Space Sunday: telescopes, wings and exoplanets

The Hubble Space Telescope – operations fully restored. Credit: NASA
NASA has successfully restored the Hubble Space Telescope (HST) to full operations after more than a month with the telescope either being in a “safe” mode, or only able to partially operate its science instruments.

The longest-running space mission in Earth orbit, HST has been subject to a range of issues throughout its career, all of which have been overcome, although this has been only of the more draw-out in getting resolved. It started on October 23rd, when the telescope started sending error codes indicating the loss of a specific synchronisation message that provides timing information used by its instruments use to respond to data requests and commands correctly. Two days later, the same error codes were again issued, prompting Hubble to cease science activities and enter a “safe” mode.

Throughout out the rest of October and early November, mission engineers on Earth worked to diagnose and rectify the issue, and on November 8th, 2021, were able to report a restart of the main computer system and a set of back-ups had allowed science operations to recommence on the telescope’s Advanced Camera for Surveys (ACS). Later in November, operations were restored to the Cosmic Origins Spectrograph (COS) and then the Wide Field Camera 3 (WFC-3), Hubble’s most heavily-used instrument, leaving just one major science instrument out of commission.

That was the Space Telescope Imaging Spectrograph (STIS),  which was finally restored to operational status on Monday, December 6th, marking Hubble’s full return to its science programmes.

However, the October glitch, following on as it does from a systems error that caused the telescope to enter a safe mode in July 2021, serves as a reminder that HST is running on software and systems designed and built in the 1980s.

As a result, the mission team has been evaluating and testing ways and means to refine and update the telescopes software on both its operating systems and its science instruments. This means that mid-December should see the COS gain a significant software update, with the remaining science instruments also being updated early in 2022.

Such upgrades are vital to Hubble’s continued career, given there has been no means to physically service it since the space shuttle was retired in 2011 – and NASA / ESA very much hope to keep the observatory running through until at least the end of the 2030s, consumables permitting.

That said, and if all goes according to plan, Hubble will so no longer be the only large-scale, space-based observatory in operation.

As I’ve frequently reported in these pages, the James Webb Space Telescope (JWST) is due to be launched from the European Spaceport, Kourou, French Guiana, on December 22nd, 2021. This is actually 4 days later than planned, the result of unexpected vibrations passing through the telescope after a clamp unexpected released as JWST was being integrated with the Launch Vehicle Adapter (LVA) – the element that physically connects the telescope to the rocket. This required a period of checks to be carried out to confirm the telescope’s instruments and systems had not been damaged by the vibrations.

However, following confirmation that no damage had been caused, two of the four remaining pre-launch operations for the telescope have now been completed and a third is in progress.

On November 23rd, European Space Agency engineers started the delicate operation to fill JWST’s propellant tanks with 168 kg of highly toxic hydrazine gas and 133 kg of equally toxic dinitrogen tetroxide oxidizer, both of which are needed to power the observatory’s thrusters. So harmful are both of these propellants, the loading took a total of 10 days, during which time engineers working in the same space as the telescope had to wear  Self-Contained Atmospheric Protective Ensemble (SCAPE) suits – essentially space suits for use on Earth that completely isolated them from their surroundings.

JWST sits within a clean room, folded ready for vehicle integration, and receiving its highly toxic thruster propellants as engineers wear SCAPE suits for their protection. Credit: ESA

With fuelling completed on December 3rd work then commenced on bringing both the telescope, mounted on its LVA, and its Ariane 5 launch vehicle together for the first time, moving both of them into the Final Assembly Building and readying them for mating together. This work was completed on December 7th, 2021, clearing the way for the mating process to commence.

Mating involves lifting JWST and its LVA up to the high bay of the building, and then lowering it on to the top of the Ariane booster. Once this has been done, a final series of tests on telescope, LVA and booster will be carried out and the Ariane payload fairings will be closed around the telescope. After this, a final check-out will take place, and the final pre-launch activity will see booster and payload moved to the launch pad a few days ahead of the launch.

The launch itself will in turn mark the start of the most complex deployment of a space instrument undertaken to date. It will take JWST 16 days to reach its operational halo orbit at the Earth-Sun L2 point, with the entire deployment taking some 29 days, as the video below explains.

In the meantime, and as a kind-of precursor to the JWST launch, on December 9th, 2021, a SpaceX Falcon 9 launched NASA’s Imaging X-ray Polarimetry Explorer (IXPE). Designed to provide insight into our understanding of X-ray production in objects such as neutron stars and pulsar wind nebulae, as well as stellar and super-massive black holes, IXPE is collaboration between NASA and the Italian Space Agency.

Launched from the Falcon launch facilities at Pad 39A, Kennedy Space Centre at the start of a 2-year mission, the telescope was safely delivered to a precise, circular low Earth orbit of 540 km altitude with zero degrees of inclination relative to the equator – a flight that required the Falcon upper stage to perform a set of unique manoeuvres.

Imaging X-ray Polarimetry Explorer (IXPE) – Credit: NASA

These involved the upper stage separating from the core stage and entering a “parking orbit” at an inclination of 28.5 degrees. Then, as it passed over the equator, it performed what is called a plane or inclination change, in order to shift it into the required orbit and deploy the satellite.

At a cost of US $188 million (+ US $50 million launch cost), IXPE is one of NASA’s low-cost missions intended to fulfil the agency’s first science objective in astrophysics: “Discover how the universe works”.

Blue Origin Launches First Six-person Crew as  FAA ends Civilian Astronaut Wings Programme

Saturday, December 11th, saw Blue Origin complete its first 6-passenger sub-orbital flight with their New Shepard vehicle, the third such “space tourist” flight by the company.

The NS-19 flight saw the vehicle’s capsule loaded to full capacity, with four fare-paying passengers and two invited guests. The latter comprised Michael Strahan, a former professional football player and current television host, who charted his preparations for the flight for ABC television’s Good Morning America programme, and Laura Shepard Churchley, the eldest daughter of Alan Shepard, the first American in space and after whom New Shepard is named.

At 74, Shepard Churchley was the eldest person on the 11-minute flight, and she and Strahan were joined by fare-paying passengers Dylan Taylor, 51, chairman and CEO of the space exploration firm Voyager Space; Evan Dick, an engineer and investor; Lane Bess, principal and founder of a technology-focused venture fund called Bess Ventures and Advisory, and his son Cameron.

Blue Origin’s NS-19 crew, from left to right: Dylan Taylor, Lane Bess, Cameron Bess, Laura Shepard Churchley, Michael Strahan and Evan Dick. Credit: Blue Origin

Their flight came a day after the US Federal Aviation Administration (FAA) announced it will allow the 21 people who have taken commercial trips to space with Blue Origin, Virgin Galactic and SpaceX to receive “official” FAA astronaut wings, but will no longer issues commercial wings to anyone not completing formal NASA / FAA astronaut training from the start of 2022 onwards. Instead, those flying with the likes of Blue Origin and Virgin Galactic will still be eligible to the “unofficial” wings the companies give out, but instead will only have their names added to a special roster of tourists the FAA will maintain.

According to the FAA, this is being done because the practice of awarding commercial wings was initiated in 2004  as a means of drawing attention to the wider potential of human spaceflight; as we are now seeing space tourists venture into space more frequently, the agency believes the programme has now fulfilled its purpose.

Fancy and 8-hour Day? Try GJ 367b!

We’re becoming increasingly familiar with planets that orbit their parent stars in periods amount to terrestrial days rather than years – and something even in hours. Most of them tend to be so-called “hot Jupiters” – gas giants ranging in size from Neptune to Jupiter (or somewhat larger).

However, there is a class of much smaller planets that orbit exceptionally close to their parent, although their proximity to their star and their size admittedly makes them much harder to spot. These planets, generally around Earth in size or slightly larger, are called ultra-short-period (USP) planets, and all of them have periods that last less than a terrestrial day. And the current fastest of them all has now been confirmed as orbiting a star relatively close to us.

Gliese 367 (GJ 367). is an M-class red dwarf star much smaller, cooler and older than the Sun, lying some 31 light years away. It was identified as a subject of interest for the Transiting Exoplanet Survey Satellite, which studied it for a 2-month period in 2019. Following a review of the data gathered, it was announced in January 2021 that a small planet – referred to simply as GJ 367b – could be orbiting it, although more data was required to confirm this.

An artist’s impression of GJ-367 orbiting its parent star. Credit: SPP 1992/Patricia Klein/Handout via Reuters

This led a team of German astronomers to review the TESS data alongside of ground-based observations using a range of instruments through early 2021, and they were able to confirm the planet was indeed there, and that is roughly the size of Mars, and zips around its star once every 7.7 hours.

Obviously, such an orbital period means the planet is really close to its parent – just 0.0071 the average distance of the Earth from our Sun. This is far too close for it to be amenable to life as we know it. For one thing, it is showered with about 576 times more radiation than Earth receives from the Sun, which means any atmosphere it may have had has long since been stripped away by the solar wind. Its proximity to its star also means it is tidally locked – the same side of the planet always faces the star as it orbits – giving the dayside surface a temperature of 1500º C.

However, by using the HARPS (High Accuracy Radial Velocity Planet Searcher) instrument at the ESO’s La Silla Observatory, the team studying the planet were able to determine its likely size, and the fact that its core is probably 86% iron mixed with nickel, which is covered by a very thin mantle  – just 600 km thick, overlaid with a relatively thick crust – around 100-200 km. All of which makes it very similar in composition to our own Mercury.

Possible interior of GJ-367, with an iron-nickel core accounting for the bulk of the planet’s mass of the planet. Credit: unknown

In particular, this composition suggests the planet formed a lot further away from its star than its current orbit – had it been so close to the star, it is unlikely it could have collected the heavier elements of it core, which would have been drawn down to the star long before they could be trapped in the gravity well of a proto-planet.

This in turn raises a host of questions about such USPs – how they might form, whether they may have existed for a time in a region around their star that might have allowed them to develop atmospheres; how were those atmospheres lost during the migration period – was it a slow bleed-off or more violent; might they have ever been capable of supporting life; is such planetary formation / migration common to systems across the galaxy; if so, does it mean “steady” planetary systems like our own are in the minority – and if so, what might this imply for the potential of life elsewhere?

We may never know the answer to these questions where GJ 376b is concerned, but by studying it and other planets like it, we may in time be able to determine how common / rare life is beyond our own solar system.

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