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.

An Earth-Sized Planet With An Atmosphere 39 Light Years Away

In 2015, astronomers discovered an intriguing extrasolar planet located in a star system some 39 light years from Earth. Orbiting fairly close to its parent star, the planet is roughly 1.4 times bigger than Earth, and initial measurements suggested it might be cool enough to harbour an atmosphere. Now a team of scientists have confirmed it does.

Led by John Southworth of Keele University and Luigi Mancini of the University of Rome Tor Vergata, the tam  used the GROND imager on the La Silla Observatory’s 2.2m ESO/MPG telescope to monitor the planet – known as GJ 1132b – in different wavelengths as it transited in front of its parent star. Given the planet’s orbital period is just 1.6 days, this gave the team plenty of opportunities gather data.

The data indicated that when viewed at infra-red wavelengths, the planet appeared bigger than it did under others, such as visible light. An atmosphere is a good absorber of infra-red light, so the findings suggested GJ 1132b has one. Simulations by the team further suggest that the atmosphere is most likely thick and rich in water and/or methane.

An artist’s impression of a “super Earth” type planet in orbit around a red dwarf star. Credit: NASA / Dana Berry.

This marks the first time that an atmosphere has been confirmed around a planet that is not significantly greater in size and mass to Earth – as noted, GJ 1132b is just 1.4 time larger than Earth, and is 1.6 times its mass. While atmospheres have been found around other exoplanets, they have all been either Jupiter-style gas giants or planets that were many times Earth’s size and mass (aka. “Super-Earths”).

In addition, these findings are a significant step in the search for life beyond our Solar System. At present, astronomers use the chemical composition of a planet’s atmosphere to determine if it could be habitable. Where the right combination of chemical imbalances exist, the presence of living organisms is seen as a possible cause. Being able to determine that a planet at lower end of the super-Earth scale has an atmosphere, brings us one step closer to being able to determine exoplanet habitability.

The detection of an atmosphere-bearing planet around an M-type (red dwarf) star is also good news in and of itself. Low-mass red dwarf stars are the most common star in the galaxy, and recent findings have indicated that they might be our best shot for finding habitable worlds.

Martian Trojans Point To Ancient Planetoid

Not long ago I wrote about an attempt to redefine the criteria used to ascertain if a planet is a planet. One of the reasons for doing this is because technically, under the current “official” criteria as determined by the International Astronomical Union (IAU), Venus, Earth, Mars, Jupiter, Uranus and Neptune don’t actually qualify as planets. This is because all of them has at least one (or in Jupiter’s case perhaps a million) Trojan asteroids.

Trojan asteroids are asteroids occupying the 4th or 5th Lagrange point of a major planet in the Solar System, thus breaking  the third criteria for a planet to be classified as a planet: that is has the neighbourhood around its orbit of other objects.

The Lagrange points around two bodies where one is in orbit about the other (such as the Sun and Earth, or the Earth and the Moon). They are points of gravitational equilibrium between the two bodies

There are a number of reasons why asteroids can settle in Trojan positions either ahead or behind a planet in its orbit. however, what is particularly fascinating about the Trojan asteroids occupying the L5 position trailing Mars in its orbit around the Sun is that they appear to be the remains of one or more mini-planets destroyed in a collision billions of years ago.

Researchers drew this conclusion after an extended study of the asteroids – eight in total and referred to as the Eureka Family. All eight are thought to have been in Mars’ L5 position ever since the formation of the Solar System. However, spectrographic and photometric data on the asteroids reveal they are rich in the mineral olivine – a magnesium iron silicate that is a primary component of the Earth’s mantle and (it is believed) other terrestrial planets.

This marks the eight asteroids as very different from those asteroids occupying the asteroid belt between Mars and Jupiter, indicating the Eureka Family are not simply rocks which strayed out of the asteroid belt to settle into Mars’ L5 position.  The presence of the olivine among all of them strongly suggests they have a common heritage – and helps shed light on the formation of the inner solar system.

Mars’ Eureka Family of asteroids suggest that before Mars and the other inner planets of the solar system formed, there was a period of intense collisions between planetesimals in the solar system, which formed, collided and left at least some of the material used in the formal of the “solid” planets. Credit: NASA

Essentially olivine only forms in objects large enough to differentiate into a crust, mantle and core. It’s Unlikely that these objects formed at the same time Mars did; they must have come into being prior to Mars forming, colliding with one another, breaking up and exposing the olivine, some of which was undoubtedly used in Mars’ formation.

Thus, the presence of the olivine in the Martian Trojans hints at a more extended planetary formation period for the inner solar system, one marked by the formation of planetesimals large enough to form olivine within their crusts and which underwent an intense period of collision with one another, breaking up and providing the material which later coalesced into Mars itself – and much the same may have occurred for Earth, Venus and Mercury. As such, the Trojan asteroids of Jupiter, Earth and Venus may well be the subject of more extensive study in the future.

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