Tag Archives: Astronomy

Space Sunday: hydrogen, imaging a black hole, and exoplanet hunting

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

I’ve written a lot of late about Saturn’s icy moon, Enceladus. Covered by an icy crust, there is a good chance this distant moon harbours a liquid water ocean beneath that ice. NASA’s Cassini mission has imaged geyser plumes erupting through the ice, and the speculation is that if Enceladus does have an ocean beneath its crust.  Now that speculation has been given a sizeable boost.

As a result of a long-term study, on April 13th, 2017 NASA announced the icy plumes of Enceladus contain hydrogen. This is a huge finding; not only does this main the plumes are water vapour, it directly points to a geo-chemical / geo-thermal interaction taking place deep within Enceladus between warm water and rocks which could provide an energy source of microbes.

Current thinking is that life requires three things to get started:  water, energy, and the right chemicals. As we know from Earth’s deep oceans, sunlight doesn’t actually enter into the equation; hydrothermal vents provide the energy to support – albeit on a fragile basis – an entire ecosystem from bacteria at the base of the food chain, through tube worms, shrimp, crabs and more. This could well be the case with Enceladus.

As the hydrogen is vented, it is possible that any microbes present in the water of Enceladus could use hydrogen and dissolved carbon dioxide in the water to produce methane in a process called biomethanation (or methanogenesis), one of the foundation processes of life on Earth.

The hydrogen was measured using Cassini’s Ion and Neutral Mass Spectrometer (INMS) instrument. Designed to sample the upper atmosphere of Saturn’s moon Titan, INMS was turned towards Enceladus to follow-up on several discoveries of plumes emanating from the moon’s southern regions dating back as far as 2005.

“This is the closest we’ve come, so far, to identifying a place with some of the ingredients needed for a habitable environment,” Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate stated in reference to the report.

Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory added,  “Confirmation that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone in our search for habitable worlds beyond Earth.”

NASA’s Orion / SLS Ambitions Face Delays

In February I wrote about NASA possibly re-scheduling the first flights of their new Space Launch  (SLS) rocket system so that the maiden flight could include a crew aboard the Orion Multiple-Purpose Crew Vehicle due to fly as a part of the mission, rather than flying it as an uncrewed mission, and then flying a crew on a second later mission.

Such a move would mean the initial flight of SLS, referred to as Exploration Mission 1 (EM-1), would need to be put back from 2018 to 2019 (at the earliest), to allow time for the Orion vehicle to be correctly outfitted and tested for a crewed mission. However, a new report from NASA indicates that Orion itself may not be ready in time to meet and EM-1 launch in either 2018 or 2019.

The Orion MPCV with its European Service Module (the section with the four solar panels), attached to a propulsion stage in Earth orbit. The Service Module is one part of the system facing delays, according to a NASA report. Credit: NASA

The report, published on April 14th, 2017, highlights three significant areas of concern for the programme. The first is that design changes made to Orion’s heat shield now raise technical risks which need to be eliminated. The second is that the Service Module for Orion, which is being developed by the European Space Agency, is facing delays. The third – which is particularly underlined in the report, is that critical software required by both the SLS / SLS systems and need for ground systems at the Kennedy Space Centre in Florida, will not be ready in time.

As a result of the report, NASA is now weighing pushing back the SLS / Orion launch schedule. Nor do the programme’s woes end there; the report also questions NASA’s ability to achieve its longer-term goals with regards to SLS, Orion and Mars, citing the fact that there is no clear roadmap for developing systems (such as a deep-space habitat module, lander / ascent vehicles, etc.) vital for Mars missions.

Without such a roadmap being put in place within the next few years, the report indicates it will be impossible to tell if planned Orion / SLS project expenditure – which is slated to rise to US $23 billion in 2018 and to US $33 billion (including Mars systems expenditure) by 2030 – will be sufficient for the space agency to meet its goals.

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Space Sunday: of atmospheres, reusable rockets and Trojans

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

Back in February 2017, I covered the news about seven Earth-sized planets found in orbit around the super-cool red dwarf star TRAPPIST-1, roughly 40 light years away (see here and here for more).

While three of the planets lie within their parent star’s “habitable zone”, and so might have both an atmosphere and liquid water on their surfaces, I mentioned in both of those articles that the planets may still not be particularly habitable for life for a number of reasons, one of which is TRAPPIST-1 itself. As I noted in a previous article:

The nature of their parent star, a super cool red dwarf with all internal action entirely convective in nature, means that all seven planets are likely subject to sufficient irradiation in the X-ray and extreme ultraviolet wavelengths to significantly alter their atmospheres, potentially rendering them unsuitable for life.

A new study of TRAPPIST-1 now appears to show that it is a particularly active and violent little star.

Utilising data gathered on it by the Kepler Space Telescope, a team at the Konkoly Observatory, Hungary, lead by astronomer Krisztián Vida, have identified 42 strong solar flares occurring with TRAPPIST-1 over a period of just 80 days. Five of these events were multi-peaked, and the average time between flares was only 28 hours.

The most violent of the outbursts correlated to the most powerful flare observed on our Sun: the Carrington Event of 1859.

This was an enormously powerful solar storm, in which a coronal mass ejection struck Earth’s magnetosphere, causing auroras as far south as the Caribbean, and which resulted in chaos in telegraph systems around the world, with some operators receiving electric shocks through their handsets and telegraph pylons throwing sparks. Such was the power of the event, telegraph messages could be sent and received even with the power supplies to telegraphic equipment turned off.

The TRAPPIST-1 planets are far closer to their parent than the Earth is to the Sun, so events on an equivalent scale to the Carrington Event would hit the seven planets with a force hundreds or even thousands of times greater than Earth experienced in 1859. This, coupled with the general frequency of TRAPPIST-1 flares would most likely destroy any stability in a planet’s  atmosphere, making it extremely difficult for life to develop. And that’s assuming any of the planets orbiting TRAPPIST-1 have atmospheres.

Repeated strikes from solar flares can, over time, strip away a planet’s atmosphere. Again, given the proximity of the TRAPPIST planets to their parent, and the frequency of the stellar outburst exhibited by the star, it would seem likely that rather than being unstable, any atmosphere which may have once formed around any one of the seven planets has long since been stripped away, leaving the as barren, exposed lumps of rock.

SpaceX Successfully Flies Refurnish Falcon 9 First Stage & Announces Falcon Heavy Hopes

In April 2016 SpaceX made the first successful recovery of the first stage of a Falcon 9 launch system. Used to lift the SpaceX Dragon CRS-8 resupply mission capsule from the launchpad up towards orbit and a rendezvous with the International Space Station (ISS), the first stage of the rocket successfully touched-down vertically on the autonomous spaceport drone ship Of Course I Still Love You, 300 km (190 mi) from the Florida coastline just nine minutes after lift-off. In doing so, it achieved a long-sought-after milestone for the SpaceX reusable launch system development programme.

The world’s first reflown rocket booster, a SpaceX Falcon 9 first stage, is towed back into Port Canaveral, serving the Kennedy Space Centre, just before sunrise on securely mounted on the autonomous landing barge Of Course I Still Love You, on which it landed less than 10 minutes after a successful launch on March 30th, 2017. Credit: Ken Kremer/Kenkremer.com

On March 30th, 2017 that booster made its second successful launch and recovery, boosting the SES-10 telecommunications satellite  on its way towards orbit, before completing a successful boost-back to Earth, where it again landed on the waiting  Of Course I Still Love You.

“This is a huge revolution in spaceflight,” billionaire SpaceX CEO and Chief Designer Elon Musk told reporters at the post launch briefing at the Kennedy Space Centre press site, barely an hour after lift-off.The ability to re-use booster in this way could dramatically cut the cost of launch operations, removing the need for a brand-new rocket to be built and then disposed of with each launch – and lowering the cost of operations will not only make SpaceX vastly more competitive on pricing compared to rivals, it is also key to the company’s longer-term goals such as human missions to Mars.

The first flight of the SpaceX Falcon Heavy, may see the company attempt to recover the three first stage boosters and the upper stage of the vehicle, marking it as fully reuseable

Following the re-launch and recovery of the “used” Falcon 9 booster, Musk provided further details on the upcoming launch of his new super-booster, the Falcon 9 Heavy.

This vehicle comprises 3 Falcon 9 First stages  – one acting as the “core” to the rocket and two as “strap-on” boosters. It’s long been known that SpaceX plans to recover all three boosters following each Falcon Heavy launch. However, given the complexities involved in the first flight of a launch system, it hadn’t been entirely clear if attempts would be made to recover the boosters when Falcon Heavy flies for the first time in summer 2017.

But speaking at the SES-10 post-launch press conference, Musk confirmed that SpaceX would indeed try to recover all three boosters used be the vehicle, two of which will be refurbished Falcon 9s used on previous missions.

Landing three boosters requires considerable planning: SpaceX only has two landing options at Florida right now: the drone ship Of Course I Still Love You (the other, Just Read The Instructions, is currently based in California to support SpaceX operations out of Vandenberg Air Force Base), and their landing facility at Cape Canaveral Air Force Station. Thus, the launch will involve some aerial ballet, as Musk explained:

It will be exciting mission, one way or another. Hopefully in a good direction. The two side boosters will come back and do sort of a synchronized aerial ballet and land … That’ll be pretty exciting to see two come in simultaneously, and the centre core will land downrange on the drone ship.

A few days after this, he upped the ante further, announcing the flight will also attempt something never tried before – the recovery of the rocket’s upper stage as well. If successful – although even Musk believes the odds of recovering the upper stage on the first attempt to do so are slim – it will signal that his  dream of a fully reusable launch vehicle: first stage, payload fairings, and second stage, has come to fruition.

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Space Sunday: Flying over Mars, JUICE for Jupiter and black holes

An impact crater which formed between July 2010 and May 2012 and imaged by the HiRISE camera on the Mars Reconnaissance Orbiter, is one of the locations featured in “A Fictive Flight Above Real Mars” by Jan Fröjdman. Credit: Jan Fröjdman; original anaglyph image NASA/JPL / University of Arizona

Ever wondered what it would be like to actually fly over Mars? I have – although I admit, I’m utterly entranced by that red world and the potentials it presents. Finnish film-maker Jan Fröjdman has as well – only he’s taken the idea a step further and produced a remarkable video,  A Fictive Flight Above Real Mars. Last just over 4.5 minutes, the film takes us on a flight over some of the must remarkable scenery imaginable, using high-resolution images and data returned by NASA’s Mars Reconnaissance Orbiter (MRO).

It’s a stunning piece showing many of the more intriguing features of Mars: the recent impact crater see in the still at the top of this article; the ice walls and melt holes of the Martian poles; gullies and cliffs rutted and marked by RSLs – recurring slope lineae – which might or might not be the result of liquid activity; the ripples of sand dunes, and the winding forms of channels which might have been shaped by the passage of water.

To make the film, Fröjdman used 3-D anaglyph images from HiRISE (the High Resolution Science Imaging Experiment aboard MRO), which contain information about the topography of Mars surface. The work involved manually picking more than 33,000 reference points in the anaglyph images, and then processing the results through six pieces of software to achieve a sense of motion and panning across the surface of Mars.

In putting the film together, Fröjdman  wanted to create a real feeling of flying over Mars and of recapturing the feel of video footage shot by the Apollo astronauts as they orbited the Moon. To help with the latter, he overlaid the video with image cross-hairs of the kind seen in some of the Apollo footage, and added little bursts of thruster firings to simulate a vehicle manoeuvring in the thin atmosphere. The film concludes with a main engine firing, presumably to lift the vehicle back into orbit.

NASA and SpaceX Consider Red Dragon Landing Site

And staying with Mars: NASA and SpaceX have started the process of selecting a landing site for SpaceX’s planned Red Dragon mission to Mars in 2020. The ambitious mission will see the company attempt to land a 10-tonne Red Dragon capsule on Mars purely by propulsive means. While paid for entirely by the company, the mission will feature a science suite provided by NASA.

There are two major criteria governing any landing site location: scientific interest, and the potential for colonisation – the 2020 mission being the first of a number which SpaceX plans to uses as precursors for human missions to Mars. As such, it had initially been decided that any landing sites put forward must be near the equator, for solar power; near large quantities of ice, for water and at low elevation, for better thermal conditions.

NASA initially identified four potential locations on Mars’ northern hemisphere which meet the broad criteria for the mission – but examination of three of them using the HiRISE system on the Mars Reconnaissance Orbiter showed they are rocky enough to pose a threat to landing a vehicle the size and mass of Red Dragon. This currently leaves a short-list of one, in the shape of Arcadia Planitia, a smooth plain containing fresh lava flows and which has a large region that was shaped by periglacial processes which suggest that ice is present just beneath the surface.

Acadia Planitia is the current sole contender to be the landing site for the SpaceX Mars 2020 mission

However, negating this is the plain’s relatively high northern latitude (40-60 degrees north), which would reduce the amount of sunlight a base of operations there would receive in the winter months. While Amazonis Planitia to the south offers a similar youthful surface, much of which is relatively smooth, it is largely volcanic in origin and unlikely to harbour sub-surface water ice which can be easily accessed.

Given both of these point, it is likely other possible landing sites will be proposed in the coming months.

Curiosity Reveals More Wheel Damage

It’s been a while since my last report on NASA’s Mars Science Laboratory rover, Curiosity. This is mostly being the updates coming out of JPL have slowed mightily in recent months.

At present, Curiosity is examining sand dunes on the lower slopes of “Mount Sharp”. Once finished, it will proceed up higher to a feature known as “Vera Rubin Ridge”, inspecting a layer that is rich in the mineral hematite. From there, it will proceeded to even higher elevations to inspect layers that contain clays and sulphates. This will require a drive of some 6 km (3.7 mi) uphill, and so will require time to complete.

A recurring area of concern for the mission – albeit not serious at this point – is the wear and tear on the rover’s wheels. In 2013, Curiosity suffered greater than expected damage to its six wheels while traversing some exceptionally rough terrain.  Although the damage was nowhere near severe enough to impeded the rover’s driving abilities, it did result in engineers keeping a much closer eye on the condition of Curiosity’s wheels using the imaging system mounted on the rover’s robot arm.

The latest of these checks was performed on  Sunday, March 19th, 2017, and it revealed two small breaks in the raised treads (“grousers”) on the rover’s left middle wheel. These seem to have occurred since the last wheel check at the end of January, 2017. These treads perform two major tasks: bearing the brunt of the rover’s weight and providing most of the traction for a wheel.

The broken “grousers” (“treads”) on one of Curiosity’s six wheels, together with older puncture holes through the wheel, as imaged on March 19th, 2017. Credit: NASA/JPL

Following the 2013 damage, testing on Earth suggested that significant breaks in three “grousers” on a wheel would indicate it has passed 60% of its expected lifespan. However, the mission team emphasise the rover has already driven more than 60% of the total distance needed for it to make it to all of its scientific destinations. As such, while the breaks will be monitored, they are not a cause for immediate or grave concern.

Overall, confidence remains high that Curiosity will achieve all of its expected science goals and will likely make an extended traverse up the side of “Mount Sharp”.

A rover’s progress: the 16 km (10 mi) travelled by Curiosity so far, and potential for future explorations up the side of Aeolis Mons. Credit: NASA/JPL / T. Reyes

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Space Sunday: 100+ planets, taking a balloon to orbit, and budgets

A chart showing the to-scale sizes of two planets, 19 moons, 2 asteroids, and 87 trans-Neptunian objects, all of which could technically be considered planets orbiting our Sun. Credit: Emily Lakdawalla. Data from NASA / JPL, JHUAPL/SwRI, SSI, and UCLA / MPS / DLR / IDA, processed by Gordan Ugarkovic, Ted Stryk, Bjorn Jonsson, Roman Tkachenko, and Emily Lakdawalla

When is a planet not a planet – or more precisely, when should what is not regarded as a planet be a planet?

Right now, according to the International Astronomical Union (IAU), our solar system comprises eight formally recognised planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. That’s been the case since 2006, when the IAU opted to classify bodies orbiting the Sun in three ways:

  • As planets – defined as a) celestial bodies that (a) are in orbit around the sun; b) have  sufficient mass for their self-gravity to overcome rigid body forces so they assume a hydrostatic equilibrium (nearly round) shape; c) have cleared the neighbourhood around their orbit of other objects
  • As Dwarf planets – defined as celestial bodies which a) orbit the sun; b) have sufficient mass for their self-gravity to overcome rigid body forces to assume hydrostatic equilibrium (aka “is nearly round” in shape);  c) have not cleared the neighbourhood around their orbit; and d) is not a natural satellite
  • As Small Solar System bodies:  all other objects except satellites orbiting the Sun.

A composite image showing Pluto and Charon to scale to one another (but not at a scale separate from one another) using images returned by the New Horizons mission. Credit: NASA / John Hopkins University APL / SwRI

Thus, since 2006, Pluto has been a dwarf planet. However, moves are afoot to get things changed – and not just for Pluto.

In a paper authored by planetary scientists involved in the New Horizons mission which zipped through the Pluto system in July 2015, there is a call for the term “planet” to be redefined; if not by the IAU then at least in popular use. Should it happen, it could see the number of planets in the solar system leap from 8 to over 100.

The scientists argue that the IAU definition of “planet” focuses only on the intrinsic qualities of the body itself, rather than external factors such as its orbit or other objects around it. In fact, under the IAU’s definition, Earth, Mars, Jupiter and Neptune don’t actually qualify as “planets” as none meet the third criteria (c) – Earth, for example, has regular “close encounters” with asteroids which cross its orbit. Instead, the team offer a simpler definition:

A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has enough gravitation to be round due to hydrostatic equilibrium regardless of its orbital parameters.

Such a definition would mean that Pluto could regain its planetary status – as would the proto-planet (or small solar system body) Ceres, the dwarf planets of 136199 Eris (discovered in 2005, and the trigger-point for Pluto’s “downgrading”) , 136472 Makemake, and 136108 Haumea, together with (possibly) 50000 Quaoar, 90377 Sedna, 90482 Orcus and a host of trans-Neptunian objects tumbling around the Sun. Nor is that all; the new definition would also mean that the likes of  Jupiter’s Galilean moons, Saturn’s Titan and  Enceladus, Neptune’s Triton and many other bodies we regard as “moons” would be lifted to planetary status – including our own Moon.

A composite image using data gathered by the radar imager aboard NASA’s Cassini mission to Saturn to look through the normally opaque haze of Titan’s dense atmosphere to reveal its planet-like surface. Credit: NASA/JPL / University of Arizona

The paper proposing the change will be presented at the Lunar and Planetary Science Conference on March 20th to 24th, 2017 in Texas. And it has already come in for some criticism.

Mike Brown is the scientist largely behind Pluto’s demotion. Currently engaged in the search for the elusive “Planet Nine”, he (somewhat harshly) sees the efforts of the New Horizons team to get Pluto reclassified as being  about them wanting the prestige of having run a planetary mission, more than anything else.

However, there are valid reasons for seeking some kind of change, even if it is only informal. One is as basic as gaining more public interest in efforts to explore and understand the many environments found on planets and moons alike within our solar system.

“Every time I talk about this [the science and data gathered about Pluto by New Horizons] to the general public, the very next thing people say is ‘Pluto is not a planet any more’,” said Kirby Runyon, the lead author of the paper. “People’s interest in a body and exploring it seems tied to whether or not it has the name ‘planet’ labelled on it.”

How Pluto compares with other large Trans-Neptunian Objects, some of which also have their own moons. Earth and our moon can be seen at the bottom of the picture. Credit: Lexicon / Wikipedia, using NASA / Hubble Space Telescope data

There are scientific reasons for the definition to be broadened as well. Places like Pluto, Ceres, Europa, Io, Ganyemede, Callisto and Triton all evidence geophysical, hydrothermal, atmospheric and other characteristics very much in keeping with bodies such as Earth, Mars, and Venus. They are thus of exceptional interest to planetary scientists the world over. In fact, many of them (like Pluto) are completely re-writing our understanding of “planetary bodies”.

Ultimately, the team behind the paper aren’t going to put their proposal before the IAU for a change in the “official” definition of “planet”.  “As a geophysical definition, this does not fall under the domain of the IAU, Runyon notes, “[It]  is an alternate and parallel definition that can be used by different scientists. It is “official” without IAU approval, partly via usage.”

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