on the right, comprising a habitation module and docking ports unit, an on the far right, a power and propulsion unit. In the left foreground is an Orion crewed vehicle. Credit: NASA

Elsewhere, the programme is far from smooth in its progress. On September 11th, the US House of Representative issued a draft  continuing resolution (CR) on the 2020 federal budget that provides no additional funding for NASA’s lunar ambitions – a result NASA Administrator Jim Bridenstine stated would be “devastating” to the development of the Artemis lunar lander.

Then at a hearing of the space subcommittee of the U.S. House of Representatives’ Science, Space and Technology Committee on September 18th, NASA’s acting associate administrator for human exploration and operations, Ken Bowersox (himself an ex-astronaut) came under heavy questioning on whether NASA really could achieve a successful human return to the Moon by 2024. His reply wasn’t entirely reassuring, “I wouldn’t bet my oldest child’s upcoming birthday present or anything like that.” He went on:

We’re going to do our best to make it. But, like I said, what’s important is that we launch when we’re ready, that we have a successful mission when it launches.

I’m not going to sit here and tell you that, just arbitrarily, we’re going to make. We have to have a lot of things come together to make it happen. We have to get our funding, we have to balance our resources with our requirements, and then we’ve got to execute it really well. And so, there’s a lot of risk to making the date, but we want to try to do it.

 – NASA acting associate administrator for human exploration, September 18th, 2019

In particular, there are concerns surrounding NASA’s new Space Launch System rocket – vital to the effort. This is been plagued by issues to the point where Bridenstine suggested a critical test for the vehicle’s core stage and rocket engines, called the “green run” could be skipped in favour of “other means” of testing – an idea ultimately dropped after considerable push-back from within NASA and safety bodies. As it is, SLS will not be in a position to undertake all of the missions required to return humans to the surface of the Moon – such as delivering hardware to the halo orbit around the Moon that will be used by LOP-G, and so NASA has indicated it would be willing to use commercial vehicles such as the SpaceX Falcon Heavy for a number of cargo flights.

Continue reading “Space Sunday: Venus and getting to the Moon” →

Space Sunday: exoplanets, exocomets and Titan’s craters

Posted on by Inara Pey
K2-18b as it might appear in orbit around its red dwarf parent star and with the other known planet in the system – K2-18c – also visible. Credit: ESA/Hubble, M. Kornmesser

I first wrote about K2-18, a red dwarf star some 11 light-years from Earth, and its two companion planets in December 2017. At that time, the outermost of the two planets, called K2-18b or EPIC 201912552 b and discovered in 2015, was the subject of a study to determine its mass in an attempt to better understand the planet’s possible atmospheric properties and bulk composition. This was of particular interest to scientists as K2-18b lay within its parent star’s habitable zone – where liquid water might exist on the planet’s surface.

That study ultimately revealed K2-18b has a mass of around 8 times that of Earth, putting it in the “super-Earth” category of rocky worlds, with a diameter roughly 2.3 times greater than Earth’s (see: Space Sunday: Exoplanets Update). Since then, K2-18b has continued to be the subject of study – and it has now become the first exoplanet thus far discovered confirmed to have water vapour, mostly likely liquid water clouds, within its atmosphere.

The news came via two independent studies that have been carried out using the data gathered by the Hubble Space Telescope (HST). The first study, written by the team who originally gathered the data, appeared on September 10th, 2019 on arXiv.org, but has not been peer-reviewed. The second study – which has been peer-reviewed – appeared in the September 11th edition of Nature Astronomy.

The team responsible for gathering the data – led by Björn Benneke, a professor at the Institute for Research on Exoplanets,  Université de Montréal – did so after applying to use Hubble to observe K2-18b shortly after its discovery. They were ultimately granted telescope time in in 2016 and 2017, using Hubble to gather data in the light from the red dwarf star, and how that light changed under the influence of any atmosphere surrounding K2-18b as it transited in front of the star. Spectrographic analysis of the data confirmed the planet has a fairly dense atmosphere rich in hydrogen and helium – and which also contains the molecular signature of water.

Researchers gathered data on K2-18b’s atmosphere by using the Hubble Space Telescope to observe changes in the light from its parent star as it passed through the planet’s atmosphere during transits. Credit: NASA / ESA simulation

After gathering the data, Benneke’s team wanted time to carry out further observations to both confirm what they had found and make additional discoveries. In the meantime, their findings were available for others to study – which is exactly what a team led by Dr. Angelos Tsiaras based at the University College London (UCL), UK did.

Using independent means of analysing the data, both teams reached the same overall conclusions concerning the major finds within K2-18b’s atmosphere – although they come to different conclusions as to the planet’s likely form. The UCL specify K2-18b as a rocky planet with a dense atmosphere, between 0.01% and 50% of which is water vapour. By comparison, the amount of water vapour in our atmosphere is put at between 0.1% and 4% – so, K2-18b could have anything from a comparable amount of water vapour in its atmosphere to Earth through to being a completely flooded world.

By contrast, Benneke’s team believe the planet is more of a “mini-Neptune”: a planet with a small, solid core surrounded with a thick atmosphere that is predominantly hydrogen / helium in nature, with only trace amounts of water vapour – albeit enough to create liquid water clouds, and possibly even rain. However, the idea that the planet is a mini-Neptune is somewhat at odds with other findings about the planet – such as the December 2017 study.

There is also some tension between the two teams. While Benneke acknowledges his team’s research was open to others to use, he is somewhat aggrieved the UCL team did not bother to contact him or his team concerning their work or their intentions. However, he also sees the results of the UCL’s work as positive in respect to understanding the nature of K2-18b.

The presence of liquid water in the planet’s atmosphere doesn’t automatically mean it is home to life. There are some significant issues around this. For one thing, while the plant is within the habitable zone, the precise surface temperature has yet to be determined, and could range from -73ºC  to +47ºC (-100ºF and +116ºF), meaning it could be colder or hotter than the coldest / hottest places on Earth.

There’s also the fact that the planet is so close to its parent, orbiting once every 33 days, that it is likely tidally-locked with its star. This means one side of the planet will be in perpetual sunlight, and the other in perpetual darkness – something that could well give rise to extreme weather conditions. Finally, there’s the fact that K2-18 is a red dwarf star. These, as I’ve noted before, can be exceptionally violent, and flares and coronal mass ejections from the star are likely to both expose the planet to high levels of radiation and could strip away its atmosphere over time, although it is possible K2-18b’s atmosphere might be dense enough to help it withstand at least some of this stripping away.

Finding water on a potentially habitable world other than Earth is incredibly exciting. K2-18b is not ‘Earth 2.0’ as it is significantly heavier and has a different atmospheric composition. However, it brings us closer to answering the fundamental question: Is the Earth unique?

– Dr. Angelos Tsiaras (UCL Centre for Space Exochemistry Data)
co-author of the UCL study on K2-18b

The next phases in studying K2-18b will likely come in the mid-to-late 2020s. Benneke and his team are already planning to continue their work using NASA’s James Webb telescope, due to be launched in 2021, while Giovanna Tinetti, a member of the UCL team studying K2-18b also happens to be the Principal Investigator for Europe’s Atmospheric Remote-sensing Infra-red Exoplanet Large-survey (ARIEL). She has already indicated the planet will be target for study by that mission when it launches in 2028.

Continue reading “Space Sunday: exoplanets, exocomets and Titan’s craters” →

Space Sunday: Lunar landers, and robots in space

Posted on by Inara Pey
The bulky Vikram lander, with the Pragyan rover”garaged” inside, is hoisted aloft in a clean room, ready to be mated to the “top” of the Chandrayaan-2 orbiter (right). One section of the payload fairing that enclosed the craft during launch is visible in the background. Credit: ISRO

On Friday, September 6th, India was due to become the fourth country to successfully reach the surface of the Moon, with the touch-down of the Vikram lander, part of the Chandrayaan-2 (“moon craft-2” in Hindi) mission.

Launched in late July 2019, Chandrayaan-2 was set to be the latest in a series of high-profile missions undertaken by the Indian Space Research Organisation (ISRO) over the course of the last 11 years, which have included the  Chandrayaan-1 lunar orbiter (2008/2009) and the Mangalayaan (“Mars-craft”), launched in 2013 and still operational today.

As I’ve noted in recent Space Sunday articles, Chandrayaan-2 comprises three parts: the orbiter vehicle, the Vikram lander and a small rover called Pragyan (“Wisdom” in Hindi) carried by the lander. Vikram departed the orbiter vehicle on Monday, September 2nd, allowing it to begin a series of manoeuvres in readiness for a final decent and landing, scheduled for Friday, September 6th (western time, the early hours of Saturday, September 7th for India) in the Moon’s South polar region.

An artist’s impression of the Vikram lander coming in to land in the Moon’s south polar region. Credit: ISRO official video

Initially, that final descent started well enough, with the lander about 550 km (344 mi) from the south pole as it fired its descent motor start the start of its final approach. At an altitude of 6 km (3.75 mi), it started a final sequence of engine burns referred to as the “fine braking phase”. Then all communications ceased.

ISRO issued a statement that the vehicle was performing nominally until around 2.1 km above the Moon, when the loss of communications occurred. However, images of the data received from the vehicle and released by ISRO appeared to suggest telemetry was being received when the lander was within 400 m of the lunar surface – and altitude at which it would be fully under its automatic guidance and landing software, and not reliant on commands from Earth. This seemed to suggest Vikram may have made a landing.

ISO stated communications with the Vikram lander were lost some 2.1 km above ground. However, a graphic of the vehicle’s descent towards the Moon (green above), appears to suggest telemetry was lost when the vehicle was between 300-400m above the lunar surface, and that it had drifted perhaps a mile from its planned descent track (red). If accurate, this suggests Vikram was in the fully automated terminal descent phase of its landing. Credit: ISRO

This idea gained ground as this article was being prepared, when an article published by Asia News international suggested Vikram has been spotted on the surface of the Moon, possibly 500m to 1 kilometre from its designated landing point. The article quotes ISRO’s director, Kailasavadivoo Sivan as saying:

We’ve found the location of Vikram Lander on lunar surface & orbiter has clicked a thermal image of Lander. But there is no communication yet. We are trying to have contact. It will be communicated soon.

Since then, the report has been repeated numerous times through various media (including an entirely UNofficial and unverified “ISRO Official Update” Twitter account) without (at the time of publication) official confirmation. This has made it hard to determine the veracity of the ANI report. Hopefully, the situation will become clearer in the coming days. One thing that could help define the lander’s condition would be an image captured by Chandrayaan-2’s main imaging camera. With a resolution of a third of a metre, it is the highest resolution camera in operation around the Moon.

The planned landing site for the Vikram lander. Credit: ISRO

But even though the lander and rover may have been lost, the mission is far from over; the orbiter continues to function perfectly. It also carries the bulk of the mission’s science experiments – eight of the 13 carried by the mission. he data gathered by these systems should enable scientists to compile detailed maps of the lunar surface, revealing key insights about the Moon’s elemental composition, formation and evolution, and potentially help in assessing the moon’s stores of water ice.

In this latter regard, the mission builds on work performed by Chandrayaan-1, which revealed water is present at the lunar poles, with subsequent studies suggesting much of this water is ice on the floors of polar craters, which have been in permanent shadow for billions of years. If this ice is easily accessible, it could be a critical enabling resource for the eventual human settlement of the moon, providing water, oxygen and fuel (hydrogen).

In all, Chandrayaan-2 is expected to operate for some 7 years.

Proxima Centauri: An Angry Star with Bad News for its Planet

In 2016, I wrote about Proixma b, a planet roughly 1.5 times the mass of Earth orbiting our nearest stellar neighbour, Proxima Centauri, 4.25 light years away (see: Exoplanets, dark matter, rovers and recoveries). Since then, and as a result of the planet being within the star’s zone of habitability, there has been a lot of debate about the potential for it to support life.

An artist’s impression of Proxima b with Proxima Centauri low on the horizon. The double star above and to the right of it is Alpha Centauri A and B. Credit: ESO

Numerical models have indicated that Proxima b probably lost a large amount of its water in its early life stages, possibly as much as one of Earth’s oceans. however, those models also suggest liquid water could have survived in warmer regions of the planet – such as on the side of the planet facing its star (Proxima b is potentially tidally locked with its parent star, always keeping the same face towards it). This means other factors that might affect habitability must be examined. Chief among these is the overall activity of the parent star – notably flares, coronal mass ejections and strong UV flux -, all of which can erode a planet’s atmosphere, rendering it uninhabitable in the long term.

That Proxima Centauri is very active with flares has been known for some time, as has been the star’s ability to generate “super-flares”, one of which in 2016 briefly raised the star’s brightness to the point of making it briefly visible to the naked eye from Earth. This activity has suggested that Proxima b is unlikely to support life (see: Curiosity’s 5th, Proxima b and WASP-121b). But the debate has remained.

Over the past year, a team of scientists at the Konkoly Observatory in Hungary have been using data from the Transiting Exoplanet Survey Satellite (TESS) to observe Proxima Centauri’s flare activity over a two month period, split between April and June 2019. They found that in the roughly 55-day period, the star pent around 7% of its time violently flaring, with a total of 72 relatively large-scale flares observed. In particular, the energy of the eruptions put them as not far below “super flare” status, suggesting the star could produce a super flare perhaps once every two years.

TESS data on flare activity on Proxima Centauri: yellow triangles indicate flare activity, green triangles show particularly violent flare events. Credit: Krisztián Vida / Konkoly Observatory

Such frequent, high-energy eruptions almost certainly have a severe impact on the atmosphere of Proxima Centauri b, disrupting it to a point where it cannot reach any steady state, leaving it continuously in a state of disruption and alteration, making the potential for the planet to support life even more remote. However, it also raises a curiosity about the star: the underlying magnetic frequency evidenced by Proxima Centaur. Such activity is normally associated with fast-rotating stars with periods of a few days. However, Proxima Centauri has a rotation period of ~80 days; so why it should be so active is now a subject for investigation.

Continue reading “Space Sunday: Lunar landers, and robots in space” →

Space Sunday: flying water tanks, telescopes and weird rocks

Posted on by Inara Pey
The “Flying Water Tank”, aka “R2D2’s Dad”, otherwise know as the Starhopper – rises to 120m (500ft) during its second major test flight, August 27th, 2019. Credit: SpaceX

SpaceX successfully few their Starhopper vehicle – designed to prove the viability of their upcoming Starship space vehicle – on August 27th, in its most complex test flight to date.

The Starhopper craft, dubbed “the flying water tank” on account it both lacks its conical nose (damaged beyond repair during a storm at the start of the year) and the fact it was fabricated for SpaceX by a company that specialises in building water tanks, lifted off from a pad at SpaceX’s test site in Boca Chica, Texas, rising vertically to a height of 150 metres (488 ft) before translating to horizontal flight to crab across to another pad at the test facility and then descended under power to touch down once more.

While the flight lasted less than a minute, it has, according to Musk, paved the way for two dramatic follow-up flights.

Aiming for 20km flight in Oct & orbit attempt shortly thereafter. Starship update will be on Sept 28th, anniversary of SpaceX reaching orbit. Starship Mk 1 will be fully assembled by that time.

– Elon Musk via Twitter, after the successful flight

As well as the Starhopper vehicle, SpaceX is currently building two full-size Starship prototypes – “Mk 1” is being built at Boca Chica, with “MK 2” under construction in Florida. It appears that the “Mk 1” vehicle will be used for the 20km flight.

Starship Mk 2 on the left of the image, standing upright and with additional elements nearby, under construction in Cocoa, Florida. Credit: SpaceX

Musk’s announcement of a potential attempt to reach orbital altitude drew questions on whether SpaceX plan to use their Super Heavy  – essentially the “first stage” for Starship launches – with one of the Starship prototypes, or just make the attempt with the Starship on its own. In the past, Musk has indicated that a fuelled but unladen Starship should have the power to achieve orbit, but that would presumably be using all six of an operational Starship’s Raptor engines. By comparison, the Starhopper has a single Raptor motor and the Starship Mk 1 and Mk 2 craft will have 3 Raptors – at least initially.

As it stands, the “first generation” of Starship / Super Heavy is designed to be 9m (29 ft) in diameter and stand around 118m (390 ft) tall on the launch pad. Super Heavy is to be powered by 31 Raptor engines and the 48m tall Starship by 6 Raptors. Together they will be capable of lifting around 100 tonnes of payload to orbit, with Starship capable of reaching the Moon or Mars with that payload or up to 100 crew and passengers.

All of that is pretty mind-boggling. It makes Starship / Super Heavy the most powerful launch system ever built in terms of thrust. But SpaceX is apparently going to go beyond that. Following the Starhopper test, and responding to a question, Musk indicated that a “next generation” craft based on Starship / Super Heavy could follow in “several years”. While planning a follow-up to Starship / Super Heavy is not surprising, the scale of the follow-up version is: in a further tweet, Musk suggested it will be 18m (60 ft) in diameter – twice that of Starship / Super Heavy.

Mathematics tells us that doubling the diameter of a circle quadruples its area. This means that if the current ratio of dimensions for Starship / Super Heavy is retained, the “next generation” version would stand a mind-boggling 230 m (780 ft) tall and have eight times both the surface area and propellant tank volume of the current Starship / Super Heavy. All of which leads to a fuelled launch mass of around 40,000 tonnes.

An artist’s impression of a future “next generation” Starship / Super Heavy launch combination compared to SpaceX’s current family of launch vehicles, the current (2018) and previous (2016 and 2017) BFR designs. This assumes the “next generation” vehicle will have Musk’s stated 18m diameter and retain the same proportions as the current Starship / Super Heavy combination. Credit: Teslerati.

Given the size of such a vehicle, coupled with all the support infrastructure it would require during fabrication (never mind launching), it would seem unlikely it would retain the same proportions as the current Super Heavy / Starship combination. But whatever overall dimensions are proposed, the new vehicle will require some new motor system – were it to use the Raptor engines that Super Heavy will use, the lower stage would require 100 of them to get the stack off the ground.

More information on this possible “next generation” vehicle might be given when Musk provides a public update on the status of Starship / Super Heavy on September 28th, 2019.

Continue reading “Space Sunday: flying water tanks, telescopes and weird rocks” →

Space Sunday: Pluto’s names, Jupiter’s core

Posted on by Inara Pey
The 14 new surface feature names (in yellow) approved for Pluto by the International Astronomical Union on August 8th, 2019. The names in white were approved by the IAU in 2017. Credit: NASA / JHU/APL

On August 8th, 2019, the International Astronomical Union (IAU) approved the names for 14 more significant features on the surface of Pluto, imaged by the New Horizons space vehicle as it flew past the Pluto-Charon system in 2015.

The IAU claimed the authority to officially name or approve the name of planets, dwarf planets, moons, asteroids and planetary features in our solar system during its inaugural General Assembly, held in Rome in May 1922, 3 years after it had been formed by the founding nations of Belgium, Canada, France, Great Britain, Greece, Japan, and the United States, and by which point its membership had grown to 19 nations around the world (today membership stands at 82 nations).

As the sole authority, it means that any names given to things like planetary surface features  – such as “Mount Sharp” on the surface of Mars are entirely unofficial, hence why they are referred to in quotes in these Space Sunday articles. The IAU may determine names on things like surface features entirely by itself (as is the case with “Mount Sharp”, which is officially designated Aeolis Mons), or they may take recommendations from other organisations or groups.

In the case of the 14 names first assigned to features on Pluto by the IAU in 2017, the organisation ratified the suggestions made by the New Horizons mission team. Keeping with this “tradition”, the August 8th, 2019 announcement of the 14 “new” names for surface features first employed by the mission team.

The first 14 names to be approved by the IAU (2017) for features on Pluto include the Tombaugh Regio, named for Clyde Tombaugh, who first identified Pluto as a planetary body; the great frozen nitrogen lake of Sputnik Planitia, and the Hillary and Tenzing mountains, named for the two men formally recorded as the first to reach the summit of Mount Everest. Credit: NASA / JHU/APL

All 14 represent people and missions that contributed to the understanding of Pluto and the Kuiper Belt, as well as drawing on figures from mythology and aerospace exploration in general. They cover a range of surface features on Pluto images by the New Horizons vehicle as it dashed through the Pluto-Charon system that include entire regions of the planet and items such as mountain ranges, plains, valleys and craters. They comprise (in alphabetically order):

  • Alcyonia Lacus, possibly a frozen nitrogen lake, it is named for the “bottomless” lake in the vicinity of Lerna, Greece, and regarded as one of the entrances to the underworld in Greek mythology.
  • Elcano Montes, a mountain range named for Juan Sebastián Elcano (1476–1526), the Spanish explorer who in 1522 completed the first circumnavigation of the Earth (a voyage started in 1519 by Magellan).
  • Hunahpu Valles, a system of canyons named for after one of the Mayan Hero Twins who defeated the lords of the underworld in a ball game.
  • Khare crater honours planetary scientist Bishun Khare (1933–2013), who specialised in the chemistry of planetary atmospheres and who published several seminal papers on tholins, the organic molecules that probably account for the darkest and reddest regions on Pluto.
  • Kiladze crater is named for Rolan Il’ich Kiladze (1931–2010), who made pioneering early investigations the dynamics, astrometry and photometry of Pluto.
  • Lowell Regio, is a large region honouring Percival Lowell (1855–1916), founder of the Lowell Observatory and organiser of the search that eventually led Clyde Tombaugh to locate Pluto.
  • Mwindo Fossae, a network of long, narrow depressions named for the Mwindo Epic of the Nyanga people.
  • Piccard Mons, a mountain and suspected cryovolcano named for Swiss inventor and physicist and high altitude balloon pioneer, Auguste Piccard (1884–1962).
  • Pigafetta Montes, a mountain range honouring Antonio Pigafetta (c. 1491–c. 1531), the Italian scholar and explorer who chronicled the discoveries made during the first circumnavigation of the Earth, aboard Magellan’s ships.
  • Piri Rupes, a range of cliffs named for Piri Reis (also Ahmed Muhiddin Piri c. 1470–1553), an Ottoman navigator and cartographer known for his world map. He also drew some of the earliest existing maps of North and Central America.
  • Simonelli crater, name after astronomer Damon Simonelli (1959–2004), whose wide-ranging research included the formation history of Pluto.
  • Wright Mons, a mountain named for powered flight pioneers Orville and Wilbur Wright.
  • Vega Terra, a large land mass named after the Soviet Vega 1 and 2 missions, the first spacecraft to fly balloons on another planet (Venus) and to image the nucleus of a comet (1P/Halley).
  • Venera Terra, named for the Venera missions sent to Venus by the Soviet Union from 1961–1984; they included the first human-made device to enter the atmosphere of another planet, to make a soft landing on another planet and to return images from another planetary surface.
A computer-generated image showing New Horizons’ location in our solar system on August 10, 2019. The green line shows where the vehicle has travelled since its 2006 launch, the red indicates its future path. This perspective is from above the Sun and “north” of Earth’s orbit. Credit: JHU/APl

Since its flyby of the Pluto-Charon system, the New Horizons vehicle has continued its voyage out through the Kuiper Belt. Most of this has been with the vehicle in a state of hibernation to conserve power, however, in January 2019, the craft encountered  Kuiper Belt Object (KBO) Ultima Thule, aka 2014 MU69 (see my January 28th 2019 Space Sunday article), and data from that encounter is still being transmitted back to Earth.

Currently, the New Horizons mission is funded until April 2021, and may well be extended beyond that date. The vehicle’s radioisotope thermoelectric generator (RTG), which uses the heat from the radioactive decay of plutonium 238 to provide it with electrical power, is expected to provide sufficient energy for its science instruments until the mid-to-late 2030s. So the science team responsible for the mission at the John Hopkins University Applied Physics Laboratory are currently seeking potential KBO targets the craft could fly by in the mid or late 2020s.

Ultima Thule from a distance of 6,700 km, January 1st, 2019. Credit: NASA / JHU/APL / SwRI

Should the vehicle retain sufficient power for some of its instruments, it may be able to study the outer heliosphere (the “bubble” of space surrounding our solar system and created by the outward flow of energise particles from the Sun) in the late 2030s. If it does, it will add to the data gathered on that distant region of space, 100+ AU from Earth (1 AU = the average distance of the Earth from the Sun) by the Voyager spacecraft.

Parker Solar Probe: One Year In

August 12th, 2019, marked the first anniversary of NASA’s Parker Solar Probe. As I reported in Space Sunday: to touch the face of the Sun, this is an ambitious mission to repeatedly fly through the Sun’s corona – the hazardous region of intense heat and solar radiation in the Sun’s atmosphere that is visible during an eclipse – to gather data that could help answer questions about solar physics that have puzzled scientists for decades.

Named for Eugene Parker, the physicist who first theorised the solar wind, the constant outflow of particles and magnetic fields from the sun, the mission is now into its third orbit of the Sun, and due to make a further close solar approach on September 1st, 2019.

The spacecraft carries four suites of scientific instruments to gather data on the particles, solar wind plasma, electric and magnetic fields, solar radio emission, and structures in the Sun’s corona. This information will help scientists unravel the physics driving the extreme temperatures that make the corona hotter than the “surface” of the Sun – and the mechanisms that drive particles and plasma out into the solar system.

So much information has been gathered by the probe during its first two orbits of the Sun that the mission team on Earth is still analysing it. They hope to have the first results available before the end of the year – not that they are complaining!

We’re very happy. We’ve managed to bring down at least twice as much data as we originally suspected we’d get from those first two perihelion passes.

– Nicky Fox, director of NASA’s Heliophysics Division

An artist’s impression of the Parker Solar Probe swinging around the Sun at a distance of 6.2 million km (3.85 million mi) . Credit: NASA

Nor is that all; the probe’s elliptical 170-188 day orbit means that it has just 11 days per orbit in which to gather data – and these coincide with perihelion, when the craft must withstand temperatures of around 1,370ºC (2,500ºF). To achieve this, the probe is equipped with a 2.3m hexagonal solar shadow-shield that performs three tasks: it absorbs and reflects sunlight away from the vehicle whilst also preventing radiation penetrating its instrument bay and burning-out its circuits and instruments (incident solar radiation at perihelion is approximately 475 times the intensity at low Earth orbit) and also casting a long shadow in which the rest of the vehicle can remain relatively “cool”. Data on the shadow-shield and from within the vehicle as it passes through the corona reveal the shield is working better than anticipated.

So, with another six years of its planned 7-year primary mission, the Parker Solar Probe is set to revolutionise our understanding of the Sun’s corona and the mechanisms powering it.

The data we’re seeing is showing us details about solar structures and processes that we have never seen before. Flying close to the sun—a very dangerous environment—is the only way to obtain this data, and the spacecraft is performing with flying colours.

– Nour Raouafi, Parker Solar Probe project scientist, JHU/APL

Continue reading “Space Sunday: Pluto’s names, Jupiter’s core” →