Space Sunday: SpaceX Starship update

A Starship / Super Heavy pairing lifts-off from a dedicated launch facility in this still from an animated video produced by SpaceX for the September 28th, 2019 update. Credit: SpaceX

On the occasion of the eleventh anniversary of SpaceX achieving orbit for the first time with their Falcon 1 rocket on September 28th, 2008, CEO Elon Musk presented an update on the company’s progress developing its massive Super Heavy booster and interplanetary class vehicle, Starship.

It has been some 12 months since the last update on the development of the two vehicles – the last update really being overshadowed by the announcement SpaceX planned to fly a Japanese billionaire and his entourage around the Moon and back (see Moon trips, Mr Spock’s “home” and roving an asteroid for more), and the programme has moved on significantly since then, as indicated by the fact that the 2019 update took place at the SpaceX facilities in Boca Chica and against the backdrop of the first of the Starship prototype vehicle.

Starship Mk1 under construction at the SpaceX facilities near Boca Chica, Texas. Credit: unknown

Since its first public unveiling in 2016, the Starship / Super Heavy combination has been through a number of iterations and name changes. However, it is fair to say that things have now settled down on the design front, and what was presented at Boca Chica is liable to remain largely unchanged, assuming everything proceeds as SpaceX hopes.

In this, the flight capable prototype Starship at Boca Chica is the first in a series of such vehicles. A second is  under construction at the SpaceX facilities in Cocoa, Florida, and three more are planned, one of which will be used to make the first orbital flight within the next 6 months, and Musk suggesting another could be used in a crewed orbital flight within the next 12 months – which sounds exceptionally ambitious. Construction of the two initial Starship prototypes has not exactly been secret: both have been literally assembled in the open. So even ahead of the September 28th event, some were already developing renderings of the new Starship design compared to the last known iteration.

A rendering by Kimi Talvitie comparing the 2018 design for Starship (l) with the prototype (r). The rendering of the 2019 prototype was based on direct feedback from Elon Musk

The new design sees some significant changes in Starship – notably with the fins, canards and landing legs. The 2018 variant was marked by three large fins, two of which would be actuated (hinged for up / down motion relative to the hull) for atmospheric flight, with all three fins containing the vehicle’s landing legs. At the time of that design, I commented that this approach appeared risky: a heavy landing on the Moon or Mars might conceivably damage one of the actuated fins, affecting the vehicle’s ability to undertake atmospheric flight on its return to Earth.

With the new design, the fins are reduced to two and reshaped, both of which are actuated to hinge “up” and “down”. In addition, the landing system is now independent of the fins, removing the greater part of the risk of damaging them on landing. The number of landing legs is also increased to six. At the forward end of the vehicle, the canards are enlarged and hinged in a similar manner to the fins.

Starship’s basic specification. Note the “dry” mass of 85 tonnes is incorrectly stated in the slide: it is expected the production version of Starship will mass around 120 tonnes (the prototype masses around 200 tonnes. Credit: SpaceX

The remaining aspects of the design are more-or-less unchanged as far as the body of the ship is concerned: it will be some 50 metres (162.5ft) in length and have a diameter of 9m (29ft). The forward end of the vehicle will be given over to crew and passengers or cargo (or a mix of the two), although Musk now estimates the vehicle will – with the aid of the Super Heavy booster – be lifting up to 150 tonnes to low Earth orbit – an increase of roughly a third – and return up to 50 tonnes to Earth.

To help achieve this, the motor system has been slight revised. While six engines will still be used, three will now be optimised for vacuum thrust, ideal for orbital flight and pushing the vehicle out to the Moon or Mars, and the remaining three optimised for sea level thrust and capable of being gimballed for use during a descent through an atmosphere and landing.

Starship’s motor arrangement: three central Raptor engines optimised for sea level thrust and capable of gimballing and three outer vacuum optimised motors with fixed, large diameter exhaust bells for maximum efficiency. The “boxes” visible in the rendering are potentially additional cargo bins. Credit: SpaceX

During the presentation, Musk explained the rationale behind the use of 301 cold rolled stainless steel in the design, noting a number of reasons. Firstly, the cold rolling process results in a stronger, light finished product, and this becomes even stronger when exposed to the very low temperatures of cryogenic fuels. Thus, Starship and Super Heavy in theory have a structural strength equitable to that of carbon composites – but at a much lower overall mass.

Secondly, the cold rolled steel has very high melt temperatures, reducing the amount of direct heat shielding required, again reducing the vehicle’s overall mass. It is also both highly corrosion-resistant and easy to work with. This means that basic repairs to a vehicle on the surface of the Moon or Mars could be effected, or even that a Starship could even be dismantled and the steel from the hull re-purposed. Finally, there’s the fact that all these advantages are gained in a product costing around 2% that of an equivalent mass of carbon composite.

Starship Mk 1 filmed during the September 28th livestream event. Credit: SpaceX

In terms of heat shielding, the “windward” side of Starship (the side facing the fictional heat of entry into an atmosphere) will be coated with lightweight ceramic tiles. Somewhat similar in nature to those used within the space shuttle, they will be of a hardier material and less prone to damage. The re-entry profile was also discussed, with Musk comparing Starship to a sky diver.

To explain: the vehicle will approach the atmosphere at a relatively high 60-degree incidence, using the heat generated by contact with the upper atmosphere to slow its velocity from Mach 25 to a point where, once within the denser atmosphere, the vehicle is literally falling more-or-less horizontally. The fins and canards can then be used to maintain the vehicles orientation in a similar manner to that of a sky diver using his arms and legs. in addition, the lift generated by fins and canards will further help slow its descent until, roughly 2 km above the ground, the vehicle will rotate to a vertical position and use the three gimballed Raptor motors to make a propulsive, tail-first landing.

SpaceX plan to offer Starship in support of lunar operations – but the company’s goal is to establish a permanent human presence on Mars. Credit: SpaceX

Starship Mk 1 is equipped with the same sea level optimised Raptor motors as intended for the production vehicles.  SpaceX hope to see it make at least one flight before the end of the year – although the company has yet to secure a permit from the US Federal Aviation Authority to commence flights. This first attempt will be to an altitude of around 20 km (12.5 mi) before a descent and landing. If successful, the test programme involving the various prototype vehicles will unfold from there.

Continue reading “Space Sunday: SpaceX Starship update”

Space Sunday: rocket power and space stations

Dude, why’s my car in orbit? Musk’s cherry-red Tesla photographed from its payload mounting on the Falcon Heavy upper stage. Credit: SpaceX

On Tuesday, February 6th, SpaceX launched one of the world’s most powerful launch vehicles – in fact, currently, the most powerful launcher in operation since NASA’s massive Saturn V rocket by a factor of 2 in terms of lift capability.

I’m of course talking about the Falcon Heavy, which after years of development and launch delays, finally took the to skies at 15:45 EST (20:45 UTC) on the 6th, after upper altitude wind shear delayed the launch from its planned 13:30 EST lift-off time – which would have been at the start of the four-hour launch window required to send its payload on a trans-Mars injection heliocentric orbit.

Three cores, 27 Merlin engines, 5 million pounds of thrust. A remarkable shot of the lower part of the Falcon Heavy at lift-off, captured by Ryan Chylinski. Credit: R. Chylinski / SpaceFlight Insider

The run-up to the launch was handled fairly conservatively by SpaceX: Falcon Heavy is a complex system – effectively three individual Falcon 9 rockets which have to operate in unison. So much might go wrong that even Elon Musk was stating he’d be happy if the vehicle was lost after it had cleared the launch pad. This was not a joke: in September 2016, a pre-flight test of a Falcon 9 lead to the loss of the vehicle, its payload and massive damage to its Cape Canaveral launch pad, putting a dent in SpaceX’s launch capabilities at the time. A similar event at Kennedy Space Centre’s pad 39-A, the only launch facility capable of handling the Falcon Heavy, would be a massive setback for the company’s 2018 aspirations.

However, and as we all know, the launch proved to be flawless. All 27 engines fired as required, generating the same thrust as 18 747 running all their engines at full throttle, and the vehicle took to the air. Two minutes later, the “stack” reached the point of “max-Q”, the point at which aerodynamic stress on a vehicle in atmospheric flight is maximised (symbolised in a formula as “q” – hence “max Q”). At this point, were the rocket’s engines to continue to run at full thrust, the combined stresses could literally shake the vehicle apart; so instead the motors are throttled back, easing the strain on the vehicle, prior to them returning to full thrust as “max-Q” has passed.

The Falcon Heavy flight path. Credit: SpaceX

After passing through “max-Q”, the vehicle completed perhaps the most spectacular part of its flight. Their job done, the two outer Falcon 9 stages shut down their engines and separated from the core rocket. Then then re-lit their engines to boost them vertically to where both could perform a back-flip and then return for a landing at Cape Canaveral Air Force Station, just south of Kennedy Space Centre. So perfect was this aerial ballet that the two boosters landed almost simultaneously.

The central first stage should have also made a return to Earth after separating from the upper stage, landing aboard one of the company’s two autonomous spaceport drone ship (ASDS) – necessary because the stage had flown too far and too high to make a return to dry land. This was the only point of failure for the flight. Unfortunately, it over-burnt its propellants, leaving it without enough fuel to land on the floating platform. Instead, it slammed into the sea at an estimated 480 km/h (300 mph), some 100 metres (300ft) from the ASDS – the only notable failure in the launch.

Two from one: the moment at which two Falcon 9 cores are about to touch-down at Cape Canaveral Air Force Station following the February 6th, 2018 launch of Falcon Heavy. Credit: SpaceX

The second stage, however, performed perfectly, the payload fairings jettisoned, and the world got its first look at a car in space: Musk’s own Tesla Roadster, complete with a spacesuited mannequin (“Starman”) at the wheel, Don’t Panic – a reference to The Hitch Hiker’s Guide to the Galaxy – displayed on the dashboard. During the ascent, he was apparently listening to David Bowie’s Space Oddity played on the car’s stereo.

Right now, “Starman” and the car are en-route to a point out just beyond the orbit of Mars. It is is on a heliocentric (Sun-centred)  orbit, travelling between 147 million and 260 million km (91.3 million and 161.5 million mi) from the Sun, and passing across both the orbits of Mars and Earth in the process – but without actually coming close to either. It will continue in this orbit for millions of years. Continue reading “Space Sunday: rocket power and space stations”

Space Sunday: reusability, habitability, survivability

SpX-13 lifts-off from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida, marking the first time SpaceX has launched a previously-flown Dragon 1 resupply capsule atop a previously flown Falcon 9 first stage, in SpaceX’s 17th launch for 2017. Credit: NASA

SpaceX Has completed its first mission to the International Space Station with a Falcon 9 first stage and a Dragon 1 resupply vehicle which have both previously flown.

The launch took place at 15:36 GMT (10:36 EST) on Friday, from Space Launch Complex 40 at Cape Canaveral Air Force Station. As well as being the first time a previously used Falcon 9 first stage and Dragon capsule have flown together, the launch also marked the first from SLC-40 since a pre-launch explosion of a Falcon 9 rocket in September 2016, which completely destroyed the rocket and its Israeli payload, and severely damaged the launch facilities.

Three minutes after the launch, the first and second stages of the Falcon 9 separated, the latter continuing towards orbit while the former performed its “boost-back” manoeuvre, and completed a safe return to Earth and a vertical landing at SpaceX’s Landing Complex 1 at Canaveral Air Force Station. The landing marked the 20th successful recovery of the Falcon 9 first stage – with 14 of those recoveries occurring in 2017.

The Dragon capsule, carrying some 2.2 tonnes of supplies for the ISS, was first used in a resupply mission in April 2015. In its current mission, it reached the station on Sunday, December 17th, where it was captured by the station’s robotic arm and moved to a safe docking at one of the ISS’s adaptors where unloading of supplies will take place. The capsule will remain at the station through January, allowing science experiments, waste and equipment to be loaded aboard, ready for a return to Earth and splashdown in the Pacific ocean, where a joint NASA / SpaceX operation will recover it.

The SpX-13 Dragon sits alongside the International Space Station on Sunday, December 17th, waiting to be grappled by one of the station’s robot arms and moved to its docking port. Credit: NASA/JSC

The mission is a significant milestone for SpaceX, bringing the company a step closer to it goal of developing a fully reusable booster launch system. Thus far the company has successfully demonstrated the routine launch, recovery and reuse of the Dragon 1 capsule and the Falcon 9 first stage. On March 30th, 2017, as part of the SES-10 mission, SpaceX performed the first controlled landing of the payload fairing, using thrusters to properly orient the fairing during atmospheric re-entry and a steerable parachute to achieve an intact splashdown. This fairing might be re-flown in 2018. That “just” leaves the Falcon 9 upper stage, the recovery of which would make the system 80% reusable.

However, recovering the second stage is a harder proposition for SpaceX – at one point the company had all but abandoned plans to develop a reusable stage, but in March 2017, CEO Elon Musk indicated they are once again working towards that goal – although primary focus is on getting the crew-carrying Dragon 2 ready to start operations ferrying crews to and from the ISS.

The major issues in recovering the system’s second stage are speed and re-entry. The second stage will be travelling much faster than the first stage, and will have to endure a harsher period of re-entry into the Earth’s denser atmosphere. This means the stage will require heat shielding and a means to protect the exposed rocket motor, as well as the propulsion, guidance and landing capabilities required for a full recovery.

SpaceX has proven the reusability of the Falcon 9 first stage (left) and the Dragon capsule system (right). All that remains is developing a reusable second stage, most likely for use with the Falcon Heavy – or as a part of the ITS / BFR. This image shows the discontinued proposal for a reusable Falcon 9 second stage. Credit: SpaceX

The problem here is that of mass. The nature of rocket staging means that – very approximately, every two kilos of rocket mass on the first stage reduces the payload capability by around half a kilogramme.  With a second stage unit, this can drop to a 1:1 ratio. So, all the extra mass of the re-entry / recovery systems can reduce the total payload mass, making the entire recovery aspect of a Falcon 9 second stage both complex and of questionable value, given the possible reduction in payload capability. However, with the Falcon Heavy due to enter service in 2018, a reusable second stage system does potentially have merit, as the combined first stages of the system can do more of the raw shunt work needed to get the upper stage and its payload up to orbit.

The Habitability of Rocky Worlds Around a Red Dwarf Star

Red Dwarf stars are currently the most common class (M-type) of star to be found to have one or more planets orbiting them. Many of these worlds appear to lie within their parent’s habitable zone, and while that doesn’t guarantee they will support life, it does obviously raise a lot of questions around the potential habitability of such worlds.

There tend to be a couple of things which often run against such planets when it comes to their ability to support life. The first is that often, they are tidally locked with their parent star, always keeping the same face towards it. This creates extremes of temperature between the two side of the planet, which might as a result drive extreme atmospheric storm conditions. The second is – as I’ve noted in past Space Sunday articles – red dwarf stars tend to be extremely violent in nature. Their internal action is entirely convective, making them unstable and subject to powerful solar flares, generating high levels of radiation in the ultraviolet and infra-red wavelengths. Not only can these outbursts leave planets close to them subject to high levels of radiation, they can cause the star to have a violent solar wind which could, over time, literally rip any atmosphere which might otherwise form away from a planet. This latter point means that one of the most vexing questions for those studying exoplanets is how long might such worlds retain their atmospheres?

In an attempt to answer to that question, planetary astronomers have turned to a planet far closer to us than any exoplanet: Mars.

Continue reading “Space Sunday: reusability, habitability, survivability”

Space Sunday: looking back on Earth and landing rockets and probes

The Earth and Moon, as seen from orbit over Mars, November 20th 2016
The Earth and Moon, as seen from orbit over Mars, November 20th 2016

Two marbles sit on a midnight background, one a swirl of blue, white, brown and green, the other tinted in shades of grey. Together they are the Earth and her Moon as seen by the most powerful imagining system currently orbiting the planet Mars.

It is, in fact a composite image, although Earth and the Moon are the correct sizes and the correct position / distance relative to one another. The images were captured by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter (MRO) on November 26th, 2016.

The images were taken to calibrate HiRISE data, since the reflectance of the moon’s Earth-facing side is well-known. As such, this is not the first image of our home planet and its natural satellite captured from Martian orbit, but it is one of the most striking. Whilst a composite image, only the Moon’s brightness has been altered to enhance its visibility; were it to be shown at the same brightness scale as Earth, it would barely be visible. That it appears to be unnaturally close to Earth is in fact an illusion of perspective: at the time the pictures were taken, the Moon was on the far side of Earth relative to Mars, and about to pass behind it.

The image of Earth shows Australia prominent in the central area of the image, its shape just discernible in this high-resolution image, taken when Mars and the MRO were 205 million kilometres (147 million miles) from Earth.

For me, this is another picture demonstrating just how small, fragile and unique our home world actually is.

 Falcon 9 Makes Triumphant Return to Flight

With Federal Aviation Authority (FAA) approval given, SpaceX, the private space company founded by Elon Musk, made a triumphant return to flight status with its Falcon 9 launch system on Saturday, January 14th.

January 14th, 2017: the SpaceX Falcon 9, carry 10 advanced Iridium Next communications satellites in its bulbous paylod fairing, lifts-off from Space Launch Complex 4E, Vandenberg Air Force Base, California Credit: SpaceX
January 14th, 2017: the SpaceX Falcon 9, carry 10 advanced Iridium NEXT communications satellites in its bulbous payload fairing, lifts-off from Space Launch Complex 4E, Vandenberg Air Force Base, California Credit: SpaceX

SpaceX launches had been suspended in September 2016, after a Falcon 9 and its US $200 million payload were loss in an explosion during what should have been a routine test just two days ahead of the planned launch (see here for more). Towards the end of 2016, and following extensive joint investigations involving NASA and the US Air Force (The Falcon 9 was located at Launch Complex 40 at the Canaveral Air Force Station when the explosion occurred), SpaceX were confident they had traced the root cause for the loss to a failure of process, rather than a structural or other failure within the vehicle itself. However, they had to wait until the FAA had reviewed the investigation findings and approved the Falcon 9’s return to flight readiness before they could resume operations.

The January 14th launch came via the SpaceX West Coast facilities, again leased from the US Air Force, and saw a Falcon 9 booster lift-off from Space Launch Complex 4E at Vandenberg Air Force Base in California. The rocket was carrying the first ten out of at least 70 advanced Iridium NEXT mobile voice and data relay satellites SpaceX will launch over the coming months, as Iridium Communications place a “constellation” of 81 of the satellites in orbit around the Earth in a US $3 billion project.

All ten satellites were successfully lifted to orbit and deployed following a pitch-perfect launch, which had to take place at precisely 9:54:34 local time (17:54:34 UT) in order for all ten satellites to be correctly deployed to reach their assigned orbits. However, all eyes were on the Falcon 9’s first stage, which was set to make a return to Earth for an at-sea landing aboard one of the company’s two autonomous drone landing barges, Just Follow The Instructions.

Down and safe: the Falcon 9 first stage, seen via a camera aboard the autonomous drone barge Just Follow The Instructions, shortly after touch-down on January 14th, 2017. Credit: SpaceX
Down and safe: the Falcon 9 first stage, seen via a camera aboard the autonomous drone barge Just Follow The Instructions, shortly after touch-down on January 14th, 2017. Credit: SpaceX

Operating the Falcon 9 on a basis of reusability is core to SpaceX’s future plans to reduce the overall cost of space launches. While the company has previously made six successful returns and landings with the Falcon 9 first stage, this being the first attempt since September 2016’s loss added further pressure on the attempt. but in the event, it went flawlessly.

After separation from the upper stage carrying the payload to orbit, the first stage of the Falcon 9 completed what are called “burn back” manoeuvres designed to drop it back into the denser atmosphere. Vanes on the rocket’s side were deployed to provide it with stability so that it dropped vertically back down to Earth, using its engines as a braking system and deploying landing legs shortly before touchdown – and the entire journey was captured on video, courtesy of camera built-into the rocket’s fuselage.

Continue reading “Space Sunday: looking back on Earth and landing rockets and probes”

Space Sunday: water on Europa, Rosetta on a comet and Musk on Mars

Euorpa's icy, mineral-stained surface as imaged by NASA's Galileo mission - see bwlow (credit: NASA / JPL)
Euorpa’s icy, mineral-stained surface as imaged by NASA’s Galileo mission – see below (credit: NASA / JPL)

On Monday, September 26th, after some teasing beforehand, NASA provided an update on the venting of water by Jupiter’s icy moon, Europa.

As I noted in my last Space Sunday report, Europa is covered by shell of water ice, much of it discoloured by mineral deposits and by deep cracks, beneath which it is believed to have a liquid water ocean about 100 km (62.5 miles) deep. The ocean is believed to be made possible by tidal flexing enacted by the massive gravity of Jupiter as well as from the other large Galilean moons. This generates heat within Europa, and this heat stops the water from freezing solid.

In 2012, The Hubble Space Telescope (HST) captured what appeared to be a huge plume of water erupting some 200 kilometres (125 mi) above the surface of Europa, using its Space Telescope Imaging Spectrograph (STIS) instrument. The update offered on September 26th provided information on further plumes, strengthening the case of water existing under the ice crust of Europa in the process – a crust which may be far thinner than thought.

Europa transit illustration. Europa orbits Jupiter every 3 and a half days, and on every orbit it passes in front of Jupiter, raising the possibility of plumes being seen as silhouettes absorbing the background light of Jupiter. Credit: A. Field (Space Telescope Science Institute)
Europa transit illustration. Europa orbits Jupiter every 3 and a half days, and on every orbit it passes in front of Jupiter, raising the possibility of plumes being seen as silhouettes absorbing the background light of Jupiter. Credit: A. Field (Space Telescope Science Institute)

Over a 15-month period, astronomers used Hubble’s STIS to observe Jupiter and Europa in the ultra-violet spectrum. During that time, Europa occulted (passed in front) of Jupiter on 10 separate occasions. The observations were an attempt to examine a possible extended atmosphere around the moon, which is slightly smaller than our own. However, on three of the passes, astronomers witnessed what appeared to be plumes of water erupting from the surface – and in pretty much the same location as seen in 2012. Analysis of the plumes revealed they were made up of hydrogen and oxygen consistent with water vapour being broken apart by Jupiter’s radiation in a process known as radiolysis.

The plumes are not constant, but rather flare up intermittently, possibly as a result of the surface ice on Europa flexing in response to the same gravitational influences that are keeping the ocean beneath the ice from freezing out. This suggests that the icy crust is, at least around the region where the plumes are occurring, thinner than had been thought. This is important, because it could mean that any automated mission sent to Europa could have a fair chance of cutting its way through the ice to deploy a submersible vehicle which could then search for any evidence of life in Europa’s salty ocean – which contains between two and three times as much water as all of Earth’s oceans combined.

The Gentle Crunch: Rosetta Mission Ends

The European Space Agency’s Rosetta spacecraft said farewell on Friday, September 30th, bringing the 12-year mission that bears its name to a close.

Launched in 2004, Rosetta was a daring attempt to rendezvous with a short-period comet, 67P/Churyumov-Gerasimenko, then orbit it and study it as it swept through the inner solar system and around the sun on its (roughly) 6-year obit. The aim was to give us unique insight into cometary behaviour and – more directly – to study one of these tiny lumps of mineral and chemical rich rock “left over” from the solar system’s formation, and thus gain greater understanding as to how things came to be, and perhaps how life itself might have begun.

Rosetta, Europe's mission to unlock the secrets of the early solar system through the study of comet 67p-C/G, and the Philae comet lander (image: European Space Agency)
Rosetta, Europe’s mission to unlock the secrets of the early solar system through the study of comet 67P-C/G, and the Philae comet lander (image: European Space Agency)

Rosetta travelled almost 8 billion km (5 billion miles), including three flybys of Earth and one of Mars, and two asteroid encounters, before finally arriving at 67P/C-G in August 2014. In November of that year, The Philae lander was deployed in the hope of studying the comet from the surface and gathering samples of its material for analysis. Unfortunately, Philae’s anchoring mechanism failed, sending the little lander bouncing across the comet, until it came to rest in a location where it was receiving insufficient sunlight to recharge its batteries. Nevertheless, in the time it did have before its batteries were almost depleted, the washing machine sized lander some 80%+ of its science goals.

Meanwhile, Rosetta studied the comet in the long fall towards the Sun, and carried out an extensive mission of study, analysis and image capture, much of which has completely altered thinking around comets like 67P/C-G. For example, the mission discovered that water within the comet has a different ‘flavour’ to that of Earth’s oceans, suggesting that the impact of such comets with primordial Earth played far less of a role in helping start Earth’s oceans than had been thought.

The final descent: Rosetta’s OSIRIS narrow-angle camera captured this image of Comet 67P/Churyumov-Gerasimenko from an altitude of about 16 km above the surface during the spacecraft’s final descent on September 30, 2016. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
The final descent: Rosetta’s OSIRIS narrow-angle camera captured this image of Comet 67P/C-G from an altitude of about 16 km above the surface, as the spacecraft commenced its final descent on September 29th, 2016. Craggy hills about 614 metres wide rise from a surface smothered in dust redeposited on the comet’s surface after being outgassed during its active phase. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

As the comet became more active during its approach to the Sun, Rosetta found complex organic molecules – amino acid glycine, which is commonly found in proteins, and phosphorus, a key component of DNA and cell membranes – were present in the dust vented by 67P/C-G, reinforcing the idea that the basic building blocks for life may have been delivered to Earth from an early bombardment of such rocks. The mission also confirmed that the comet’s odd shape – two potato-like lobes of different sizes joined at a narrow waist – was the result of a very slow-speed collision very early in the comet’s 4.5 billion-year age.

In all the spacecraft  operated in the harsh environment of the comet for 786 days, made a number of dramatic flybys close to its surface, survived several unexpected outgassings, and made two full recoveries for potentially serious “safe mode” situations. However, all things must inevitably come to an end, and with its manoeuvring propellants almost exhausted, on September 29th, Rosetta set course for a gentle crash landing on 67P/C-G.

Continue reading “Space Sunday: water on Europa, Rosetta on a comet and Musk on Mars”

Space Sunday: rockets, billions of stars and black holes

The moment of destruction: the SpaceX Falcon 9 explodes on Launch Complex 40 at Kennedy Space Centre, Florida
The moment of destruction: the SpaceX Falcon 9 explodes on Launch Complex 40 at Kennedy Space Centre, Florida

SpaceX Look to Resume Falcon Flights in November 2016

SpaceX President Gwynne Shotwell has indicated the company hopes to resume Falcon 9 launches from November 2016, despite the September 1st loss of the launch vehicle and its US $200 million Amos 6 Israeli-built communications satellite during the preparations for a full static fire test of the rocket’s main engines.

It’s an ambitious aim, given that the cause of the loss is still unknown – and until it is known, it is highly unlikely the Falcon 9 will be cleared for flight by the FAA. However, the comments might suggest company  feel that the cause of the loss may not have been with the booster itself, but may have been triggered by an external event, in which case such a target might be possible.

Launch Complex 40, Canaveral Air Force Station, after the Loss of the Falcon 9 booster and payload on September 1st, 2016
Launch Complex 40, Canaveral Air Force Station, after the Loss of the Falcon 9 booster and payload on September 1st, 2016. Credit: Ken Kremer

The static fire test is a part of pre-launch preparations unique to SpaceX. Basically a full dress rehearsal of a launch, it includes fuelling the booster and briefly firing the main engines with the rocket locked-down on the pad. It was during fuelling operations, eight minutes before the rocket motors were to be fired, the that a series of explosion occurred, destroying the booster and its payload.

Video footage seems to suggest the point of origin for the explosions was outside of the vehicle, in what SpaceX has called a “fast fire”, which started at, or near, the liquid oxygen fuelling umbilical.  As well as the complete loss of the vehicle, the explosions and fireball caused extensive damage to Space Launch Complex (SLC) 40 at Canaveral Air Force Station, which had been leased to SpaceX for Falcon 9 launches.

It is the second lost of a Falcon 9 rocket in 15 months. In June 2015, the vehicle carrying the Dragon CRS-7 cargo resupply vehicle to the International Space Station disintegrated a little over two minutes after lift-off, following the failure of an internal strut.

In order to resume launches and meet obligations, SpaceX are planning on pivoting Falcon 9 launches to Kennedy Space Centre’s Pad 39A until such time as SLC 40 can be repaired. SpaceX leased the pad – a part of the complex used to launch the Saturn IB, Saturn V and space shuttles – in 2014 in a 20-year deal. It is currently being refurbished at the company’s expense to launch crewed Dragon 2 flights to the International Space Station, and commercial missions using their new Falcon Heavy launcher. Currently, there is still much work to be completed at the launch complex – previously used to launch the space shuttle, and before that, the mighty Saturn V rocket, although SpaceX plan to have the work completed by November.

Launch Complex 39A at Kennedy Space Centre undergoing refurbishment by SpaceX in preparation for Falcon Heavy and crewed Falcon 9 launches. The Rotatating Service Structure, seen on the left and used for space shuttle launches, is due for demolition
Launch Complex 39A at Kennedy Space Centre undergoing refurbishment by SpaceX in preparation for Falcon Heavy and crewed Falcon 9 launches. The Rotating Service Structure, seen on the left and used for space shuttle launches, is due for demolition

Whether or not the root cause of the September 1st accident will be known by then, and the Falcon 9 cleared for flight is a major unknown. The investigations into the June 2015 loss took six months to complete and – due to it being caused by a failure within the vehicle – the rocket had to undergo several engineering changes.

Blue Origin Announces the New Glenn Booster Family

Blue Origin, the company founded by Amazon founder Jeff Bezos, revealed its plans for a family of reusable boosters for both orbital and deep space launches. Called New Glenn, the vehicles are a significant step forward for the company.

The New Glenn family. Credit: Blue Origin
The New Glenn family. Credit: Blue Origin

Although more widely known for their efforts in the sub-orbital space tourism field, with their New Shephard reusable system, Blue Origin has long indicated it has wider aspirations, whilst remaining somewhat tight-lipped about exactly what it is developing.

Like the smaller New Shephard sub-orbital launch vehicle, New Glenn is to comprise a reusable first stage – referred to as the “propulsion module” on New Shepard. The vehicle has been under development for about 4 years, and the plan is for the first launch to take place in 2020.

Seven metres (23ft) in diameter, the New Glenn first stage will be powered by seven of the company’s new BE-4 engines. These are the same engines United Launch Alliance have selected as the primary propulsion unit for their own upcoming new Vulcan launch vehicle, which will enter service in 2019 to replace the expensive Atlas V booster.

This core stage of the new Blue Origin rocket – which is named for John Glenn, the first American to orbit the Earth, just as New Shephard is named after Alan Shephard, the country’s first astronaut to fly in space – will be topped by either a second stage for launches to low-Earth orbit, or a combination of a second stage and third stage system capable of a broader range of launch options. In both variants, the second stage will be powered by a single BE-4 engine, while the third stage will be powered by an uprated version of the BE-3 engine, currently used by the New Shephard. Neither the second nor third stages will be recoverable. It is anticipated that New Glenn will be capable of lifting between 35 to 70 tonnes to low Earth orbit, placing it in the same class of launch vehicle as SpaceX’s Falcon Heavy – and thus competing directly with it.

When it enters service, the new booster will be launched from America’s Space Coast, from the historic Space Launch Complex 36 at Canaveral Air Force Station, which Blue Origin took over in September 2015 in a deal with the USAF’s 45th Space Wing.

New Gleen compared to other current launch vehicles. The two-stage variant will be 85 metres (270ft) tall, and the 3-stage variant 95m (313 ft) tall. Both will have a 7m (23 ft) diameter
New Glenn compared to other current launch vehicles. The two-stage variant will be 85 metres (270ft) tall, and the 3-stage variant 95m (313 ft) tall. Both will have a 7m (23 ft) diameter. Credit: Blue Origin

In its time, SLC 36 was was used to launch the Mariner missions, the first US interplanetary probes to visit over worlds, Pioneer 10 and Surveyor-1, the first US vehicle to soft-land on the Moon. It was largely demolished in 2010, leaving just a single pad. Blue Origin are expected to construct a rocket fabrication and assembly facility there, as well as a new launch complex. Currently, it is not clear how the first stage of the booster will be recovered, but the company have hinted at an automated at-sea landing in the style of SpaceX might be used.

China Launches Tiangong-2

On Thursday, September 15th, 2016, and as expected, China launched the Tiangong-2 (“Heavenly Palace 2”) orbital laboratory from their Jiuquan Satellite Launch Centre in Gansu Province, and on the edge of the Gobi Desert in northern China. The Long March 2F booster (and not a long March 7, as incorrectly reported in some space news outlets) lifted-off at 14:04 UTC, making for a night launch, local time.

The Long March 2F carrying the Tiangong-2 orbital laboratory, lifts-off from China's Jiuquan Satellite Launch Centre in Gansu Province at 14:04 UTC on Thursday, September 15th
The Long March 2F carrying the Tiangong-2 orbital laboratory, lifts-off from China’s Jiuquan Satellite Launch Centre in Gansu Province at 14:04 UTC on Thursday, September 15th

Tiangong-2 is the second phase of China’s goal to establish a permanently crewed space station in the early to mid 2020s. This work started in 2011 with the launch of the Tiangong-1 facility, which was briefly visited by two crews in 2012 and 2013. It will culminate in the on-orbit construction of a large space station, starting with the launch of the Tianhe  (“Harmony of the Heavens”, and formerly Tiangong-3) space station core module in 2022.

an artist's impression of Tiangong-2 (centre right) with the Tianzhou resupply vehicle docked (left), together with the Shenzou-12 crew vehicle at the laboratory's far docking port
an artist’s impression of Tiangong-2 (centre right) with the Tianzhou resupply vehicle docked (left), together with the Shenzhou-12 crew vehicle at the laboratory’s far docking port. Credit: CCTV

It is expected that at least two crews will visit the facility. The first 2-person crew will fly to the laboratory in October aboard Shenzhou-11. They will commence the first round of a fairly extensive science programme, remaining at the lab for around 30 days.

After this, the facility will be left dormant until April 2017, when a Long March 7 booster is due to deliver the Tianzhou (“Heavenly Ship”) uncrewed resupply vehicle to orbit. This craft will then perform an automated docking with Tiangong-2, providing it with additional fuel, water and other consumables and also use its engine to boost the laboratory into a higher orbit to await the arrival of the second crew.

The second crew, comprising 3 personnel, should fly to the facility in mid-2017 Shenzhou-12. They are expected to say for less than 30 days, but while there carry out a number of tasks connected to developing a full space station, including performing an EVA. Whether further crews will visit the station after this has yet to be determined.

A Billion Stars – A Map to Our Galactic Neighbourhood

The first one billion: a billion stars in our galaxy mapped by distance and brightest - with a few extra-galactic objects shown for good measure
The first one billion: a billion stars in our galaxy mapped by distance and brightest – with a few extra-galactic objects shown for good measure. Credit: ESA/Gaia/DPAC

The above image might not look like much, but it is the largest all-sky survey of celestial objects published to date, pinning down the precise position on the sky and the brightness of 1142 million stars in our galaxy.

It is the product of the European Space Agency’s (ESA) Gaia Project, which is approaching the mid-point in its 5-year mission. Launched in December 2013, and orbiting the L2 Lagrange point, Gaia commenced its mapping operation in July 2014 – and it will continue doing so through until 2017. This map, released by the European Space Agency on September 14th, covers the data gathered from July 2014 through to September 2015. A further map, which includes data through to August 2016, is currently in development.

An artist's impression of the Gaia vehicle at the L2 position relative to the Earth and Sun
An artist’s impression of the Gaia vehicle at the L2 position relative to the Earth and Sun

The intention is to create a precise three-dimensional map of astronomical objects throughout the Milky Way, mapping their motions, which reflect the origin and subsequent evolution of the galaxy. Spectrophotometric measurements by the craft will provide a detailed survey of all observed stars, characterising their luminosity, effective temperature, gravity and elemental composition. The data gathered will provide the basic observational data to tackle a wide range of important questions related to the origin, structure, and evolutionary history of our galaxy.

It is the second such survey to be undertaken. The first was ESA’s Hipparcos mission, almost two decades ago, which surveyed around 200 million stars. One aspect of the Gaia survey will be to compare its findings with those of Hipparcos, so it will hopefully be possible to start disentangling the effects of “parallax”, a small motion in the apparent position of a star caused by Earth’s yearly revolution around the Sun, and the “proper motion” of the star’s physical movement through the galaxy.

The Gaia map includes globular clusters without our own galaxy, and images of clusters and galaxies beyond our own. Credit:
The Gaia map includes globular clusters without our own galaxy, and images of clusters and galaxies beyond our own. Credit: ESA/Gaia/DPAC

The Gaia map means it is now possible to measure the distances and motions of stars in about 400 clusters up to 4,800 light-years away, and includes 3194 , which rhythmically swell and shrink in size, leading to periodic brightness changes. Many of these are located in the Large Magellanic Cloud, one of our galactic neighbours, a region that was scanned repeatedly during the first month of observations, allowing accurate measurement of their changing brightness. During the first phase of the mission, Gaia also discovered its first supernova in another galaxy, and the science and engineering team had to overcome a “stray light” issue where fibres used in the vehicle’s sun shield protrude beyond the edges of the shield and into the field of view. In doing so, they reflect unwanted light, resulting a degradation in science performance when mapping the faintest of stars in Gaia‘s view.

The Birth of a Black Hole?

Black holes; the boogie-men of the cosmos. Deep wells of gravity so intense that not even light can directly escape after passing the event horizon. They are formed in one of two ways, during the death of super-massive stars.

In the first, the star gobbles up the last of its fusionable fuel, causing the core to suddenly and violently contract, in turn triggering a violent explosion – a supernova – completely shedding the star’s outer shell of mass, and leaving behind a super-dense neutron star. Generally only 10 or so kilometres across, this have a greater mass than our Sun. It is thought that if this mass is too great, the neutron star also collapses in on itself, forming a black hole. In the second, the star doesn’t go supernova, but experiences a “failed supernova” brightening for a very brief period as some matter is lost, but then continuing to collapse in on itself until a black hole is formed. In both cases, the star vanishes from the visible spectrum, leaving behind tell-tale signs in the infra-red and in x-rays.

The Large Binocular Telescope, one of two instruments so far used in observing N6946-BH1
The Large Binocular Telescope, one of three instruments so far used in gathering data on N6946-BH1. Credit: NASA

A team of astronomers now believe they have captured the birth of a black hole through this second process.

They were studying data relating to N6946-BH1, a red giant thought to be coming to the end of its life, when they noticed something odd. In 2009 the star, roughly 25 times bigger than our Sun and 20 million light years away, could be seen in the visible light wavelengths. By 2015, however, it had vanished, leaving only an infra-red afterglow. A subsequent check on Hubble Space Telescope data revealed the same: in 2007 the star was visible, in 2015, it wasn’t.

Intrigued, the team checked data on the star from the Palomar Transit Factory (PTF). This revealed that in 2009, N6946-BH1 blossomed briefly in luminosity, with a massive burst of neutrinos occurring at the same time – events both consistent with the star collapsing, but not going supernova. Add these to the infra-red tell-tale, and it would seem N6946-BH1 might have formed a black hole.

If so, it should now be a source of x-rays emitted in a particular spectrum as local matter fails into it. The team are now hoping that the Chandra X-ray Observatory in Earth orbit  will be able to take a look at N6946-BH1 in the next two months or so to see if those x-rays can be detected. Should it be determined that N6946-BH1 has collapsed into a black Hole – even one now 20 million years old – studying it could help describe the beginning of the life cycle of a black hole, and better inform us on how black holes form, potentially why some super-massive stars form a neutron star rather than collapsing all the way to a black hole.