Space Sunday: TRAPPIST-1, planet 9 and Europa

An artist's impression of the seven TRAPPIST planets, with -1b lower left and -1h lower right. The three planets in the star's habitable zone, -!e, -1f and -1g are the right-hand three in the top row. Credit: NASA
An artist’s impression of the seven TRAPPIST planets, with -1b lower left and -1h lower right. The three planets in the star’s habitable zone, -!e, -1f and -1g are the right-hand three in the top row. Credit: NASA

I recently wrote a space update special on the TRAPPIST-1 star system with its seven roughly Earth-sized planets. Since then, there has been speculation about whether any of them might support life, and what conditions for life might be like.

Whether life may have arisen on any of the worlds is tough question to answer. Three of the seven lie within the “habitable zone” where liquid water might exist (TRAPPIST-1e, -1f and -1g) – which is a positive for life as we know it. But for that liquid water to remain liquid, the planets must have an atmosphere. Currently, only TRAPPIST-1b and -1c have, through spectral analysis, been shown to harbour atmospheres, but these seem to be limited in scope, and could range from a water vapour rich atmosphere through to an environment similar to that of Venus.

On the negative side of the equation, 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. Further, all seven are tidally locked, meaning they always keep the same face towards their parent star. This will inevitably give rise to extreme conditions, with one side of each world bathed in perpetual daylight and the other in perpetual, freezing darkness, resulting in extreme atmospheric movements and likely harsh weather.

Comparing the TRAPPIST-1 system with the solar system. Credit: European Southern Observatory / O. Furtak
Comparing the TRAPPIST-1 system with the solar system. Credit: European Southern Observatory / O. Furtak

Daylight on the planets would also be very different. Although one side of these worlds be forever in daytime, and despite the relative proximity with which they orbit their parent star, days on their surfaces would never be much brighter than sunset here on Earth, both in terms of colour and light intensity. This is because most of the light emitted by TRAPPIST-1 is radiated in the infra-red wavelengths, rather than visible wavelengths.

One the more positive side of the equation, despite the low levels of visible light, TRAPPIST-1 could still be able to sufficiently warm an atmospheres the planets might have, and the weather conditions might actually dissipate this warmth evenly over the planet’s surface, perhaps making it more hospitable to life.

It’s also likely the planets experience a lot of tidal flexing as they come under the influence of one another as well as their parent star. This flexing might give rise to hydrothermal and volcanic vents, which in turn could provide the necessary heat (energy), minerals and chemicals necessary to kick-start basic life.

Artist's impression of the three planets in TRAPPIST-1's habitable zone and to scale relative to one another. -1e (l) is the most likely to have extensive liquid water. It is 92% as big as Earth, with a mass of 62% that of Earth. It orbits its parent star about 10.8 times the distance from Earth to the Moon. -1f (c) is 1.04 times the size of Earth, but with only 62% of its mass. It is potentially water rich, and gets as much light from its star as Mars does from the Sun. -1g (r) is the outermost of the three
Artist’s impression of the three planets in TRAPPIST-1’s habitable zone and to scale relative to one another. -1e (l) is the most likely to have extensive liquid water. It is 92% as big as Earth, with a mass of 62% that of Earth. It orbits its parent star about 10.8 times the distance from Earth to the Moon. -1f (c) is 1.04 times the size of Earth, but also with  62% of its mass. It is potentially water rich, and gets as much light from its star as Mars does from the Sun. -1g (r) is the outermost of the three. It is 1.13 times Earth’s size with 1.34 times its mass. It is far enough away from its parent star that the surface is likely to be entirely frozen, but the gravitational influence of the other planets could give rise to a liquid water ocean under the ice. Credit: NASA

Studies of the TRAPPIST system will continue using the Spitzer and Hubble space telescopes and via ground-based observatories. However, as mentioned in my special report, it is likely to be the James Webb Space Telescope which will hopefully reveal many of the secrets of the TRAPPIST-1 system.

That said, and for those still wondering about intelligent life arising on any of these worlds, SETI, the Search for Extra-Terrestrial Intelligence has been “listening in” on the star for indications of radio traffic for some time (pre-dating the discovery of the first two planets in the system in 2016). Those surveys haven’t revealed any kind of radio emissions from the system that might be of artificial origin, but now we know there are seven planets, SETI has marked TRAPPIST-1 for further investigations with their Allen Telescope Array (ATA).

A Further Clue in the Hunt for Planet 9

Last year, Caltech astronomers Mike Brown and Konstantin Batygin found indirect evidence for the existence of a large planet in the outer reaches of our Solar System well beyond Pluto; since then, the search has been on. I first covered the hunt in January 2016, and followed it with updates in February 2016 and October 2016, and it now seems a new clue to the planet’s existence may have been revealed.

Planet X, if it exists,could equal Neptune in size, and orbits the Sun 200 times further away than Earth. Credit: Caltech / R. Hurt
Planet X, if it exists,could equal Neptune in size, and orbits the Sun 200 times further away than Earth. Credit: Caltech / R. Hurt

Astronomers using the Gran Telescopio CANARIAS (GTC) in the Canary Islands looked at two distant asteroids, called Extreme Trans Neptunian Objects (ETNOs). Spectroscopic observations 2004 VN112 and 2013 RF98 suggest that the two were once a binary asteroid pairing that were pulled apart as a result of the influence of a mass massive body between 10 and 20 Earth masses in size and about 300 to 600 AU from the Sun. As a result of this, the two bodies drew further and further apart over, time they became more and more separated to become how we see them today.

“The similar spectral gradients observed for the pair 2004 VN112 – 2013 RF98 suggests a common physical origin,” said Julia de León, an astrophysicist at the Instituto de Astrofísica de Canarias (IAC). “We are proposing the possibility that they were previously a binary asteroid which became unbound during an encounter with a more massive object.”

de León and his team carried out thousands of computer-based simulations to see how this might have happened, and found the most consistent result suggested the bodies were separated as a result of a close passage by a massive planetary object around 5-10 million years ago.

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

What is particularly interesting here is that the location of the two asteroids, coupled with the suggested mass of the body which pulled them apart and the distance it is believed to have been from the Sun, also fit the broader parameters for where the orbit of Planet 9 might reside, and the estimated mass of the planet. Thus, when combined with the eccentric orbits of several Kuiper Belt Objects believed to have been perturbed in their orbits around the Sun by planet 9, it gives further credence to the idea it really is out there, somewhere.

When – and if – it might eventually be found is open to question. However, it is hoped that a  recently started “citizen scientist project will encourage amateur astronomers around the world to join in the hunt for Planet 9.

Europa Mission Moves Forward

There are several candidate locations in the solar system where we might find life beyond Earth. One of them is Jupiter’s ice-shrouded moon, Europa, which has a deep liquid water ocean beneath its icy crust, heated by hydrothermal vents on the sea beds. These vents – as is the case on Earth’s deep ocean floors – may not only heat the water around them, they might also provide all the energy, minerals, organics and nutrients needed for basic life to get started. As such, scientists would love to study Europa more closely. And they are now likely to get their wish.

Artist's impression of the Europa multiple flyby mission spacecraft. Credit: NASA
Artist’s impression of the Europa multiple flyby mission spacecraft. Credit: NASA

On February 24th, NASA’s proposed Europa Multiple Flyby mission, sometimes also called Europa Clipper, passed a critical review phase, and is now allowed to enter into a preliminary design phase which will run through until September 28th, when it will undergo a further review to determine if NASA should proceed with it. Right now, that seems highly likely. The mission has strong support in Congress, and despite earlier opposition, that support has ensured the mission has received higher than required funding thus far – funding which could ease the way to an important follow-up mission.

The goals of the Europa Multiple Flyby mission are to explore Europa, investigate its habitability and aid in the selection of a suitable location where a lander might be put down on Europa with reasonable safety – the follow-on mission mentioned above which, thanks to the added expenditure directed towards the flyby mission, could take place just a couple of years after the flyby mission reaches Europa.

When that will be is unclear. NASA has yet to specify a cost or schedule for the mission, but again, in a demonstration of the level of support for it, language in recent appropriations bills funding the agency have directed it to launch the mission by 2022.

Artist's impression of the follow-up lander mission vehicle
Artist’s impression of the follow-up lander mission vehicle. Credit: NASA

Another decision yet to be made is the vehicle used to launch the flyby mission. This could either be a Delta 4 Heavy, with a long duration flight of around 6 years to Jupiter, using gravity assists from Earth and other planets along the way, or the mission could be launched via the SLS, which would place it on a 3-year direct flight to Jupiter / Europa. The follow-up mission, which would place a lander with around 50 kg of science equipment on board, would have to use the SLS.

Both missions, if approved, are expected to operate in concert with Europe’s Jupiter Icy Moons Explorer, which will fly-by Callisto multiple times before moving into orbit around Ganymede, the outermost two of Jupiter’s Galilean moons, which also may harbour liquid water oceans under their crusts. (Fun fact: Ganymede’s ocean might contain more water than all of Earth’s oceans combined.)

NASA confirms Mulling Crewed SLS First Launch and Orion for ISS?

In my last Space Sunday report, I noted that NASA was mulling a proposal by Acting Administrator Richard Lightfoot to make the first launch of the Space Launch System (SLS) and the Orion Multi-Purpose Crew Vehicle a crewed launched. On Friday, February 24th, the US space agency confirmed that they are now formally investigating the option, and expect to make a decision in about a month.

An artist's impression of a Space Launch System / Orion combination lifting off from Kennedy Space Centre's Pad 39B. Credit: NASA
NASA is to report on the feasibility of the first SLS / Orion flight carrying a 2-person crew, probably in late March. Credit: NASA

As I’ve previously noted, were the plan to go ahead, the first SLS / Orion Launch (Orion already having flown into space in December 2014, atop a Delta 4 Heavy rocket) would be pushed back to 2019 and include a crew of two. An alternative option, to bring forwards the second SLS launch from 2021/2023 isn’t feasible, and that launch has too many additional dependencies, including making significant changes to the SLS launch platform to accommodate a taller upper stage to the rocket.

The biggest question on flying EM-1 with a crew, again as mentioned previously, is whether or not the Orion vehicle can be properly outfitted with all the necessary life support and flight systems required by a crew in a time frame short enough to warrant the attempt. If it turns out Orion cannot be prepared for a launch earlier than 2020, the it is unlikely the current plans to fly it uncrewed in 2018 will be changed.

In the meantime, a NASA authorisation bill passed by the Senate Feb. 17 directs NASA to re-examine using the Orion spacecraft to transport crews to and from the International Space Station (ISS). It is one of the few major changes in the NASA Transition Authorisation Act of 2017, and NASA will have to submit a report within 60 days of the bill’s enactment on whether  Orion is still capable of flying crews to and from the space station, if called upon to do so.

In accordance with language of the 2010 space authorisation bill, NASA is, under a new bill, being directed to confirm whether the Orion Multi-Purpose Crew Vehicle will be capable of ferrying crews to / from the ISS were it necessary to do so. Credit: NASA
In accordance with language of the 2010 space authorisation bill, NASA is, under a new bill, being directed to confirm whether the Orion Multi-Purpose Crew Vehicle will be capable of ferrying crews to / from the ISS were it necessary to do so. Credit: NASA

The 2010 NASA authorisation act – the last one to become law – originally required NASA to give Orion just such a capability. But with the ISS “taxi service” intended to be carried out by SpaceX and Boeing, NASA has focused more on Orion’s ability to undertake missions well beyond low Earth orbit. The new directive doesn’t mean Orion will be used for ISS crew missions, but is rather to tap on the agency’s shoulder.

However, it would appear that flying Orion to ISS would involve a number of challenges, including adapting it to an unspecified alternative launch vehicle (using the SLS for such flights would be a waste and prohibitively expensive). This means adapting it for launch atop the SpaceX Falcon 9 and / or the ULA Atlas V, the vehicles which will be used to launch the Dragon 2 and Boeing CST-100 Starliner to the ISS with crews.

 2017 Annular Solar Eclipse

Sunday February 26th saw an annular eclipse of the Sun take place. This is when is when the disk of the Moon comes between the Earth and the Sun, but disk of the Moon is not large enough to cover that of the Sun to leave only the solar atmosphere visible (as with a total eclipse). Instead, a part of the Sun’s surface remains visible around the edge of the Moon, creating what is called a “ring of fire” – or more formally, an “annulus”.

A southern hemisphere event, the eclipse was best seen in South America, notably Chile and Argentina, and was livestreamed by the likes of Slooh (highlights of that broadcast below). The next annular eclipse will take place on December 26th, 2019, and will be visible from Eastern Europe through India to western Australia.

The event was the first of two major eclipses which will occur in 2017. The other will be the Great American Total Eclipse on August  21st. This will see totality (the complete eclipsing of the Sun by the Moon) visible along a narrow band stretching from coast to coast across the middle of the United States.

Advertisements

Have any thoughts?

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s