Tag: Astronomy

Space update special: the 7-exoplanet system

Posted on by Inara Pey
An artist's impression of the sky from the outermost of the three TRAPPIST exoplanets in the star's habitable zone (see the 360-video below)
An artist’s impression of the sky from the outermost of the three TRAPPIST exoplanets in the star’s habitable zone (see the 360-video below). Credit: NASA

On Wednesday, February 22nd, US space agency NASA, working with a team of European astronomers, confirmed no fewer than seven extra-solar planets are orbiting a star some 39 light years away – with three of them within the so-called “Goldilocks zone” of habitability.

The star in question is TRAPPIST-1, named for the instruments used in its discovery, the Transiting Planets and Planetesimals Small Telescope (TRAPPIST),  and more formally known as 2MASS J23062928-0502285. Regular readers of my Space Sunday column might remember that I referred to the system back in November 2016, whilst discussing the James Webb Space Telescope and the hunt of exoplanets. The NASA announcement, which coincides with the publication of a new paper by the TRAPPIST team, adds dramatic new information to the distant star system.

The first two of the planets orbiting the star were located in May 2016, after the TRAPPIST team had studied the results of a continuous series of observations of the star between September and December 2015 using the telescope, located at the European Southern Observatory’s (ESO) La Silla Observatory in Chile.

Artist’s concept showing what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances. Credit: NASA
Artist’s concept showing what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances. Credit: NASA

What was intriguing about the two world was that not only were both within the so-called “Goldilocks zone” of their parent planet, where conditions might be “just right” for life to start, but both were roughly comparable to Earth in size, and therefore likely solid bodies, and spectral analysis suggested both have atmospheres.

A third planet, TRAPPIST-1d was also discovered the the same time, but it was behaving oddly. This prompted a further extended period of observation between September and October 2016, using both the ESO’s ground-based Very Large Telescope, and the Spitzer Space Telescope. This work revealed at “TRAPPIST-1d” was not one, but three worlds, again, all roughly in the Earth-sized category. Spitzer’s data additionally revealed two more planets of roughly the same size, taking the total to seven. Following this, Hubble turned its attention on the planets, looking for signs of hydrogen and helium – the chemical signatures that would indicate if any of them might be gas giants. It found none, further confirming they are likely rocky in nature.

The size, mass and density of these telluric worlds were obtained by measuring the periodic dips in TRAPPIST-1’s luminosity as a result of each of the planets passing in front of it. This allowed the international team studying the system to further assess whether each world was rocky, icy, or gaseous and determine which might be habitable.

trappist-1-3
Via: Space.com. Click for full size

TRAPPIST-1 is an ultra-cool red dwarf star only slightly larger than the planet Jupiter, and about 2,000 times dimmer than the sun.

Such stars, designated Class M, are the most frequent type of star in the Universe – making up an estimated 70% of stars in our galaxy alone. However, they do not radiate energy like our own sun, instead they are very volatile; all activity within them is entirely convective in nature, giving rise to massive stellar flares.

Given TRAPPIST-1 is so small, all of its planets orbit in very close proximity to it – closer than Mercury is to the Sun (the nearest orbits its parent star once every 1.5 terrestrial days, and the outermost, about once every 20 terrestrial days). This makes them very vulnerable to violent outbursts by the star, and could affect their surface conditions and their ability to retain an atmosphere.

This close proximity also means all of the planets are tidally locked – they always have the same side facing their sun. Thus they all are likely to have extremes of temperature, and those with an atmosphere are likely to have quite extreme weather as well. However – and conversely – it also means they could have the potential for liquid water to exist on their surfaces.

The innermost of the three planets in the habitable zone, TRAPPIST-1e, is very close in size to Earth, and receives about the same amount of light as Earth does, and may well have similar day time temperatures. The middle planet of the three, TRAPPIST-1f, meanwhile, might be a water rich world, also roughly the same size as Earth. It has a 9-day orbit, and receives about the same amount of light from its sun as Mars does from our own.

Another artist's impression of how the TRAPPIST system might look from the surface of one of the worlds - assuming they have liquid water present
Another artist’s impression of how the TRAPPIST system might look from the surface of one of TRAPPIST-1f, the middle one of the three planets in the star’s habitable zone – assuming it has liquid water present. Credit: NASA

Continue reading “Space update special: the 7-exoplanet system” →

Space Sunday: Jupiter, Enceladus and Ceres; SLS, SpaceX and Dream Chaser

Posted on by Inara Pey
This stunning enhanced colour images of Jupiter's south polar region was captured by the JunoCam instrument aboard the Juno spacecraft on February 2nd, 2017. It reveals a complex series of interactions occurring in the fast-spinning atmosphere
This stunning enhanced colour images of Jupiter’s south polar region was captured by the JunoCam instrument aboard the Juno spacecraft on February 2nd, 2017. It reveals a complex series of interactions occurring in the fast-spinning atmosphere. Credit: NASA/JPL / SwRI

Following its latest close flyby of Jupiter – passing just 4,200 km (2,600 mi) above the gas giant’s cloud tops on February 2nd, 2017, NASA’s Juno mission spacecraft is now heading away from the planet once more and the next of its 53.5 day orbits. As I’ve previously reported in these Space Sunday columns, the original plan had been to use one of these close passes over the planet (October 2016), in conjunction with a sustained burn of the spacecraft’s British-built rocket motor, to move it into a short, 14-day period orbit around Jupiter.

However, a potential fault detected within the engine system meant the October burn was cancelled, and since then, engineers had been trying to assess if the issue  – a set of faulty valves – could be overcome, and the consequences of attempting an additional engine burn if not. No definitive answer has been found and so, following the February 2nd flyby, the decision was taken to cancel all plans for the engine burn and leave the spacecraft in its current 53.5 day orbit around Jupiter.

Doing so doesn’t compromise the overall mission objectives, but it does reduce the number of close passes over Jupiter the vehicle can make. If the reduced orbital period had been possible, the spacecraft would have made some 30 close flybys over Jupiter’s cloud tops during the primary mission period, set to end in July 2018. Remaining in the 53.5 day orbit means it will only make around 12 such close flybys in the same period.

The Juno spacecraft was supposed to complete two 53-day orbits around Jupiter, then lower its orbit Oct. 19 to fly around the planet once every 14 days. That engine burn has been postponed. Credit: NASA / JPL
The Juno spacecraft was supposed to complete two 53.5-day orbits around Jupiter in July and August 2016 (shown in green), before using its main engine to brake itself into a 14-primary science orbit (shown in blue). Due to continued concerns about the vehicle’s engine unit, the decisions has now been made to leave it in the 53.5 day orbit. Credit: NASA / JPL

A positive point with the spacecraft remaining in its more extended orbit is that it will spend less time within the harsher regions of Jupiter’s radiation belts, and could thus remain active for longer than the primary mission period – and mission planners are already considering applying for further funding to allow the mission to extend beyond July 2018. It also means that the spacecraft will be able to engage in additional science activities.

The close encounters with Jupiter have already allowed the spacecraft to probe deep within the planet’s cloud belts and discover they extend far deeper into the planet’s atmosphere than had been imagined, and that Jupiter’s magnetic field and auroras are more powerful than previously thought.

“Juno is providing spectacular results, and we are rewriting our ideas of how giant planets work,” Juno principal investigator Scott Bolton, of the South-west Research Institute in San Antonio, Texas, said of the decision to leave the spacecraft in its current orbit. “The science will be just as spectacular as with our original plan.”

NASA Considering Crewed Option for Orion / SLS First Launch

NASA is considering making the first launch of its new Space Launch System (SLS) rocket, currently slated for September 2018, a crewed mission.

Under the agency’s existing plans, the first launch of the new rocket, topped by an Orion Multi-Purpose Crew Vehicle and dubbed Exploration Mission 1 (EM-1), would have seen SLS send an uncrewed Orion vehicle to the Moon and back, with around 6 days spent in lunar orbit. A crewed flight of the SLS / Orion combination would not take place until at least 2021, when crew would use Orion to rendezvous to a small asteroid previously captured via robotic means and moved to an extended orbit around the Moon – an idea which has garnered a certain amount of criticism from politicians.

An artist's impression of a Space Launch System / Orion combination lifting off from Kennedy Space Centre's Pad 39B. Credit: NASA
An artist’s impression of a Space Launch System / Orion combination lifting off from Kennedy Space Centre’s Pad 39B. Credit: NASA

If approved, the new proposal – put forward by NASA’s Acting Administrator, Robert Lightfoot – would see the planned EM-1 mission pushed back to 2019 (allowing the Orion vehicle to be outfitted with the crew lift support and flight systems) and flown with a crew of two. While this would mean a delay in the initial launch of SLS / Orion, it could ultimately accelerate NASA’s plans, allowing the agency to present a wider choice of crewed missions in the 2020s, and respond to criticism that it is not doing enough to demonstrate how it plans to achieve a return to the Moon and / or  missions to Mars.

Enceladus: Cradle for Life?

On February 17th, 2005 NASA’s Cassini space probe, part of the Cassini / Huygens mission, made its first flyby of Saturn’s moon Enceladus.

Scientists were naturally curious about the 500 km (360 mi) diameter moon, which is the most reflective object in the solar system, but assumed it was essentially a dead, airless world. However, Cassini immediately found this was not the case.

A dramatic plume sprays water ice and vapor from the south polar region of Saturn's moon Enceladus. Cassini's first hint of this plume came during the spacecraft's first close flyby of the icy moon on February 17, 2005. Credit: NASA/JPL / Space Science Institute
A dramatic plume sprays water ice and vapour from the south polar region of Saturn’s moon Enceladus. Cassini’s first hint of this plume came during the spacecraft’s first close flyby of the icy moon on February 17, 2005. Credit: NASA/JPL / Space Science Institute

The first thing that happened was the magnetometer on the spacecraft revealed that Saturn’s magnetic field, which envelops Enceladus, was perturbed above the moon’s south pole in a way that didn’t make sense for an inactive world – it was as if there was some interaction with an atmosphere.

In the second flyby, a month later, Cassini found the interaction seemed to suggest a plume of water vapour was rising from the moon. Then, in the third flyby, in July 2005, the probe imaged geysers of water vapour erupting from the moon’s south polar region, and thus Enceladus became the target of intense study. So much so, that while only those initial 3 flybys of the moon had been a part of the primary Cassini /Huygens mission profile, the mission was updated to allow 20 more flyby of the moon.

Today, we know that beneath the mantle of ice enclosing Enceladus there is an ocean of liquid water – the geysers are the results of that water breaking through this ice and jetting into space, giving rise to Saturn’s E-ring in the process. This ocean is likely to be warmed and kept liquid by hydrothermal vents on the sea floor, and these in turn – just like the vents theorised to be on the ocean floor of Jupiter’s Europa – might provide all the ingredients for basic life to arise.

To celebrate the 12th anniversary of Cassini’s discoveries with Enceladus, NASA has released a video documenting those initial findings from 2005.

Continue reading “Space Sunday: Jupiter, Enceladus and Ceres; SLS, SpaceX and Dream Chaser” →

Space Sunday: Martian quandaries, universal epochs and Jovian journeys

Posted on by Inara Pey
"Yellowknife Bay" a region examined by the Curiosity Rover in 2012/13 indicated that a lake was once present in Gale Crater. However, the same rock has revealed that potentially, there was not sufficient carbon dioxide present in the atmosphere to help keep the water unfrozen
“Yellowknife Bay” a region examined by the Curiosity Rover in 2013 indicated that a lake was once present in Gale Crater. However, the same rock has revealed that potentially, there was not sufficient carbon dioxide present in the atmosphere to help keep the water unfrozen. Credit: NASA

Mars scientists are wrestling with a problem. Ample evidence says ancient Mars was sometimes wet, with water flowing and pooling on the planet’s surface. Yet, the ancient sun was about one-third less warm and climate modellers struggle to produce scenarios that get the surface of Mars warm enough for keeping water unfrozen.

A leading theory is that ancient Mars had a thicker carbon-dioxide atmosphere forming a greenhouse-gas blanket, helping to warm the surface. However an analysis of data from NASA’s Mars rover Curiosity, suggests that even 3.5 billion years ago there was too little carbon dioxide present in the Martian atmosphere to provide enough greenhouse-effect warming to prevent water freezing.

The source of these findings is the very same bedrock in which the rover found sediments from an ancient lake in which microbes might have thrived. When analysing the bedrock, Curiosity detected no carbonate minerals, leading to the conclusion that Mars’ atmosphere was almost devoid of carbon dioxide when the lake existed 3.5 billion years ago. And that’s a quandary for scientists.

Curiosity took this selfie while at "Yellowknife Bay" in 2013 whilst gathering rock samples for analysis. Note that while the shadow of the rover's robot arm can be assn, the arm itself is blanked from the images purely as a result of the angles used in individual shots and the way the images have been stitched together to provide a view of the rover
Curiosity took this selfie while at “Yellowknife Bay” in 2013 whilst gathering rock samples for analysis. Note that while the shadow of the rover’s robot arm can be seen, the arm itself is blanked from the images purely as a result of the angles used in individual shots and the way the images have been stitched together to provide a view of the rover. Credit: NASA

“We’ve been particularly struck with the absence of carbonate minerals in sedimentary rock the rover has examined,” Thomas Bristow, the principal investigator for Curiosity’s Chemistry and Mineralogy (CheMin) instrument,  the primary source of the analysis work. “It would be really hard to get liquid water even if there were a hundred times more carbon dioxide in the atmosphere than what the mineral evidence in the rock tells us.”

In water, carbon dioxide combines with positively charged ions such as magnesium and ferrous iron to form carbonate minerals, and CheMin can identify carbonate if it makes up just a few percent of the rock. Yet Curiosity has made no definitive detection of carbonates in any lakebed rocks sampled since it landed in Gale Crater in 2012. However, other minerals – magnetite and clay minerals – not only indicated in the same rocks indicate the ions needed to form carbonates were readily available, they also provide evidence that subsequent conditions never became so acidic that carbonates would have dissolved away over time.

The dilemma between a warm, wet Mars and the lack of carbonates has actually been growing for years. For two decades researchers have been using spectrometers on Mars orbiters to search for carbonate that could have resulted from an early era of more abundant carbon dioxide in the atmosphere, only to find far less than anticipated. Yet clues such as isotope ratios in today’s Martian atmosphere continue to indicate the planet once held a much denser atmosphere than it does now, which has largely been seen as being rich in carbon dioxide. Thus, a paradox has arisen.

Curiosity uses a spectrometer on its robot arm to check a rock dubbed "John Klein" in "Yellowknife Bay" for its suitability as a drilling target, January 25th, 2013. The drill itself can be seen on the robot arm's "hand", pointing up and to the right
Curiosity uses a spectrometer on its robot arm to check a rock dubbed “John Klein” in “Yellowknife Bay” for its suitability as a drilling target, January 25th, 2013. The drill itself can be seen on the robot arm’s rotating “hand”, pointing up and to the right. Credit: NASA

It had been thought that the lack of evidence for carbonates when seen from orbit could simply be the result of  dust covering them, or the carbonates having moved underground. Finding them would thus resolve the paradox and reveal what had happened. However, the Curiosity results tend to overturn this idea. Simply put, the rover has failed to detect carbonate minerals precisely where they should be located, within rocks formed from sediments deposited under water.

“This analysis fits with many theoretical studies that the surface of Mars, even that long ago, was not warm enough for water to be liquid,” said Robert Haberle, a Mars-climate scientist at NASA Ames. “It’s really a puzzle to me.”

One idea put forward is that perhaps the lake was never a body of open water, but was covered in ice. The problem with this idea is none of the expected evidence for an ice-covered lake, such as large and deep cracks called ice wedges, or “dropstones,” which become embedded in soft lakebed sediments when they penetrate thinning ice, have been found. Thus, scientists have a lot of head scratching and theorising to do in order to make sense of the dilemma.

Traversing Mars with Curiosity

A simulated Curiosity rolls over the "Naukluft Plateau" in this still from Seán Doran's video simulation of the rover's traverse
A simulated Curiosity rolls over the “Naukluft Plateau” in this still from Seán Doran’s video simulation of the rover’s traverse. Credit: Seán Doran

Ever wondered what it would be like to witness Curiosity trundling across the surface of Mars? Seán Doran has. What’s more, he’s been putting together animated films using Digital Terrain Model (DTM) data from the HiRISE imaging system on NASA’s Mars Reconnaissance Orbiter together with photomosaics of images from the rover, and combining them with a drivable correctly scaled model of the rover to provide movies of Curiosity as it rolls across Mars.

Continue reading “Space Sunday: Martian quandaries, universal epochs and Jovian journeys” →

Space Sunday: looking back on Earth and landing rockets and probes

Posted on by Inara Pey
The Earth and Moon, as seen from orbit over Mars, November 20th 2016
The Earth and Moon, as seen from orbit over Mars, November 20th 2016

Two marbles sit on a midnight background, one a swirl of blue, white, brown and green, the other tinted in shades of grey. Together they are the Earth and her Moon as seen by the most powerful imagining system currently orbiting the planet Mars.

It is, in fact a composite image, although Earth and the Moon are the correct sizes and the correct position / distance relative to one another. The images were captured by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter (MRO) on November 26th, 2016.

The images were taken to calibrate HiRISE data, since the reflectance of the moon’s Earth-facing side is well-known. As such, this is not the first image of our home planet and its natural satellite captured from Martian orbit, but it is one of the most striking. Whilst a composite image, only the Moon’s brightness has been altered to enhance its visibility; were it to be shown at the same brightness scale as Earth, it would barely be visible. That it appears to be unnaturally close to Earth is in fact an illusion of perspective: at the time the pictures were taken, the Moon was on the far side of Earth relative to Mars, and about to pass behind it.

The image of Earth shows Australia prominent in the central area of the image, its shape just discernible in this high-resolution image, taken when Mars and the MRO were 205 million kilometres (147 million miles) from Earth.

For me, this is another picture demonstrating just how small, fragile and unique our home world actually is.

 Falcon 9 Makes Triumphant Return to Flight

With Federal Aviation Authority (FAA) approval given, SpaceX, the private space company founded by Elon Musk, made a triumphant return to flight status with its Falcon 9 launch system on Saturday, January 14th.

January 14th, 2017: the SpaceX Falcon 9, carry 10 advanced Iridium Next communications satellites in its bulbous paylod fairing, lifts-off from Space Launch Complex 4E, Vandenberg Air Force Base, California Credit: SpaceX
January 14th, 2017: the SpaceX Falcon 9, carry 10 advanced Iridium NEXT communications satellites in its bulbous payload fairing, lifts-off from Space Launch Complex 4E, Vandenberg Air Force Base, California Credit: SpaceX

SpaceX launches had been suspended in September 2016, after a Falcon 9 and its US $200 million payload were loss in an explosion during what should have been a routine test just two days ahead of the planned launch (see here for more). Towards the end of 2016, and following extensive joint investigations involving NASA and the US Air Force (The Falcon 9 was located at Launch Complex 40 at the Canaveral Air Force Station when the explosion occurred), SpaceX were confident they had traced the root cause for the loss to a failure of process, rather than a structural or other failure within the vehicle itself. However, they had to wait until the FAA had reviewed the investigation findings and approved the Falcon 9’s return to flight readiness before they could resume operations.

The January 14th launch came via the SpaceX West Coast facilities, again leased from the US Air Force, and saw a Falcon 9 booster lift-off from Space Launch Complex 4E at Vandenberg Air Force Base in California. The rocket was carrying the first ten out of at least 70 advanced Iridium NEXT mobile voice and data relay satellites SpaceX will launch over the coming months, as Iridium Communications place a “constellation” of 81 of the satellites in orbit around the Earth in a US $3 billion project.

All ten satellites were successfully lifted to orbit and deployed following a pitch-perfect launch, which had to take place at precisely 9:54:34 local time (17:54:34 UT) in order for all ten satellites to be correctly deployed to reach their assigned orbits. However, all eyes were on the Falcon 9’s first stage, which was set to make a return to Earth for an at-sea landing aboard one of the company’s two autonomous drone landing barges, Just Follow The Instructions.

Down and safe: the Falcon 9 first stage, seen via a camera aboard the autonomous drone barge Just Follow The Instructions, shortly after touch-down on January 14th, 2017. Credit: SpaceX
Down and safe: the Falcon 9 first stage, seen via a camera aboard the autonomous drone barge Just Follow The Instructions, shortly after touch-down on January 14th, 2017. Credit: SpaceX

Operating the Falcon 9 on a basis of reusability is core to SpaceX’s future plans to reduce the overall cost of space launches. While the company has previously made six successful returns and landings with the Falcon 9 first stage, this being the first attempt since September 2016’s loss added further pressure on the attempt. but in the event, it went flawlessly.

After separation from the upper stage carrying the payload to orbit, the first stage of the Falcon 9 completed what are called “burn back” manoeuvres designed to drop it back into the denser atmosphere. Vanes on the rocket’s side were deployed to provide it with stability so that it dropped vertically back down to Earth, using its engines as a braking system and deploying landing legs shortly before touchdown – and the entire journey was captured on video, courtesy of camera built-into the rocket’s fuselage.

Continue reading “Space Sunday: looking back on Earth and landing rockets and probes” →

Space Sunday: a look at the year ahead

Posted on by Inara Pey
Artist's concept of Cassini's final orbits between the innermost rings and Saturn's cloud tops (see below). Credit: NASA
Artist’s concept of Cassini’s final orbits between the innermost rings and Saturn’s cloud tops (see below). Credit: NASA

As we enter a new year, I thought I’d take a quick dip into some of the astronomical and space events which will occur in 2017.

January / February

  • The Quantids Meteor Shower: reaching a peak on January 3rd / 4th, this should be visible for those in the northern hemisphere graced with clear night skies, as the Earth passes through the debris trail from asteroid 2003 EH1. Just look towards Ursa Major (The Plough / The Big Dipper) and you could see up to 100 “shooting stars” per hour as dust and minute debris from the comet’s tail burn up in the upper atmosphere.
  • SpaceX Return to Flight: while no date has been confirmed, it is expected this will take place in January / February 2017 – see my expanded report below.
  • Catch a Comet: February will see  Comet 45P/Honda-Mrkos-Pajdusakova pass the Earth on its way back out into space, having swung around the Sun in December. A short period comet, orbiting the Sun every 5.5 years, it should be visible just before dawn between the constellations Aquila and Hercules. On the morning of February 11th it will be at its closest to Earth – 12,320,000 km (7,700,000 mi), and should be visible to the naked eyes as a tiny fuzzy ball.
  • Southern Hemisphere Annular Eclipse: Africa and South America get to see an annular eclipse on February 26th. This is when the Sun and Moon are exactly in line with the Earth, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulus, surrounding the dark disk of the Moon.

March / April

  • The Moon-Mars-Mercury Triangle: looking out toward the crescent moon just after dusk on March 29th should reveal the celestial triangle between the Moon, ruddy Mars (relatively high above the horizon) and tiny Mercury, much closer to the horizon. The latter will actually be at its most distant from the Sun at the time and at the highest above the horizon it ever gets, marking one of the rare occasions it can easily be seen as a naked eye object.
The Moon-Mars-Mercury "triangle". Credit: Andrew Fazekas
The Moon-Mars-Mercury “triangle”. Credit: Andrew Fazekas
  • Jupiter’s Bright Opposition: Jupiter and the Sun will be sitting almost exactly on opposite sides of the Earth relative to one another during March and April (opposition actually occurring on April 7th). This means that Jupiter will be one of the brightest objects in the night sky, and on April 10th will be a brilliant companion for the full Moon, appearing just above and to the right of the Moon’s limb.
  • Cassini’s Final Grand Tour: On April 22nd, NASA’s long running Cassini mission to Saturn will enter its final phase as the spaceraft bearing the mission’s name commences 22 final orbits which will see it passing between the planet and its rings to come within 1,630 km (1,013 mi) of Saturn’s cloud tops.
  • China’s Tianzhou 1 to Fly: while it has yet to be confirmed, April has been earmarked for the maiden flight of China’s automated resupply vehicle, Tianzhou 1, which should rendezvous with the Tiangong-2 orbital laboratory to deliver consumables, fuel and other supplies. The mission is key to China’s longer-term aim of establishing a crewed space station in orbit.

June

  • Saturn’s Opposition and Rings:  Saturn will also be in opposition in June, revealing it as one of the brightest objects in the night sky, sitting within the in the constellation Ophiuchus. Saturn will be angled to show its northern hemisphere at this opposition, so the rings will inclined at an angle of 26° to our line of sight, which is almost the maximum inclination they can have, making them visible to even a modest telescope (30-cm / 6-in).

August / September

  • Perseids Sparkle:  it’s the most prolific meteor shower in the year visible in the northern hemisphere, with 60-110 “shooting stars” visible per hour at peak times, with some visible for up to a second at a time. Peak activity will occur between the 9th and 14th August – just look towards the constellation Perseus. But you’ll have to be out really early to see them – around 2:00am local time where you are. They’re the result of the Earth passing through the debris trail left by 1992’s Comet Swift-Tuttle,
  • The Great American Eclipse: the United States gets the best of this year’s solar eclipses, with a total eclipse occurring on August  21st. Totality (the complete eclipsing of the Sun by the Moon) will be visible in a narrow band stretching across the continental United States – see the video from NASA, below. Check with NASA for the best observing times in your location.

  • Dragon V2’s fiery ascent: although the first crewed flight of the Dragon V2 capsule has been delayed until 2018, SpaceX are targeting August 2017 as the month for the first uncrewed flight of the system, an important step on the way toward full certification to carry astronauts to and from the International Space Station.
  • Farewell to Cassini: it won’t be visible from Earth, but at 11:07 UT on September 15th, 2017, NASA’s Cassini mission to Saturn will come to an end as the vehicle, which has been in space for 20 years, 13 of them in orbit around the planet, plunges into the upper reaches of Saturn’s atmosphere and burns up. It will be a fiery and sad end to a magnificent mission, and I hope to present a Cassini special in these pages later in the year.

Continue reading “Space Sunday: a look at the year ahead” →

Space Sunday: loss, glides and the avalanche model

Posted on by Inara Pey
Piers Sellers ( April 11th, 1955 – December 23rd, 2016): climatologist and astronaut
Piers Sellers ( April 11th, 1955 – December 23rd, 2016): climatologist and astronaut. Credit: NASA

On Friday, December 23rd, news broke that astronaut Piers Sellers had passed away at the age of 61. His name might not be familiar to some, but British-born Sellers quietly achieved a lot both in orbit and here on the ground.

Born in 1955 in Crowborough, Sussex, Sellers held a bachelor’s degree ecological science and a doctorate in biometeorology. He was regarded as an expert on climate change, studying the relationship between the living world and the atmosphere for the better part of two decades starting in 1982, shortly after he and his wife (they later divorced) relocated from the UK to the United States. At that time he joined  NASA’s Goddard Space Flight Centre in Greenbelt, Maryland, working on climate change computer modelling. He then moved to leading the US team developing the multi-national Terra research satellite, regarded as the flagship Earth Observing System (EOS).

A qualified pilot, having trained as an RAF cadet while at college, he maintained his flight status throughout his first ten years in the United States, repeatedly applying for a position in the NASA Astronaut Corps. However, it wasn’t until 1991, when he gained US citizenship that he met all of the criteria to be considered for a place in the Corps, and he was selected for training in 1996.

After completing two years of training, Sellers was initially assigned technical duties in the Astronaut Office Computer Support Branch, followed by service in the Astronaut Office Space Station Branch, which saw him based in Moscow for periods of time, working with Russian colleges as a technical liaison for the development of computer software for the International Space Station (ISS).

Sellers on EVA during STS-121, his second flight into orbit,
Sellers on EVA during STS-121, his second flight into orbit, July 4th through 17th, 2006. Credit: NASA

In all, Sellers flew in space the times, starting with STS-112 (October 7th – 18th, 2002, Space Shuttle Atlantis), during which he logged a total of 19 hours and 41 minutes of extra vehicular activity (EVA) work, assembling elements of the ISS). In 2006, he flew aboard the Space Shuttle Discovery for the Return To Flight Mission, STS-121, of July 4th through 17th. This mission marked the first flight of the shuttle fleet following the tragic loss of the Columbia and all seven crew on board, on February 1st, 2003. Sellers performed three  further EVAs on that mission, testing the 50-foot robotic arm boom extension as a work platform.

His final flight in space came in 2010 with STS-132, when he once again flew aboard Atlantis in what was to have been its final mission (although it actually flew once more, in July 2011). The mission delivered Russian Rassvet Mini-Research Module along with an Integrated Cargo Carrier-Vertical Light Deployable (ICC-VLD) to the ISS. In total, Sellers logged 35 days, 9 hours and 2 minutes in space, including more than 41 hours on six spacewalks.

In 2011, Sellers resigned from the Astronaut Corps to become Deputy Director of Goddard Space Flight Centre’s Sciences and Exploration Directorate, a position he still held at the time of his death, and later the Acting Director for Earth Sciences at Goddard. He was the author of 70 research papers, and in 2011 he was appointed Officer of the Order of the British Empire (OBE) for services to science. In June 2016 he was bestowed the NASA Distinguished Service Medal, while shortly before his death it was announced he would receive e Gen. James E. Hill Lifetime Space Achievement Award, the highest award the Space Foundation can bestow.

Sellers (l) discusses the realities of climate change with Leonardo DiCaprio in the National Geographic documentary, Before The Flood. Credit: National Geographic
Sellers (l) discusses the realities of climate change with Leonardo DiCaprio in the National Geographic documentary, Before The Flood. Credit: National Geographic

At the start of 2016, Sellers revealed he had been diagnosed with stage 4 pancreatic cancer, and chose to do so by way of an article written for The New York Times entitled Cancer and Climate Change. Commenting on his diagnosis in the piece, he wrote:

I’ve no complaints. I’m very grateful for the experiences I’ve had on this planet. As an astronaut I spacewalked 220 miles above the Earth. Floating alongside the International Space Station, I watched hurricanes cartwheel across oceans, the Amazon snake its way to the sea through a brilliant green carpet of forest, and gigantic night-time thunderstorms flash and flare for hundreds of miles along the Equator. From this God’s-eye-view, I saw how fragile and infinitely precious the Earth is. I’m hopeful for its future.

Despite his diagnosis, Sellers continued his work and research almost right up to his death. In October 2016, he appeared with Leonardo DiCaprio in National Geographic’s documentary Before the Flood. He described climate change plainly and simply:

Here are the facts: The climate is warming, We’ve measured it, from the beginning of the industrial revolution to now. It correlates so well with emissions and theory, we know within almost an absolute certainty that it’s us who are causing the warming and the CO2 [carbon dioxide] emissions.

Commenting on Sellers’ passing, NASA Administrator Charles Bowden, himself a veteran of four flights into space, said:

Piers devoted his life to saving the planet. His legacy will be one not only of urgency that the climate is warming but also of hope that we can yet improve humanity’s stewardship of this planet.

Piers Sellers is survived by his ex-wife, his wife of 36 years, Amanda, their son Thomas and daughter Imogen and a grandson, Jack.

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