Tag: Spaceflight

Space Sunday: of Jupiter, Titan and Mars

Posted on by Inara Pey

“NASA did it again!” an elated Scott Bolton, Principal Investigator for the Juno mission to Jupiter, announced on the night of Monday July 4th / Tuesday July 5th. He was speaking shortly after the Juno space craft, having travelled 2.8 billion kilometres (1.7 billion miles), achieved an initial orbit around the largest planet in the solar system, becoming one of the fastest human made objects ever built.

“We are in orbit and now the fun begins, the science,” he added during the post-insertion press briefing. “We just did the hardest thing NASA’s ever done! That’s my claim. I am so happy … and proud of this team.”

Solar powered Juno successfully entered a polar elliptical orbit around Jupiter after completing a must-do 35-minute-long firing of the main engine known as Jupiter Orbital Insertion or JOI. The vehicle approached Jupiter over the planet’s north pole – an orbit which will afford some unique views of Jupiter and its system of rings and moons in the coming months.

Due to the time delay, some 48 minutes for a one-way signal, Juno completed the insertion burn entirely on autopilot and, for this initial pass through the planet’s radiation belts, with many of its more critical systems powered-down as a precaution and to preserve battery power – the manoeuvre meant Juno had to turn its solar panels away from the Sun, limiting its ability to generate electrical power for all of its systems.

This image was captured by Juno on June 29th, 2016, and was the final picture taken by the vehicle's camera prior to major systems being shut down as a precautionary move while the craft made an it's initial approach over Jupiter's north pole. Visible and labelled are the Galilean moons, which today form just 4 of the 53 named moons orbiting the planet
This image was captured by Juno on June 29th, 2016, and was the final picture taken by the vehicle’s camera prior to major systems being shut down as a precautionary move while the craft made an its initial approach over Jupiter’s north pole. Visible and labelled are the Galilean moons, which today form just 4 of the 53 named moons orbiting the planet

As I reported last week, the do-or-die burn of the Leros-1b engine had to be carried out flawlessly if the spacecraft were to achieve and initial orbit around Jupiter. By the time it started at 20:18 PDT on Monday July 4th (04:18 UT, Tuesday July 5th), Juno had already accelerated to an incredible 250,000 kph (156,000 mph) relative to the planet, as a result of Jupiter’s massive gravity well, and the 35-minute engine burn was designed to reduce this huge speed by just 1,939 kph (1212 mph).

As tiny as this velocity change might sound, it meant the difference between Juno simply whipping around Jupiter to be thrown back out into deep space and being trapped in a 53.5 day orbit are the planet by that same enormous gravity well. In October 2016, a further 22-minute burn of the Leros-1b will reduce this orbital period to just 14 day, allowing the primary science mission to commence.

Scott Bolton (with arms raised) celebrates Juno's orbital insertion burn with members of the mission team (l to r) Goeff Yoder, Diane Brown, Rick Nybakken, Guy Beutelschies, and Steve Levin Credit: AP Photo / Ringo H.W. Chiu
Scott Bolton (with arms raised) celebrates Juno’s orbital insertion burn flanked by members of the mission team (l to r) Goeff Yoder, Diane Brown, Rick Nybakken, Guy Beutelschies, and Steve Levin Credit: AP Photo / Ringo H.W. Chiu

That mission is all about peering far beneath Jupiter’s banded clouds for the first time and investigating the planet’s deep interior with a suite of nine instruments. The hope is that Juno will probe the mysteries of Jupiter’s genesis and evolution, and by extension, how we came to be. Or, as Scott Bolton phrased it, “The deep interior of Jupiter is nearly unknown. That’s what we are trying to learn about. The origin of us.”

Life on Titan Without Water?

Further out in space and orbiting Saturn, is massive Titan, another of the solar system’s enigmas. Examined by the NASA Cassini space vehicle and (briefly) by the European Space Agency’s Huygens lander, Titan is fascinating for a number of reasons, including the fact it is the only natural satellite known to have a dense atmosphere rich in minerals and hydrocarbons.

Huygens revealed Titan has a very mixed surface environment, complete with hydrocarbon seas, lakes and tributary networks filled with liquid ethane, methane and dissolved nitrogen. This surface is also very young; while Titan has been around since very early in the solar system’s history – some 4 billion years – the surface environment is estimated to be somewhere between 100 million to 1 billion years old; suggesting geological processes have been and are at work.

Titan's structure (via wikipedia)
Titan’s structure, which includes a subsurface liquid water ocean sealed beneath a mantle of ice just below the moon’s thin trust (via wikipedia)

All of this   – particularly the thick atmosphere (which has a comparable density to that of Earth), the presence of hydrocarbon rich liquids (which also fall as rain) – has caused many astronomers and planetary scientists to speculate that Titan might have all the prebiotic conditions necessary to kick-start life. The only thing which has been seen as potentially mitigating this is the absence of surface water.

However, a team of scientists from Cornell University, New York, led by Dr. Martin Rahm, has proposed that condition on Titan are such that it might support life even without the presence of water.

An image of Titan's surface, as taken by the European Space Agency's Huygens probe as it plunged through the moon's thick, orange-brown atmosphere on Jan. 14, 2005. Credit: ESA / NASA / JPL / Univ. of Arizona
An image of Titan’s surface, as taken by the European Space Agency’s Huygens probe as it plunged through the moon’s thick, orange-brown atmosphere on Jan. 14, 2005. Credit: ESA / NASA / JPL / Univ. of Arizona

Specifically, the team has been examining the role that hydrogen cyanide (HCN) might have on Titan. This is an organic chemical, which although poisonous to life today, is seen in some circles as a precursor to amino acids and nucleic acids, and thus a basic building block in the development of organic compounds which in turn might give rise to life.

In particular, hydrogen cyanide is the most abundant hydrogen-containing molecule in Titan’s atmosphere – although it is missing from the moon’s surface – and has some unique properties. It can, for example, react with itself or with other molecules to form long chains, or polymers. One such polymer is called polyimine, which is capable of absorbing light of many wavelengths and might therefore as as a catalyst for photochemically driven chemistry, some of which might be prebiotic in nature and which might in turn give rise to more complex organic reactions.

Continue reading “Space Sunday: of Jupiter, Titan and Mars” →

Space Sunday: Jupiter and Juno

Posted on by Inara Pey

Update, July 5th: The insertion burn on July 4th/5th was successful, and Juno is safely in its initial orbit around Jupiter. I’ll have an update on the mission in the next Space Sunday.

rAt 20:18 PDT on Monday, July 4th (03:18 UT, Tuesday, July 5th) a spacecraft called Juno will fire its UK-built Leros-1b engine to commence a 35-minute burn designed to allow the spacecraft  enter an initial orbit around the largest planet in the solar system, ready to begin a comprehensive science campaign.

As I write this, the craft is already inside the orbit of Callisto, the furthest of Jupiter’s four massive Galilean satellites,  which orbits the planet at a distance of roughly 1.88 million kilometres. During the early hours of July 4th, (PDT), the vehicle will cross the orbits of the remaining three Galilean satellites, Ganyemede, Europa and Io, prior to commencing its orbital insertion burn.

In the run-up to the burn, Juno will complete a series of manoeuvres designed to correctly orient itself to fire the Leros-1b, which will be the third of four planned uses of the engine in order to get the craft into its final science orbit. Two previous burns of the engine – which NASA regards as one of the most reliable deep space probe motors they can obtain – in 2012 ensured the craft was on the correct trajectory from this phase of the mission.

Getting into orbit around Jupiter isn’t particularly easy. The planet has a huge gravity well – 2.5 times greater than Earth’s. This means that an approaching spacecraft is effectively running “downhill” as it approaches the planet, accelerating all the way. In Juno’s case, this means that as the vehicle passes north-to-south around Jupiter for the first time, it will reach a velocity of nigh-on 250,000 kph (156,000 mph), making it one of the fastest human-made objects ever.

An Artist's impression of Juno approaching the Jovian system. Credit: NASA
An Artist’s impression of Juno approaching the Jovian system. Credit: NASA

Slowing the vehicle directly into a science orbit from these kinds of velocities would take an inordinate amount of fuel, so the July 4th manoeuvre isn’t intended to do this. Instead, it is designed to hold the vehicle’s peak accelerate at a point where although it will be thrown around Jupiter and back into space, it will be going “uphill” against Jupiter’s gravity well, decelerating all the time. So much so, that at around 8 million kilometres (5 million miles) away from Jupiter, and travelling at just 1,933 kph (1,208 mph), Juno will start to “fall back” towards Jupiter, once more accelerating under gravity, to loop around the planet a second time on August 27th, coming to within (4,200 km (2,600 mi) of Jupiter’s cloud tops, before looping back out into space.

On October 19th, Juno will complete the second of these highly elliptical orbits, coming to within 4,185 km (2,620 mi) of the Jovian cloud tops as it completes a final 22-minute burn of the Leros-1b motor. This will be sufficient for Jupiter’s gravity to swing  Juno into an elliptical 14-orbit around the planet, passing just 4,185 km from Jupiter at its closest approach before flying out to 3.2 million kilometres (2 million miles) at it’s furthest from the planet.

Juno's journey to Jupiter, with a flyby-of Earth in 2013
Juno’s journey to Jupiter, with a flyby-of Earth in 2013

The July 4th insertion burn is also significant in that it marks the end of a 5-year interplanetary journey for Juno, which has seen the vehicle cover a distance of 2.8 billion km (1.74 billion miles).

It’s a voyage which began on August 5th, 2011, atop a United Launch Alliance (ULA) Atlas V, launched from Cape Canaveral Air Force Station, Florida.

As powerful as it is, the Atlas isn’t powerful enough to send a payload like Juno directly to Jupiter. Instead, the craft flew out beyond the orbit of Mars before dropping back to Earth, passing us again in October 2013 and using Earth’s gravity to both accelerate and to slingshot itself into a Jupiter transfer orbit.

While, at 35 minutes, the engine burn for orbital insertion is a long time, the distance from Juno to Earth means that confirmation that the burn has started will not be received until 13 minutes after the manoeuvre has actually completed. That’s how long is takes for a radio signal to travel from the vehicle back to Earth (and obviously, for instructions to be passed from Earth to Juno.  Thus, the manoeuvre is carried out entirely automatically by the vehicle

Juno is not the first mission to Jupiter, but it is only the second orbital mission to the giant of the solar system.

The Jovian system was first briefly visited by Pioneer 10 in 1973, followed by Pioneer 11 a year later. Both of these were deep space missions (which are still continuing today), destined to continue outward through the solar system and into interstellar space beyond. They were followed by the Voyager 1 and Voyager 2 missions in January and July 1979 respectively, again en route for interstellar space by way of the outer solar system.

In 1992 the Ulysses solar mission used Jupiter as a “slingshot” to curve itself up into a polar orbit around the Sun. Then in 2000, the Cassini mission used Jupiter’s immense gravity to accelerate and “bend” itself towards Saturn, its intended destination. New Horizons similarly used Jupiter for a “gravity assist” push in 2007, while en route to Pluto / Charon and the Kuiper Belt beyond.

It was in 1995 that the first orbital mission reached Jupiter and its moons. The nuclear RTG-powered Galileo was intended to study Jupiter for just 24 months. However, it remained largely operational until late 2002 before the intense radiation fields around the planet took their final toll on the vehicle’s systems. Already blind, and with fuel supplies dwindling, Galileo was ordered to crash into the upper limits of Jupiter’s atmosphere in 2003, where it burned up.

In the eight years it operated around Jupiter, Galileo complete changed our perspective on the planet. Juno has a 20-month primary mission, and it is hoped its impact on our understanding of Jupiter will be greater than Galileo’s. However, it is unlikely the mission will be extended.

Unlike all of NASA’s previous missions beyond the orbit of Mars, which have used RTG power units, Juno is entirely solar-powered, making it the farthest solar-powered trip in the history of space exploration. However, the three 8.9 metre (29 ft) long, 2.7 metre (8.9 ft) wide solar panels are particularly vulnerable to the ravages of radiation around Jupiter, and it is anticipated that by February 2018, their performance will have degraded to a point where they can no longer generate the levels of electrical energy required to keep the craft functioning – if indeed, its science instruments and electronics haven’t also been damaged beyond use by radiation. This being the case, Juno will be commanded to fly into Jupiter’s upper atmosphere and burn up.

Juno's science instruments - click for full size. Credit: NASA / JPL
Juno’s science instruments – click for full size. Credit: NASA / JPL

Continue reading “Space Sunday: Jupiter and Juno” →

Space Sunday: minerals, ice, rockets and capsules

Posted on by Inara Pey

CuriosityNASA’s Curiosity rover has resumed its long, slow climb up the slopes of “Mount Sharp”, the 5 km high mound abutting the central impact peak of Gale Crater on Mars.

For the last few months, the rover has been easing its way over what is called the “Murray Formation”, a transitional layer marking the separation points between the materials deposited over the aeons to create the gigantic mound, and the material considered to be common to the crater floor. Named in honour of the late co-founder of The Planetary Society, Bruce Murray, the formation comprises a number of different land forms, which the rover has been gradually examining.

On June 4th, 2016, Curiosity collected its latest set of drilling samples – the 11th and 12th it has gathered since arriving on Mars – on the “Naukluft Plateau”, a further region of sandstone within the Murray Formation, similar to the area dubbed the “Stimson Formation”, where the rover collected samples in 2015.

The Murray formation extends about 200 metres (650ft) up the side of "Mount Sharp". Starting at the "Pahrump Hills" below "Murray Buttes" in late 2014, Curiosity is about one fifth of the way across the region, spending extended periods examined various features within the formation. Credit: NASA JPL
The Murray formation extends about 200 metres (650ft) up the side of “Mount Sharp”. Starting at the “Pahrump Hills” below “Murray Buttes” in late 2014, Curiosity is about one fifth of the way across the region, spending extended periods examined various features within the formation. Credit: NASA JPL

The aim is to carry out comparative geology between the two sites to determine whether or not their formation is related. The “Stimson Formation” sandstone strongly suggested it has been laid down by wind after the core slopes of “Mount Sharp” had been laid down by sedimentary processes the result of Gale Crater once being home to s huge lake, but which had then been subjected to fracturing by the passage of water. These bands of fractured sandstone have become more prevalent as the rover has continued up through the “Murray Formation”, so it is hoped that by obtaining samples from “Naukluft Plateau”, the science team will gain further understanding of precisely what part water played in the evolution of the slopes of “Mount Sharp” after the lake waters had receded.

The HiRise imaging system on the Mars Reconnaissance Orbiter (MRO) captured the the Mars Science Laboratory rover Curiosity on the Naukluft Plateau in May 2016 (credit: NASA/JPL / University of Arizona)
The HiRise imaging system on the Mars Reconnaissance Orbiter (MRO) captured the Mars Science Laboratory rover Curiosity on the Naukluft Plateau in May 2016 Credit: NASA/JPL / University of Arizona

Since completing the drilling operations, Curiosity has turned south, and is now climbing the mound “head on”, rather than gradually zig-zagging its way upwards.

The MSL rover has also provided geologists with another surprise. In mid-2015, the rover collected samples from a rock dubbed “Buckskin”. Reviewing the analysis of the minerals in the samples, as discovered by Curiosity’s on-board laboratory suite, scientists have found significant amounts of a silica mineral called tridymite.

“On Earth, tridymite is formed at high temperatures in an explosive process called silicic volcanism. Mount St. Helens, the active volcano in Washington State, and the Satsuma-Iwojima volcano in Japan are examples of such volcanoes,” said Richard Morris, a NASA planetary scientist at Johnson Space Centre. “The tridymite in the Buckskin sample is thought to have been incorporated into “Lake Gale”  mudstone as sediment from erosion of silicic volcanic rocks.”

The find is significant because although volcanism did once take place on Mars, it has never been thought of as being silicic volcanism, which is far more violent that the kind of volcanism associated with the formation of the great shield volcanoes of the Tharsis Bulge and other regions of Mars. So this discovery means geologists may have to re-think the volcanic period of Mars’ early history.

China Launches Long March 7

Saturday, June 25th saw the inaugural launch of China’s Long March 7 booster, a vehicle I wrote about back in April 2016. The launch was also the first from China’s fourth and newest space launch facility, the Wenchang Satellite Launch Centre, located on Hainan Island, the country’s southernmost point.

The Long March 7 is a core component to China’s evolving space ambitions. Classified as a medium lift vehicle, it can carry around 13.5 tonnes to low Earth orbit (LEO), it will operate alongside China’s upcoming heavy lift launcher, the Long March 5. This craft will be capable of lifting around the same payload mass directly to geosynchronous orbit, and around 25 tonnes to LEO. Both vehicles will play a lead role in China’s plans to expand her explorations of the Moon, establish a permanent space station in Earth orbit by 2022, and reach Mars with automated missions.

China's Long March 5 (l) and Long March 7 (r) next generation launch vehicles
China’s Long March 7 (right) launched on it inaugural flight on Saturday, June 25th. The bigger Long March 5 (left) is due to launch later in 2016. Credit: China state media

The inaugural launch of the Long March 7 took place at noon GMT on Saturday, June 25th (20:00 local time). It carried a Yuanzheng 1A upper stage and a scale model of China’s next generation crewed orbital vehicle into an orbit of 200 km (120 mi) by 394 km (244 mi) as confirmed by US tracking networks.

Yuanzheng is an automated “space tug” China has used numerous times to deliver payloads to their orbits, and is capable of re-using its engine multiple times. It is most often used to boost China’s communications satellites into higher orbits.

The sub-scale capsule was used to carry out an atmospheric re-entry test to gather data which will be use to further refine and improve the re-entry vehicle which will form a part of China’s replacement for its ageing, Soyuz-inspired Shenzhou crew vehicle. This unit returned to Earth, landing in a desert in Inner Mongolia on Sunday, June 26th, after orbiting the planet 13 times. Also aboard the vehicle was a “cubesat” mission to test a navigation system, and a prototype refuelling system.

Continue reading “Space Sunday: minerals, ice, rockets and capsules” →

Space Sunday: Martian tsunamis, Indian space planes, Chinese telescopes

Posted on by Inara Pey
Mars as seen from 80 million km (50 million mi): a Hubble Space Telescope image of Mars captured during opposition on May 12th, 2016. Coincidentally, the Arabia Terra, one of the subjects in the report below, is the dark area in the centre of the image,
Mars as seen from 80 million km (50 million mi): a Hubble Space Telescope image of Mars captured during opposition on May 12th, 2016. Coincidentally, the Arabia Terra, one of the subjects in the report below, is the dark area in the centre of the image, together with Xanthe Terra. Cryse Planitia (Plain of Gold) is in the lower part of the light-coloured circular area dipping into the dark mass of Arabia and Xanthe Terra. North is to the top of the image, south to the bottom. Credit: NASA / ESA

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 northern hemisphere of Mars when it was once home to an world-circling ocean, 3.4 billion years ago
The northern hemisphere of Mars when it was once home to an world-circling ocean, 3.4 billion years ago

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.

In this image
This set of images show the region where Arabia Terra flows down to Chryse Planitia. In figure A, the red line denotes the original ancient shoreline of the region. The grey area below and to the left of it denotes depositions believed to be the result of the first tsunami, together with outflow channels carved by the receding flood (blue arrows). The black line indicates the much younger shoreline of the region at the time of the second impact, which saw the formation of icy lobes in the region, and the embaying of features by slurry and material deposit by the receding waters. Images B and C focus on the coastal areas of deposition and embayment. Image created by Esri’s ArcGIS® 10.3 software

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.

Radar imaging has revealed subsurface large lobes of icy deposits along the outwash plains and channels in the Arabia Teraa / Chryse Planitia abutment, indicative of the study's suggestion that some of the material deposited after the second tsunami event froze out before it could flow back to the ancient sea
Radar imaging has revealed subsurface large lobes of icy deposits along the outwash plains and channels in the Arabia Teraa / Chryse Planitia abutment, indicative of the study’s suggestion that some of the material deposited after the second tsunami event froze out before it could flow back to the ancient sea

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.

Continue reading “Space Sunday: Martian tsunamis, Indian space planes, Chinese telescopes” →

Space Sunday: naming a (dwarf) planet and weather watching on Mars

Posted on by Inara Pey
A revised infographic of the six largest dwarf planets, showing 2007 OR10's revised 3rd place
A revised infographic of the six largest dwarf planets, showing 2007 OR10’s revised 3rd place

While opinions may be in a state of flux over what constitutes a dwarf planet – the recent discoveries around Pluto’s interaction with the solar wind once again highlighting the debate, the fact remains that there are a fair few to be found in the solar system, with the largest five, as traditionally listed in descending order of volume, being: Pluto, Eris, Haumea, Makemake and … 2007 OR10.

These worlds are so small and so far away – in relative terms – that gathering data on them without actually paying them a visit, as we’ve done with Pluto, isn’t easy. In the case of 2007 OR10, this lack of information means it has been left without a name, only a designation related to its year of discovery.

An artist's conception of 2007 OR10. Astronomers suspect that its rosy color is due to the presence of irradiated methane. Credit: NASA
An artist’s conception of 2007 OR10. Astronomers suspect that its rosy color is due to the presence of irradiated methane. Credit: NASA

However, all this might now be changing after data gathered by the Kepler observatory (about which I’ve written in recent Space Sunday reports) has helped reveal the dwarf planet – which orbits the Sun once every 547.5 years – is actually the third largest such body beyond the orbit of Neptune, sitting behind Pluto and Eris, and thus it could be a lot more interesting than first thought.

Up until now, it had been thought 2007 OR10 was about 1280 km (795 mi) in diameter. However, such is the sensitivity of Kepler’s instruments in measuring light variations whilst seeking extra-solar planets orbiting nearby stars, that the observatory has been able to precisely measure variations in the brightness of this unusually dark little world. These measurements, combined with data obtained from the Herschel Space Observatory, suggest that 2007 OR10 is around 1535 km (955 mi) in diameter, or about 255 km (160 mi) larger than previously thought.

2007 OR10The upshot of this is the dwarf planet is liable to be a far more interesting place than previously thought, potentially covered in volatile ices of methane, carbon monoxide and nitrogen, and may even be somewhat active as a result of its interaction with the solar wind. It also means that it is really overdue for a decent name.

According to convention, the honour of naming it goes to the planet’s discoverers, in this case Meg Schwamb, Mike Brown and David Rabinowitz. They discovered it in 2007 during a search for distant bodies in the Solar System. In fact, Mike Brown has already suggested a name: Snow White, in recognition of the planet’s ice surface composition.

However, this hasn’t stopped suggestions rolling in from the general public – up to and including, “Dwarfy McDwarfface”, in recognition of the recent public voting on the name for the UK’s new polar research ship.

I have to admit that – and indifference to Mike Brown’s suggestion, which doesn’t take into account 2007 OR10’s likely rusty complexion – my personal favourite suggestion has to be that from Greenwood Space Travel Supply Co (shown above right), which puts forward a very strong case for the name of this little world.  I’m also wearing my Dwarf Planet Pride Day badge with … pride!

Two Years of Weather Reporting on Mars

NASA’s Curiosity rover has completed its second year on Mars – its second Martian year, that is; August 2016 will actually mark the end of its fourth Earth year of operations in Gale Crater. This milestone is important, as it means that the rover has been able to accumulate data on two full cycles of Martian seasons and weather.

Gathering data over so long a period helps distinguish seasonal effects from sporadic events. For example, a large spike in methane in the local atmosphere during the first southern-hemisphere autumn in Gale Crater was not repeated the second autumn; it was an episodic release, albeit still unexplained. However, the rover’s measurements do suggest that much subtler changes in the background methane concentration may follow a seasonal pattern; while measurements of temperature, pressure, ultraviolet light reaching the surface and the scant water vapour in the air at Gale Crater show strong, repeated seasonal changes.

Monitoring the modern atmosphere, weather and climate fulfils a MSL mission goal, supplementing the better-known investigations of conditions billions of years ago. Back then, Gale Crater had lakes and groundwater that could have been good habitats for microbes, if Mars has ever had any. Today, though dry and much less hospitable, environmental factors are still dynamic.

Curiosity’s Rover Environmental Monitoring Station (REMS), supplied by Spain’s Centro de Astrobiología, has measured air temperatures from 15.9o C (60.5o F) on a summer afternoon, to -100o C (-148o F) on a winter night.

Comparing temperatures at Mars’ Gale Crater (lower set of bars) to temperatures in Los Angeles. It shows key differences both in how much colder the Martian site is throughout the year, and also how much greater the difference between daily highs and lows. Mars has only about one one-hundredth as much atmosphere as Earth, and without that thick blanket of atmosphere the air temperature around Curiosity usually plummets by more than  55o C (100o F) between the afternoon high and the overnight low.

Continue reading “Space Sunday: naming a (dwarf) planet and weather watching on Mars” →

Space Sunday: rockets, water, wind and transits

Posted on by Inara Pey

For the second time in less than a month, SpaceX has landed the first stage of a Falcon 9 rocket on a platform at sea, bringing the total of successful landings the company has so far achieved to three.

The landing came at 05:30 GMT on the morning of Friday, May 6th, just nine minutes after the rocket had lifted-off from Cape Canaveral Air Force Station in Florida on a successful mission to carry the Japanese communications satellite JCSAT-14 to orbit.

Following separation, the first stage of the Falcon 9 1a rocket performed a series of flight manoeuvres referred to as “boost back”, which culminated in the first stage making a successful touch-down on the deck of the drone ship Of Course I Still Love You, the same craft used to recover the first stage of the Falcon 9 rocket to lift the CRS-8 resupply mission to a safe rendezvous with the International Space Station in April.

The recovery of the booster stage was actually an unexpected event – SpaceX had believed that the nature of the mission would more than likely result in a failure to achieve a successful landing.

“Given this mission’s GTO [Geostationary Transfer Orbit) destination, the first stage will be subject to extreme velocities and re-entry heating, making a successful landing unlikely,” SpaceX representatives stated ahead of the launch.

The Falcon 9 1a first stage secured on the deck of Of Course I Still Love You, following the successful May 6th landing
The Falcon 9 1a first stage secured on the deck of Of Course I Still Love You, following the successful May 6th landing. Credit: SpaceX

Ideally, the company would like to bring all of its boosters back to a touch-down on land, as was the case with their first successful landing in December 2015. However, some mission profiles mean that the Falcon 9 cannot carry sufficient fuel reserves to complete a set of “boost back” manoeuvres that would be enough for it to make landfall, so some landings at sea are inevitable if SpaceX is to get anywhere close to recovering the majority of its launchers.

Nevertheless, with three successful landings under its belt, and three first stage rockets requiring refurbishment in order to be able to fly again, SPaceX boss Elon Musk jokingly conceded, in a Tweet made after the landing, “May need to increase size of rocket storage hangar!”

The “Boiling” Waters of Mars

An international team from  France, the UK and the USA have produced the strongest evidence yet that the distinctive recurring slope lineae (RSL) features seen on the slopes of Martian craters are produced by liquid water. And not just any water; the study suggests the water is “boiling”.

RSLs have been the subject of intense debate and discussion since 2011; in essence, they are ridges and rills which appear on the slopes of hills and craters, notably in the equatorial regions of Mars during the summertime. The significance here being that on Earth, identical features are always the result of free-flowing water. As the “recurring” in the title suggests, the Martian RSLs appear to be active – frequently renewing themselves on a seasonal basis, with new RSLs sometimes also appearing at the same time.

Two images showing the flank of the same crater, revealing what appear to be active RSL, periodically renewed during the Martian summer
Two images showing the flank of the same crater, revealing what appear to be active RSL, periodically renewed during the Martian summer. Credit: NASA/JPL

However, the low pressure of Mars’ atmosphere means that water cannot survive long on the surface unprotected: it will either freeze or sublimate. So the idea of it surviving long enough to create trails in the sides of craters had many scientists scratching their heads. Then, in 2015, a NASA study put forward evidence RSLs might actually be the result of water containing a strong suspension of mineral salts – magnesium perchlorate, magnesium chlorate and sodium perchlorate. Such minerals could be sufficient enough to prevent water exposed to the surface environment on Mars either immediately freezing or sublimating.

Building on this idea, the French-led international team used blocks of water ice containing the same minerals and placed them on the slope of a simulated Martian crater housed inside a special Mars Chamber at the Open University in the UK. When the pressure in the chamber was reduced to the ambient surface pressure on Mars and the temperature adjusted to a typical Martian summer’s day, the team found the ice would melt, producing a liquid mix which effectively “boiled” filtering into the sand and moving down-slope. As it did so. the resultant vapour “blasted” sand grains upwards, creating ridges which would collapse onto themselves when they became too steep, forming channels almost identical in form to Martian RSLs.

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