Tag: Astronomy

When a star like our own reaches the end of its life, two things happen: first, in a desperate attempt to keep itself burning after using its hydrogen and helium, it expands outwards into a red giant as it burns heavier elements in turn (our Sun will expand to a size sufficient to consume Mercury, Venus and Earth) before it collapses into a hot, white dwarf, a fraction of its former size (perhaps no bigger than the Earth).

But what of any gas giants orbiting the star well beyond the limits of its red giant expansion? What happens to them following the star’s collapse to a white dwarf? Do they simply continue until such time as their own internal heating fails? Might they have some additional interaction with their former parent?

A team from Warwick University, England, appear to have the answer. They’ve discovered a Neptune-sized planet some 4 times larger than its white dwarf host star, and the two have entered into what is – at this point in our understanding of such situations – a unique relationship.

The star is called WDJ0914+1914 and is some 2,000 light years away. Whilst reviewing data on it gathered by the Sloan Digital Sky Survey (SDSS), the astronomers came across something odd: the star was apparently giving off oxygen, sulphur and hydrogen emissions. While the oxygen was to be expected – by this time in a star’s life most of what is left is actually oxygen and carbon – the hydrogen and sulphur simply shouldn’t have been there.

Turning to the Very Large Telescope (VLT), the Warwick team found the emissions corresponded to to a ring of gas surrounding the star. At first they thought they had discovered a binary system in which the mass of one star was being drawn off by the other, forming a dust ring around both. However, further analysis revealed the composition of the disc matches the deeper layers of planets in our own Solar System like Neptune and Uranus, suggesting a planetary body still exists orbiting the star and material from that planet is feeding the disc, allowing it to survive.

While fusion has long since ended at WDJ0914+1914, the star is still radiating at some 28,000ºC – enough energy to tear material from the upper layers of a planet’s atmosphere. Much of this atmosphere would trail outwards from the planet as a hot plume – which the Warwick team detected – while some would collapse to feed the disc of material surrounding the star.

Putting their calculations together, the Warwick team worked out that the planet – which cannot be directly sighted – is likely to be around the size of Neptune, and it is losing its atmosphere at a rate of around 2,700 tonnes per second to both to the disc of material around the star, and eventually onto the star itself – “feeding” it, if you will. Although this sounds a lot, it actually adds up to a relative small amount given the size of the planet, and so the loss is unlikely to alter its overall structure as the star continues to cool.

This discovery at WDJ0914+1914 is unique at the moment – but it makes the case that other white dwarf stars may also be survived by planets, some of which we may be able to detect using the transiting method of observation (WDJ0914+1914 is simply too dim for this to work). Certainly, the Warwick team’s research has opened the door on this form of research, one that could help with our understanding of exoplanet atmospheres.  It also offers a cold look at the far future (roughly 4.5 to 5 billion years from now) of our own solar system.

New Dates For Commercial Crew Test Flights

NASA has issued new dates for the final test flights for the SpaceX Crew Dragon and Boeing CST-100 Starliner that, if passed, should allow both vehicles to move on towards actually transporting astronauts to and from the International Space Station.

On December 20th, 2019, a United Launch Alliance Atlas V will launch the first CST-100 Starliner into orbit on an uncrewed orbital test flight (OTF) to the International Space Station. As well as testing the Starliner’s avionics and flight systems, the flight will also test a new docking system that is intended to become the “”standard docking system for sending humans to Gateway and to Mars” as a part of the Artemis programme, and used to deliver additional supplies and some Christmas / New Year’s extras to the ISS crew.

Also flying on the vehicle will be a flight test dummy christened “Rosie the Rocketeer”, named for “Rosie the Riveter”, the iconic role model for U.S. women working in factories and on production lines in WW II. The dummy is fitted with an array of sensors to measure critical data including G-forces endured during the flight to inform the team about the stresses a human crew will experience during an ascent to orbit on the vehicle. Results from this data, and all telemetry gathered during the flight will help inform NASA and Boeing on the Starliner’s readiness to commence crewed flights.

The vehicle will not spend long at the ISS – it will be undocked on December 28th and make a return to Earth in a full dress-rehearsal for a crewed landing for the CST-100 capsule. Should weather interfere with the planned launch, both December 21st and 23rd offer suitable windows for the launch to take place.

Then, on January 4th, 2020, SpaceX is expected to complete an in-flight abort test. For that test, a Falcon 9 will lift off from Launch Complex 39A at Kennedy Space Centre carrying a test Crew Dragon vehicle – which has previously performed  a successful static fire test of its SuperDraco escape motors in November. Around 90 seconds into the flight, and the time of maximum dynamic pressure on the vehicle, the escape system will be triggered, the capsule hopefully escaping the rocket to make a safe splash-down under parachute.

SpaceX had hoped to complete this test before the end of the year, but assorted delays – including that of the CRS-19 resupply mission, which launched earlier in December (see: On the ISS – mighty mice and robots) – meant that target could not be met. If the abort flight test is successful, it should allow NASA and SpaceX to determine when crewed flights to the ISS can commence – an uncrewed test flight of the vehicle to the ISS having been completed in March 2019.

Overall. NASA would like both Boeing and SpaceX to complete their first crewed flights to the ISS – also regarded as test flights – by mid-2020.

Continue reading “Space Sunday: tiny stars & giant planets, and an interstellar visitor” →

What has long been suspected has likely now confirmed: water is present under the ice of Jupiter’s moon Europa.

As I’ve noted on numerous occasions in this space Sunday articles, it’s long been thought that an ocean of water exists under the cracked icy crust of Europa, potentially kept liquid by tidal forces created by the moon being constantly “flexed” by the competing gravities of Jupiter and the other large Moons pulling on it, thus generating large amounts of heat deep within its core – heat sufficient to keep an ocean possibly tens of kilometres deep in a liquid state.

Circumstantial evidence for this water has already been found:

• During its time studying the Jovian system between 1995 and 2003, NASA’s Galileo probe detected perturbations in Jupiter’s magnetic field near Europa – perturbations scientists attributed to a salty ocean under the moon’s frozen surface, since a salty ocean can conduct electricity.
• In 2012 the Hubble Space Telescope (HST) captured an image of Europa showing what appeared to be a plume of water vapour rising from one of the many cracks in Europa’s surface – crack themselves pointed to as evidence of the tidal flexing mentioned above. The plume rose some 200 km from the moon.
• In 2014, HST captured images of a similar plume rising some 160 km above Europa.

Now a new paper, A measurement of water vapour amid a largely quiescent environment on Europa, published on November 18th, 2019 in Nature, offers the first direct evidence that water is indeed present on Europa. Specifically, the team behind the study, led by US planetary scientist Lucas Paganini, claims to have confirmed the existence of water vapour on the surface of the moon.

Essential chemical elements (carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulphur) and sources of energy, two of three requirements for life, are found all over the solar system. But the third — liquid water — is somewhat hard to find beyond Earth. While scientists have not yet detected liquid water directly, we’ve found the next best thing: water in vapour form.

– Lucas Paganini

Using the W.M. Keck Observatory in Hawaii, Paganini and his team studied Europa over a total of 17 nights between 2016 and 2017. Using the telescope’s spectrograph, they looked for the specific frequencies of infra-red light given off by water when it interacts with solar radiation. When observing Europa’s leading hemisphere as it orbits Jupiter, the team found those signals, estimating that they’d discovered sufficient water vapour to fill an Olympic-size swimming pool in a matter of minutes. However, the discovery has been somewhat tempered by the fact water may only be released relatively infrequently.

Such infrequent releases help explain why it has taken so long to confirm the existence above Europa, but there are other reasons as well. The components that comprise water have long been known to exist on the moon whether or not they indicate the presence of water. Thus, detecting these components within a plume doesn’t necessarily equate to the discovery of water vapour – not unless they are in the right combinations. There’s a further pair of complications in that none of our orbital capabilities are specifically designed to seek signs of water within the atmospheres of the other planets or expelled from icy moons. So Earth-based instruments  – like the Keck telescope spectrographs – must be used, and these deal with the naturally occurring water vapour in our own atmosphere.

Within Paganini’s team there is confidence that their findings are correct, as they diligently perform a number of checks and tests to remove possible contamination of their data by Earth-based water vapour. Even so, they are the first to acknowledge that close-up, direct studies of Europa are required – particularly to ascertain if any water under the surface of Europa does form a globe-spanning ocean, or if it is confined to reservoirs or fully liquid water trapped within an icy, slushly mantle. It is hoped that NASA’s Europa Clipper and Europe’s JUICE mission (both of which I’ve “previewed” in Space Sunday: to explore Europa, August 2019) will help address questions like this.

Continue reading “Space Sunday: Europa’s water and a Starship’s mishap” →

Sunday, October 27th, 2019 saw the return to Earth of one of the US Air Force X-37B “mini-shuttles” after a record-breaking 780 days in space.

The uncrewed vehicle, originally developed by NASA, has been operated by the USAF since it took over the programme in 2004, undertaking the first drop-tests of the vehicle in 2006. Since starting orbital missions in 2010, the vehicle has been subject to much speculation and conspiracy theories, largely because most of its orbital operations have been classified, with only a few details of experiments carried being offered to the public.

Officially designated Orbital Test Vehicle (OTV), there are two X-37B vehicles known to be in operation, although it is not clear which vehicle returned to Earth on October 27th, 2019 at 03:51 EST – while the USAF has previously noted the vehicle engaged in a mission as either OTV 1 or OTV 2, they remained silent on the vehicle involved in this 5th mission both prior to its September 7th, 2017 launch atop a SpaceX Falcon 9 booster, and throughout the mission, although it is believed that based on the mission count to date, it was most likely OTV 1.

As with previous missions, the majority of the vehicle’s payload has been classified, with the USAF only confirming one experiment carried was the Advanced Structurally Embedded Thermal Spreader II (ASETS-II), a system for dispersing heat build-up across flat surfaces such as electronic systems such as CPUs and GPUs through to the likes of spacecraft surfaces.

Elsewhere, the USAF has indicated that OTV will be used to test advanced guidance, navigation and control systems, experimental thermal protection systems, advanced avionics and propulsion systems and  lightweight electromechanical flight systems. Some of these have been witnessed through all five of OTV’s missions to date – notably the vehicle’s guidance, navigation, control and flight systems. It is some of these uses that have led to the speculation around the vehicle’s intended purpose.

This latest mission, for example, saw an OTV inserted into a higher inclination orbit than previous missions. This both expanded its operational envelope and allowed the vehicle to modify its orbit during flight. Both of these aspects of the mission caused some to again point to the idea that that OTV is intended to be some form of weapons platform (highly unlikely when one considers the complexity of orbital mechanics), to the the idea that it is some kind of super-secret spyplane (again unlikely, given that the US operates a network of highly-capable “spy” satellites).

Even when it comes to the tasks OTV is designed to perform, fact is liable to be more mundane than conspiracy theory would like. For example, while OTV has been used to test a new propulsion system, it is not some super-secret (and mythical) EM drive NASA has supposedly developed, but rather a Hall effect ion drive thruster.

OTV-5 / USA-277 not only achieved the longest duration flight of the programme to date, it marked the first time an X-37B was launched from Kennedy Space Centre and return to KSC – all the previous flights had been been launched from either Cape Canaveral Air Force Station, Florida (adjacent to KSC) or Vandenberg, California, Air Force Base, although the previous mission, OTV-4 / USA-212 was the first to land at KSC’s Shuttle Landing Facility (the first 3 missions all landing at Vandenberg AFB). Overall, the 780 day mission brings the total time the X-37B vehicles have spent in space over 5 missions to an astonishing 2,865 days, or (approx) 7 years and 10 months, in orbit – more than double the total amount of time (1,323 NASA’s entire shuttle fleet spend in orbit over 30 years of operations.

The next flight for the system is expected to launch in the first half 2020.

Pluto’s Far Side Revealed

In July of 2015, NASA’s New Horizons vehicle, the core part of a mission of the same name, shot through the Pluto – Charon system, making its closest approach to the dwarf planet and its (by comparison) oversized moon on July 14th of that year. Launched in 2006 the mission spent a relatively brief amount of time in close proximity to Pluto as it shot through the system at 50,700 km/h (31,500 mph), but it has completely turned our understanding of this tiny, cold world completely on its head – as I’ve hopefully shown in writing about Pluto and the mission in these pages.

So much data was gathered during the fly-by that it took months for the probe to return it all to Earth, and even now, four years after the encounter, that data is still being sifted through and researched. Within the data were many, many splendid high-resolutions of the “encounter side” of Pluto – the sunward-facing side of the planet the spacecraft could clearly image as it sped into closest approach – many of which have again appeared in these pages as well as elsewhere.

However, the joy at the amount of information the mission returned has been mixed with a degree of frustration. The nature of the fly-by means that while New Horizons gathered spectacular images of the “encounter side” of Pluto, by the time sunlight was falling across what had been the “far side” of the dwarf planet during closest approach, the probe was so far away it could not capture images to the same level of resolution as gained with the “encounter side”.

Continue reading “Space Sunday: a mini-shuttle, Pluto’s far side & mole woes” →

NASA’s attempts to free the heat-sensing “mole”, deployed onto the surface of Mars by the InSight lander mission at the end of 2018 have met with some success.

As I reported at the start of October, the “mole”, a special probe that forms a key part of the Heat Flow and Physical Properties Package (HP³), is designed to propel itself up to 5 metres (16 ft) beneath the surface of Mars in order to record the amount of heat escaping from the planet’s interior, helping scientists determine more about the planet. However, Since February of 2019, it has been stuck, having travelled just 30 cm and leaving it partially sticking out of the ground. Numerous attempts to get it moving again have been tried, none of which, up until this most recent attempt, had managed to get the “mole” moving again.

The problem was believed to be down to the self-propelled probe being unable to generate sufficient friction against whatever material it had burrowed into in more to gain downward traction. At that time, I noted that the mission team where hoping to use the lander’s robot arm to apply direct pressure against the exposed portion of the probe in the hope of pushing it against the side of the hole it has so far created, giving it sufficient traction to resume burrowing.

On October 14th, 2019, the German team responsible for the “mole” confirmed the attempt had worked: the probe had resumed progress during the initial test, burrowing a further 3 cm (just over an inch). That may not sound much, and it certainly doesn’t mean the “mole” is in the clear; however, it does tend remove the other lurking fear: that the probe had in fact hit a solid mass such as a boulder or rock that was impeding its downward progress.

The mole still has a way to go, but we’re all thrilled to see it digging again. When we first encountered this problem, it was crushing. But I thought, ‘Maybe there’s a chance; let’s keep pressing on.’ And right now, I’m feeling giddy.

– Troy Hudson, JPL engineer-scientist leading the US side of
efforts to get the “mole” moving again

This doesn’t mean the “mole” is free and clear however; the extent of the loose material it appears to have burrowed into is unknown, and as the data cable connected to it cannot be used to simply haul it back out of the initial hole, the decision has been made to keep the scoop of InSight’s robot arm pressed against the exposed portion of the probe until such time as it can no longer provide support. The hope is that by the time this has happened, the mole will have moved beyond the looser material that seems to be hampering downward movement. However, in case if it has not, the team are now looking at other options to try to assist the probe – such as filling-in the hole behind it in the hope that sufficient material falls around it to provide it with the traction it needs.

Throughout its time on Mars, InSight has been under observation by NASA’s Mars Reconnaissance Orbiter, which routinely passes over the Elysium Planitia region where InSight landed. As such, it has been able to image the lander on several occasions, but on September 23rd, 2019, MRO directly overflew InSight’s landing site at an altitude of 272 km (169 mi), and the orbiter’s HiRISE imaging system captured what is regarded as the best image yet of InSight (blow).

The main image above shows the lander on the surface of Mars surrounded by the blast circle left by its landing motors. The inset image shows the lander in greater detail, revealing its two circular solar panels, each just over 2 m (7 ft) across (in green), with the body of the lander between them (brighter green). The bright dot just below the lander is the protective dome covering the seismometer deployed to the surface of Mars along with the HP³ mentioned above. Also visible in the main image is a series of diagonal streaks on the Martian surface. These are the tracks left by dust devils that have passing through the area.

As well as issuing the image of InSight on October 16th, NASA also released an animated GIF showing the Mars Science Laboratory’s progress up the slopes of “Mount Sharp” (Aeolis Mons). The GIF switches between two shots of “Mount Sharp” taken at the same overhead angle and roughly two months apart. Between them, they show Curiosity’s progress across 337 m (1,106 ft) of what was dubbed the “clay bearing unit”. The first image, which has Curiosity circled near the top, was captured on May 31st, 2019 as the rover was sitting within “Woodland Bay”. The second image shows Curiosity on July 20th, 2019, as it sat on a part of the unit called “Sandside Harbour” further up the slopes of “Mount Sharp”.

UK and Japan Plan to Send Rovers to the Moon

Both the United Kingdom and Japan are planning to become part of a select community (thus far!) of countries that have operated rover vehicles on the surface of the Moon.

To date, only three nations have operated rover vehicles on the lunar surface: Russia, with its Lunokhod 1 and Lunokhod 2 rovers, China with its Yutu rovers (all of which were automated vehicles) and America with the Apollo lunar roving vehicle famously driven by the astronauts of Apollo 15 through 17. The Japanese and British rovers will be very small, as carried to the Moon as part of a robotic lander called Peregrine being developed by US commercial organisation, Astrobotic, one of the former contenders for the Google Lunar X Prize.

The Japanese rover, called Yaoki, is a single axle vehicle designed by Dymon Co., Ltd, based in Tokyo and specialising in robotic systems development. The company has been working on the design for eight years, with the overall technology design having been finalised in 2018, and the development cycle including several hundred hours of field testing, causing Dymon to dub it, “the smallest but most effective wheeled rover ever produced.” A video of the little rover undergoing field testing has been released by one of the engineers working on the project that – while a little dramatic in places – highlights Yaoki’s capabilities.

The British rover weighs-in at just 1 kg (2.2 Lb) and is solar-powered with a range of some 10 m (33 ft). However, unlike traditional rovers, it will not have wheels or even tracks – it will get around by walking on four spider-like jointed legs. Like the Japanese rover, it will be equipped with high-definition video and camera systems.

Developed by a London-based company called Spacebit, the rover is more of a proof-of-concept unit than outright science instrument; if Successful, Spacebit hope that the little rovers will become a feature of multiple missions, exploring both the surface and sub-surface regions of the lunar surface – they are specifically designed to scuttle into small lava tubes and explore them.

The Peregrine lander is designed to deliver payloads to the Moon at a cost of US 1.2 million per kilogramme in support of NASA’s Artemis lunar exploration programme. Its payload limit is some 264 kg (584 lb), although the mission carrying the two rovers  – which will be the first flight for the lander will only carry 90 kg of payload. It is currently scheduled for a July 2021 launch using a United Launch Alliance Vulcan rocket – the first certification launch for that vehicle.

The cost of the mission – US $79.5 million – is being met by NASA, with the agency supply providing 14 of the lander’s total of 21 payloads, which between them will mass 90 kg and will include at least one other, larger rover vehicle. The proposed landing site is Lacus Mortis, a relatively flat northern latitude plateau. Once there, the lander and its rovers are expected to operate for 8 terrestrial days.

Continue reading “Space Sunday: moles, rovers, and spacewalks” →