Space Sunday: crashes, tests and an Inspiration

Two seconds from disaster: an inverted Starship prototype SN9 about to impact the landing pad at Boca Chica, February 2nd,2021. Directly below the vehicle and on the horizon is the angled base of the Super Heavy launch platform (under construction). Centred on the ground is the Starhopper test vehicle with the SN7.2 test tank to the right. Image credit: Cosmic Perspective

On Tuesday, February 2nd, and after Federal Aviation Authority (FAA) related delays, SpaceX Starship prototype SN9 took to the skies over southern Texas in the second high altitude flight test for the Starship programme.

The flight itself, to some 10 km altitude, followed by a skydive descent to around the 2 km altitude mark, was remarkably successfully – as was the case with the first high-altitude flight (to 12 km on that occasion) seen with Starship prototype SN8 in December 2020 (see: Space Sunday: the flight of SN8 and a round-up). However, and also like the SN8 flight, things went off-kilter during the final element of the flight, resulting in a complete loss of the vehicle.

Lift-off: SN9 rises from its launch platform with SN10 beyond it. he angle of this shot makes the two vehicles appear closer than they were in reality; SN10 was in fact well clear of its sister. Image credit: LabPadre

As I’ve previously noted, the route of Staship prototype SN9 from fabrication high bay to launch stand had been remarkably fast compared to that of SN8, leading to speculation that the anticipated second flight test could occur in January. However, while the vehicle remained on the launch stand going through numerous pre-flight tests, including numerous Raptor engine re-start tests (which actually saw two of the motors swapped-out), things appeared stalled before that final step of an actual flight.

This now appears to be down to the fact that the FAA weren’t entirely happy with SpaceX over the flight of SN8, which effectively went ahead without proper approval. In short, SpaceX applied for a waiver against the licence the FAA had granted for Starship flight testing which would have allowed the company to exceed “maximum public risk as allowed by federal  safety regulations”.

At the time, the waiver was denied – but the SN8 launch went ahead, violating the required safety limits, and whilst no-one was injured in the crash of SN8, the FAA correctly ordered a full investigation into the flight and also the safety culture and management oversight of SpaceX operations. Those investigations not only took time to complete, but also afterwards required FAA review and modifications made to the licence granted to SpaceX to carry out Starship prototype flights.

Boca Chica from space: captured by a SkySat satellite approximately 568 km above the Earth, this image shows the SpaceX Boca Chica launch facility with the two Starship prototypes on their launch stands, the SN7.2 tank test unit, the Super Heavy booster launch stand under construction, and other elements such as the fuel farm, and Highway 4 running from the coast (r) back to the SpaceX construction and fabrication facilities (off to the left of the image). Image credit: Planet Labs
If a licensee violates the terms of their launch license, they did so knowing that an uninvolved member of the public could have been hurt or killed. That is not exaggeration. They took a calculated risk with your life and property … If the FAA does not enforce their launch licenses, it will damage the long-term viability of the launch industry and damage their credibility with Congress. It is possible that the industry could suffer significant regulatory burdens enforced by Congress to ensure safety.

– Former deputy chief of staff and senior FAA adviser Jared Zambrano-Stout,
commenting on SpaceX launching SN8 without the request licence waiver

The required licence modifications were not completed until February 1st, the day on which SpaceX initially attempted to launch SN9, and their lack of their availability may have been the reason that attempt was scrubbed, resulting in the February 2nd attempt.

Coverage of the test flight started very early on the morning (local time) on February 2nd, with SpaceX providing multiple camera points around the launch stand and on the vehicle, as well as via drones.flying overhead In addition, space flght enthusiast such as also provided coverage from multiple points around the Boca Chica, Texas, site, including video recorded by Mary “BocaChicaGirl”, who provides a daily 24/7 feed of activity at the site.

The vehicle, with prototype SN10 occupying a second launch stand nearby, lifted-off at 20:25:15 UTC, following the ignition of all three Raptor engines. The launch was delayed by some 25 minutes as a result of a range safety violation – one of the circumstances of concern to the FAA. However, the ascent itself was flawless, with the vehicle rapidly climbing to altitude over the next four minutes, two of the Raptors shutting down as it did so to reduce the dynamic stresses on the vehicle in light of it being only partially fuelled and to ensure it didn’t overshoot the planned apogee for the flight.

Flip over: at 10 km altitude, the one operational Raptor motor gimbals its thrust as the leeward midships RCS thruster fires, tipping SN9 over to start its 2-minute skydive back to the ground. Image credit: SpaceX

This came at 20:29:15 UTC, with the vehicle entering a brief hover using its one firing motor, as fuel supplies were switched from the main tanks to the smaller “header” tanks that would be used to power the engines during landing manoeuvres. At this point, the remaining motor shut down as the reaction control  system (RCS) thrusters fired, gently pushing the vehicle over from vertical and into its skydive position, where the fore and aft aerodynamic surfaces could be used to stabilise the vehicle during descent.

This phase of the descent lasted just over 2 minutes, with the order given to re-start two of the Raptor engines given at 20:31:35 UTC. These engines should have then gimballed and used their thrust, together with the forward RCS thrusters to return the vehicle to a vertical pose before one of the motors again shut down and the second slowed the vehicle into a propulsive, tail-first landing.

From below: a camera on the ground dramatically captures the moment one of the Raptor engines on SN9 re-starts as RCS systems fire to help maintain stability. Image credit: SpaceX

Both of these motors fire a split second apart, and footage of the rear of the vehicle suggests that the first may have suffered a mis-fire before starting correctly. However, the second motor appears to have suffered a catastrophic failure on re-start, possibly involving a turbopump failure: as it ignited, debris could clearly be seen being blown clear of the vehicle.

With only one operational main engine, SN9 was unable to stop its change in flight profile and remain upright. Instead, it continued to rotate and become inverted just before it struck the landing pad in what SpaceX refer to as “an energetic, rapid unscheduled disassembly” (that’s “exploded on impact” for the rest of us).

No official word on the failure has been given – obviously, SpaceX will need time for a thorough investigation, and will likely have the FAA watching closely. It is also not clear if the material coming away from the vehicle is actually parts of the engine, or sections of the engine skirt blown clear of the vehicle. As some are still to be drifting down to the ground fairly close to SN10 on its launch stand, it is possible they are from the vehicle’s skin.

A wider image of the inverted SN9 prototype just before impact, with the Super Heavy launch stand, SN7.2 tank and Starhopper prototype overlapping one another, and the SN10 prototype to the right. Note the debris (arrowed) drifting down behind the vehicle. Image credit:

Continue reading “Space Sunday: crashes, tests and an Inspiration”

Space Sunday: Hops, glows, plans and Perseids

SpaceX SN5 rises from its launch stand at the SpaceX Boca Chica, Texas, centre. Credit: SpaceX

SpaceX once again heads this week’s column after the Starship SN5 prototype became the first of the units to successfully make a “hop” into the air and back again, travelling some 150 metres up and several tens of metres sideways to navigate its way from launch platform to landing pad.

The flight of the “flying spray can” – the nickname derived from the vehicle’s cylindrical form topped by the nozzle-like 23 tonne ballast mass – only lasted around a minute once the Raptor engine fired, but the hop represented a huge leap forward for SpaceX in their development of the Starship vehicle.

As I noted in July, SN5’s unusual shape is due to it only comprising the section of the vehicle containing its fuel tanks, single raptor engine and landing legs. It lacks any upper sections (replacing by the ballast block) and the aerodynamic surfaces that will give Starship a lifting body capability during atmospheric operations. These will all be present in future prototypes, But for SN5, they are not currently required, as its initial flight(s) are purely about testing Starship’s ability to make a vertical descent and landing.

A starship cutaway showing the fuel tanks and engine bay (outlined in red) that form the prototype vehicle SN5, and the upper cargo / habitation space and aerodynamic surfaces that are not included on the current prototype. Credit: WAI (with additional annotation)

The successful test flight took place on Tuesday, August 4th – an attempt on Sunday, August 2nd was cancelled  due to unfavourable weather in the Boca Chica, Texas, area. Engine ignition came at 23:57 UTC (18:57 local time), the prototype rising vertically, but canted at a slight angle. This  was due to the initial prototypes being designed to operate with three Raptor motors, by SN5 is currently only fitting with one, offset from the vehicle’s vertical centreline, so the vehicle is canted (with the ad of the top ballast block) to compensate for the offset thrust from the motor, with small reaction control system (RCS) jets near the base and top of the vehicle occasionally firing to help maintain a stable flight angle.

As the craft rose, the Raptor motor was also gimballed (moved around like you move a joystick on a game controller, a common practice for rocket motors to allow them to use directed thrust to adjust a flight trajectory), vectoring its thrust so it could translate across to the landing pad for a successful landing.

Prototype nose cones being fabricated at Boca Chica. Credit: / BocaChicaGal

SpaceX released a video afterwards the flight showing the highlights. In it, SN5 can be seen lifting off, trailing a plume of vented cooling gas, the RCS jets visible as they fire to help maintain stability. The footage also clearly shows the Raptor’s offset exhaust plume moving as the motor in vectored, as well as the craft maintaining a brief hover at the apex of its flight before descending sideways and down towards the landing pad.

Cameras at the base of the vehicle show the landing legs being deployed, as well as a small, non-hazardous fire on the Raptor motor, likely the result of dust blown into the engine space at lift-off that subsequently ignited. This “inside” camera and one on the SN5 hull then captured the moment of landing and engine shut down.

Prototypes SN6, 7, and 8 are in development, and some of these will fly with the aforementioned forward / upper sections and flight surfaces in loftier (literally) and more complex flight tests. Currently, it not clear how many more flights SN5 will make. However, Musk has already indicated he would like to have Starship use a more “Falcon Like” set of landing legs to provide broader support when landing on uneven planetary surfaces, so SN5 might by used to test new landing leg configurations alongside testing of other prototypes.

Continue reading “Space Sunday: Hops, glows, plans and Perseids”

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”