Tag: SpaceX

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.

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 make modifications to the licence granted to SpaceX to carry out starship prototype flights.

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, spaceflight enthusiast such as NASASpaceflight.com 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 a 25 minutes delay due 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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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” →

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.

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.

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.

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” →