Category: Other Worlds and Tech

The first science findings from NASA’s Juno mission were published at the end of May 2017, revealing Jupiter to be far more complex a world than had been previously envisioned.

The Juno mission hopes to answer many questions about Jupiter – the structure and composition of its atmosphere, a greater understanding of the forces driving that atmosphere and the distinctive upper layer cloud formations, its magnetic field, weather patterns, and so on. It is also hoped the mission will resolve the question of what actually lies at Jupiter’s core.

Two theories have tended to dominate thinking around the latter: that Jupiter either has a relatively compact solid core 1 to 10 times as massive as Earth or it has no solid core at all, just gases compressed to a liquid state. However, the data returned by the spacecraft since it arrived in orbit around Jupiter in July 2016 doesn’t support either hypothesis. Instead, it suggests Jupiter has a large, partially dissolved core of ices and rock.

This conclusion comes via measurements of the magnitude planet’s magnetic field, which has not only proven to be significantly higher than expected, but also exhibits large spatial variations, being significantly higher than expected in some locations, and markedly lower in others. These results suggest that Jupiter’s core has a molecular hydrogen layer which appears to be the dynamo layer driving Jupiter’s magnet field, sitting over a metallic hydrogen layer which gradually transitions into a “fuzzy core” of ices and rock.

The Juno data also suggest the turbulent “meteorological layer” of Jupiter’s atmosphere, where the familiar bands of cloud exist, extends downwards more than 1,000 km (625 mi), with the tropical zoning of banded cloud layers extending down to pressures of up to 100 bars – or 100 times Earth’s air pressure at sea level), before transitioning to slightly less turbulent regions.

It had been thought that somewhere beneath the cloud layers the gasses present in the atmosphere would be more well mixed. But again, the Juno data suggests otherwise. “We’re finding that that’s just not true at all,” Dr. Scott Bolton, Juno’s principal investigator said as the first set findings was published on May 25th. “There’s structure down deep, but it doesn’t seem to match the zones and belts. And so we’re still trying to figure it out.”

“What we’ve learned so far is earth-shattering. Or should I say, Jupiter-shattering,” he also stated. “Discoveries about its core, composition, magnetosphere, and poles are as stunning as the photographs the mission is generating. Juno is re-writing all we thought we knew about Jupiter.” It is also adding new mysteries to Jupiter’s story as well.

One of the most remarkable aspects of the Juno mission so far have been the amazing images of the planet’s north and south polar regions. Rather than being banded, as with the rest of the atmosphere, or uniformly regimented into a geometric form, like Saturn’s north polar region, the atmosphere over Jupiter’s poles is a chaotic mix of swirling cyclones and storms, some of them 1,400 km (870 mi) across, towering bove the bluish backdrop of Jupiter’s deeper atmosphere.

“it’s ‘s unclear what, exactly, drives these polar cyclones,” Bolton states. “Over the course of the mission, we’ll be able to watch the poles and see how they evolve. Maybe these cyclones are always there, but maybe they just come and go.”

Juno has also suggested the cause of Jupiter’s auroral displays might be more complex than previously thought.

Earth’s auroras result when the solar wind — charged particles streaming from the sun — are funnelled by the planet’s magnetic field to slam into the atmosphere over the north and south pole in a complex two-way interaction which results in the glow of the northern and southern lights.

It had been thought to be the massive flux tube linking the polar regions of Io, Jupiter’s innermost Galilean moon, and Jupiter’s own polar regions was the driver of the planet’s auroral displays thanks to the 5 million ampere electrical current flowing through the flux. However, data from Juno, which has been combined with observations from Japan’s Hisaki  satellite and the Hubble Space Telescope suggest the gases spreading outward from Io as a result of its extreme volcanism, undergo a complex interaction with the “shock wave” formed by the solar wind as it strikes the outer limits of Jupiter’s massive magnetic field.

This interaction deflects energy from the gases back towards Jupiter at velocities of between 400 and 800 kilometres a second (250 and 500 miles per second). When this energy strikes and penetrates Jupiter’s atmosphere, it gives rise to bright, transient aurora. In addition, it is being theorised that this energy, when it reaches icy Europa and Ganymede – both of which are thought might harbour basic life in the oceans beneath their icy crusts, could provide support for chemical processes on their icy surfaces. This is liable to be something scientists will be considering carefully as more data from Juno is scrutinised.

Continue reading “Space Sunday: Jupiter revealed, methanol found” →

Proxima b, the planet discovered orbiting the closest star to our own, Proxima Centauri (see here for more), has been the subject of much speculation regarding its potential habitability (see here for more). Now a new study is underway which may bright us a lot closer to understanding the conditions on the planet.

Located 4.25 light years away, Proxima Centauri is a M-type red dwarf star. Such stars are highly variable and unstable compared to other types of stars, and this might weigh heavily against Proxima b having the right conditions for life to arise. The new study involves a team of astrophysicists from the University of Exeter, England, and staff from the UK’s Meteorological Office, who have been using the latter’s state-of-the-art Unified Model (UM).

Used to study Earth’s atmosphere, with applications ranging from weather prediction to the effects of climate change, the Unified Model allowed the team to simulate what Proxima b might be like if it had a similar atmospheric composition to Earth, and also what it might be like if had a much simpler atmosphere – one composed of nitrogen with trace amounts of carbon dioxide. Last, but not least, they made allowances for variations in the planet’s orbit.

This last point is important because given the planet’s distance from its parent – around 7.5 million km (4.6 million mi) – Proxima b is likely to either be tidally locked so that one face constantly faces its sun, or it is in a 3:2 orbital resonance, rotating three times on its axis for every two orbits around its sun. In the former situation, the main atmospheric gases on the night-facing side would likely freeze, leaving the daylight zone exposed and dry; in the latter, a single solar “day” would last a long time, resulting in the sunward side of the planet being extremely hot and day and the night side very cold and dry.

Taking all of this into account, and using data from previous studies, the UK team found that Proxima b, with either a complex or a simple atmosphere, could have regions where water might exist in liquid form. In addition, any substantive eccentricity in the planet’s orbit around its sun could further increase its potential habitability.

It will still be some time before more can be directly discerned about Proxima b, but it is hoped that the study will help in our understanding of the potential habitability of other exoplanets, and demonstrates how the study of conditions here on Earth can be used to predict what may exist in extra-solar environments.  It may also improve our understanding of how our own climate has and will evolve.

US Military “Close” To Awarding Spaceplane Contract

The US Defence Advanced Research Projects Agency (DARPA) is reportedly “close” to awarding a contract to build its XS-1 spaceplane launch vehicle.

Announced in 2013, the XS-1 is intended to provide the US military with the means to rapidly deploy small satellite payloads to Earth orbit using a re-usable first stage and expendable upper stage which may be carried piggyback by the first stage vehicle. The goal of the programme is to provide an uncrewed launch vehicle capable of delivering payloads of up to 2,300 kg (5,000 lb) to orbit, which can be rapidly re-used – the target of the development programme is to have the vehicle complete 10 launches in 10 days. In addition, the vehicle must:

• Be capable of hypersonic flight to Mach 10 (12,250 km/h) or higher
• Lifting an expendable upper stage unit which it can then launch, and which can carry the payload to orbit
• Operate with a launch cost less than 1/10 that of current launch systems (i.e. around US $5 million per flight).

Three groups of companies were awarded initial design concept contracts:  Boeing and Blue Origin, Masten Space Systems and XCOR Aerospace, and Northrop Grumman and Virgin Galactic. None of these may be awarded the development contract, which is intended to see the project to a point where test flights could commence in 2020.

To be successful, the vehicle will make use of advanced materials, cryogenic tanks, durable thermal protection, and modular subsystems. These, coupled with a reliable, re-usable propulsion system, would make it possible for the vehicle to achieve the hoped-of low-cost, rapid launch and re-use capability.

Continue reading “Space Sunday: planets, stars and spacecraft” →

To Babylon 5 fans, Epsilon Eridani is (will be?) the home to our “last, best hope for peace”. To some loosely versed in Star Trek lore, it is credited as being the star orbited by the planet Vulcan (although somewhat more officially, Vulcan is placed in the 40 Eridani star system). To astronomers, it is a very Sun-like star some 10.5 light years away, which may be the home of two (or more) planets. And now it appears it is something of a younger version of our own solar system.

The star has long been of interest to astronomers as  the possible location of exoplanets, and in 1987, it appeared as if a Jupiter-sized planet had been discovered orbiting Epsilon Eridani at roughly seven times the distance of the Earth from the Sun, and with an orbital period of some 7 terrestrial years. Initially called Epsilon Eridani b, the planet has been strongly contested over the decades for assorted reasons – even though in 2016 it was granted a formal name: AEgir (sic).

Observations of the system also revealed that the star appears to be surrounded by a cometary ring, somewhat akin to out own Kuiper Belt, and in 2008, the Spitzer Space Telescope revealed that the Epsilon Eridani system may have two major asteroid belts. the first of which correlates to the position of the asteroid belt in our own system, and the second, much broader and denser belt lying roughly at the same distance from the star as orbit of Uranus around the Sun.

Like Epsilon Eridani’s planets, the existence of the debris material surrounding the star as two distinct asteroid belts has been contested.Because the Spitzer data failed to indicate a clearly defined band of “warm material” of gas and dust within each of the rings, it has been hypothesised that rather than being two individual belts, they might actually mark the inner and outer boundaries of a single accretion disk.

The difference here is important. If the debris exists as to separate rings of material, it raises the prospect that there are planetary bodies orbiting Epsilon Eridani which may have both helped order the rings and remove debris from the space between them. If there is only one extended accretion disk around the star, it reduces the potential for planets having formed. Now the results of a 2-year study, published in the April edition of Astronomical Journal, sheds new light not only on the asteroid belts, but on the Epislon Eridani system as a whole.

The study, led by Kate Su, an Associate Astronomer with the Steward Observatory at the University of Arizona, used data gathered during a 2015 observation of Epsilon Eridani by the remarkable Stratospheric Observatory For Infrared Astronomy (SOFIA) observation platform developed by NASA and the German Aerospace Centre, DLR. This is a specially modified 747 jet aircraft designed to carry out extended studies of celestial targets.

Operating at almost 14 kilometres (45,000 ft) altitude, SOFIA flies well above the major distorting effects of Earth’s atmosphere, allowing it to use a 2.5 metre optical telescope with 3 times the resolution power of Spitzer, together with an ultra-sensitive infra-red imaging system called FORCAST, the Faint Object infraRed CAmera for the SOFIA Telescope, to observe targets.

Su and her team used the data gathered by SOFIA’s 2015 observations of Epsilon Eridani, coupled with the Spitzer data and the results of other ground-based observations of the star to build a series of computer models of the system. The results of the models tend to very much confirm that Epsilon Eridani does have two asteroid belts, each with its own distinct “warm band”, and that there could be at least three Jupiter-sized planets within the system helping to organise the rings.

Not only that, but the study suggest that the Epsilon Eiridani system might be directly comparable to our own as it was not long after the inner planets formed.  If this is the case, the study of Epsilon Eridani could help astronomers gain greater insights into the history of our own Solar System.

Continue reading “Space Sunday: solar systems, flying telescopes, and spaceplanes” →