Tag: Spaceflight

Space Sunday: dunes, rockets and asteroids

Posted on by Inara Pey

CuriosityNASA’s Mar Science Laboratory rover, Curiosity, continues to perform the first up-close study ever conducted of extraterrestrial sand dunes as it slowly explores the slopes of “Mount Sharp” dubbed the “Bagnold Dunes”.

Located on the north-west slope of the mound which lies at the centre of Gale Crater, the dunes differ from those drifts and sand fields the rover has previously encountered on Mars in terms of both their size and height – some cover an area the size of a football field and are 2 storeys high – and their general shape, something which marks them out as “classic” sand dunes.

This latter point is most evident by the dunes exhibiting a steep, downwind slope, referred to as the slip face, and which exhibits certain features of its own, such as gain fall, ripples and grain flow, as well as the dune as a whole exhibiting typical features such as the horn and toe.

For the last couple of weeks, the rover has been working its way around one dune in particular, dubbed “Namib”, which is somewhat smaller than the “high dunes” images at the start of December, but which still rises to a height of some 5 metres (16 ft). The leeward side of “Namib” in particular demonstrates the classic features of a sand dune, and helps to confirm the fact that the dunes are slowly progressing down the slope of “Mount Sharp” at a rate of about 1 metre (39 inches) a year.

The leeward side of Namib:
The leeward side of “Namib”:Horn – where sand is escaping the main dune and escaping downhill, as indicated by the ripples; Toe – the downwind extent of the dune; ripples – signs of the sand bouncing sideways over the dune as the wind blows it downslope towards the horn;  Brink – the ridge between the windward, gentle slope of the dune and the leeward, steeper slope of the dune; Grail Fall – areas where sand is blown / falls from the brink and comes to rest on the leeward slope; Gain Flow – tongue-like area indicating where large amounts of sand have slumped down the side of the dune towards the toe, again indicative of a dune in motion

The dune-investigation campaign is designed to increase understanding about how wind moves and sorts grains of sand in an environment with less gravity and much less atmosphere than well-studied dune fields on Earth. Such an understanding of how the wind moves sand could lead to a clearer picture of how big a role the Martian wind played in depositing concentrations of minerals often associated with water across the planet, and by extension, the behaviour and disposition of liquid water across Mars.

This rather odd-looking image is a foreshortened 360-degree view of the area around Curiosity. In the immediate foregound is the rover's main deck, with the cylindrical, finned nuclear RTG at the back of it. Beyond this is the "Namib" dune, with a taller dune beyond it. The view was constructed froma series of images taken by the rover's Mastcam on December 18th, 2015 (Sol 1,197 on Mars), all of which have been white-balanced to present the view under normal Earth daylight conditions
This rather odd-looking image is a foreshortened 360-degree view of the area around Curiosity. In the immediate foreground is the rover’s main deck, with the cylindrical, finned nuclear RTG at the back of it. Beyond this is the “Namib” dune, with a taller dune beyond it. The view was constructed from a series of images taken by the rover’s Mastcam on December 18th, 2015 (Sol 1,197 on Mars), all of which have been white-balanced to present the view under normal Earth daylight conditions

Back to Sea for SpaceX

SpaceX, the private space launch company, is keeping itself busy. Following the successful launch of the Orbcomm mission from Florida’s Cape Canaveral Air force Station, together with the successful recovery of the first stage of the booster when it flew back to the Cape and performed a flawless vertical landing, the company’s next launch is scheduled for Sunday, January 17th.

The launch will take place from Vandenberg Air force Base, California, which is the company’s Pacific Coast launch operations centre. The primary aim of the mission is to place the third in a series of joint U.S.-European satellites into a near-polar orbit (for which Vandenberg AFB is ideally suited, as a polar launch from there does not pass over inhabited land during ascent, lessening the risk to human lives should a launch vehicle suffer a failure).

The Jason-3 series of missions is part of a very long-term series of studies (started in 1992) to study the topography of the ocean surface (i.e. the formation and movement of waves and the troughs between them), which can provide scientists with critical information about circulation patterns in the ocean, and about both global and regional changes in sea level and the climate implications of a warming world.

Jason-3, the latest in a series of joint US-European satellites studying the topography of the ocean's surface, is due for launch on December 17th, 2016, using a SpaceX Falcon 9 1.1 rocket
Jason-3, the latest in a series of joint US-European satellites studying the topography of the ocean’s surface, is due for launch on December 17th, 2016, using a SpaceX Falcon 9 1.1 rocket (image: NASA / CNES)

The polar orbit used for this kind of earth-observing mission, being almost perpendicular to the Earth’s rotation, allows the spacecraft to at some point travel over almost every part of the world’s oceans, vastly increasing its ability to gather data when compared to a vehicle in an equatorial orbit.

What is also significant about the mission is that it will use a SpaceX Falcon 9 1.1 booster, the first stage of which will once again attempt to return to Earth and make a safe landing. However, unlike the December 2015, this landing will once again be at sea, using a SpaceX droneship landing platform.

Continue reading “Space Sunday: dunes, rockets and asteroids” →

Space Sunday: cosmic lightsabers, monkeys to Mars and junk in orbit

Posted on by Inara Pey

There were many remarkable space images published throughout 2015. However, perhaps one of the most memorable came at the end of the year, and coincided  with the release of Disney’s Star Wars: The Force Awakens. Captured by the Hubble Space Telescope, the image was immediately dubbed by the media as the “cosmic lightsaber” due to the manner in which part of the image resembles the double-sided lightsaber used by Darth Maul in an earlier Star Wars film.

It shows a new-born star laying within a cloud of dust, which is shooting out two beams of light from its poles and which seem to cut through the surrounding material and space.

Two beams of light slice through space from the polar regions of a new-born star. Captured by the Hubble Space Telescope, the image was immediately dubbed "the cosmic lightsaber" (image: ESA / NASA / D. Padgett / T. Megeath / B. Reipurth) - click for full size
Two beams of light slice through space from the polar regions of a new-born star. Captured by the Hubble Space Telescope, the image was immediately dubbed “the cosmic lightsaber” (image: ESA / NASA / D. Padgett / T. Megeath / B. Reipurth) – click for full size

The beams are no optical illusion, but the result of material from the surrounding dust cloud falling into the star, only to erupt into supersonic jets of material ejected up through the star’s poles and into space. As the jets travel outwards, so they encounter other dust and material, and distinctive arced shock waves form within the “beams”, which gradually give rise to knotted clumps of material called Herbig-Haro (HH) objects, and are ubiquitous in star-forming regions, although they are relatively short-lived in astronomical terms.

Given the nature of the HH object seen by Hubble (officially designated HH24), it is thought that the star causing it is very young – just a few thousand years old. It lies in a “stellar nursery” some 1,350 light-years away “in” the constellation of Orion, and which has one of the highest concentrations of HH objects yet found in our galaxy.

Another view of the "stellar nursery" where stars are being formed, captured by Hubble. HH24 can be seen at the top left, with further HH objects just visible in the lower right. Both this image and the one above were captured in infrared, allowing Hubble to "look through" the intervening clouds of dust and "see" the jets
Another view of the “stellar nursery” where stars are being formed, captured by Hubble. HH24 can be seen at the top left, with further HH objects just visible in the lower right. Both this image and the one above were captured in infra-red, allowing Hubble to “look through” the intervening clouds of dust and “see” the jets

Monkeys to Mars?

There is a mounting effort to see humans set foot on Mars some time within the next 25 years; however, Russia is apparently set on getting “crew” to Mars by 2017, in the form of four macaque monkeys.

The simians have been selected on the basis of their cognitive and learning abilities, and have been undergoing 3 hours a day of training for a possible flight to Mars, with news of the proposal first reaching the public domain in October 2015. The training is has been taking place at the Institute of Biomedical Problems in Moscow, and initially comprised training the monkeys to operate a joystick system to “shoot” targets on a screen, as indicated by a cursor.  Successful “hits” saw the monkeys rewarded with a sip of juice.

This has been followed by training the monkeys to solve simple puzzles and mathematical problems. “What we are trying to do,”  Inessa Kozlovskaya, responsible for the team training the monkeys, “is to make them as intelligent as possible so we can use them to explore space beyond our orbit,”

The Russian plan is to send the monkeys on a six-month voyage to Mars, during which their heath and ability to function during a prolonged stay in zero gravity conditions will be assessed, together with their exposure to cosmic radiation. However, Russian officials have refused to indicate whether the mission will include a return trip to Earth.

Rhesus macaques are one of the least endangered, most familiar of the "old world" monkeys, and are known for their intelligence and their social bonds (image: "carcoalfeather", deviant art)
Rhesus macaques are one of the least endangered, most familiar of the “old world” monkeys, and are known for their intelligence and their social bonds (image: “carcoalfeather”, deviant art)

Sending animals into space isn’t new. The very first animal to enter space was in fact a rhesus macaque called Albert. He flew a short-duration ballistic flight atop a US V2  in 1948, but died of suffocation mid-flight. His successors were no less fortunate. Alberts II, and IV were killed on impact when their capsule parachutes failed to deploy, and Albert III died when his V2 exploded on the edge of space.

Continue reading “Space Sunday: cosmic lightsabers, monkeys to Mars and junk in orbit” →

Space Sunday: bringing a rocket home; uncovering Ceres

Posted on by Inara Pey
A second from touchdown: the Falcon 9 first stage booster, with landing legs deployed, about to make a successful landing at "Landing Zone 1", Cape Canaveral Air Force Station, having been launched from the space facility 10 minutes earlier as a part of a flight to deploy 11 Orbcomm telecommunications satellites
A second from touchdown: the Falcon 9 first stage booster, with landing legs deployed, about to make a successful landing at “Landing Zone 1”, Cape Canaveral Air Force Station, having been launched from the space facility 10 minutes earlier as a part of a flight to deploy 11 Orbcomm telecommunications satellites

On Monday, December 21st, the private space launch company SpaceX achieved a remarkable first in the annals of space flight: they successfully launched a payload carrying rocket into orbit, and then returned its first stage to a safe landing back on Earth, close to its original launch point.

The Falcon 9 rocket, in its first launch since June 2015 when a fuel tank failure lead to the vehicle’s destruction together with the Dragon resupply vehicle it was lifting to the International Space Station, was lifting a total of 11 communications satellites into orbit on behalf of Orbcomm.

The booster lifted-off from Florida’s Cape Canaveral Air Force Station at 20:29 EST on Monday, December 21st (01:29 UTC, Tuesday December 22nd).  At 2 minutes 27 seconds into the flight, having pushed the vehicle through the densest part of the atmosphere, the first stage engines shut down, and shortly afterwards, the first and second stages separated, allowing the latter’s Merlin engine to ignite.

As the second stage continued to accelerate up to deployment orbit, the first stage coasted upwards before using cold gas thrusters to effectively “flip” the booster around so it could use the first in a series of “boostback burns” of its main engines to slow itself down as well as pushing it back towards Cape Canaveral.

With this completed, the booster used the cold gas thrusters to again flip itself over so it would be descending engines first towards the ground, performing two further “boostback burns” to control its descent before making a final engine burn during the last few dozen metres of the descent and deploying its 4 landing legs and steering vanes for a successful touch down some 10 minutes after lift-off, which was captured by cameras on the ground and aboard an observing helicopter.

The SpaceX success came less than a month after Blue Origin, the private space company founded by Amazon billionaire Jeff Bezos, also landed the initial stage of their New Shephard launch system following a test launch. However, the latter is not intended to achieve orbital velocities at present, and so the booster stage – referred to as the “propulsion module” by Blue Origin – was not travelling nearly as fast as the Falcon 9 first stage, nor did it have to perform the complex “boostback” manoeuvres.

In the meantime, the second stage continued upwards, successfully deploying the Orbcomm satellites into LEO – low Earth orbit, at around 630 kilometres (just under 400 miles) altitude. With this part of the mission completed, the second stage booster also re-ignited its main engine, allowing it to achieve a geostationary transfer orbit and coast phase.

This was as important as the first stage landing because, while existing Falcon 9 rockets are capable of placing large payloads into geosynchronous equatorial orbit, some 36,000 km (22,000 miles) above the surface of the Earth, it has required the first stage of the rocket to do much more of the work, leaving it with insufficient fuel reserves to attempt a return to Earth and landing. The uprated second stage, tested as a part of this flight, alleviates the first stage of some of the booster phase work, allowing it to retain the fuel it needs to make a successful return to Earth.

The overall hope with the upgraded Falcon 9 and the new landing facilities at Cape Canaveral, is that they will allow SpaceX to lower launch costs to the benefit of customers, and allow them to make more efficient use of their boosters rather than just tossing them away into the Atlantic or Pacific after a single use.

However, even with this first successful landing, the company still has some significant hurdles to clear. One of these will be demonstrating it can refurbish used first stages at a fast enough pace to be able to maintain a launch cadence high enough to be attractive to commercial operators looking for launch opportunities, rather than risking them look to those companies able to offer a faster launch rate.

Nevertheless, SpaceX’s achievement is clear, and after the disappointments in trying to recover the Falcon 9 first stage at sea (initially seen as a “safer” option due to the negligible risk of civilian injuries if anything went wrong when compared to  returning a rocket to Earth near populated areas), deserves every congratulation.

Dawn over Ceres

Dawn mission patch (NASA / JPL)
Dawn mission patch (NASA / JPL)

Dawn, the NASA / ESA joint mission currently mapping Ceres, one of the solar system’s three “protoplanets” located in the asteroid belt between the orbits of Mars and Jupiter, reached its lowest planned orbital altitude in early December, ready to start the final phase of its mission.

The new orbit, just 385 km (230 miles) above Ceres mains the craft can image the surface at a resolution of 35 metres (120 feet) per pixel.

Of particular interest to the science team has been determining the mysterious bright patches seen within the crater Occator during Dawn’s approach to Ceres and during its higher mapping orbits. While perhaps the largest found, the bright spots in Occator are not alone – around 130 bright spots have been located, almost all of them within Ceres’ craters, and analysis now shows that the material  seems to be consistent with salts, such as sulfates, with silicate materials also very likely present.

A false-colour representation Occator Crater on Ceres reveals the short wavelength of the bright deposits in the crater, pointing to them being salts. Occator measures about 90 km (60 miles) across
A false-colour representation Occator Crater on Ceres reveals the short wavelength of the bright deposits in the crater, pointing to them being salts. Occator measures about 90 km (60 miles) across

Continue reading “Space Sunday: bringing a rocket home; uncovering Ceres” →

Space Update: silica mysteries, Brits in space and tracking Santa

Posted on by Inara Pey

new-horizonNew Horizons is still less than half way through transmitting the data gathered during its fly-past of the Pluto-Charon system in July 2015, but the wealth of information received thus far has already revealed much about Pluto and its “twin”.

Geological evidence has been found for widespread past and present glacial activity, including the formation of networks of eroded valleys, some of which are “hanging valleys,” much like those in Yellowstone National Park, Wyoming. A major part of this activity is occurring in and around “Sputnik Planum”, the left half of Pluto’s “heart”, a 1,000 km (620 mile) wide basin, which is seen as key to understanding much of the current geological activity on Pluto.

Images and data gathered for this region has given rise to new numerical models of thermal convection with “Sputnik Planum”, which is formed by a deep layer of solid nitrogen and other volatile ices. These not only explain the numerous polygonal ice features seen on Sputnik Planum’s surface, but suggest the layer is likely to be a few kilometres in depth.

Evaporation of this nitrogen, together with condensation on higher surrounding terrain is believed causing a glacial flow from the higher lands back down into the basin, where the ice already there is pushed, reshaping the landscape over time.

A ture colour image of Pluto's surface, captures just before the point of closest approach, and created by combining black-and-while images from from the LORRI camera with data gathered by the Ralph instrument suite. The picture show the highlands to one side of "Sputnik Planum with the pockmarked ices of the basin. A combination of evaporation and condensation between the two is giving rise to sustained glaciation on Pluto, showing it to be an active world
A true colour image of Pluto’s surface, captures just before the point of closest approach, and created by combining black-and-while images from from the LORRI camera with data gathered by the Ralph instrument suite. The picture show the highlands to one side of “Sputnik Planum” with the pockmarked ices of the basin. A combination of evaporation and condensation between the two is giving rise to sustained glaciation on Pluto, showing it to be an active world (image: NASA, JHU/APL SwRI)

More data and images have also been received regarding Pluto’s atmosphere, allowing scientists start to probe precisely what processes are at work in generating and renewing the atmosphere, the upper limits of which are subject to erosion by the solar wind, which strike Pluto at some 1.4 million kilometres per hour (900,000 mph).

As well as understanding the processes which are at work renewing the atmosphere, and thus preventing it from being completely blasted away by the solar wind, science teams are hoping to better further why the haze of Pluto’s atmosphere forms a complicated set of layers – some of which are the result of the formation and descent of tholins through the atmosphere – and why it varies spatially around the planet.

The Mars Silica Mystery

In July I covered some of the work going into investigating the mystery of silica on Mars. This is a mineral of particular interest to scientists because high levels of it within rocks could indicate conditions on Mars which may have been conducive to life, or which might preserve any ancient organic material which might be present. In addition.

As I reported back in July, scientists have been particularly interested in the fact that as Curiosity has ascended “Mount Sharp”, so have the amounts of silica present in rocks increased: in some rocks it accounts for nine-tenths of their composition. Trying to work out why this should be, and identifying the nature of some of the silica deposits has given rise to a new set of mysteries.

The first mystery is trying to understand how the silica was deposited – something which could be crucial in understanding how conducive the environment on “Mount Sharp” might have been for life. Water tends to contribute to silica being deposited in rocks in one of two ways. If it is acidic in nature, it tends to leach away other minerals, leaving the silica behind. If it is more neutral or alkaline in nature, then it tends to deposit silica as it filters through rooks.

This May 22, 2015, view from the Mast Camera (Mastcam) in NASA's Curiosity Mars rover shows the "Marias Pass" area where a lower and older geological unit of mudstone -- the pale zone in the center of the image -- lies in contact with an overlying geological unit of sandstone. This view from the Mast Camera (Mastcam) in NASA's Curiosity Mars rover shows the "Marias Pass" area where a lower and older geological unit of mudstone -- the pale zone in the center of the image -- lies in contact with an overlying geological unit of sandstone. Just before Curiosity reached Marias Pass, the rover's laser-firing Chemistry and Camera (ChemCam) instrument examined a rock found to be rich in silica, a mineral-forming chemical. This scene combines several images taken on May 22, 2015, during the 992nd Martian day, or sol, of Curiosity's work on Mars. The scene is presented with a color adjustment that approximates white balancing, to resemble how the rocks and sand would appear under daytime lighting conditions on Earth.
This mosaic of images captures by Curiosity’s Mastcam on May 22nd 2015 (Sol 992), shows the “Marias Pass” region where mudstone (the pale rock in the centre of the image) of the kind the rover had been studying, overlaid by a geological unit of sandstone. rocks in this area should very high concentrations of silica in them, much higher than previously encountered, which the rocks above the area show strong evidence of silica deposition as a result of water action. This image has been white balanced to show the rock under Earth equivalent natural lighting conditions (image: NASA / JPL)

If the water which once flowed down / through “Mount Sharp” was acidic in nature, it would likely mean that the wet environments found on the flanks of the mound were hostile to life having ever arisen there or may have removed any evidence for life having once been present. If evidence that the water was acidic in nature, then it would also possibly point to conditions on “Mount Sharp” may have been somewhat different to those found on the crater floor, where evidence of environments formed with more alkaline water and with all the right building blocks for life to have started, have already been discovered.

The second mystery with the silica is the kind of silica which has been discovered in at least one rock.  Tridymite is a polymorph of silica which on Earth is associated with high temperatures in igneous or metamorphic rocks and volcanic activity. Until Curiosity discovered significantly high concentrations of silica in the “Marias Pass area of “Mount Sharp” some seven months ago – something which led to a four month investigation of the area – tridymite had never been found on Mars.

The region just above "Marias Pass" contained an area referred to as the "Stimson Unit" which showed fracturing rich in silica when compared to the surrounding rocks, suggesting deposition of silica / leaching of other minerals as a result of water action
The region just above “Marias Pass” contained an area referred to as the “Stimson Unit” which showed fracturing rich in silica when compared to the surrounding rocks, suggesting deposition of silica / leaching of other minerals as a result of water action (images: NASA / JPL)

“Marias Pass” and the region directly above it, called the “Stimson Unit” show some of the strongest examples of silica deposition on “Mount Sharp”, and  it was in one of the first rocks, dubbed “Buckskin”, exhibiting evidence of silica deposits in which the tridymite was found.

The question now is: how did it get there? All the evidence for the formation of “Mount Sharp” points to it being sedimentary in nature, rather than volcanic. While Mars was very volcanic early on in its history, the presence of the tridymite on “Mount Sharp” might point to volcanic /  magmatic evolution on Mars continuing for longer than might have been thought, with the mineral being deposited on the slopes of the mound as a result of wind action. Or alternatively, it might point to something else occurring on Mars.

Continue reading “Space Update: silica mysteries, Brits in space and tracking Santa” →

Space Sunday: clouds, sand, meteors and launches

Posted on by Inara Pey
Artist's impression of Akatsuki in orbit around Venus
Artist’s impression of Akatsuki in orbit around Venus

In my last Space Sunday update, I was writing at the very time a final effort was being made to see a little Japanese space probe finally achieve an operational orbit around Venus, precisely five years to the date after the first attempt failed as a result of the craft’s primary motor malfunctioning.

At the time of writing that update, it appeared as if little Akatsuki (“Dawn”), designed to probe the Venusian climate and atmosphere had finally arrived in orbit about the planet, but as I noted, final confirmation would take a while.  In the end, it wasn’t until Wednesday, December 9th that the Japan Aerospace eXploration Agency (JAXA) did confirm Akatsuki, less than a metre on a side (excluding its solar panels) was secure in its orbit around Venus and would likely be able to complete its mission.

Following the failure of its main engine on December 7th 2010 during a critical braking manoeuvre, the probe had finished up in a heliocentric orbit, circling the sun and heading away from Venus. However, orbital mechanics being as they are, both the probe and Venus would occupy the same part of space once again in December 2015, presenting final opportunity to push the probe into orbit using its RCS manoeuvring thrusters. This is precisely what happened on the night of December 6th / 7th, 2015. While not designed for this purpose, a set of the probe’s RCS thrusters undertook a 20-minute burn just before midnight UTC on December 6th, and preliminary telemetry received on Earth some 30+ minutes later showed Akatsuki had achieved sufficient braking to enter a very elliptical orbit around Venus.

A simple orbital diagram released as a part of the low-key JAXA press release confirming Akatsuki had arrived in orbit around Venus
A simple orbital diagram released as a part of the low-key JAXA press release confirming Akatsuki had arrived in orbit around Venus (image: JAXA)

Data received since then show that the craft is in an eccentric orbit with an apoasis altitude (the point at which it is furthest from the surface of Venus) of around 440,000km, and a periapsis altitude (the point at which it is closest to the surface of Venus) of around 400km. This is a considerably broader orbit than the mission had originally intended back in 2010, giving the vehicle an orbital period of around 13.5 days, the orbit slightly inclined relative to Venus’ equator.

An ultra-violet image of Venus, returned by Akatsuki shortly after achieving its initial orbit around the planet, and having passed through periapis, already heading away from the planet
An ultra-violet image of Venus, returned by Akatsuki shortly after achieving its initial orbit around the planet, having passed periapsis during the braking manoeuvre, to head away from the planet (image: JAXA)

In order to maximise the science return from the vehicle – which is now operating well in excess of its designed operational life – JAXA plan to use the next few months to gradually ease Akatsuki in an orbit which reduces both the apoasis distance from Venus, and bring down the orbital period to about 9 days.

These manoeuvres will likely be completed by April 2016, allowing the full science mission to finally commence.  This is aimed at learning more about the atmosphere and weather on Venus as well as confirm the presence of active volcanoes and thunder, and also to try to understand exactly why  Earth and Venus developed so differently from each other, despite being seen as sister planets in some regards.

Even so, right from its arrival in its initial orbit, Akatsuki has been flexing its muscles, testing its imaging systems and returning a number of preliminary pictures of Venus to Earth, such as the ultra-violet image shown above right, captured just after the craft finally achieved orbit.

Curiosity reaches Sea of Sand

NASA’s Mars Science Laboratory rover Curiosity has reached the edge of the major “sea” of sand dunes located on the flank of “Mount Sharp”. Dubbed the ““Bagnold Dunes” after British military engineer Ralph Bagnold, who pioneered the study of sand dune formation and motion, doing much to further the understanding of mineral movements and transport by wind action. Such studies are seen as an essential part of understanding how big a role the Marian wind played in depositing concentrations of minerals often associated with water across the planet, and by extension, the behaviour and disposition of liquid water across Mars.

Sand is not a new phenomenon for rovers on Mars to encounter – Curiosity, Opportunity and Spirit have all had dealings with it in the past; in fact Spirit’s mission as a rover came to an end in 2009, after it effectively got stuck in a “sand trap”. However, the “Bagnold Dunes” are very different to the sandy environs previously encountered by rovers; it is a huge “genuine” dune field where the sand hills can reach the height of 2-storey buildings and cover areas equivalent to an American football field.

The rippled surface of the first Martian sand dune ever studied up close. Captured by Curiosity's Mastcam on November 27th, 2015 (Sol 1,176 on Mars), the view is looking up the curved slope of "High Dune", revealing a rippled surface of sand sculpted by the wind. The Bagnold dunes" are "active", in that they are migrating down the slope of "Mount Sharp" at the rate of around one metre (39 inches) a year. The dunes are active, migrating up to about one yard or meter a year.
The rippled surface of the first Martian sand dune ever studied up close. Captured by Curiosity’s Mastcam on November 27th, 2015 (Sol 1,176 on Mars), looking up the curved slope of “High Dune” as it rises above Curiosity. The “Bagnold Dunes” are “active”, in that they are migrating down the slope of “Mount Sharp” at the rate of around one metre (39 inches) a year  (image: NASA / JPL)

So far, Curiosity has only probed the edge of the dune field around a sand hill originally dubbed “Dune 1”, and now called “High Dune”, using both its camera to image the region and its wheels to test the surface material prior to moving deeper into the sands. Wheel slippage is a genuine concern for the rover when moving on loose surfaces, as it can both overtax the motors and put the rover at risk of toppling over. Given this, and while there are no plans to attempt any ascent up the side of a dune, the mission team are taking things cautiously.

Continue reading “Space Sunday: clouds, sand, meteors and launches” →

Space Sunday: of Venus, Cosmic Girl and Cygnus

Posted on by Inara Pey
Artist's impression of Akatsuki in orbit around Venus
Artist’s impression of Akatsuki in orbit around Venus

It is not often that I get to report on a space event that is happening right as I’m wiring about it; but that is precisely what happened as I wrote this edition of Space Sunday.

As I was typing, high above Venus, a little cube-like space craft measuring just over a metre on a side and supported by two stubby solar panel “wings”, had been making a final desperate attempt to enter orbit around the planet.

Akatsuki (“Dawn”), is a Japanese space probe also known by the names Venus Climate Orbiter (VCO) and Planet-C. Its mission is to study the dense, intense atmosphere of Venus and gain greater insight into how it formed, whether it has active weather phenomena such as lightning, and whether Venus itself may still be volcanically active. It is also a vehicle which has taken “the long way around” in order to reach its target.

Originally launched on May 20th, 2010 Akatsuki should have entered orbit around Venus on December 7th of that year. In order to do so, the vehicle had to carry out a 12-minute “burn” of its main engine to slow itself to the point where it would be caught by Venus’ gravity and so swing into an elliptical orbit. However, while the engine did fire as expected, a fuel valve failed, preventing the burn from being completed as required, and Akatsuki failed to achieve the desired orbit, and instead was left strained in a heliocentric (Sun-centred orbit) which would bring the craft back into proximity with Venus five years later – on the evening (UK time) of the 6th / 7th December 2015.

Having managed to keep the little craft alive and functioning during the intervening years, this second encounter offer a final opportunity to get Akatsuki safely into orbit around Venus, where it might complete its primary mission. Final because the craft has already far exceeded its operational life span, and such an opportunity is unlikely to come again.

Emily Lakdawalla provided this diagram of the Akatsuki orbit insertion attempt
Emily Lakdawalla of The Planetary Society provided this diagram of the Akatsuki orbit insertion attempt

So it was that at around 23:51 UTC on Sunday, December 6th, Akatsuki fired one set of its reaction control system (RCS) thrusters for 20 minutes in an attempt to push itself into an extended orbit around Venus (VOI – for Venus Orbital Insertion – in the diagram above).  Entirely automated, the attempt could, if required, be followed by an additional motor firing if telemetry received on Earth indicated the first burn had failed.

At 00:24 UTC on December 7th, data received from the vehicle, having taken over 8 minutes to be transmitted to Earth and then be processed, indicated the initial motor firing had been successful, and that Akatsuki should have established itself in an extended elliptical orbit around Venus, between 300,000 to 400,000 km above the surface of the planet. This is somewhat greater than the original orbit for the craft, which would have varied between 300 to 80,000 km, but it still should be close enough for the probe to undertake most of its science mission, although it will be several hours before this is confirmed.

 Cosmic Girl Gets Ready to Launch

Virgin Galactic is probably best known for two things: Richard Branson and trying to develop a sub-orbital flight capability which will allow fare-paying tourists enjoy a few minutes of “weightlessness” at the edge of space, marketing itself as the “world’s first commercial space line”.

However, the company is also looking to enter the lucrative market of commercial satellite launches, using a vehicle they’ve christened LauncherOne. The vehicle is specifically intended to to provide a launch capability for “smallsats”, sub-500 kg satellites, an increasingly poplar market sector, but one where very often the main means of getting into orbit is by “hitch-hiking” aboard launchers carrying other payloads.

Virgin Galactic: entering the satellite launch market with the 2-stage LauncherOne
Virgin Galactic: entering the satellite launch market with the 2-stage LauncherOne

Unlike most boosters, LauncherOne is designed to be air-launched. That is, carried aloft by an aircraft to an altitude of some 10,770 metres (35,000 ft) before being released to allow its first and second stage motors carry its payload up to the required orbit.

The technique isn’t new – it is used most notably by the Pegasus launch system developed by Orbital ATK, and which first flew in 1990. However, the technique offers some significant advantages. The most obvious of these is that by lifting the booster a fair way out of the denser part of the Earth’s atmosphere, less fuel is required for the rocket to reach orbit, reducing its overall mass and cost. Air-launched missions also aren’t restricted to a launchpad; they can be undertaken from any airport where there are suitable facilities for handling the booster itself, thus maximising the potential launch profiles a customer might need. When all the benefits are put together, it means that Virgin Atlantic can offer tailor-made smallsat launch capabilities to clients for just US $10 million a shot.

White Knight Two flying to the Farnborough air Show in 2012 with a mock-up of the original LauncherOne mounted beneath it (Image: Virgin Galactic)
White Knight Two flying to the Farnborough air Show in 2012 with a mock-up of the original LauncherOne mounted beneath it (Image: Virgin Galactic)

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