Curiosity, NASA’s Mars Science Laboratory rover, has found further evidence that Gale Crater had liquid water present within it for a long time, and the data the rover has gathered during its explorations is allowing scientists to better characterise the nature of the lake which once occupied the crater.
In 2015 Curiosity encountered pale “halos” around fractures the bedrock on the lower slopes of “Mount Sharp”. Analysis of spectrographic data gathered by the rover’s on-board Chemistry and Camera (ChemCam) instrument has confirmed they contain copious silica. This indicates the crater held liquid water for a long time in aeons past.
“The concentration of silica is very high at the centre lines of these halos,” said Jens Frydenvang, a rover-team scientist at Los Alamos National Laboratory in New Mexico, and the University of Copenhagen in Denmark. “What we’re seeing is that silica appears to have migrated between very old sedimentary bedrock and into younger overlying rocks. These findings tells us is that, even when the lake eventually evaporated, substantial amounts of groundwater were present for longer than we previously thought — further expanding the window for when life might have existed on Mars.””
Further to this, a new study reveals that the ancient lake in Gale Crater likely provided stable environmental conditions that differed significantly from one part of to another, potentially allowing different types of microbes to exist at different points simultaneously in the same lake, the water within it being stratified in a similar manner to water in lakes on Earth. In Gale Crater’s case, the shallow water was richer in oxidants than deeper water was.
The study combines the analyses of the chemical and mineral composition of rocks found at different points along Curiosity’s ascent up mount sharp reveal a clear correspondence between the physical characteristics of sedimentary rock from different parts of the lake, and how strongly oxidised they were. In essence, those rocks with the physical characteristics of having been deposited near the edge of the lake have a stronger oxidised composition than those with physical characteristics indicative of being deposited in deeper water.
“These were very different, co-existing environments in the same lake,” said Joel Hurowitz of Stony Brook University, Stony Brook, New York, lead author of the study. “The diversity of environments in this Martian lake would have provided multiple opportunities for different types of microbes to survive, including those that thrive in oxidant-rich conditions, those that thrive in oxidant-poor conditions, and those that inhabit the interface between.”
This doesn’t mean that there were microbes swimming around in the waters of Gale Crater, but it does offer a further indication that the lake was a potentially benign environment for such microbes, if life on Mars ever developed that far.
In addition, the study offers further insights to the overall environmental changes which occurred on Mars, suggesting that while across the aeons, things went from warm and wet to cold and arid, Gale Crater exhibited short-term fluctuations in the other direction, at times becoming warmer and wetter. Findings which correspond to earlier studies suggesting the sediments comprising “Mount Sharp” were laid down as a result of several different wet periods in the crater’s history.
LIGO Records Third Gravitational Wave Event
In February 2016, I wrote about LIGO – the Large Interferometer Gravitational Wave Observatory – an international quest established in 1992 to detect gravitational waves. At that time, it had just been confirmed that, quiet unexpectedly, two brand-new LIGO detectors in the United States had almost simultaneously recorded gravitational waves as they came out of “engineering mode” tests and were being run up to full operational mode, in September 2015.
It was later confirmed that the two detectors, funded National Science Foundation and located in Livingston, Louisiana, and Hanford, Washington State, had made a further detection of gravitational waves in December 2015. On June 2nd, 2017, it was confirmed the instruments at Livingston and Hanford had detected gravitational waves for a thirdtime in January 2017.
Predicted over a century ago by Einstein in his theory of general relativity, gravitational waves (not to be confused with “gravity waves”, which are something else entirely) are at their most basic, ripples in space-time, generated by the acceleration or deceleration of massive objects in the cosmos. So, for example, if a star goes supernova or two black holes collide or if two super-massive neutron stars orbit closely about one another, they will distort space-time, creating ripples which propagate outwards from their source, like ripples across the surface of a pond. As such, their detection goes a long way to confirming Einstein’s description of space-time as an integrated continuum.
In all three of the case so far detected, the gravitational waves have been traced to the merger of black holes. In the case on the latest detection – called GW170104 after the date of its detection – the two black holes are roughly three billion light years away from Earth, twice the distance of the first two detections.
That all three events have been the result of the merger of black holes suggests that binary black hole systems are potentially far more common than had been believed, and mergers between them could be occurring a lot faster than previously predicted. They are, however, an ideal target for gravitational wave detection: when they do merge they can produce more power than is radiated as light by all the stars and galaxies in the universe at any given time.
Having three sources for gravitational waves now means that scientists can now analyse them in detail. The two already discovered have not only confirmed Einstein’s prediction that such phenomena would exist, but also that the waves themselves do not suffer from dispersion – again as Einstein predicted would be the case. the readings from GW170104 further indicate no dispersion is apparent in the waves, even across 3 billion light years of propagation from their source.
As well as helping confirm Einstein’s model of space-time, LIGO’s studies of these black holes will allow for a more detailed examination of the nature and properties of black holes themselves, presenting a treasure trove of understanding for science. Currently, LIGO is mid-way through its third run of observations of deep space, which will end in late summer. Thereafter the facilities at Livingston and Hanford will undergo a period of upgrade and testing, before a fourth round of observations commence in 2018.
Stratolaunch Rolls-Out “Roc”
On May 31st, 2017, Stratolaunch Systems, co-founded by Paul G. Allen of Microsoft fame, rolled out the carrier aircraft which will form the central part of their planned air-launched satellite launching capability. Called the Scaled Composites Model 351, and dubbed “Roc”, the aircraft is a six-engined, “twin-hulled” behemoth which will weigh 569.6 tonnes when fully laden, and will be capable of carrying up to 250 tonnes of payload / rocket launch vehicles to high altitudes.
The idea behind Stratolaunch Systems is to provide a relatively low-cost means of delivering satellites into low-Earth orbit. The carrier aircraft, measuring 72.5 meters (238 ft) from nose to tail and 117 meters (385 ft) from wing tip to wing tip, is designed to carry aloft rocket-powered launchers and payloads under the central “wing” structure connecting the two fuselage sections. Once at altitude, the payload launcher(s) can then be dropped horizontally and once safely clear of the aircraft, ignite their motors and carry their payload to orbit while the carrier aircraft returns to its base of operations.
The reason “Roc” is so big is that originally, Stratolaunch planned to deliver payloads of around 6.8 tonnes (13,500 lb) to low-Earth orbit using a version of SpaceX’s Falcon 9. When the partnership with SpaceX ended in 2012, a little over a year since it had started, Stratolaunch contracted Orbital ATK to develop a new, larger version of their veritable Pegasus air-launched rocket, to be called Pegasus II, also capable of launching 6.8 tonne to orbit. In 2016, that project was shelved when Stratolaunch decided to focus on the growing demand for small satellites, and instead use the existing Pegasus XL launcher with a 443 kg (997 lb) payload capability, potentially launching up to three such rockets per flight.
The aircraft will now take part in an extended series of ground tests, which will include fuelling operations, taxi and ground handling, and weight and balance tests. These will be followed by assorted flight tests, moving towards a first launch flight, currently scheduled for 2019. The video below offers a visualisation of the system in action, using the (shelved) Pegasus II rocket vehicle, and includes footage of the carrier aircraft”s roll-out.
Juno and Jupiter: Perijove 6
As I’ve been reporting, NASA’s Juno mission to Jupiter is stunning the world with amazing images of the gas giant’s atmosphere and cloud systems, even as the vehicle probes the depths of Jupiter’s atmosphere to find what might lie beneath.
During of five of its six close passes over Jupiter so far completed, Juno’s camera system has been active, returning the most spectacular shots. However, what is truly remarkable about these images is that the camera isn’t capable of colour imagery – simply put, for the purposes of the mission a colour camera wasn’t required. Instead, the pictures we see of Jupiter as captured by JunoCam has been carefully colour composited by an army of citizen scientists from around the world, who have been working in their own time with the original monochrome images and with other data provided by NASA to put together colour pictures white-balanced to approximate how Jupiter would look to the human eye under sunlight conditions.
“The contributions of the amateurs are essential,” Candy Hansen, Juno co-investigator, said at a press conference showcasing Juno’s science. “I cannot overstate how important the contributions are. We don’t have a way to plan our data without the contributions of the amateur astronomers. We don’t have a big image processing team, so we are completely relying on the help of our citizen scientists.
“What I find the most phenomenal of all is that this takes real work. When you download a JunoCam image and process it, it’s not something you do in five minutes. The pictures that we get that people upload back onto our site, they’ve invested hours and hours of their own time, and then generously returned that to us.”
One of those citizen scientists is Seán Doran, who regularly posts his work with Juno and in relation to other space mission to Flickr (if you have any interest at all in space exploration, his Flickr stream is a definite must follow). One of his most recent pieces is a collaboration with Gerald Eichstädt, which takes processed images from Juno and projects them along the trajectory the spacecraft followed during perijove 6 – the 6th pass over Jupiter’s cloud tops – on May 19th, 2017.
In addition, the Planetary Society hosts a gallery of processed images which is available for browsing.
- On Thursday, June 9th, Virgin Galactic completed the 9th unpowered flight of the VSS Unity. The glide flight was distinctive in that the spaceplane carried a special ballast tank filled with water to check handling qualities during flight. Following release from the WhiteKnightTwo carrier, pilots Dave Mackay and CJ Sturckow used the ballast to test handling as if the vehicle were carrying a full fuel load, moving the centre of gravity to the rear. The water was then jettisoned, moving the centre of gravity forward, allowing the pilots to further check Unity’s handling characteristics. The flight marks one of the final tests before Virgin Galactic move to powered flight tests.
- SpaceX achieved another first on Saturday, June 3rd, with the launch of the CRS-11 resupply mission to the International Space Station (ISS). The launch marked the first time SpaceX has re-used a previously flown Dragon 1 cargo capsule, and step towards the company developing a fully reusable launch system. The capsule is due to arrive at the space station on Monday, June 5th; meanwhile, the first stage of the Falcon rocket made a successful return and landing at Cape Canaveral Air Force Station, 7.5 minutes after launch.
- NASA’s Aerospace Safety Advisory Panel has raised concerns that the Boeing’s CST-100 Starliner and SpaceX Dragon 2 “crew taxis” for flying crews to the ISS may not meet the required Loss of Crew Requirement (LOC). This specifies that the potential for the death or permanent disability of one or more of the crew must be no greater than 1 in 270 launches for either vehicle (by comparison, the space shuttle’s LOC was 1 in 90 at the time of its retirement). While it is not clear what direct technical challenges Boeing and SpaceX face in trying to achieve the requirement, the Safety Advisory Panel noted that a part of the risk lay outside either company’s control, being down to the risk of collision with orbital debris or a fatal / near-fatal micro-meteoroid strike. As such, it is anticipated NASA might issue waivers against the LOC requirement, rather than having both companies attempt to blindly meet it, something which could make both the Starliner and Dragon 2 less safe.