Tag: Astronomy

The Kepler Space Telescope might be shut down, but the work of analysing the data it gathered on possible exoplanets continues, and an international team of scientists reviewing some of the earliest data from the mission have confiemd what had been thought of as a “false positive” is in fact an Earth-size exoplanet orbiting within its star’s habitable zone, the area around a star where a rocky planet could support liquid water.

The planet, Kepler-1649c orbits its small red dwarf star some 300 light years from Earth. It is so close to its parent, that its year is the equivalent to 19.5 Earth days. It is actually the second planet to have been found orbiting the star, hence the “c” designation in its name, and the system as a whole contains a series of points of interest for astronomers that make it particularly intriguing.

The first is that the data Kepler gathered on the planet suggest it is one of the closest in terms of size to Earth so far discovered, being just 1.06 times larger. The second is that its parent, Kepler-1649, is a class-M red dwarf with relatively low luminosity, so that despite it’s close proximity, that planet receives around 75% of the sunlight Earth receives from Sol. so it is entirely possible that if it has an atmosphere, conditions on it surface might be somewhat similar to our own in terms of average temperatures and with regards to surface water.

However, whether the planet does have an atmosphere has yet to be determined. As I’ve previously noted in this column, red dwarf stars are so small they rely on convection as the main form of energy transport to the surface, and this can give rise to violent solar outbursts which over time can rip away a nearby planet’s atmosphere. There’s also the question of how stable any atmosphere might be. Again, its close proximity to its parent means it is liable to be tidally locked, always keeping the same face towards its star. This is liable to make any atmosphere the planet does have could be exceptionally turbulent and prone to storms along the terminator dividing the light and dark halves.

However, Kepler-1649 has thus far shown itself to be one of the more stable M-class stars that has been observed over the years from Earth – which means it may well still possess a temperate atmosphere. If this is so, the combination of size and atmosphere then of all the red dwarf orbiting exoplanets thus far discovered, Kepler-1649c could be closer to Earth than most so far discovered.

An additional intrigue with the Kepler-1649 system is that the two planets share an unusual orbit resonance: for every nine times Kepler-1649c orbits its parent, the inner planet, Kepler-16949b, orbits almost exactly four times, giving a 9:4 ratio. This indicates the system is extremely stable, likely to survive for a long time.

9:4 is also something of a unique ratio; usually resonances take the form of ratios like 2:1 or 3:2. As such, it is thought that the Kepler’s system’s resonance might be indicative of a third planet between Keplert-1649b and Kelper-1649c, which would give the system a more regular pairing of 3:2 resonances between the middle and inner planets and the middle and outer planets. However, the existence of any third planet has yet to be confirmed.

In the meantime, the discovery of Kepler-1649c adds significantly to our understanding on exoplanets around M-class stars.

The more data we get, the more signs we see pointing to the notion that potentially habitable and Earth-size exoplanets are common around these kinds of stars. With red dwarfs almost everywhere around our galaxy, and these small, potentially habitable and rocky planets around them, the chance one of them isn’t too different than our Earth looks a bit brighter.

– Andrew Vanderburg, co-author of a paper on Kepler-1649c exoplanet

Curiosity: A New Level of Remote Working

As the SARS-CoV-2 virus continues to prevent us from working normally, members of NASA’s Mars Science Laboratory Curiosity team have revealed how they’ve been continuing with normal operations since the Jet Propulsion Laboratory (JPL) shut down operations in February 2020.

Of course, in some respects the rover team has always been working remotely from their “office”, the rover never being at least 56 million km from Earth. However, the shut-down of NASA facilities ordered by Administrator Jim Bridenstine brought additional challenges to operating a rover so far away – and I’m not talking about distractions caused by the need to feed the cats or take the dog for a walk, being reliant on e-mail and video conferencing, etc.

Take driving the rover, for example. This requires a complex process of scanning the rover’s surroundings to build up a complete view of the rover’s environment, having the means to view this in 3D and to compare it to high-resolution images of the rover’s surroundings captured from orbit, then mapping a potential route that avoids any aspects of the landscape that present a risk to the rover whilst also encompassing points of interest, converting the commands into software code, testing it, and finally transmitting it to the rover for execution. Similarly, manoeuvring and using the rover’s robot arm requires precision and care, rehearsal and coding.

Much of this work requires high-powered computers. Analysing potential route from images, for example, requires not only high-resolution image processing, but also high-end gaming PCs and 3D headsets to give a greater depth of field and better visualisation of contours of the landscape and rocks. A similar approach is used to manoeuvring and manipulating the robot arm. The problem is, not all of the systems required to achieve all of this could easily be transitioned from JPL’s facilities to home use. Teams are, for example, restricted to using laptops, rather than gaming PCs; they’ve therefore had to swap from using specialised 3D headsets that rapidly shift between left- and right-eye views to better reveal the contours of the landscape, and instead rely ordinary anaglyph glasses to achieve the same ends.

I’ve covered the development and plans SpaceX have for their mighty Starship vehicle – designed to be capable of lifting up to 100 tonnes of cargo, or 100 people to the Moon or Mars – and its equally massive reusable booster on numerous occasions. For the last 12+ months, the company has been engaged in fabricating a series of prototype / test versions of the Starship vehicle, some of which are (or were) intended for actual flight testing. But it has been far from plain sailing for the company.

The first vehicle in the series, called simply “Starship Mark 1”, and built at the company’s Boca Chica test facilities in southern Texas, underwent a series of tank pressurisation tests that were initially positive, at least up until a full pressure test – mimicking the pressure the vehicle’s tanks would be under when fully fuelled and awaiting launch – on November 20th, 2019. SpaceX CEO Elon Musk anticipated this test might end in failure – and it did, the fuel tank bulkheads suffering a catastrophic failure.

A second prototype, Starship SN1, had a series of refinements built into the tank bulkheads and was subjected to a similar test on February 28th, 2020. This time, the bulkheads survived, but a failure occurred with a “thrust puck” at the base of the tank that takes the load from the vehicle’s Raptor engines, again resulting in the loss of the vehicle. As a result, the third prototype, SN2 was modified and then stripped back just to its tanks so that a further test of the “thrust puck” weld on March 3rd – which it passed successfully.

The adjustments were then made to the next prototype: SN3, a vehicle intended to start flight tests. The sections of SN3 were revealed on March 26th, 2020, after which the main tank section was moved to a test stand where it would also undergo a series of pressurisation tests, culminating a full pressurisation using liquid nitrogen to simulate a fuel load at typical launch temperatures. This took place on April 2nd (CST) / April 3rd (UK / CET), and once again ended in failure and the loss of the tank section.

Video recorded by NASASpaceflight.com (not an official NASA site) shows the tank under pressure and venting gas (as expected) before the upper portion initially buckles before completely collapsing.

Immediately following the test, Musk indicated via Twitter the the loss of the section may have been a result of the test being incorrectly configured, rather than a failure with the vehicle itself – although analysis of the data is continuing.

A significant difference between the SN3 vehicle and the prototypes that came before it was the inclusion of deployable landing legs, included in the vehicle to allow it to undertake the system’s first, low-altitude “hops”. SpaceX had already applied to the Federal Aviation Administration (FAA) for permission to complete a static fire of the vehicle’s raptor engine – a required precursor for any test flights – and the FAA had in turn issued a notification to airmen to remain clear of the airspace around the Boca Chica test area between April 6th to 8th, a move consistent with an engine static fire test, which the failed pressurisation test was in turn something of a precursor.

It’s not clear how the incident with SN3 affects Starship testing; a further test vehicle, Starship SN4 is under construction specifically to complete higher-altitude flight tests before SN5 undertakes flights in excess of 20km altitude. Whether this SN4 will now be used for the low altitude hops and SN5 and SN6 for the higher flights, or the range of flights for SN4 is extended to cover both low and intermediate altitude tests remains to be seen. All the company has indicated is that the failures encountered so far shouldn’t deflect them too much in their aspirational goals of a lunar vicinity flight in 2022 and a Mars flight in 2024. In respect of these, in March 2020, SpaceX issued payload and crew guidelines for customer wishing to launch cargoes to orbit – a further option for the Starship / Super Heavy booster combination being cargo flights and payload deployments, replacing the company’s Falcon 9 and Falcon Heavy boosters.

James Web Unfurls its Telescope for the First Time

NASA’s next great observatory, the James Webb Space Telescope, has fully deployed its primary mirror under test conditions for the first time, marking another milestone on its journey to space.

The giant mirror, 6.5 metres across, is so large, it must be folded and stowed during launch, requiring it to be carefully deployed while on-route to its final L2 halo orbit beyond the Moon – which will take it around 14 days to initially reach, and another 14 to settle into.

Prior to the SARS-CoV-2 situation caused NASA to suspend work on the telescope, it was hooked-up to a gravity / mass compensating rig – needed to support the weight of the two deployable “sides” of the mirror as well as the mass of the central section – allowing the mirror’s deployment motors to be spun up and the entire mirror assembly put through its actual deployment routine.

The test was one of the final large-scale crucial test of JWST’s key systems. Integration testing of the telescope’s systems and those of it’s “bus” that includes the sun shield were completed in early 2019, while a test deployment of the complex and delicate sun shield “sandwich” – vital to keeping the telescope cool and allowing it to “see” in the glare of the sun – was successfully in October 2019.

Even so, the project has several more hurdles to clear before its actual launch date can be confirmed without risk of further significant delays, and such confirmation will not be given until after the coronavirus situation is no longer impacting the project, and a further review of its overall status completed.

Thirty years ago, in February 1990, the Voyager 1 space craft had completed its primary mission and was about to shut down its imaging system. However, before it did so, and in response to lobbying from the late Carl Sagan, celebrated astronomer, teacher, broadcaster, writer, futurist and member of the Voyager programme’s imaging team, mission managers order the spacecraft to turn its imaging system back towards Earth to take a final photograph of its former home.

Captured on February 14th, 1990, the image revealed Earth as little more than a tiny blue pixel caught in a  streak of sunlight falling across the camera’s lens. Sagan immediately dubbed the image Pale Blue Dot, and it became his – and Voyager 1’s – Valentine’s Day gift to all of humanity; a last goodbye from the probe taken at a distance of 6 billion km (40.5 AU); 34 minutes later, its camera system was permanently powered down to conserve the vehicle’s power generation system.

From the moment it was published, the image became iconic: a representation of the sum total of humanity, something Sagan recognised at a time when the Cold War still dominated world politics.

Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilisation, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ‘superstar,’ every ‘supreme leader,’ every saint and sinner in the history of our species lived there–on a mote of dust suspended in a sunbeam.

…It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.

– Carl Sagan, Pale Blue Dot, 1994

To mark the 30th anniversary of the original image, NASA issued a newly enhanced version of the image, carefully processed by a team led by software engineer and imagining specialist, Kevin M. Gill, seen at the top of this article. It once again reveals just how small and lonely our world really is. And while the Cold War has long since past, in this age of global warming and climate change, this new image of that tiny, pale blue dot and Sagan’s words remain as powerful a reminder of our fragile place in the Cosmos as they did more than two decades ago.

Betelgeuse: Extent of Dimming Revealed

I’ve previously written about the dimming of Betelgeuseas seen from Earth on a couple of occasions over the past few months (see: Space Sunday: a look at Betelgeuse (December 2019) and A farewell to Spitzer, capsules, stars and space planes (January 2020)). Now two images and a video have been released to show just how startling the apparent changes in the star have been over the course of a year.

As an irregular – and massive – variable star, Betelgeuse goes through cycles of dimming and brightening over time. However, what has occurred over the course of the past year is without precedent in the 125-year history of observations marking the star’s behaviour.

Overall, Betelgeuse’s apparently magnitude (brightness as seen from Earth) has fallen by a factor of 2.5 (or roughly 25-30%). This has prompted speculation that the star may have exploded into a supernova – its eventual fate – and we are currently seeing the light, which takes approximately 643 years to reach us, from the run-up to that cataclysmic event. While most astronomers do not believe this to be the case, the two images do present a stunning spectacle of a star in flux.

The images were captured by the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument attached to the Very Large Telescope (VLT, currently the most advanced visible light telescope in the world) operated by the European Southern Observatory Captured in January and December 2019, they not only show just how much  Betelgeuse has dimmed in that time, but also how it seems to have changed its shape.

Again, such changes of shape aren’t unusual for a pulsating variable star like Betelgeuse. The surface of such a star tends to be made up of giant convective cells that move, shrink and swell. However, while these pulses – referred to as stellar activity – have likely been responsible for past changes in Betelgeuse’s shape observed from Earth, they have never been anywhere as extreme as those indicated by SPHERE – although it has been acknowledged that they could also be exaggerated by a cloud of dust ejected by the star long enough ago to have cooled, and is now partially obscuring our view of Betelgeuse.

Continue reading “Space Sunday: A pale blue dot, and more on Betelgeuse” →

At 04:03 UTC  on Monday, February 10th (23:03 EDT, USA), the European Space Agency’s Solar Orbiter is due to be launched atop a United Launch Alliance Atlas V from Cape Canaveral Air Force Station, Florida. Referred to as SolO, the mission is intended to perform detailed measurements of the inner heliosphere and nascent solar wind, and perform close observations of the polar regions of the Sun, which is difficult to do from Earth, in order to gain a much deeper understanding of the processes at work within and around the Sun that create the heliosphere and which give rise to space weather.

The launch will mark the start of a three 3-year journey that will use a fly-by of Earth and three of Venus to use their gravities to help shift the satellite into a polar orbit around the Sun. Once there, and at an average distance of some 41.6 million km, SolO will move at the same speed at which the Sun’s atmosphere rotates, allowing it to study specific regions of the solar atmosphere beyond the reach of NASA’s Parker Solar Probe and Earth observatories for long periods of time.

Our understanding of space weather, its origin on the Sun, and its progression and threat to Earth, comes with critical gaps; the hope is by studying the the polar regions of the Sun’s heliosphere, scientists hope they can fill in some of these gaps. The outflow of this plasma interacts with the Earth’s magnetic field and can have a range of potential effects, including overloading transformers and causing power cuts, disrupting communications and can potentially damage satellites. Further, the disruption of the Earth’s magnetic fields can affect the ability of whales and some species of bird to navigate.

We don’t fully understand how space weather originates on the sun. In fact, events on the sun are very hard to predict right now, though they are observable after the fact. We can’t predict them with the accuracy that we really need. We hope that the connections that we’ll be making with Solar Orbiter will lay more of the groundwork needed to build a system that is able to predict space weather accurately.

– Jim Raines, an associate research scientist in climate and
space sciences engineering

Specific questions scientists hope SolO will help answer include:

• How and where do the solar wind plasma and magnetic field originate in the corona?
• How do solar transients drive heliospheric variability?
• How do solar eruptions produce energetic particle radiation that fills the heliosphere?
• How does the solar dynamo work and drive connections between the Sun and the heliosphere?

To do this, the satellite is equipped with a suite of 10 instruments, some of which will be used to track active solar regions that might explode into a coronal mass ejections (CMEs), a major driver of space weather. When a CME occurs, SolO will be able to track it and use other instruments to be able to break down the composition of the energetic outflow (and that of the outflowing solar wind in general).

Knowing the composition of this outflow should help determine where energy is being deposited and fed into the solar wind from eruptions on the Sun, and how particles are accelerated in the heliosphere – the bubble of space where the Sun is the dominant influence, protecting us from galactic cosmic radiation.

Combined with the work of the Parker Solar Probe, launched in August 2018 (see: Space Sunday: to touch the face of the Sun) and which gathers data from within the Sun’s corona, and observations from Earth-based observatories such as the Daniel K. Inouye Solar Telescope (DKIST), Solar Orbiter’s data should dramatically increase our understanding of the processes at work within and around the Sun.

Like the Parker Solar Probe, SolO will operate so close to the Sun it requires special protection – in this case a solar shield that will face temperatures averaging 5,000º C on one side, while keeping the vehicle and its equipment a cool 50º C less than a metre away on the other side. This shield is a complex “sandwich” starting with a Sun-facing series of titanium foil layers designed to reflect as much heat away from the craft as possible. Closest to the vehicle is a aluminium “radiator” that is designed to regulate the heat generated by the craft and its instruments. Between the two is a 25-cm gap containing a series of titanium “stars” connecting them into a single whole. This gap creates a heat convection flow, with the heat absorbed by the titanium layers venting through it, drawing the heat from the radiator with it, allowing Solar Orbiter to both expect excess solar heating and present itself from overheating.

SolO’s primary mission is due to last 7 years, and those wishing to see the launch can watch it livestreamed across a number of platforms, including You Tube.

Continue reading “Space Sunday: solar studies and rocket tests” →