The Pluto – Charon system is, as I’ve reported through various Space Sunday reports, turning out to be far more remarkable a place than scientists ever imagined. While NASA’s New Horizons space vehicle, which zapped past both Pluto and Charon during its closest approach to both on July 14th, 2015.
On February 18th, NASA revealed the most recent surprise to be revealed by New Horizons: Charon may have once had a subsurface ocean that has long since frozen and expanded, pushing outward and causing the moon’s surface to stretch and fracture on a massive scale.
The side of Charon imaged by NASA’s probe is characterised by a system of “pull apart” tectonic faults, which are expressed as ridges, scarps and valleys—the latter sometimes reaching more than 6.5 kilometres (4 miles) deep. Charon’s tectonic landscape shows that, somehow, the moon expanded in its past, fracturing as it stretched.
The outer layer of Charon is primarily water ice. This layer was kept warm when the tiny world / moon was young by heat provided through the decay of radioactive elements, as well as Charon’s own internal heat of formation. Scientists say Charon could have been warm enough to cause the water ice to melt deep down, creating a subsurface ocean. However, as it cooled over time, this ocean would have frozen and expanded (as happens when water freezes), lifting the outermost layers of the moon and producing the massive chasms we see today.
In an image gathered by the Long-Range Reconnaissance Imager (LORRI) in July 2015 and release by NASA on February 18th, reveals a vast equatorial belt of chasms on Charon. This network is around 1,800 km (1,100 mi) long and in places is 7.5 km (4.5 mi) deep. By comparison, the Grand Canyon is 446 km (277 mi) long and around 1.6 km (1 mile) deep.
The inset images on the picture show one section of the network of chasms, informally named “Serenity Chasma”, with a matching colour-coded topography map. Measurements of “Serenity Chasma” strongly suggest Charon’s water ice layer may have been at least partially liquid in its early history, and has since refrozen.
Virgin Galactic, Sir Richard Branson’s private venture company which is aiming to become the world’s first commercial space line, offering fare-paying passengers sub-orbital flights into space. rolled out it new SpaceshipTwo vehicle on Friday February 19th.
The event came more than a year after the loss of the first SpaceShipTwo craft, the VSS Enterprise, in a tragic accident in which the craft broke up in mid-air on October 31st, 2014, killing co-pilot Michael Alsbury, and seriously injuring pilot Peter Siebold. At the time of the accident, several other figures involved in private sector space efforts were quick to point to Virgin Galactic’s use of nitrous-oxide as a vehicle propellant and to suggest corner-cutting by the company as causes of the accident.
However, after investigating the incident, the US National Safety Transportation Board (NTSB) drew the conclusion that the incident was largely the result of pilot error: the “feathering” mechanism designed to be used at the edge of space to allow the vehicle to gently re-enter the denser layers of Earth’s atmosphere was inadvertently deployed by co-pilot Alsbury, resulting in the immediate aerodynamic destabilisation and break-up of the vehicle. As a result of these findings, and as a part of a series of improvements made to the vehicle, the new SpaceShipTwo includes a locking mechanism designed to prevent the feathering system being deployed in error.
The new vehicle, christened VSS Unity by Professional Stephen Hawking (assisted by Branson’s year-old granddaughter), was rolled-out at a special media event held at Virgin Galactic’s operations and flight facilities in the Mojave Desert, California. It marks the start of a long programme to get the vehicle to a point where it is ready to undertake its first powered flight.
This programme will include a series of ground tests of various vehicle systems, followed by taxi tests on the runway at the Mojave Air and Space Port. after these will come “captive carry” flights, where SpaceShipTwo remains attached to its WhiteKnightTwo carrier aircraft, then unpowered glide flights before the first in a series of powered test flights. While this test programme is not expected to be as protracted as the flight evaluation programme undertaken by VSS Enterprise prior to its crash, iy does mean that the company is not ready to provide any suggested dates by which fare-paying flights might commence.
Hubble Telescope Directly Measures Rotation of ‘Super-Jupiter’
Astronomers using the Hubble Space Telescope have measured the rotation rate of an extreme exoplanet, called 2M1207b, by observing the varied brightness in its atmosphere. The calculations mark the first time the rotation of an exoplanet has been made by means of direct imaging.
2M1207b lies 170 light years from Earth and orbits a brown dwarf , designated 2M1207, at a distance of approximately 8 billion km (5 billion mi). To put this in context, this is almost half as far again as Pluto’s average distance from the Sun. Both the planet and the star it orbits are curiosities, holding considerable interest for scientists and astronomers.
As a brown dwarf star, 2M1207 falls into a category of stellar bodies which sits between the heaviest gas giant planets and the “lightest” (by mass) of what might be called “true” stars. Their mass is such that they are too small to sustain hydrogen-1 fusion reactions in their cores (like the Sun), and are thought to fuse deuterium and lithium instead.
Hubble’s imaging measurements reveal 2M1207b, which is only slightly larger than Jupiter but has 4 times its mass, is rotating about its axis once every 10 hours – more-or-less the same as Jupiter’s own spin. However, this isn’t the thing which has caught the attention of scientists.
2M1207b is a very young planet, only around 10 million years old (compare that to Earth’s 4.5 billion years!), and is still contracting under its own gravity, generating heat (like Jupiter and Saturn, 2M1207b radiates far more heat than it absorbs from its parent star). Scientists believe this heat is sufficient to form “rain” clouds in the planet’s upper atmosphere made of glass-like particles, and that lower down in the atmosphere the heat and pressure combine to form iron droplets which also fall as “rain” prior to being evaporated as the heat and pressure build.
The other point of interest with 2M1207b is its size relative to the star it is orbiting. Within the solar system, all of the planets are made up of matter from the accretion disk – the stuff left over after the Sun was born. As such, their combined mass is just a tiny fraction of the Sun’s. However, 2M1207b is just 6 times less massive than the start it is orbiting, leading scientists to believe planet and star formed independently of one another, from separate clouds of dust.
All of this makes 2M1207 and its giant planet prime targets for study by the James Web telescope, due to be launched in 2018.
Have Your Art Sent to an Asteroid
NASA is calling all space enthusiasts to send their artistic endeavours on a mission to a near-Earth asteroid.
Slated for a September 2015 launch, the Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) is designed to rendezvous with the asteroid, gather between 60 grams and 2 kg (2.1 ounces and 4.4 lbs) of materials and return it to Earth for study.
As a part of the mission, the #WeTheExplorers campaign invites the public to take part in this mission by expressing, through art, how the mission’s spirit of exploration is reflected in their own lives. Submitted works of art will be saved on a chip on the spacecraft, which already carries a chip with more than 442,000 names submitted through the 2014 “Messages to Bennu” campaign.
A submission may take the form of a sketch, photograph, graphic, poem, song, short video or other creative or artistic expression that reflects what it means to be an explorer. Submissions will be accepted via Twitter (tagged @OSIRISREx) and Instagram (tagged @OSIRIS_Rex) until March 20th.
Note that all submission must include the hashtag #WeTheExplorers. Videos may be submitted by direct upload to Twitter or Instagram or by including a link to your YouTube or Vimeo video in a correctly tagged tweet. Videos must be no longer than 2 minutes and 30 seconds in length.
Bennu, which is approximately 492 m (1,614 ft) in diameter, has been chosen due to it being a carbonaceous asteroid passing relatively close to Earth in its orbit around the Sun. Carbonaceous material is of significant interest to scientists as it is a key element in organic molecules necessary for life as well as representative of matter from before the formation of Earth. Organic molecules, such as amino acids, have previously been found in meteorite and comet samples, indicating that some ingredients necessary for life can be naturally synthesized in outer space.
The mission will take 7 years to complete: a two-year flight to Bennu following launch, then 505 days spent in orbit mapping the asteroid at a distance of approximately 5 km (3.1 mi). Data from this work will be used to select a sample site. OSIRIS-REx will then commence a very slow descent toward the asteroid, stopping short of actually touching down. Instead, and at an altitude of 5 metres (16ft) above the surface, it will employ a robotic arm system called TAGSAM (Touch-And-Go Sample Acquisition Mechanism), in three sample gathering attempts designed to collect a minimum of 60 grams of material from the asteroid.
The sample gathering should take place around September 2019, before the vehicle makes a return to Earth. On its return, the sample container will be ejected, enter the Earth’s atmosphere and make a parachute landing in Utah in September 2023.
As well as gathering the sample, the Bennu mission will serve to increase our understanding of the asteroid’s physical properties – but not just for reasons of scientific discovery. Recent calculations suggest that the asteroid, which orbits the Sun every 1.2 years, and passes close to Earth every 6 years, could impact our world some time between 2169 and 2199, with the greatest risk of impact potentially occurring on September 24th, 2182. A deeper understand of the asteroid’s composition and physical properties will therefore assist in developing an asteroid impact avoidance mission.