Space update: seeking planet X, examining comets and sifting sand

CuriosityNASA’s Curiosity rover has been sampling the sands of the “Namib Dune” the vehicle has been studying / circumnavigating for the last few weeks as it studies an extensive dune field which is slowly making its way down the slopes of “Mount Sharp” on Mars at the rate of about a metre per year.

“Mount Sharp”, more formally called Aeolis Mons, is the huge mound of material gathered against the central impact peak of Gale Crater. It forms the rover’s primary mission target in its quest to better understand conditions on Mars down through the ages, and to look for areas which at some point in the planet’s past, may have had all the right conditions – minerals, chemicals, water, heat, shelter, etc., – which might have allows life to arise.

The dune field on the north-east flank of “Mount Sharp” is of considerable interest to scientist, as it is the first genuine dune field to be studied on another world, and obtaining a clearer understanding of how the Martian wind moves sand could lead to a clearer picture of how big a role the wind plays in depositing concentrations of minerals often associated with water across the planet, and by extension, the behaviour and disposition of liquid water across Mars.

Tracks on a sand dune: this image from Curiosity's front Hazard Avoidance Camera (Hazcam) shows the rover's tracks on the same of "Namib Dune" as it starts sample gathering
Tracks on a sand dune: this image from Curiosity’s front Hazard Avoidance Camera (Hazcam) shows the rover’s tracks on the same of “Namib Dune” as it starts sample gathering

On January 12th, the rover reached a target area for sample gathering dubbed “Gobabeb”, and even this presented a challenge. Curiosity had to manoeuvre up onto the dune, and then turn in place in order to start sample gathering operations. This meant a cautious approach to the location, initially “scuffing” the sand to obtain and indication of its depth and composition (loose firm material). After this the rover gently edged onto the sand and deployed the robot arm to use its small scoop in only its second major sample gathering exercise, which took place on January 14th.

The sand gathered by the operations well be sorted within the CHIMRA system inside the robot arm, which uses a series of sieves to divide the sand grains by coarseness. Once sorted, the samples are delivered to the rover on-board chemical and analysis systems  – ChemMin, the Chemical and Mineralogical laboratory and SAM, the Sample Analysis at Mars suite – for examination.

A second sample of sand was gathered on January 19th, and is currently awaiting processing.

CHIMRA – the Collection and Handling for In-Situ Martian Rock Analysis device attached to the turret at the end of Curiosity’s robotic arm, processes samples acquired from the built-in scoop (red) and the drill, which is not shown but is also part of the turret. CHIMRA also delivers samples to the analytical lab instruments inside the rover. Two paths to get material into CHIMRA are shown (the scoop delivers material to the location marked at the bottom, and the drill deposits material to the sample transfer tube shown at top). Also marked are the location of the vibration mechanism used to shake the turret and cause the sample to move inside CHIMRA, and the portion box (yellow) from which the material processed through a sieve is delivered to the analytical lab instruments.

Europe Joins Dream Chaser

In my last Space Sunday report, I covered the news that Sierra Nevada Corporation (SNC) will be joining SpaceX and Orbital ATK in supporting US work to delivery supplies to, and remove waste from, the International Space Station.

As a part of a new contract which commences in 2019 and runs until 2024, the expected end of ISS operations, SNC will utilise an unmanned cargo version of its Dream Chaser “mini shuttle”, which is based on a lifting body design, to carry up to 5 tonnes of material to the space station. Now Europe has officially joined SNC as a strategic partner.

The Drem Chaser Cargo, bult by SNC, and the International Berth and Docking Mechanism, to be supplied to SNC for Dream Chaser flights by the European Space Agency
The Dream Chaser Cargo, built by SNC, and the International Berth and Docking Mechanism, to be supplied to SNC for Dream Chaser flights by the European Space Agency

SNC and Europe have been looking at options for Dream Chaser development since SNC lost out to SpaceX and Boeing to supply the crewed version of Dream Chaser to NASA for ferrying crews back and forth between the ISS and US soil. Confirmation that NASA will be using Dream Chaser for the resupply flights means that ESA can nor push ahead with developing an International Berthing and Docking Mechanism (IBDM) for Dream Chaser.

This a module designed to attach to the rear of the Dream Chaser vehicle, allowing it to dock with the space station. It also has solar arrays and an electrical power generation system which can be used to support Dream Chaser during on-orbit operations.

As well as supporting the vehicle in its role as ISS resupply craft, the IBDM will allow Dream Chaser to perform payload flights into orbit for SNC clients, allowing them to fly microgravity experiments, etc., something ESA is particularly interested in doing. A further part of the SNC / ESA collaboration might see a “folding wing” version of Dream Chaser Cargo developed, allowing it to be launched within a payload fairing atop Europe’s Ariane booster, opening new opportunities for SNC.

The agreement marks the second such move by ESA to provide support and power equipment for a US space vehicle in recent years. The Agency is also responsible for building the Service Module which will power NASA’s deep space Orion space capsule vehicle.

Is There A Ninth Planet Lurking?

Planet X, if it exists, could be 10 times bigger than Earth and 200 times as far from the Sun
Planet Nine, if it exists, could be 10 times bigger than Earth and 200 times as far from the Sun (Image: Catech)

Despite turning out to be a remarkable world, Pluto is unlikely to regain its classification as a “true” planet orbiting the Sun; it is simply too small. However, in a subtle twist of fate, one of the people responsible for the International Astronomical Union’s decision to downgrade Pluto’s status from “planet” to “minor planet” may have found genuine evidence that the solar system does have a ninth planet, and it could be around 10 times bigger than the Earth.

The search for “planet X”, the mystery world beyond the orbit of Neptune, has been going on for decades. It was in fact the cause for Pluto’s original discovery. But while theories have been put forward, the skies scoured over and over again, no direct visual evidence for a further big planet orbiting the Sun at an enormous distance has ever been found.

And it would have to be at an enormous distance, otherwise it would influence the orbits of bodies like Neptune and Uranus, causing perturbations in their orbits as its gravity “tugs” at them. This, together with mathematics, is exactly how Neptune was discovered in the 1800s, the planet’s position being calculated based on the perturbations it caused in Uranus’ orbit. While  neither Neptune or Uranus suffer further unexplained perturbations in their orbits which might point to a further planet awaiting discovery, that doesn’t mean it isn’t there.

If it does exist, Planet X is probably around 10 times the mass of Earth, putting it between Earth and Neptune in size
If it does exist, Planet Nine is probably around 10 times the mass of Earth, putting it between Earth and Neptune in size (image: Caltech)

Over the last decade or so, as astronomers have been able to probe more deeply into places such as the scattered disk,  a sparsely populated region of space between 30 AU (1 AU being the average distance of the Earth to the Sun) out as far as 100 AU, and which overlaps with the Kuiper belt. In doing so, they have come across a number of objects, such as the minor planet Sedna, lie in highly eccentric orbits.

In 2014, astronomers Chad Trujillo and Scott Sheppard published a paper on their studies of these objects, suggesting their strange orbits could be the result of them being influenced by a large, unknown planetary body far out from the Sun. Now, building to their work, Mike Brown, a leading planetary astronomer at the California Institute of Technology (Caltech), and one of the people who supported downgrading Pluto to minor planet status, and his colleague Konstantin  Batygin, have produced a computer model which explains how such a distant planet could collectively and uniformly influence  Sedna and the SDOs known to be occupying eccentric orbits.

However, in order to do so, the planet itself would have to be a massively eccentric orbit relative to the plane of the ecliptic (in which all the other major planets of the solar system lie), that Batygin initially doubted the model’s findings. “I had never seen anything like this in celestial mechanics,” he said. “I was sceptical.”

But the model also pointed to something else – such a planet would also affect the orbits of larger bodies within the Kuiper belt in a specific way – and this is precisely what Brown and Batygin have been found. “It’s almost like having six hands on a clock all moving at different rates,” Brown said in a press release accompanying the publication of their findings, which have been undergoing peer review by other astronomers. “And when you happen to look up, they’re all in exactly the same place.” He added that the  odds of that happening are about one-in-100.

A planet 10 times as massive as Earth, called Planet Nine in the diagram (and informally “George,” “Jehoshaphat,” and “Planet of the Apes” by scientists) explains the paths of six distant objects in the solar system with mysterious orbits (magenta).
A planet 10 times as massive as Earth, called Planet Nine in the diagram (and informally “George,” “Jehoshaphat,” and “Planet of the Apes” by scientists) explains the paths of six distant objects in the solar system with mysterious orbits (magenta). Image: Caltech

If it does exist, Planet Nine is liable to be about 10 times the mass of the Earth – putting it between Earth and Neptune in size, and probably around 200 AU from the Sun, with a single orbit taking around 20,000 years.  Now all that is required for it to be confirmed is for a telescope to image it; that might not be so easy.

We don’t know exactly where it is, or else we’d just point the telescope at it tomorrow and it would be right there. But the sky is really big and this thing might be pretty faint, depending on how far out it is,” says Chad Trujillo of the Gemini Observatory in Hawaii. “But that doesn’t mean we’re not going to try.”

One thing Planet Nine most certainly isn’t, however, is the mythical “Planet Nibiru” the cult-created planet which is supposedly going to sweep into the solar system and bring calamity to Earth early this century. That is an object firmly rooted in over-active imaginations.

New Shephard Flies and Lands Again

In November, I reported on the successful sub-orbital launch and recovery of Blue Origin’s New Shephard  launch system. The system, which comprises a capsule designed to carry tourists on a sub-orbital hop, allowing them to enjoy a short period of weightlessness in micro-gravity, and a booster unit simply called the “propulsion module”, are both designed to be fully reusable. The capsule unit (which is actually New Shepard) returns to Earth under parachutes, while the propulsion unit flies itself back to a landing at its original launch point.

On January 23rd, 2016, the same pairing of uncrewed capsule and propulsion module – the latter fully refurbished – repeated their feat of November 2015. Following a successful launch, the capsule separated from the propulsion module, continuing to an altitude of 101.7 kilometres (333,582 ft), before dropping gently back down to Earth for a parachute-slowed touch-down. Meanwhile, the propulsion module made a much faster descent before using its main engine to slow itself and make a flawless landing.

Rosetta: of Water ice and Oxygen

Europe’s Rosetta mission studying Comet 67P/Churyumov–Gerasimenko as it hurtled around the Sun, has discovered the presence of water ice on the surface of the comet.

The announcement of the discovery came after detailed analysis of measurements taken of the comet by Rosetta’s VIRTIS infra-red instrument between September and November 2014, not long after the vehicle arrived in orbit around the comet. The ice is associated with cliff walls and debris falls in a region of the comet dubbed “Imhotep”, and was at an average temperature of about –120ºC at the time.

Water ice is a key constituent of comets like 67P/C-G, however, until now it had been thought that as a comet approaches the Sun and is heated, any ice that is sublimated is completely outgassed by the comet and lost to space. The discovery of water ice on the surface of the comet, however, suggests there is a more complex process of sublimation and deposition occurring with a comet as it approaches the Sun, which tend to alter the traditional view of a comet’s internal make-up.

Images of Comet 67P/Churyumov-Gerasimenko captured by the Rosetta spacecraft's navigation camera, showing two patches of exposed water ice (which are seen close up in images C and D).
Images of Comet 67P/C-G taken by Rosetta’s navigation camera reveal two patches of exposed water ice, shown in close up in images C and D – click for full size (image: ESA).

It is now thought that as a comet tumbles slowly through space, the ice heated by the Sun sublimates rapidly, but then as the tumbling carries a heated part of the comet away from the Sun, it cools rapidly, causing the water vapour to re-deposit in layers throughout the core of the comet, with perhaps as much of 80% of it being retained by a comet like 67P/C-G, and only around 20% being lost to space as a result of solar-powered outgassing.

Another surprise 67P/C-G has given scientists is that it contains molecular oxygen, something which is causing some considerable re-thinking of planetary evolution, and may affect thinking on possible life-bearing exoplanets.

As a very reactive, it had long been thought that any free oxygen within a comet would have long ago combined with hydrogen aeons ago. But Rosetta has revealed 7P/C-G was constantly outgassing molecular oxygen (O2), as it approached and rounded the Sun.

“It is the most surprising discovery we have made so far in 67P,” said Rosetta scientist Kathrin Altwegg, with the Physics Institute and Center for Space and Habitability at the University of Bern in Germany. “The first time we really saw it I think we all went a little bit into denial because … oxygen was not among the molecules suspected in a cometary coma. All models show that molecular oxygen will react with the hydrogen and will no longer be present.”

 dramatic outburst from the nucleus of Comet 67P/Churyumov-Gerasimenko occured on August 12, just hours before perihelion
Gases given off by Comet 67P/C-G have been shown to contain molecular oxygen, a discovery which has surprised scientists and is causing a re-think on the early history of the solar system as well as on ideas for locating possible signs of life on planets beyond our solar system (image: ESA)

The the outgassing of the oxygen has remained relatively stable suggests that there is molecular oxygen deposited throughout the comet, strongly indicative of it being frozen into the rocks when 67P/C-G formed.

“This tells us something about the accretion — the building process — of our solar system. It had to very gentle. This ice has never been heated up enough to get reprocessed. It seems like it’s a pretty pristine material still,” André Bieler, a research fellow and Rosetta scientist said.

The discovery also may complicate an evolving strategy to look for signs of extraterrestrial life by scanning the atmospheres of distant planets for tell-tale chemical signatures. Molecular oxygen, along with methane, is a key biosignature of life on Earth.

“If we look at exoplanets, our goal of course will be to detect biosignatures, to see if the planet contains life. And as far as I know, so far the combination of methane and O2 was a hint that you have life underneath it. On the comet, we have both methane and O2, but we don’t have life. So it’s probably not a very good biosignature,” Altwegg said.