Tag: Spaceflight

Space Sunday: “super Earth”, “supermoon”, and Orion’s future

Posted on by Inara Pey
An artist's impression of a "super Earth" type planet in orbit around a red dwarf star. Credit: NASA / Dana Berry.
An artist’s impression of a “super Earth” type planet in orbit around a red dwarf star. Credit: NASA / Dana Berry.

In a couple of recent Space Sunday reports, I covered the discovery of an Earth-size planet orbiting  our nearest stellar neighbour, the red dwarf Proxima Centuari (see here and here). Red dwarfs  are a class of star which has proven rich ground for planet hunters  –  and this has once again proved the case.

The European Southern Observatory ESO), one of the leading hunters of exoplanets, has  reported the discovery of a “super Earth”, a sold planetary body with roughly five times the mass of Earth. It is orbiting GJ 536, an M-class red dwarf star some 32.7 light years from the Sun. The planet is orbiting its parent once every 8.7 days, at a distance of 0.06661 AU.

The planet was discovered using a pair of instruments operated by ESO: the High Accuracy Radial velocity Planet Searcher (HARPS), mounted on ESO’s 3.6 metre telescope at the La Silla Observatory in Chile, and its sister instrument, HARPS-N, at the La Palma Observatory in Spain. The findings from these instruments were combined with photometric data from the All Sky Automated Survey (ASAS), which has observatories in Chile and Maui, to confirm the existence of the planet.

Red dwarf stars are entirely convective in nature, making them extremely volatile in nature, and subject to massive stellar flares. Credit: NASA/CXC/M.Weiss
Red dwarf stars are entirely convective in nature, making them extremely volatile in nature, and subject to massive stellar flares. Credit: NASA/CXC/M.Weiss

However, its was no rapid-fire discovery. In all, data from over eight years of observations of the star went into confirming the presence of the planet. Such is the extended period of observations, that the science team were able to gather a huge amount of spectroscopic data on the star. This has revealed it has a rotational period of about 44 days, and magnetic cycle that lasts less than three years. By comparison, the Sun has a rotational period of 25 days and a magnetic cycle of 11 years.

This indicates that GJ536 is, in keeping with most red dwarf stars, exceptional volatile. Such stars are so small, all activity within them is entirely convective in nature, which gives rise to massive stellar flares. So while the new planet may well have “earth” in its description, it is unlikely to be “Earth like”, particularly given its relatively close proximity to its parent star.

Not much more is known about the planet at this point, but this is liable to change over time, and in the meantime, the survey team will continue to gather data on GJ 536 to see if it is home to other planets, such as gas giants further away from it.

November’s Supermoon

A dramatic supermoon is seen behind the Christ the Redeemer statue in Rio de Janeiro, in May 2012. Credit: AP Photo/Victor R. Caivano
A dramatic supermoon is seen behind the Christ the Redeemer statue in Rio de Janeiro, in May 2012. Credit: AP Photo/Victor R. Caivano

The last three months of 2016 are marked by three so-called “supermoons”, and the biggest will be in the night skies on Monday 14th November 2016.

The Moon is in an elliptical orbit around the Earth, at apogee, the point furthest from the Earth, it is between 404,000–406,700 km (252,500-254,187 mi) from Earth. At perigee, the point closest to the Earth, the Moon is between 356,400–370,400 km (222,500-231,500 mi) away. A “supermoon” occurs when the Moon is both full and at perigee, when it can appear up to 14% large in diameter than “normal” full moons.

Apogee and preigee in the Moon's orbit around Earth. Credit: NASA
Apogee and perigee in the Moon’s orbit around Earth. Credit: NASA

“Supermoons” aren’t actually rare events; they take to occur once every 14 months on average.  However, the supermoon on November 14th, scores double. Not only will be “just” 356,509 kilometres (221,524 miles) from Earth, pushing it to that 14% increase in apparent size, but also because the Earth/Moon system is approaching the time of year when it is closest to the Sun (which will occur on January 4th, 2017). Therefore, the Moon will be receiving more sunlight than average, further boosting its apparent brightness.

Together, these two events mean that the Moon will be at its “largest” and brightest in the sky since 1948. The next comparable event will not occur again until 2034 – although there will be a further “supermoon” on December 14th, when the Moon again reaches its full phase, but it will be slightly further away from the Earth in its orbit at that time, so not quite as “super”.

How the Moon can appear to differ i size at apogee (the point furthest from Earth in its orbit) and perigee (the point in its orbit closest to Earth). Credit: Catalin Paduraru
How the Moon can appear to differ in size at apogee (the point furthest from Earth in its orbit) and perigee (the point in its orbit closest to Earth). Credit: Catalin Paduraru

Continue reading “Space Sunday: “super Earth”, “supermoon”, and Orion’s future” →

Space Sunday: of moons, storms and rockets

Posted on by Inara Pey
A joint Belgian-French-Japanese study has provided the strongest evidence yet for the Martian moons being the result of a massive collision between the planet and other object very early in the solar system's history
The traditional theory of the Moon’s formation is that a Mars-sized body grazed the young Earth, throwing of a cloud of material which  eventually condensed into the Moon. Credit: NASA

We’re all familiar with the Moon, Earth’s cosmic companion. So familiar with it in fact, that we probably all think we know the theory behind how it got to be where it is – the result of a “giant impact” far back in Earth’s early history. However, a new study, published on October 31st in Nature, suggests what actually led to the creation of the Moon was possibly a lot  more elegant than previously realised.

The Moon is actually quite unique among the solar system’s satellites. It’s relatively large when compared to its parent planet, and it is a made of pretty much the same stuff, minus some more volatile compounds that evaporated long ago. Other moons tend to be a lot more chemically diverse when compared to one another and their parent worlds.

The accepted theory of lunar formation has it that not long after primordial Earth formed, a Mars-sized object grazed it, throwing off a mass of material from which the Moon subsequently condensed. This impact set the angular momentum for the Earth-moon system, and gave the early Earth a five-hour day. Then, over the aeons, the Moon slowly receded from the Earth (as it continues to do so to this day), and Earth’s rotation has slowed to our current 24-hour day.

The Moon is is an elliptical orbit around the Earth which varies from 364,397 km at its closest, to 406,731 km at its most distant. When it’s full and at its closest point to Earth (perigee), the Moon can look over 10% bigger, and 30% brighter than when it’s at a more distant point in its orbit (apogee). However, such is the momentum of the Moon's oribt, it is actually slowly moving further and further away from Earth, as it has been throughout its history
The Moon is in an elliptical orbit around the Earth which varies from 364,397 km at its closest, to 406,731 km at its most distant. When it’s full and at its closest point to Earth (perigee), the Moon can look over 10% bigger, and 30% brighter than when it’s at a more distant point in its orbit (apogee). However, such is the momentum of the Moon’s orbit, it is actually slowly moving further and further away from Earth, as it has been throughout its history. Credit: Wikipedia

It’s a theory all worked out be a combination on mathematics based on the moon’s current orbit, the angular momentum of the Earth-Moon system, the influence of various tidal forces, a little bit of guesswork, etc.  However, it does have a couple of holes in it.

The first is that if the Moon was formed as a result of material set free during a slight collision between Earth and another body, then that material should have been a mix of debris from both Earth and the other body, giving rise to a lunar composition that should be at least somewhat different to that of Earth. The second is that if the Moon condensed from a disk of material rotating around Earth’s equator, it should be in orbit over the equator – but instead, its orbit is tilted 5 degrees off the equator.

Both of these issues have previously been explained in terms of “intervening steps” between what we see today and the original  “giant impact”. However, a team of scientists led by Sarah Stewart, professor of earth and planetary sciences at the University of California, have posited an alternative explanation, which requires no “intervening steps”, but always natural mechanics to explain everything.

In their model, the “giant impact” still occurs –  but it completely destroys the nascent Earth and whatever hit it, leaving a mass of vaporised and molten material  orbiting the Sun, which eventually condenses to form a “new” Earth and the Moon – thus giving them similar chemical compositions. Initially, the Earth would have likely been tipped so its axis was pointing towards the Sun while spinning in a two-hour day.

Then, as angular momentum was dissipated through tidal forces, the Moon started receding from Earth, eventually reaching a point called the “LaPlace plane transition”. At this point the forces from the Earth on the Moon became less important than gravitational forces from the sun, resulting in some of the angular momentum of the Earth-Moon system transferring to the Earth-Sun system, causing the Earth to tip “upright”, while leaving the Moon in a very highly inclined orbit relative to Earth’s equator. However, as the Moon continued to slowly and naturally recede from the Earth, it eventually reached the Cassini transition, gradually reducing the Moon’s angle of inclination relative to the Earth’s equator, bringing it to the five-degree offset we see today.

Thus, with this model, no exotic intermediary steps are required to account for the Moon’s composition or why it is where it is today; everything can be explained through the application of mathematics and planetary mechanics, offering a compelling alternative to the accepted theory of lunar evolution.

China Launches the Long March 5 Heavy Lifter

China's Long March 5 (l) and Long March 7 (r) next generation launch vehicles
China’s Long March 5 heavy lift launch vehicle (l) is the centrepiece of China’s long-term space ambitions alongside the medium lift Long March 7 (r), which entered service earlier in 2016. Credit: CCTV

China’s newest and biggest heavy-lift rocket, the Long March 5 (Chang Zheng-5) lifted-off from the Wenchang launch centre on Hainan Island, off China’s southern coast, at 12:43:14 UT or 20:43 Beijing time on Thursday, November 3rd, carrying an experimental satellite designed to test electric-propulsion technology.

With a 25 tonne low Earth orbit payload capacity, the Long March 5 stands on a par with the current crop of heavy lift launch vehicles in operation around the world. The product of two decades of research and development, it is destined to become a centrepiece of China’s growing space ambitions.

Among its may missions, the Long March 5 will play a leading role in the construction of China’s upcoming space station, starting with the launch of the core Tianhe (“Harmony of the Heavens”) module in 2018. When completed in 2022, the 60-tonne station will comprise the core module supported by the Wentian (“Quest for the Heavens”) and Mengtian (“Dreaming of the Heavens”) pressurised experiments modules, all of which will be linked by a multi-port adaptor / EVA airlock.

Continue reading “Space Sunday: of moons, storms and rockets” →

Space Update: Planet Nine, “signalling” stars and a quick round-up

Posted on by Inara Pey
Planet Nine, if it exists,could equal Neptune in size, and orbits the Sun 200 times further away than Earth. Credit: Caltech / R. Hurt
Planet Nine, if it exists,could equal Neptune in size, and orbit the Sun 200 times further away than Earth. Credit: Caltech / R. Hurt

In January and February 2016, I wrote about Planet Nine (or Planet X, George, Jehoshaphat, or Planet of the Apes, depending  your preference), the Neptune-sized world believed to be orbiting the sun on the very edge of the solar system in a highly eccentric orbit. Since then, the search for this mysterious world has continued, and while it has yet to be located, evidence that it exists has been mounting. Not only that, but astronomers now believe it might explain why the solar system is “tipped”.

The Hunt started after Mike Brown, a leading planetary astronomer at the California Institute of Technology (Caltech), and his colleague Konstantin Batygin developed a computer model which showed that the very eccentric orbits of six Trans-Neptunian Objects (TNOs) located in what is called the scattered disk,  a sparsely populated region of space between 30 100 AU from the sun, overlapping with the Kuiper belt, could have been due to the influence of a massive, distant planet. At the time, they noted that if the model was correct, other TNOs would likely  occupy equally distinct orbits.

A planet averaging about 10 times as massive as Earth, called Planet Nine could explain the paths of six distant objects in the solar system with mysterious orbits
A planet averaging about 10 times as massive as Earth, called Planet Nine could explain the paths of six distant objects in the solar system with mysterious orbits. Credit: Caltech / R Hurt

At the joint European Planetary Science Congress (EPSC) and American Astronomical Society’s Division for Planetary Sciences (DPS) in October, it was revealed more TNOs fitting the model have been discovered over the past several months. Two of them,  2013 FT28 and 2014 SR349, precisely fit the same type of orbit seen the original six objects used by Brown and Batygin model. Five more have been found in orbits which are effective perpendicular to Planet Nine’s believed orbit around the Sun, something predicted by the computer model.

All of this is helping to narrow down Planet Nine’s potential orbit around the Sun, and the arc of that orbit where it might be found. So much so that Batygin, Brown have teamed with original proponents for Planet Nine Chad Trujillo and Scott Sheppard to use the 8-metre Subaru Telescope atop Mauna Kea in Hawaii to carry out a  search of the night sky. Sheppard and Trujillo are also using two telescopes in Chile to search the possible sweep of the planet through the southern hemisphere’s night sky. And they are not alone.

The Brown / Batygin model for Planet Nine indicated the planet would cause some TNOs to ine in orbits perpendicular to the planet's own eccentric orbit around the Sun - and five such object have now been discovered (shown in teal, with the original TNOs possibly influenced shown in magenta. Credit: Caltech
The Brown / Batygin model for Planet Nine indicated the planet would cause some TNOs to lie in orbits perpendicular to the planet’s own eccentric orbit around the Sun – and five such object have now been discovered (shown in teal, with the original TNOs possibly influenced shown in magenta. Credit: Caltech

Also at the planetary conference, graduate student Elizabeth Bailey, using Brown and Batygin’s data presented a paper proposing how the odd tilt to the solar system’s major planets relative to the Sun might be due to Planet Nine.

With the exceptional of Mercury, all the major planets in the solar system orbit along a plane tilted by about six degrees from the Sun’s equator. This suggests either the Sun was somehow tipped on its axis in the past, or the planets have been pulled from their original alignment along the Sun’s equatorial plane. Of these two ideas, the preferred option has been for exotic interactions between the early Sun’s magnetic field and the primordial disk of gas surrounding it, inclining the latter, which then formed the planets. However, Bailey’s simulations suggest that a large body occupying Planet Nine’s predicted orbit could have had sufficient influence on the Sun over some 4 billion years to have slowly tipped it over by six degrees. Bailey’s hypothesis was supported by a  Brazilian team of astronomers, who used a different analytical method while working independently from her, and reached the same conclusion.

As it might be: estimates concerning Planet Nine's possible size, mass, etc., should it exist. Credit: Space.com / Karl Tate
As it might be: estimates concerning Planet Nine’s possible size, mass, etc., should it exist. Credit: Space.com / Karl Tate

Even so, some remain sceptical that the mysterious world exists. “I give it about a 1% chance of turning out to be real,” says astronomer JJ Kavelaars, of the Dominion Astrophysical Observatory in Victoria, Canada. Interestingly, his fellow researcher and collaborator Cory Shankman,  has created models with the exact orbits of the original six TNOs used by Brown and Batygin, and found that a massive planet would not maintain their tell-tale clustering for long periods.

Thus, the search for the solar system’s mysterious Planet Nine, continues.

ETs Phone Home?

Are aliens sending signals using their own stars? That’s what might be happening, according to astrophysicists Ermanno Borra and Eric Trottier, from Laval University in Quebec; although they admit it’s only one possible explanation for what they appear to have discovered.

It was in 2012 that Borra predicted intelligent aliens might use the light from their own stars to signal their existence to the cosmos. Using data from the Sloan Digital Sky Survey, Borra and Trottier analysed the spectra of 2.5 million stars to see if this might be the case – and found 234  which seem to be broadcasting a signal of the kind predicted by Borra.

The “signals” are pulses in the stars’ light, separated by a constant time interval. What’s more, all 234 stars are predominantly in the F2 to K1 spectral range, which is the small range of stars centred on the spectrum of our own life-supporting Sun, and thus the broad group of stars thought might support life on planets orbiting them.

The Sloan Digital Sky Survey telescope, New Mexico. Credit: SDSS / Fermilab Visual Media Services / NASA
The Sloan Digital Sky Survey telescope, New Mexico. Credit: SDSS / Fermilab Visual Media Services / NASA

However, as Borra and Trottier note in their paper – which has yet to be comprehensively peer-reviewed – the pulses could be the result of natural factors such as rotational transitions in molecules or the Fourier transform of spectral lines. It might even be due to rapid pulsations in the stars themselves. Nevertheless Borra and Trottier have tended to dismiss rotational transitions on the grounds that such behaviour isn’t common to these types of star. They also think it unlikely a Fourier transform is responsible.

Instead, they lead towards either the “signals”  being an artefact produced by data reduction on the part of the Sloan instrument, or the work of ET, with a slight emphasis towards the ET side of their thinking.  Others, having read their paper, are far more sceptical.

“It seems unlikely that 234 separate alien societies would be sending out such similar signals more or less simultaneously” Seth Shostak, a senior astronomer at the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California said. “It would be like expecting us to send the same signals as the Abyssinians — it doesn’t make a whole lot of sense.” Instead, Shostak leans towards the data reduction explanation; as does Occam’s Razor.

But a further possible explanation has been suggested: that the signals are due to highly peculiar chemical compositions in a small fraction of galactic halo stars which has  never been previously encountered. While not as exotic as aliens using their stars as signalling devices, should this prove to be the case, it would still be a remarkable new discovery.

Continue reading “Space Update: Planet Nine, “signalling” stars and a quick round-up” →

Space Sunday: success, loss and safe modes

Posted on by Inara Pey
A colour-enhanced image of Jupiter's south pole, created by "citizen scientist" Alex Mai, as a part of the public Junocam project. using data from Juno's JunoCam instrument. Credit: NASA/JPL / SwRI / MSSS / Alex Mai - see later in this article for an update on the Juno mission
A colour-enhanced image of Jupiter’s south pole, created by “citizen scientist” Alex Mai, as a part of the public JunoCam project. Credit: NASA/JPL / SwRI / MSSS / Alex Mai – see later in this article for an update on the Juno mission

On Wednesday, October 19th, 2016, the European Space Agency (ESA) attempted, for them, a double first: placing a vehicle successfully in orbit around Mars (the Trace Gas Orbiter, or TGO) and landing a vehicle on the planet’s surface (the Schiaparelli demonstrator).

Launched in March 2016, TGO is the second European orbiter mission to Mars, the first being Mars Express, which has been operating around the red planet for 12 years. TGO’s mission is to perform detailed, remote observations of the Martian atmosphere, searching for evidence of gases which may be possible biological importance, such as methane and its degradation products. At the same time, it will to image Mars, and act as a communications for Europe’s planned 2020 Mar rover vehicle.

October 16th, 2016: the Schiaparelli EDM separates from ESA's TGO, en-route for what had been hoped would be a safe landing on Mars. Credit: ESA
October 16th, 2016: the Schiaparelli EDM separates from ESA’s TGO, en-route for what had been hoped would be a safe landing on Mars. Credit: ESA

TGO’s primary mission won’t actually start until late 2017. However, October 19th marked the point at which the vehicle entered its preliminary orbit around Mars.  Orbital insertion was achieved following a 139-minute engine burn which slowed the vehicle sufficiently  to place  it in a highly elliptical, four-day orbit around Mars. Early next year, the spacecraft will begin shifting to its final science orbit, a circular path with an altitude of 400 km (250 mi), ready to start its main science mission.

On Sunday, October 16th, prior to orbital insertion, TGO had bid farewell to the 2-metre diameter Schiaparelli  Entry, Descent and Landing Demonstrator Module (EDM), which it had carried to Mars. The EDM was specifically designed to gather data on entry into, and passage through, the Martian atmosphere and test landing systems in preparation for ESA’s 2020 rover mission landing. 

Schiaparelli's route to the surface of Mars. Credit: ESA
Schiaparelli’s route to the surface of Mars (click for full size). Credit: ESA

Once separated from TGO, Schiaparelli travelled ahead of the orbiter, entering the Martian atmosphere at a speed of 21,000 km/h (13,000 mph; 5.8 km/s / 3.6 mi/s), at 14:42 UT on October 19th. After using the upper reaches of the Martian atmosphere to reduce much of its velocity, Schiaparelli should have proceeded to the surface of Mars using a mix of parachute and propulsive descent, ending with a short drop to the ground, cushioned by a crushable structure designed to deform and absorb the final touchdown impact. Initially, everything appeared to go according to plan. Data confirmed Schiaparelli had successfully entered the Martian atmosphere and dropped low enough for the parachute system to deploy. Then things went awry.

Analysis of the telemetry suggests Schiaparelli prematurely separated from its parachute, entering a period of free fall before the descent motors fired very briefly, at too high an altitude and while the lander was moving too fast. Shortly after this, data was lost. While attempts were made to contact the EDM using ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter (MRO) it was not until October 20th that Schiaparelli’s fate became clear.

Images taken by MRO  of Schiaparelli’s landing zone revealed a new 15x40m (49x130ft) impact crater, together with a new bright object about 1 kilometre south of it. The crater is thought to be Schiaparelli’s impact point, and the latter the lander’s parachute and aeroshell.

In releasing the NASA images on October 21st, the European Space Agency stated,”Estimates are that Schiaparelli dropped from a height of between 2 and 4 km (1.4-2.4 mi), impacting at a  speed greater than 300 km/h (186 mph). It is also possible that the lander exploded on impact, as its thruster propellant tanks were likely still full.”

Point of impact: on the left, images of Schiaparelli's landing zone taken in May 2016 and on October 20th, 2016, superimposed on one another, the October 20th image clearing showing an impact feature. On the right, an enlarged view of the same two images, showing the impact feature and, south of it, the white canopy of Schiaparelli's parachute. Credit: NASA/JPL / MSSS
Point of impact: on the left, images of Schiaparelli’s landing zone taken in May 2016 and on October 20th, 2016, superimposed on one another. The October 20th image clearly shows an impact feature with a bright object to the south, thought to be Schiaparelli’s parachute canopy. On the right, an enlarged view of the same two images. Credit: NASA/JPL / MSSS

While the lander carried a small suite of science instruments which would have been used to monitor the environment around it for a few days following the landing, the major part of the mission was to gather data atmospheric entry and the use of parachute and propulsive descent capabilities. ESA believe this part of the mission to have been a success, even with minimal data gathered on the propulsive element of the descent.

In the meantime, TGO is currently on a 101,000 km x 3691 km orbit (with respect to the centre of the planet). It is fully functional, and will undertake instrument calibration operations in November, prior to commencing the gentle aerobraking manoeuvres designed to reduce and circularise its orbit around Mars.

Continue reading “Space Sunday: success, loss and safe modes” →

Space Sunday: landings, launches and tiny worlds

Posted on by Inara Pey
An artist's impression of ESA's Trace Gas Orbiter approaching Mars on October 16, 2016, having just released the Schiaparelli lander demonstrator
An artist’s impression of ESA’s Trace Gas Orbiter approaching Mars on October 16, 2016, having just released the Schiaparelli lander demonstrator. Credit: ESA

Sunday, October 16th, 2016, marked the first in two important dates during the month for the European Space Agency. It  was at 14:42 UT that the Schiaparelli Entry, Descent and Landing Demonstrator Module (EDM) separated from its parent orbiter, the Mars Trace Gas Orbiter (TGO) as the two entered the final three days of their approach to Mars.

TGO / Schiaparelli  form the first part of the European Space Agency’s ExoMars mission, which represents an ambitious expansion of European studies of Mars by placing TGO in orbit around Mars where it will study the atmosphere, then following it in 2020 with a rover mission, for which Schiaparelli is a pre-cursor.

It’s been a mission a long time in the making – in the case of the still-to-fly rover mission, more than a decade has already passed since its inception, was a certain amount of the delay due to NASA. Originally, both TGO and rover were to launch aboard Russian vehicles, but a 2009 agreement with the US space agency resulted in a comprehensive re-design of both missions, which were to fly aboard / as part of US vehicles / missions (the TGO science was to have flown on NASA’s Mars Science Orbiter (MSO) mission, for example). However, NASA unilaterally cancelled the agreement at the start of 2012 due to cost overruns with the James Webb Space Telescope, forcing a further complete redesign of both TGO and rover vehicle.

Schiaparelli should touch down in the Meridiani Planum during the dust storm season
Schiaparelli should touch down in the Meridiani Planum during the dust storm season

October 16th was an important milestone for the mission, as it saw TGO release the Schiaparelli  demonstrator in what was a textbook operation, watched via telemetry at mission control, with a nine-and-a-half-minute time delay separating events from receipt of data. It was  a single line of that data that indicated separation had been successful.

Schiaparelli will not proceed ahead of TGO, their paths slowly diverging, until Wednesday, October 19th, when TGO will enter its preliminary orbit around Mars. Over the  course of the next year, that orbit will be further and further refined until the vehicle is correctly positioned to commence its 5-year primary mission. For this, TGO will perform detailed, remote observations of the Martian atmosphere, searching for evidence of gases which may be possible biological importance, such as methane and its degradation products. At the same time, TGO will continue to image Mars, and act as a communications for both Schiaparelli and for the 2020 rover vehicle. 

At the same time as TGO enters that preliminary orbit, Schiaparelli will commence a much more hazardous journey to the surface of Mars. This will commence with the 2.4 metre (8ft) diameter EDM slamming into the Martian atmosphere at 21,000 km/h (13,000 mph; 5.8 km/s / 3.6 mi/s), where it will use a heat shield and atmospheric friction to rapidly decelerate.

Once through the upper reaches of the Martian atmosphere, the EDM will jettison the heat shield and deploy a parachute system from its protective aeroshell. This will carry it down to an altitude of several dozen metres above the surface, before the lander drops clear of the aeroshell.  Rocket motors on the lander will then fire, slowly bringing it to around 2 metres (6.6ft) above the ground, where they’ll shut down, allowing Schiaparelli to drop to the surface, the impact cushioned by a crushable structure designed to deform and absorb the final touchdown impact. The entry, descent and landing should take around 6 minutes.

Throughout the descent, Schiaparelli will record a number of atmospheric parameters and lander performance, with a camera system recording its descent. Once on the surface, it will measure the wind speed and direction, humidity, pressure and surface temperature, and determine the transparency of the atmosphere. It will also make the first measurements of electrical fields at the planet’s surface.

The EDM will only operate for a short time on the surface of Mars – between 2 and 8 sols (Martian days) is the estimate. Its small size, coupled with the limited amount of space within it, means it is not equipped with solar arrays to re-charge its battery systems. However, the core aim of the mission is to better characterise the Martian atmosphere and test critical descent and landing systems needed for future missions, rather than carrying out long-term surface studies.

The Schiaparelli EDM
The Schiaparelli EDM and science instruments which will analyse the environment on the surface of Mars – wind speed, atmospheric pressure and temperature, humidity, dust content, atmospheric transparency, and local electric fields

The planned landing point for Schiaparelli is Meridiani Planum, the region NASA’s Opportunity rover has been exploring since 2004. The EDM will be arriving during the dust storm season, which will provide a unique chance to characterize a dust-loaded atmosphere during entry and descent, and to conduct surface measurements associated with a dust-rich environment.

I’ll have more on TGO and Schiaparelli in my next Space Sunday update.

Continue reading “Space Sunday: landings, launches and tiny worlds” →

Space Sunday: eyeball worlds, stellar cannonballs, water and rockets

Posted on by Inara Pey
A comparison of sunsets on Earth (l) and simulated on a watery Proxima-b, 4.25 light years away (r). While the parent star, Proxima Centauri, is a lot smaller than our Sun, it would appear much larger in the planet's sky due to the planet being a mere 7 million km from the star
A comparison of sunsets on Earth (l) and simulated on a watery Proxima b as it orbits Proxima Cantauri (r). While the latter is approximately one-seventh the diameter of our Sun, it appears much larger in Proxima-b’s sky, because the planet is just 7.5 million miles from its sun. Credit: PHL Arecibo

In August 2016, I wrote about the discovery of a Earth-size planet orbiting the Sun’s nearest stellar neighbour, Proxima Centauri, a “mere” 4.25 light years away.

The planet, Proxima b, has a mass roughly 1.3 times that of Earth and orbits its dwarf star parent once every 11.2 terrestrial days at a distance of just 7.5 million km (4.7 million miles). It is of particular interest to astronomers because it lies within Proxima Centauri’s habitable zone – the region around a star where it is neither too hot nor too cold for liquid water to exist on the surface of a planet, and where conditions might be conducive for life to arise.

The Earth-sized Proxima-B and its parent star
The Earth-sized Proxima b and its parent star. Credit: AFP

Which is not to say life does exist on the planet. Proxima Centauri is a red dwarf star, just 1.5 times bigger than Jupiter, and stars of that size are subject to massive stellar flares which could easily strip away a planet’s atmosphere, or at least leave it awash in ultra-violet radiation, which is not entirely agreeable for life to arise. What’s more, the planet is liable to be tidally locked with Proxima Centauri, leaving one side baked in perpetual daylight and the other in a frozen night. None of this makes it terribly amenable for life gaining a toe hold.

One of the big questions concerning the planet is how much liquid water it may have. Normally this can be determined by using the planet’s size and mass, and working from there. But while we have an estimate of Proixma b’s mass, there is no definite measurement of its size. Normally, this is done by measuring how much light a planet blocks out, from Earth’s perspective, when it pass in front of its host star. So far, this hasn’t been possible with Proxima b.

In the video above, by the Planetary Habitability Laboratory, Arecibo, the star and orbit are to scale, but the planet was enlarged (x30) for visibility. The planet is represented here as a mostly desert-like, tidally-locked world with shallow oceans and a strong atmospheric circulation allowing heat exchange between the light and dark hemispheres.

Instead, a team at France’s CNRS research institute has been working on simulations based on the “best guess” estimates gathered from the data which is available on Proxima-B, and their findings are intriguing.  This data suggests the planet could be between 0.94 and 1.4 times the size of Earth, depending on  its internal structure.

At the lower end of this scale (planetary radius = 5,990 km / 3,743.75 mi), the CNRS simulations indicate that the planet likely comprises a metallic core surrounded by a rocky mantle, with 0.05% of that mass accounted for by liquid water. While this might not sound a lot, it is worth pointing out that Earth, with a radius of 6,371 km / 3,982 mi has just 0.02% of its mass made up of liquid water. At the upper end of the scale (planetary radius = 8,000-9,000 km / 5,000 – 5,600 mi), the planet likely has a rocky centre surrounded by an ocean up to 200 km (125 mi) deep.

Any significant amount of free water on the planet could mean that the atmosphere is being renewed against loss from solar activity. However, the fact that the planet may well be tidally locked could mean that there is a strong atmospheric circulation between the “dark” and “light” sides of the planet due to the temperature differential between the two, giving rise to massive, hurricane-like storms. A further aspect of tidal locking is that if there is a significant amount of liquid water on the planet, it will have long-since frozen out into ice on the dark side.

Could Proxima-b be an "eyeball" world, staring at its parent star?
Could Proxima-b be an “eyeball” world, staring at its parent star? Credit: Beau, Rare Earth Wiki

This in turn leaves us with the equally intriguing possibility that Proxima-b is a potential “eyeball” world “staring” at its parent star.

“Eyeball” worlds are thought to be  tidally locked planets where the hemisphere facing the parent sun is thought to be baked dry under the unrelenting light of their sun, forming a “pupil”. Around this, close to the the day / night terminator, is an iris-like temperate region of land and water which extends back to the terminator between the day and night sides of the planet, where the water is frozen out into ice, forming the “white” of the “eye”.

None of these most recent findings point to Proxima-b being potentially habitable, and again, it’s worth remembering that even with water and warmth, Proxima b isn’t the most amiable environment in which life might gain a toe-hold. But what they do suggest is that even without life scurrying or swimming about on / in them, exoplanets could be remarkably exotic places, even by our own solar system’s standards.

New Shepard: One Step Closer to Tourist Flights

Blue Origin, the private space company launched by Amazon founder Jeff Bezos achieved another milestone on the road to starting their sub-orbital flights into space for tourists.

On Wednesday, October 5th the company launched another test flight of its New Shephard system of capsule unit and “propulsion module” in order to test the launch abort system of the capsule unit during flight. This system is designed to safely separate the New Shepherd crew capsule from the rocket booster in the event of an anomaly during flight, protecting a future crew and passengers.

The test saw the booster and capsule climb to 4,893 metres (16,053 ft) where, 45 seconds into the flight, the “full-envelope escape system” activated, separating the capsule from the booster, allowing its escape motors on the capsule to fire, accelerating it away from the booster at 400 mph in a 2-second burn. The capsule continued to rise to 7,092 metres (23,269 ft), before it started its decent, the parachute landing system deploying and bringing it to a safe touch-down.

It had been expected that the 70,000 pounds of off-axis thrust delivered by the capsule’s motors would seriously deflect the booster from its flight track and result in its complete loss. However, in a move that surprised many watching, the booster continued upwards to an altitude of 93,713 metres (307,458 ft) where, some 7.5 minutes into its flight, it  re-ignited its motor to execute a controlled vertical descent back to the launch pad and a safe landing.

If all goes according to plan, Blue Origin plans to launch its first passengers on a sub-orbital hop in which they get to enjoy around four minutes of weightlessness, in 2018. The price of tickets has yet to be confirmed. However, competitors Virgin Galactic and XCOR Aersopace are looking to charge US $250,000 and $150,000 respectively, when they commence operations.

Continue reading “Space Sunday: eyeball worlds, stellar cannonballs, water and rockets” →