It has long been believed that Mars once had oceans which covered most of the northern hemisphere lowlands about 3.4 billion years ago. Radar mapping from orbit has revealed layers of water-borne sediment similar to those found on Earth’s ocean floors, sitting on top of a layer of volcanic rock. In addition, there is strong evidence for an ancient shoreline and coastal areas around the rim of the ocean. The problem is, the evidence for the coastal areas is far from complete, leading to one of Mars’ many mysteries: if the lowlands were once home to a vast ocean, where did the shoreline go?
Alexis Rodriguez of the Planetary Science Institute in Tucson Arizona believes a study she and her colleagues have been carrying out may hold the key: sections of the Martian coastline may have been washed away as a result of massive tsunamis. And when I say huge – I mean waves towering some 120 metres (400ft) into the air.
The time of the Martian ocean coincides when the end of the period known as the Late Heavy Bombardment, when the planets of the inner solar system were subject to a disproportionately large number of asteroid impacts. Rodriguez and her colleagues have suggested that two particularly large meteoroids smashed into the northern hemisphere during this period, driving the tsunamis and reshaping the ancient shoreline.
The focus of the study is a region on Mars where the Arabia Terra upland region meets the lower-lying Chryse Planitia, and which should form a part of the ancient shoreline. Within it, Rodriguez and her team have identified two separate geological formations which may have been created by two separate tsunami events.
The older of the two looks every bit like a coastal region struck by a huge wave which deposited boulders over 10 metres across. As the water then receded back into the ocean, it cut large backwash channels through its debris and boulder field, depositing large amounts of surface material back into the ocean. Then, several million years later, the second impact took place.
This later event came at a time when Mars was effectively entering an ice age, and caused not so much massive tidal waves, but huge ice slurries which spread across the landscape, much of it freezing out, forming lobes of ice. The material which did make it back into the ocean also “embayed” older features there, partially burying them in the slurry.
The study isn’t conclusive, but does offer up some strong supporting evidence. Rodriguez and her team are the first to admit more research is required before the tsunami hypothesis might be confirmed or refuted. They are now examining other areas where the ancient coastline is “missing” to see if they exhibit similar evidence for tsunami events.
India Launches Spaceplane Demonstrator
Sunday, May 22nd saw India take a further step in its space ambitions with the launch of a scale model of a space plane.
The Reusable Launch Vehicle-Technology Demonstrator (RLV-TD), developed by the Indian Space Research Organization (ISRO), is the first phase of a major effort by India to develop a two stage to orbit (TSTO) launch system comprising a reusable space plane capable of delivering payloads to Earth orbit, and a recoverable launch booster.
Weighing 1.75 tonnes, the 6.5 metre long RLV-TD vehicle and its launch rocket were not recovered during this initial flight, which formed the first test in a programme called the Hypersonic Flight Experiment (HEX).
The focus of this programme is to gather valuable in-flight data about the thermal protection system (similar of the US space shuttle’s thermal tiles) which will protect the full-sized vehicle from the frictional heat generated during high-speed entry into Earth’s denser atmosphere, and examine the vehicle’s aerodynamic characteristics during hypersonic flight. The results from the programme, one of a series of four related research activities will inform the overall design of the eventual full-scale space plane.
The flight saw a small solid rocket booster lift the demonstrator through most of the dense part of the Earth’s atmosphere before separating 90-seconds after launch. The demonstrator then continued upwards to an altitude of around 70 km (44 mi), before dropping back through the atmosphere at hypersonic speeds, putting the thermal protection system to the test, before splashing down in the Bay of Bengal. For the purposes of the test, neither the test vehicle nor its booster were recovered
When fully developed, the Indian RLV system will comprise a booster rocket, designed to lift the full-size cargo carrying version of the RLV to an altitude of around 70 km (45mi). This booster will then fall back to Earth, using a combination of parachutes and airbags to achieve a soft landing so it can be refurbished and reused. The RLV will use a scamjet propulsion system India is developing to reach orbital velocity in order to deliver payloads to orbit, prior to making a return to Earth and a conventional runway-style landing.
Pluto’s Best Close-up
On Friday May 27th, NASA released a movie put together from high-resolution images of the surface of Pluto returned by the New Horizons space vehicle. Captured during the mission’s close fly by of Pluto on July 14th, 2015, the film reveals the stunning diversity of surface features on the tiny world.
With a resolution of about 80 metres (260 feet) per pixel, the film captures a strip of the planet’s surface which varies between 75 and 90 kilometres (47 to 56 miles) in width, and which tracks roughly north-west to south-east across Pluto, the initial views of the planet almost horizontal relative to New Horizons, the latter views captured from almost directly overhead.
Starting with hummocky, cratered uplands at top, the view crosses over parallel ridges of “washboard” terrain, chaotic and angular mountain ranges, cellular plains, coarsely “pitted” areas of sublimating nitrogen ice, zones of thin nitrogen ice draped over the topography below, and dark mountainous highlands scarred by deep pits. The images used to create the film were captured in rapid succession by New Horizons’ Long Range Reconnaissance Imager (LORRI) from a distance of approximately 15,850 km (9,850 mi) from Pluto.
SpaceX Makes Another At-Sea Landing
On May 27th, SpaceX made it a hat-trick of successful at-sea landings for the first stage of its Falcon 9 booster.
The two-stage booster lifted off from Florida’s Cape Canaveral Air Force Station at 21:40 GMT, carrying the Thaicom 8 communications satellite into orbit. Some 2.5 minutes after launch, the second stage separated to lift the satellite to its geostationary transfer orbit (GTO). Meanwhile, the first stage booster performed a series of “boost back” manoeuvres in order to fly back and descend onto the waiting autonomous drone ship Of course I Still Love You, making a successful touch-down on the deck of the barge just 9 minutes after lifting-off from Canaveral Air Force Station.
China’s Radio Telescope
The world’s biggest radio telescope is nearing completion in China. FAST – the Five-hundred-metre Aperture Spherical Telescope, is at the forefront of China’s continued drive to be a world leader in space exploration and study. Once fully operational, the radio telescope will “see” and “hear” further into the cosmos and with greater sensitivity than is possible with any other radio telescope.
To put the project into perspective, up until work commenced on FAST, the largest radio telescope on Earth was the famous Arecibo telescope in Puerto Rico, which metres some 305 metres (1,00 ft) in diameter – so FAST is over 1.5 times bigger. Like Arecibo, FAST is being built within a natural depression, and will be used for similar areas of astronomical study: listening for the radio signals from galaxies, pulsars, quasars, and supernovae, and even listening for any signs of distant extraterrestrial communications.
Unlike Arecibo, which has a fixed reflective surface coating the walls of a massive sinkhole, and a set of moveable receivers suspended 138.5 metres (450 ft) over it which allow it to be “pointed”, FAST is made up of 4,450 triangular-shaped panels which can be individually and collectively moved to focus on different parts of the sky and then reflect the signals they receive into a 30-tonne retina located 140 metres over the dish.
Whilst it is located in a remote location, the telescope – which has thus far taken around 5 years to build – has led to the relocation of some 9,200 people, who have not only been re-housed outside of a 5 kilometre “exclusion zone”, but also awarded an average of US $2,500 in compensation. This is because the telescope will be so sensitive once fully operational, even the emissions from a microwave oven could interfere with the telescope.
BEAM Inflates – Finally
BEAM – the Bigelow Expandable Activity Module – a prototype inflatable habitat module which arrived at the International Space Station on April 10th, was finally fully inflated on Saturday, May 28th after teething problems stopped the first attempt on Thursday, May 26th. At that time, higher than expected pressures within the slowly expanding module suggested the collapsed sides of the unit were sticking together, rather than opening out as air was fed into the unit.
As a result, the second attempt at inflation proceeded slowly – very slowly, taking a total of 7.5 hours, in which the unit gradually expanded from its 2.4 x 2.1 metre (8ft x 7ft) compressed size to its operational dimensions of 4m x 3.5m (13ft x 10.5ft), providing some 16 cubic metres (565 cubic ft) of working space.
BEAM will be equipped with monitoring equipment to investigate how well it protects against solar radiation, space debris and contamination over a 12-18 month period. During this time, ISS crew members will enter the unit 3 or 4 times a year to collect deployment dynamics sensor data, perform microbial surface sampling, conduct periodic change-out of the radiation area monitors, and inspect the general condition of the module.
If it proves successful, it could pave the way for the use of such inflatable modules in providing additional living and working aboard space stations – or even be used to create entire space stations, as well as habitat units on the surface of the Moon and Mars.