Tag: Astronomy

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” →

On January 29th, 2020, the latest mission to study planets beyond our own solar system opened its eye to take a first look, in what is the start of a 3.5-year-mission to examine stars with known exoplanets.

The CHaracterising ExOPlanets Satellite (CHEOPS) a joint European / Swiss mission, was launched on December 18th, 2019 by a Soyuz-Fregat from Guiana Space Centre in Kourou, French Guiana, together with a number of other payloads. It forms the first of ESA’s new S-Class (Small Class) missions, capped at a maximum budget of €50 million apiece. It’s a small mission not just in terms of cost, but also in its physical size: CHEOPS measures just 1.5 metres on a side. Following launch, it entered a 700 km Sun-synchronous polar orbit.

Once there, initial testing of the satellite commenced. These first confirmed that communications between it and mission control were all working correctly. Once these had been thoroughly tested, the command was sent to boot-up the primary computer system so it could be run through a series of diagnostics before the primary science components were initialised. These tests also included the vehicle’s temperature control systems and the primary elements of the main telescope system – a 30 cm  optical Ritchey–Chrétien telescope.

These initial commissioning tests culminated in the opening of the telescope’s primary baffle – otherwise known as its lens cap. This was the most critical aspect of the initial commissioning – if the the baffle failed to hinge open, the telescope would be unable to observe its target stars.

Fortunately, the opening went as planned, allowing the final set of tests to commence. Over the next couple of months, these will see CHEOPS take hundreds of images of stars – some with exoplanets, some without, in order to examine the measurement accuracy of the telescope systems under different conditions, and confirm its operating envelope. At the same time, this period of testing will also allow this mission team to further integrate all aspects of ground operations. Again, if all goes according to plan, some of this first light images will be released by the CHEOPS science team, and the end of the tests will see the telescope commence its primary operations.

While thousands of exoplanets have been discovered, few of them have been accurately characterised in terms of both mass and diameter. This limits our ability to fully assess their bulk density, which is needed to provide clues to there composition and their possible formation history.So to help us gain better data, CHEOPS will accurately measure the size of known transiting exoplanets orbiting bright and nearby stars. These are planets that cause dips in the brightness of their parent stars as they pass between the star and Earth.

By targeting known systems, we know exactly where to look in the sky and when in order to capture exoplanet transits very efficiently. This makes it possible for CHEOPS to return to each star on multiple occasions around the time of transit and record numerous transits, thus increasing the precision of our measurements and enabling us to perform a first-step characterisation of small planets.

– Willy Benz, CHEOPS principal investigator

The transit method offer a “direct” means of detecting exoplanets, but it is not the only option open to us. A second method, generally referred to as the radial velocity method, or Doppler spectroscopy, can detect planets “indirectly”, by directing the doppler shifted “wobble” in a star’s motion. Around 30% of all exoplanets have been detected by this method, but it can be somewhat less informative than the transit method. This being the case, another aspect of the telescope’s mission will be looking at stars where orbiting planets have been detected via the radial velocity method in an attempt to detect the planets by the more direct transit method and again, by repeated observations, allow scientists to start to characterised them.

As a whole, CHEOPS will be particularly focused on exoplanets characterised as “super-Earths” – those thought to be between Earth and Neptune in size, many of which may well be solid in nature. While it will be able to characterise these exoplanets with a new level of precision, its work will pave the ways for follow-up observations in the future by telescopes like the James Webb Space Telescope (JWST – operating in the infra-red), and by large ground-based telescopes like the 40m Extremely Large Telescope currently under construction, allowing them to both refine the CHEOPS data and add to it.

Continue reading “Space Sunday: telescopes, lunar plans and Voyager 2” →

The end of January 2020 brings with it the end of a 16-year mission to explore the galaxy in the infra-red, as the Spitzer Space Telescope (SST) is shut down.

Launched in 2003, Spitzer was one of NASA’s four Great Observatories, following in the footsteps of the Hubble Space Telescope and the Chandra X-ray Observatory. Its infra-red vision has allowed Spitzer to peer through the dusty reaches of the cosmos to witness stellar nurseries, provide insight into the deaths of stars and the very formation of the universe, and increase our understanding of the structure of galaxies and the nature of black holes.

Spitzer operated as planned for 5.5 years – three years longer than its initial primary mission – until a lack of coolant prevented the telescope from operating within its planned low temperature range. A switch to a warmer operating mode allowed the telescope’s mission to be extended another 10.5 years, albeit it with only two of its sciences instruments able to function in the higher temperature range.

The official reason for ending the mission, even though the two remaining IRAC instruments remain operational, is issues of balancing operational requirements with those of power generation and communications. Spitzer occupies a similar orbit to Earth but is moving more slowly; as the gap between them widens, so to does the triangle formed by the Sun, Earth and the telescope, and it has now reached a point where in is impossible for the telescope to maintain both line-of-sight communications with Earth and keep its solar panels pointing to the Sun to generate power. Add to this the need to orient the telescope to observe study targets, and operating the telescope has become an increasingly complex and fuel-costly dance.

In 2017, NASA attempted to spin-off the telescope’s operations and management to academic institutions in 2017, but was unsuccessful. So, on January 29th, Spitzer will transmit to Earth the last of the data it has gathered, then on January 30th, it will be put into a hibernation mode, oriented in a permanent “sun-coning attitude”. In theory, it would be possible to recover the telescope from this state at some point in the future, except for the fact that the custom ground system for operating Spitzer is to be dismantled after the telescope has been shut down.

Overall, the cost of the Spitzer mission from launch to this final close-out will have been US $1.3 billion, a modest price for the wealth of data the mission has returned to Earth: over 8,700 scientific papers related to Spitzer’s discoveries and data have been published. However, the shut down will effectively bring space-based infra-red observations of the galaxy around us to an end – at least until the James Webb Space Telescope commences operations. This is expected to launch in 2021.

The telescope has made many discoveries beyond the imaginations of its designers, such as planets outside our solar system, called exoplanets, and galaxies that formed close to the beginning of the universe. We have a lot of new questions to ask about the universe because of Spitzer. It’s very gratifying to know there’s such a powerful set of capabilities coming along to follow up on what we’ve been able to start with Spitzer.

– Michael Werner, Spitzer project scientist, NASA Jet Propulsion Laboratory

China Prepares to Test Launch Its Next Generation Crew Vehicle

In 2018, I first wrote about China’s upcoming “next generation” crewed space vehicle that will eventually replace the Soyuz-derived Shenzhou craft. Since then, work has been proceeding with the design, with structural test articles being rigorously tested together with the vehicle’s parachute and landing systems, while the first flight-ready unit has also been under development and assembly.

The new craft mirrors both the the Apollo Command and and Service Module approach to crewed space systems and Boeing’s CST-100 Starliner. Like the former, it comprises a conical crew capsule supported in space be a cylindrical Service Module equipped with a single large motor and designed to provide the capsule with power and life support whilst in space. The Service Module is also thought to offer two variants: a small version for operations in Earth orbit, and a larger unit to help support missions further afield – such as to the Moon.

Like Boeing’s Starliner, the capsule is designed to carry up to 6 crew, or a combination of crew and cargo, and can be re-used up to 10 times. At the end of each flight, it will make a dry land touchdown using both parachutes and air bags.

On January 20th, the flight test vehicle arrived at China’s Wenchang Satellite Launch Centre on Hainan island in the South China Sea. It will be integrated with a Long March 5B launch vehicle – currently China’s most powerful booster – ready to for an uncrewed flight that will carry it some 8,000km from Earth before returning and making a soft landing. This first flight could take place as early as April 2020.

The vehicle has yet to be given an official name, and no date has been given for its possible entry into service. However, it is seen as a key component in China’s upcoming new space station – construction of which may also start this year – and in their human Moon exploration programme.

Continue reading “Space Sunday: a farewell to Spitzer, capsules, stars and space planes” →

Sunday, January 19th, 2020 saw SpaceX complete a major test that should help bring their Crew Dragon vehicle much closer to the point where it can commence carrying crews to / from the the International Space Station (ISS).

The test, referred to as a in-flight abort (IFA) test saw an uncrewed Crew Dragon vehicle launched from Launch Pad 39A at Kennedy Space Centre atop a Falcon 9 rocket in what was primarily a test of the vehicle’s launch abort system, is designed to push the capsule and its crew clear of a malfunctioning launch vehicle. However, the flight also served as an opportunity to test a further update to the vehicle’s descent parachute system (marking the first time this particular type of parachute had been used on a flight) and for SpaceX to further refine its crew recovery procedures for meeting returning Crew Dragon vehicles.

All the early indicators from the test are that everything ran as expected. Following lift-off and ascent, and at 84 seconds into the flight and an altitude of around 19 km, the first stage engine cut-off triggered the simulated malfunction, causing the abort system to release the clamps attaching the Crew Dragon to the dummy upper stage of the Falcon 9, the SuperDraco engines simultaneously firing, each one generating some 16,000 lbs of thrust. These immediately powered the Crew Dragon clear of the booster, travelling at a speed of over Mach 2, just as they would when trying to get a crew away from a malfunctioning rocket during an operational launch.

With the capsule detached, the Falcon 9 continued its own ballistic flight upwards, but the open end of dummy upper stage effectively functioned like a large, open-mouthed air brake, putting huge stresses on the vehicle. These caused the booster to break up, the remaining fuel on-board igniting in an explosion the test team had been expecting.

The SuperDraco motors fired for just 10 seconds. However, this was more than enough to put the craft on its own ballistic trajectory, allowing it to reach a peak altitude of around 40 km three minutes into the flight. Shortly ahead of reaching that point, the service module – referred to as the trunk, and designed to provide power and life support to the vehicle –  was jettisoned. Then as the capsule reached the zenith of its flight, the smaller Draco manoeuvring motors fired, stabilising it as it started its descent back towards Earth, enabling the drogue parachutes to deploy.

This pair of small parachutes allowed the vehicle to properly orient itself and act as a trigger for the release of the four main parachutes – as the drogues are jettisoned, they pulled clear a hatch covering the main parachute bay, just below the docking port that forms the nose of the Crew Dragon, allowing them to deploy, slowing the craft and bringing it down to a safe splashdown.

For crew recovery operations, SpaceX make use of two specially-equipped ships, GO Searcher and Go Navigator. Originally leased by the company from Guice Offshore (hence the GO in the name) for use in the recovery of Falcon Payload fairings, Go Searcher was extensively refitted in 2018 to manage recovery operations for Crew Dragon, gaining a new radar system for tracking incoming Crew Dragon vehicles, a new crew recovery area and medical facility for post-flight check-ups of returning crew, and an upper deck helipad for emergency medivac. Go Navigator completed a similar refit in 2019.

Ahead of the test flight, GO Searcher departed SpaceX’s facilities at Port Canaveral, and took up a loitering position on the edge of the expected splashdown zone some 30 km off the coast of Florida. Following splashdown, teams aboard rigid-hulled inflatable boats (RHIBs) raced to the capsule to start the work of safing the craft and securing it ready for recovery. During normal flight recovery work, the recovery vessel and its crew will additionally have the services of Air Force Detachment-3 to call on, an emergency team of divers and personnel trained for astronaut recovery operations. For this flight, once the capsule has been recovered the the GO Searcher’s stern deck, it will be returned to SpaceX’s facilities along with the recovered parachutes for study.

While the initial response ot the flight has been positive, post-flight review is expected to take several weeks, and NASA has pointed out that there are still a number of additional tests that need to be completed ahead of crewed flights.

There are some additional system-level tests of the spacecraft’s upgraded parachutes still needed to be completed, as well as other reviews of the spacecraft. [But] stepping through that [abort test] together and making sure that we’ve dotted all the i’s and crossed the t’s before our crew demonstration flight is very, very, important We’ve got work to do, but, honestly, getting this test behind us is a huge milestone.

– NASA Commercial Crew Programme manager, Kathy Lueders

As such, no date has been confirmed for the first crewed flight – officially called Demo-2, and which will see a 2-man crew fly a Crew Dragon to the ISS, where it will remains for approximately two weeks before they return to Earth. However, should the post-flight IFA test analysis prove positive, speculation is the Demo-2 flight could be staged as early as March, with “operational” flights starting later in 2020. In the meantime, the test flight can be followed in the video below, which has a start time set to just before the Falcon 9 ignites its main engine.

Continue reading “Space Sunday: commercial crew test flights & exoplanets” →