Space Sunday: SLS roars, LauncherOne flies and a mole dies

The Green Run hot fire test: the four RS-25D engines on the SLS-1 core stage running close to full power in the Stennis test stand, January 16th, 2021. Credit: NASA
Saturday, January 16th saw NASA attempt the Green Run Hot Fire Test of the first Space Launch System (SLS) core stage.

For those who might be unaware of it, the SLS is NASA’s next-generation heavy-lift rocket designed to undertake a range of missions, with the primary focus being the US Artemis programme to return humans to the Moon. Once operational it will be the most powerful launch vehicle commissioned by NASA.

The Hot Fire test formed the final phase of the Green Run test programme, a series of tests vital to clearing the core stage of the rocket ready for it maiden – and only – flight, planned for the end of 2021. The “Green Run” title refers to the fact the test would be the first time all of the components and systems of a core stage would be operated in unison, just as they would in the lead-up to and launch of an SLS rocket.

As such, the Green Run actually comprises a sequence of tests numbered 1 through 8 – each designed to test different aspects of the core stage, gradually bringing everything together as a unified whole and culminating in the hot fire test.

The Green Run test sequence for the first SLS core stage. Credit: NASA

All of the test sequences have been carried out at the historic B-2 Test Stand at NASA’s Stennis Space Centre, Mississippi, and while some issues were encountered along the way, both technical and due to the weather, so  eating into the “reserve time”  available for getting the first SLS vehicle assembled and onto the launch pad, by Saturday January 16th, all of them – including critical fuel loading and unloading (700,000 gallons of liquid hydrogen and liquid oxygen) test – have been completed and signed-off, allowing the hot fire test to go ahead.

Planned for a 8-minute duration – this being the total time the core stage would be expected to operate its engines during a launch – the test commenced at 22:27 GMT, after some last minute minor technical delays put the count-down on a lengthy hold. Ignition saw the four RS-25D engines ignite milliseconds apart from one another in the sequence 1,3,4 and 2, quickly building up to a combined thrust of just under 726,000 kg – somewhat less than the maximum thrust of 900,000 kg they will reach in an actual launch, but sufficient for the purposes of the test.

Ahead of the test, thousands of gallons of water pour through the flame pit beneath the test stand – water is used as suppression system to absorb the sound from the engines, preventing it from being reflected back onto the vehicle, where sound concussions might damage it. Credit: NASA

The long duration of the test had been intended to allow a comprehensive test of things like engine throttling down / up and gimballing (swinging) the motors in a manner that would provide steering in a flight. However, 67.7 seconds into the test something  – at the time of writing, NASA has yet to specify what – triggered the core stage’s automated safety systems, initiating a rapid and safe shut-down of the engines.

The RS-25 is one of the most powerful and advanced rocket engines in the world. Originally built for the shuttle, it is finding new life with SLS – a total of 16 former shuttle variants of the motor will be used to power the first four SLS launches. The four motors for this first core stage already have a distinguished flight career between them, having previously be used on a Hubble Space Telescope servicing missions, the mission that saw John Glenn return to space (STS-95 in 1998), and on the final space shuttle flight, STS-135 featuring the shuttle orbiter vehicle Atlantis (thus offering a direct link between the last flight of the Space Transportation System and the first launch of the Space Launch System). In addition, between them the four engines made six flights to the International Space Station prior to the end of the shuttle programme in 2011.

Four clean burns: the four RS-25D engines under thrust. Credit: NASA

Once those first 16 motors have been used, SLS will be powered by a new generation of RS-25 motor, built using the very latest technologies including components created using 3D printing which we decrease the complexity of the engines.

Despite the hot fire test lasting less than 68 seconds, managers and engineers monitoring the test were confident that they had gathered sufficient data to classify the run as a success, although it is not yet clear if a further test will be required, or whether the core stage can be dismounted from the test stand – originally built to test the core stage of NASA’s Saturn V rocket – and shipped to Kennedy Space Centre for integration with the rest of the vehicle.

All four RS-25 engines ignited successfully, but the test was stopped early after about a minute. At this point, the test was fully automated. During the firing, the onboard software acted appropriately and initiated a safe shut-down of the engines. During the test, the propellant tanks were pressurised, and this data will be valuable as the team plans the path forward.
In [the] coming days, engineers will continue to analyse data and will inspect the core stage and its four RS-25 engines to determine the next steps.

– NASA statement following the test

Future core stages won’t go through a similar Green Run; these tests were only required for the first core stage to confirm its design and gather vital data on its behaviour during its required operations. Instead, they will generally be fabricated at NASA’s Michoud Assembly Facility, New Orleans and then shipped directly to Kennedy Space Centre for vehicle integration with the rest of their launch elements in the famous cube-like Vehicle Assembly Building, used for the “stacking” of every Saturn  rocket (both the 1B and V) and every shuttle system.

Once integrated with its upper stage, solid rocket boosters and payload, the stage will participate in the Artemis 1 mission to send an uncrewed Orion vehicle to, around, and back from, the Moon at the end of 2021.

Virgin Orbits Makes Successful Test Launch

Sunday, January 17th, 2021 saw Virgin Orbit, the small payload-to-orbit company that forms a part of Sir Richard Branson’s Virgin Group, complete the first successful air lunch of their LauncherOne rocket.

Carried aloft by the company’s converted 747 aircraft, Cosmic Girl, the LauncherOne rocket carried a payload of eight cubesats designed and built by a number of universities from across the United States and funded under NASA’s Educational Launch of NanoSatellites (ELaNa XX) initiative. A ninth cubesat, designed by NASA’s Ames Research Centre, California and flown as a part of the NASA Venture Class Launch Services (VCLS) programme, also formed a part of the payload.

Classified as a demonstration launch rather than an operational flight, it was the second attempt by the company to achieve orbit with LauncherOne – the first demo flight in May 2020 ended when the rocket suffered an “anomaly” after being released from its carrier aircraft, prompting it to be “terminated”.

Cosmic Girl, with LuancherOne cradle under its wing, lifts-off from the Mojave Air and space Port, Sunday, January 17th, 2021. Credit: Virgin Orbit

With this flight, Cosmic Girl lifted off from the Mojave Air and Space Port and headed out over the Pacific Ocean to enter the “racetrack” – a looping flight path over the southern Channel Islands, roughly 40-60km off the California coast. Using this course to climb to the release altitude of 10,000 metres, the air and ground crews performed final operational and launch check-outs on the rocket prior to the aircraft reaching the optimal point of release for LauncherOne.

Launch came at approximately 19:39 GMT, the rocket falling clear of the 747, allowing its Newton engine to ignite, pushing it into an ascent to orbit. Within minutes, the engine shut-down, its job done, and the upper stage of the rocket separated, its motor ignited to carry it up to an initial orbit. Along the way, the payload fairings were jettisoned, exposing the cubesats to space for the first time.

A 30-minute coast period followed before the craft reached the optimal point for the NewtonFour the re-ignite and push the vehicle into a circular orbit. At the same time, Cosmic Girl made a safe return to the Mojave Air and Space Port. After a lengthy delay – presumably during which the upper stage of the rocket was refining its orbit and the mission team were confirming telemetry – and at 22:28 GMT, the company finally confirmed the payload had been successfully deployed in a 500 km orbit above Earth.

Confirmation that the LauncherOne Demo 2 flight has deployed its payload.

At the time of writing this, confirmation that the cubesats were all healthy had yet to be given, with Virgin Orbit stating they were still checking through their data.

NASA Announces InSight’s Mole is Dead

After two years of trying, NASA and the German Space Agency DLR have finally given up on trying to get the Heat Flow and Physical Properties Package (HP3), carried to Mars as a part of NASA’s InSight lander and mission, to function as ordered.

NASA’s InSight lander and surface experiments, the seismometer (l) and the HP3 unit (r). Credit: NASA

Referred to simply as the “Mole”, the package comprises two elements: a base station deployed on the surface of Mars by InSight’s robot arm, and a self-propelled penetrator released by the base station and designed to “hammer” its way into the surface of Mars, trailing a string of sensors behind it to measure the sub-surface temperature.

As I’ve frequently reported, while the initial deployment was successful, the Mole barely managed to get half its length buried before it hit problems, repeated attempts to move forward bounced it back. Assorted attempts were made to get it burrowing again, until NASA and DLR worked out a way to to use InSight’s sample scoop to gently push the slender “mole” into the ground as it tried to propel itself forward.

This allowed the probe to reach a depth of around 1.5 metres out of a planned 5 metres, but then it got stuck again, limiting its ability to gather data.

Diagram of HP3, showing the deployment system, the “mole” and tether. Credit: DLR

On Saturday, January 9th, after Insight’s scoop has again been used to compress the soil around and over the Mole in the hope of giving it extra purchase, the order was sent for the probe to complete 500 firings of its internal spring mechanism in an attempt to force it into moving downwards once more – without success. As a result, operations with the HP3 package where terminated on January 14th, 2021.

We’ve given it everything we’ve got, but Mars and our heroic mole remain incompatible. Fortunately, we’ve learned a lot that will benefit future missions that attempt to dig into the subsurface

– HP3’s principal investigator, Tilman Spohn of DLR

So, RIP little Martian Mole.

Blue Origin Fly A “New” New Shephard

A Blue Origin New Shephard lifts-off

Blue Origin moved a significant step closer to commencing crewed flights of their sub-orbital launch vehicle, New Shephard on Thursday, January 14th.

The new capsule carries a series of crew system upgrades, including a new internal communications system, additional sound suppression lining in the capsule to reduce the amount of engine noise transmitted to it, an upgraded safety alert system and improved windows that should not fog as a result of the difference in internal and external temperatures, a full environmental control system and improved information displays.

As with the previous 13 New Shephard flight, this one took place from the company’s launch centre in west Texas at 17:17 GMT. Two minutes after launch, capsule and launcher separated, the later commencing a return to Earth whilst the capsule continued upwards to reach a peak altitude of 107 km, before returning to Earth under parachute, landing downrange of the launch site a few minutes after the launcher had made a successful touch-down on its landing pad.

Travelling in the capsule was a test dummy dubbed – wait for it – Mannequin Skywalker (geddit?), while the entire flight lasted some 10 minutes.

The success of this flight puts us one really big step closer to flying astronauts. There’s going to be a lot of fun ahead in 2021.

– Blue Origin launch commentator Ariane Cornell

Blue Origin plans to launch paying passengers—tourists, scientists and professional astronauts—on brief hops over West Texas’ remote desert.  Ticket prices have yet to be publicly disclosed, but that thought to be around the same as prices indicated by Virgin Galactic – $200,000-$250,000.

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