Space Sunday: ups and downs, and returns

A rendering of Starship prototype SN8 in “belly flop” mode, returning to Earth after an ascent to 15 km and using the fore and aft flaps to steady itself like a skydiver uses their arms and legs. Credit: Bart Caldwell (aka Neopork)

It had been anticipated that mid-November would see the 15km flight of  the SpaceX Starship prototype SN8.  As I’d reported last month, that vehicle had completed its initial static fire tests before going on to be fully stacked with the intermediate ring and forward nose cone with aerodynamic canards.

Speculation had been that the test flight could come around the time of the SpaceX / NASA Crew-1 mission for Crew Dragon to the International Space Station which lifted-off from Kennedy Space Centre on Sunday November 15th (see: Space Sunday: a Dragon, a telescope and a heavenly princess). However, a final static fire test of the three Raptor engines during the week leading up to the possible launch window saw an issue occur, prompting SpaceX to place all launch plans on hold until the issue had been investigated and resolved.

The was done during the week following the 15th, and SpaceX has set the first part of the week commencing Monday, November 23rd as the target time frame for that static fire test, which eventually came on Tuesday, November 24th, when all of the vehicles fuel tanks – main and “header” tanks (the latter required to provide fuel to the engines during descent) – pressured prior to a 3-second and successful simultaneous firing of all three main engines.

The moment of ignition: with flaps folded back, Starship prototype SN8 fires its three Raptor engines in a pre-flight static fire test. Credit: Mary (aka BocaChicaGal)

Currently, documents filed with the Federal Aviation Authority (FAA) show that SpaceX have requested further road closures around their Boca Chica, Texa, test facility starting on Monday, November 30th –  with Elon Musk indicating that this is likely to be the launch period for the vehicle.

The test flight itself is intended to test three core aspects of the vehicle’s flight envelope:

  • Powered ascent to altitude.
  • Controlled “belly flop” decent whilst horizontal, utilising the fore and aft flps to maintain stability and rate of descent.
  • Orientation to vertical during the final 100 metres or so, and descent to a tail-first landing under engine propulsion.

The flight comes with a high degree of risk – nothing quite like it has ever been attempted before – and SpaceX are anticipating only around a 33% chance of success, and that SN8 will in fact be lost in what they euphemistically refer to as an “unscheduled disassembly of the vehicle”.

However, Starship prototype SN9 is almost ready to start ground tests, and SN10 is following up behind it, meaning that if SN8 is lost, flight testing shouldn’t suffer too much of an interruption, and if the initial 15 km flight is successful, then SN9 and SN10 will be available to extend the testing programme such as flying to higher altitudes and / or flying with a full fuel load – SN8 will fly with its tanks carrying only the fuel to get to 15 km and then make a (hopefully) safe return and landing.

At the same time as work is continuing on the starship prototypes, SpaceX has also been engaged on the development of the test launch platform for the Super Heavy Booster and the assembly of components for what will be the first of these boosters, called simply BN1. Also appearing at the site is a mock-up of a section of the “lunar starship”, the vehicle SpaceX has put forward to help NASA in its plans to return humans to the Moon.

The SpaceX Boca Chica vehicle assembly area, complete with the new High Bay for stack the Super Heavy booster (right) and various vehicles and vehicle components. Credit RGV Aerial Photography

In terms of the Super Heavy booster, SpaceX appear to be reconsidering the idea of trying to bring such a massive beast back to Earth to land directly on the launch platform. While this would undoubtedly allow for a faster turn-around of the vehicle between launches, it also requires a high degree of pin-point accuracy on landing, and opens the launch mount to the risk of damage should any go awry with a returning booster. In a recent tweet on the subject, Musk indicated that the initial Super Heavy booster flights will aim to land the vehicles on the concrete apron alongside of the Boca Chica launch mount.

But  it is not all good news for SpaceX, as the company has been informed it must undergo a new FAA environmental  review and re-licensing specifically for the launch of the Super Heavy vehicles.

This is because at the time the original environment review took place in 2014, the license granted was for test flights of the Falcon 9 and Falcon Heavy, not the Starship or Super Heavy. The FAA allowed flight testing of the former to occur at the site, as it was deemed to pose no greater impact than flight testing either of the booster systems. However, with some 30 Raptor rocket motors powering it, the super Heavy is a significantly different proposition, particularly as SpaceX now intend to use Boca Chica not just as their test facility, but an operational launch facility – a move which has angered local environmental groups.

They went from proposing a few launches per year of an already field-tested rocket to ongoing experimentation of untested technology without doing the studies that would ensure environmental protection and public safety and without giving the local community a chance to have a say.

– Jim Chapman, president of Friends of the Wildlife Corridor

This has resulted in significant pressure on the FAA to carry out a new full review, called an Environmental Impact Statement (EIS), which could take up to two years to complete (from initial assessment through to drafting the report to debate and final report). Currently, it is not clear what impact this will have on the company’s plans for Super Heavy test flights.

Continue reading “Space Sunday: ups and downs, and returns”

Space Sunday: a Dragon, a telescope and a heavenly princess

Sunday, November 15th, 2020, 19:27 local the Crew-1 Falcon 9 booster lifts-off from Kennedy Space Centre’s Pad 39A.Credit: NASA

Sunday, November 15th saw the official start of a new era in low-Earth orbit space transportation with the launch of the NASA / SpaceX Crew-1 mission to the International Space.

Originally scheduled for launch on Saturday, November 14th, the Crew-1 mission was delayed due to weather causing concerns about the recovery of the Falcon 9 launch vehicle’s first stage. However, at 19:27 local time on Sunday (00:27 GMT on Monday, November 16th), the Falcon 9 topped by the Crew Dragon and its crew of four – NASA astronauts, Mike Hopkins, Victor Glover, Shannon Walker and Japanese astronaut Soichi Noguchi – lifted off from the SpaceX leased Pad 39A at Kennedy Space Centre, the first stage of the rocket making a successful return to Earth and landing aboard the autonomous drone ship Just Read The Instructions.

Resilience approaches the ISS on November 16th/17th 2020. Credit: NASA / SpaceX

Nine minutes after launch, the Crew Dragon capsule – named Resilience by the crew – achieved an initial orbit, and the crew followed a long tradition of space flight dating back to the first manned space mission, and revealed their “zero gee indicator”, a Baby Yoda plushy toy from the TV series, The Maldorian.

The use of toys and dolls as such indicators goes back to the flight of Yuri Gagarin and his flight aboard Vostok-1 in April 1961.  Gagarin carried a small doll into orbit out of curiosity, as he wanted to see what floating in the micro-gravity of space looked like. However, his practice was copied by other Soviet cosmonauts, and in turn by NASA missions, with crews on the Crew Dragon continuing the tradition – Doug Hurley and Bob Behnken carried a plushy planet Earth on their trip to the ISS earlier in  2020 during the Crew Dragon certification flight.

While not confirmed, it is believed the selection of Baby Yoda was due to back-up crew member Kjell Lindgren. A long-time Star Wars fan, Lindgren had used a model of R2D2 as a zero-gee indicator during a 2015 Soyuz flight to the ISS and while aboard the station, persuaded the rest of the crew to dress up as Jedi Knights for a special NASA promotional poster.

It’s been a tough year. And the fact that … SpaceX and NASA were able to get our spacecraft ready to go, the rocket ready to go, throughout this year, throughout the pandemic, and all of that — we were inspired by everybody’s effort to do that. So that’s why we named Resilience, and we hope that it puts a smile on people’s faces, it brings hope to them. Baby Yoda does the same thing. I think everybody, when you see him, it’s hard not to smile, and so it just seemed appropriate.

– Mission commander Mike Hopkins explaining the choice of name for the Dragon
capsule and the selection of Baby Yoda as the zero-gee indicator.

A NASA graphic showing the craft docked at the ISS at the time the Resilience docked. Credit: NASA

It  took some 27 hours for Resilience to catch up with the ISS, finally rendezvousing and docking with the station at 11:01 EST on Monday, November 16th (04:01 GMT, November 17th). Following a further 2 hours of post-flight checks and preparations both in the capsule and on the station, the forward hatch on Resilience was opened and the four crew were invited aboard the ISS. In doing so, they set a new record for the space station: the first time it has been occupied by full-time crew  totalling seven  people. This is actually one more person than the ISS is designed to accommodate, so Crew-1 commander Mike Hopkins is sleeping aboard the Resilience.

The Expedition 64  crew will remain on the ISS for a 6-month rotation period, Hopkins and his crew joining NASA astronaut Kate Rubins and Russian cosmonauts Sergey Ryzhikov and Sergey Kud-Sverchkov, who arrived at the ISS on October 14th, aboard the Soyuz MS-17 – a mission which was itself a record-setter, rendezvousing with the station just three hours after launch, utilising Russia’s “ultrafast” ISS launch and rendezvous flight plan for the first time.

Kate Robins, who arrived aboard ISS as a part of the Soyuz TM-17 crews, greets Victor Glover as he boards the ISS from Resilience, marking the first time an African-American astronauts has boarded the station as part of the full duration crew. Credit: NASA
Once aboard the station, the crew wasted little time in getting down to work. On November 18th, Ryzhikov – currently in overall command of the ISS – and Kud-Sverchkov made a 6-hour 48-minute spacewalk that inaugurated the operational use of the Poisk “mini research” module as an airlock.

As I noted in my previous Space Sunday update, Poisk has been delivered as an airlock / docking module in 2009. It is one of two such units attached to the Russian Zvezda module, the other being the Pirs airlock / dock, deployed to the ISS in 2001. Up until the Ryzhikov / Kud-Sverchkov EVA, Poisk had only been used as a docking module, spacewalks generally being conducted via the Pirs module.

 Sergey Ryzhikov (centre top with the red stripe on his backpack) and Sergey Kud-Sverchkov work outside of the Poisk (the vertical unit) and Zvezda modules of the ISS. Credit: Roscomos

However, Pirs is due to be removed from the ISS in 2021, so it can be de-orbited to burn up in the upper atmosphere using one of the Russian Progress resupply vehicles. It is due to be replaced by the Nauka Multipurpose Laboratory Module (MLM) – although there are some doubts about this module, as its launch has been delayed so much, several of its systems are at the end of their warranty period.

In  particular, the Poisk spacewalk was to start the process of decommissioning Pirs, by moving vital communication equipment and cabling from that module and connecting them to Poisk, allowing it to become the primary Russian EVA airlock.  As  well as this work, Ryzhikov and Kud-Sverchkov retrieved hardware used to measure space debris impacts, and repositioned an instrument used to measure the residue from thruster firings. The EVA marked the 47th Russian space walk in support of ISS operations, and the 232nd ISS spacewalk overall.

Continue reading “Space Sunday: a Dragon, a telescope and a heavenly princess”

Space Sunday: ISS – 20 years of living in space

The International Space Station seen from the space shuttle Atlantis, May 23rd, 2010. The vertical gold / maroon panels are the solar panels for generating power; the white horizontal panels are the radiators for removing excess heat from the station. Credit: NASA

On October 21st, 2000, a Soyuz vehicle lifted-off from the Baikonur Cosmodrome in Kazakhstan en route for the fledgling International Space Station ISS, carrying two cosmonauts and an American astronaut. Sergei Krikalev, Yuri Gidzenko and William Shepherd were not the first people to visit the ISS, but when Soyuz TM-31docked with the station on November 2nd, they became the first official crew to live and work aboard it, and their arrival marked the start of 20 years of continuous occupation of the station.

At the time of the arrival of the Expedition 1 crew, the ISS was a small affair, the Russian-built Zarya propulsion, attitude control, communications and electrical power distribution module, launched in 1998; the American Unity module, intended to link future US and international modules on the station with the Russian units, delivered by the shuttle Endeavour in 1998; and the Russian Zvezda, which rendezvoused and docked with the station in July 2000.

The primary role of the Expedition 1 crew was to commission the ISS and its systems and to oversee the initial expansion of the station, with the assistance of two space shuttle flights. The first of these delivered the additional solar arrays to power the station, elements of the “keel” of the station (the Integrated Truss Structure), and the second the US Destiny research module. However, the work wasn’t all construction related: the three men also started the station’s long-running science programme that continues through to today. They also caused a slight controversy as they started work.

The ISS at the time of Expedition-1 crew. On the left is the Soyuz TM-31 vehicle the crew flew to the station aboard, docked against the Russian Zvezda module. In the middle is the Zarya module, the first module launched, and the US Destiny module to the right. This image was captured by the crew of STS-97 aboard the shuttle Endeavour, December 2000. Credit: NASA

The idea of a US space station has started to come together in the 1980s under the project title Space Station Freedom. This was later revised to Space Station Alpha before finally becoming the International Space Station following the signing of a US / Russian agreement to build a joint orbital facility. However, the “Alpha” name stuck with many at NASA, including Expedition 1 commander Shepherd, who insisted on using it – much to the consternation of Russian officials, who felt they had had the first space station in Salyut and Mir, so the new station was at best “Beta” (or better yet in their eyes, Mir -2).

Once aboard the station, and with the agreement of Krikalev and Gidzenko, Shepherd insisted on using “Alpha” as the station’s radio call sign, stating it was easier to say than “International Space Station” or “ISS”. Despite the annoyance on the part of Russia, “Alpha” continued to be used by the Expedition 1 crew, resulting in it being adopted as the station’s official radio call-sign.

As well as playing hosts to three space shuttle missions – the third of which delivered the Expedition-2 crew -, Shepherd Krikalev and Gidzenko also oversaw the start of re-supply missions using the Russian Progress vehicles (essentially fully automated Soyuz vehicles) capable of delivering around 2.4 tonnes of supplies and fuel to the ISS.

Following Expedition-1, the initial crews visiting the ISS were exclusively made up of Russian cosmonauts and American astronauts, with each crew spending, on average, 5-6 months on the station. It was not until June 2006 that the first international crew member boarded the ISS in the form of German astronaut Thomas Reiter. He was followed in 2008 by Frenchman Léopold Eyharts and Japan’s Koichi Wakata in 2009 (Wakata actually served a total of 5 Expedition crew rotations: 18, 19, 20 (all back-to-back and continuous) and 38 and 39 (again back-to-back). After this, crews routinely included one or more non-American / Russian astronaut.

The men who started it all: Sergei Krikalev, William Shepherd (centre) and Yuri Gidzenko: the Expedition-1 crew. Credit: Roscosmos

In the 20 years since Expedition-1, 240 individuals have made 395 flights to the ISS (including 7 “space tourists”) – a number that represents 43%of all human flights into space. In that time, the space station has grown from those initial three units to a total of 16 permanent pressurised modules, numerous unpressurised pallets and work stations, and one commercial unit, the Bigelow Expandable Activity Module (BEAM), an inflatable unit, currently configured as a storage space.

Outside of the Zarya, Zvezda, Unity and Destiny modules, the ISS comprises the following pressurised modules:

  • For science: the Columbus European module (added February 2008); the Japanese Kibō module (which, with its unpressurised work platform is the largest crewed elements of the ISS, added between 2008 and 2009); the Russian Rassvet module (now primarily used for storage, added May 2010).
  • Airlock / docking: the US Quest Joint Airlock, supporting EVAs using either US or Russian space suits (added July 2001); the Russian Pirs and Poisk airlock / docking modules (added September 2001 and November 2009, respectively, and connected to the Zvezda module); the US International Docking Adapters 2 and 3 (IDA-1 was lost in a Falcon 9 launch failure), delivered in 2016 and 2019 respectively.
  • Other modules: the US Harmony “hub node” connecting the European and Japanese science modules to the US Destiny module (added 2007); the European Tranquillity life-support and environmental module (added November 2009); the Leonardo European multi-purpose module (added February 2011) and the European Copula module, with its seven large windows (added in 2010).

Together, the pressurised modules of the ISS offer a volume of living / working space equitable to that of a 747 airliner. The overall mass of the ISS, including the Truss, and all unpressurised / external elements is approximately 425 tonnes.

Nor is this all: four more Russian modules are awaiting launch to the ISS: the Nauka Multipurpose Laboratory Module (MLM). Delayed since 2007, it is currently slated for a 2021 launch, but this may yet be cancelled as the warranties on several of the module’s system expire in later 2021; the Prichal “docking bell”, primarily intended to provide docking for two further power modules (SPM-1 and SPM-2) and for Soyuz  / Progress docking. Prichal is slated for launch in late 2021, and the two SPM units in 2024.

Further commercial elements are also due to be added  in the form of the Bishop Airlock Module, designed for the launch of cubesats from the station (and awaiting launch before the end of 2020), and the Axiom commercial node, due to be added in 2024.

The 2 decades of ISS operations has seen the amount of equipment deployed in the station increase. This is the console for operating one of the station’s 2 robot arms (located in the US Destiny module) which has become surrounded by a plethora of laptops and monitors that help monitor EVA operations. Credit: NASA

The living spaces on the ISS can support up to 6 crew at a time, although the standard crew complement outside of rotation periods, when two crews are operating side-by-side, has tended to be 3 (even when the shuttle was still operational). With the arrival of the SpaceX Crew Dragon and the Boeing Starliner, crews can now increase to 4-6, depending on requirements.

However, we’re not talking glitzy, hi-tech living. Despite its volume, the ISS is cramped; personal space is limited to a couple of cubic metres (mostly used to hang an astronaut’s sleeping bag), and “free” space has become increasingly overcrowded with the passing years as more and more equipment has been packed into the various modules.

The first Japanese astronaut to work aboard the ISS, Koichi Wakata, attempts to get some sleep during his fifth Expedition crew rotation (Expedition-39), which saw him take command of the ISS in 2014. Credit: NASA / JAXA

The lack of gravity means that almost any surface can be used as a floor, ceiling or wall, depending on a person’s orientation. However, to try to keep a general sense of orientation within the Russian modules, surfaces facing towards Earth are considered “down” and are coloured olive green; surfaces pointing away from Earth are considered “up”, and are painted beige. Perpendicular surfaces between them flow from the one colour to the other as you look “up” or “down”.

Doe to the lack of personal space, almost any “free” space on the structural walls / ceilings / floors of the various modules tend to become the home of personal and other mementos. One area of the Zvezda module, for example, has been turned into a corner for expressions of the Russian orthodox faith, and another a shrine to Russian heroes of space flight and discovery from Tsiolkovsky to Gagarin.

The two most popular areas of the station are the Harmony module, with its communal dining area, which is also used to celebrate birthdays, anniversaries, holidays, etc., and the European Copula, due to its unparalleled views out of its windows. Overall, however, life on the ISS is described as, “noisy, smelly [if your sinuses clear, as they are usually blocked due to the lack of gravity], dirty and awash with everything from human skin and floating globs of sweat [crew are expected to undertake around 2 hours of physical exercise a day] to the pencil you misplaced yesterday and which is now floating around in the air currents between modules,” with the noise being noted as the biggest issue.

The scientific range of the ISS has been, and remains, extensive. Human and life sciences space research includes the effects of long-term space exposure on the human body, testing medical systems and procedures specifically aimed towards supporting long-duration space missions (e.g. to Mars and back), zero-ego production of pharmaceuticals to help with ailments on Earth (the lack of gravity allows compounds to be mixed that would otherwise naturally separate). The broader aspects of life sciences have included the growth of unique protein crystals, and the evolution, development, growth and internal processes of plants and animals.

A second major area of research has been materials science.  This has included the production of unique materials (again made possible due to the lack or gravity) or materials with a greater purity than can be achieved on Earth; energy production and clean energy alternatives. Astronomy and Earth sciences have formed a third leg of ISS science, with the former encompassing wide-ranging stellar and solar studies such as the impact of cosmic rays and the solar wind on out atmosphere, solar observations, research into dark matter, etc. Earth sciences have included climate change studies, monitoring ice melt, global pollution (including world-wide emissions of carbon gases and aerosols, etc.

The fourth aspect of ISS research is education and cultural outreach. This includes teaching and lecturing from orbit, working with Earth-based students by carrying out their experiments, etc. An amateur radio programme gives students from around the world the opportunity to contact the ISS and talk about science, technology, mathematics and engineering with the crew.

Research is split between the various science modules on the station, with some providing unique environments / facilities for specific research fields, others sharing larger research projects. The science programme can additionally be extended or supplemented through equipment and experiments carried up to the ISS via crewed and uncrewed vehicles.

The ISS in 2012: A – Zvezda; B – Zarya; C – Unity; D – Tranquillity; E – Quest; F – Destiny (under truss); G- Harmony; H – Kibō (with external experiments pallet); I – Columbus. Not visible: Rassvet and Leonardo. 1 – Soyuz vehicles; 2 – radiators; 3 – Integrated Truss; 4 – solar arrays. Credit: image – NASA / Roscosmos

Operating the ISS has not been easy.  It is subject to numerous international agreements, has required the involvement of some 17 nations over the years (although Brazil has officially withdrawn from the programme), with 15 nations being original signatories to the ISS Intergovernmental Agreement. A total of 25 individual space agencies and centres around the world have a hand in managing ISS operations from the ground, with Russia and America providing the primary mission control centres and staff. These two countries are also responsible for carrying all crew to / from the station, and for the core missions to keep the station supplied with consumables, fuel, equipment, etc., although Japan also provides re-supply missions as well (as did the Europeans until their Automated Transfer Vehicle (ATV) programme came to an end).

Given the number of nations involved, there have inevitably been tensions from time-to-time, with perhaps the most famous being in 2009, when a disagreement between America and Russia resulted in Russian mission managers banning US personnel from using the toilets in the Russian modules and forbidding their cosmonauts from using toilets in the US modules!

Outside of odd bouts of tension on the ground, the main challenges in operating the ISS tend to be space-based. Several parts of the station are now ageing (the Zvezda module, whilst launched in 2000, was actually built in the 1980s, for example), so maintenance of the station, inside and out, accounts for a significant about of operational time. Stress on the structure as a whole means that there are often minor pressure / atmosphere leaks – which can be exacerbated by impacts with dust and tiny particles of debris, some of which can grow to be quite serious (but not life-threatening).  There’s also the growing risk of collision with large pieces of orbital debris.

However, despite all this, the ISS today continues to be at the forefront of human space research, and can form an essential platform for research into crewed missions to Mars. It is estimated to cost US $7.5 million per crew member per day to operate the station – which, while expensive, is still less than half the anticipated cost set in 2000. Thanks to the US Senate and House finally giving approach, US funding for the station means it can now continue operating through to 2030.

Space Sunday: water on the the Moon; asteroids & comets

The Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint US / German programme, Credit: NASA

Earlier in October, NASA teased the world with news of a special announcement concerning the Moon, using social media to announce the fact … they would be making an announcement on Monday, October 26th.

The announcement of the announcement led to a lot of speculation (and a lot of ribbing at NASA’s expense) with some correctly identifying the fact that the news would have something to do with the Stratospheric Observatory for Infrared Astronomy (SOFIA), the world’s largest flying telescope. This is a joint NASA / DLR (German space agency) venture that flies a German-built 2.5m diameter reflecting telescope aboard a short-bodied 747 SP operated by NASA.

Flying at 12 km above the ground, and so well above the worst of the distorting effect of the Earth’s atmosphere and capable of 10-hour observation sorties, SOFIA is almost as capable as space-based telescopes of a similar nature (having around 85% of the infra-red capability of a similarly-sized space telescope), whilst offering fair easier and lower-priced maintenance, upgrade and general operational costs. In addition, the range of the 747 aircraft means that SOFIA can operate over almost any location on Earth and so be available for almost any observational requirements than fall without the telescope’s capabilities.

The German-built telescope on the Sofia aircraft during flight tests. The “spots” around and on the open telescope bay door are airflow indicators to help with monitoring air passing over the open door. Credit: NASA

When finally made public, the announcement – which was billed as being related to NASA’s current plans to return humans to the Moon, Project Artemis -, proved to be that SOFIA has detected water molecules on the sunlit surfaces of the Moon.

Whilst an important discovery, marking a further increase in the presence of water on the Moon (which we’ve known about since 2009), it is important to offer a measure of context to the discovery: this is about water molecules bound within the regolith (surface material) of the Moon, not actual water ice, as was confirmed in 2018 for many of the permanently shadowed and very cold craters of the Moon’s south polar regions.

In particular, SOFIA detected the infra-red signature for water molecules within the crater Clavius (perhaps most famous for being the location of the lunar administrative base in 2001: A Space Odyssey).  Located in the southern highlands at 58.4°S 14.4°W, Clavius is one of the oldest formations on the lunar surface, believed to have formed some 4 billion years ago; it is some 230 km across and some 3.5 km deep.

Clavius crater as seen via the Johannes Kepler Observatory, Linz, Austria, 2004. North is towards the top of this image. Credit: H. Raab

That water molecules may be widely present in lunar regolith had been long suspected. However, previous estimates as to how much might be present had been hampered by the fact that previous studies could not clear differentiate between the presence of water molecules (H2O) and hydroxyl (OH). During extended observations of Clavius, utilising  a special instrument, the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST), the airborne observatory was able to detect water molecules at around 100 to 400 parts per million in a cubic metre of regolith.

To put this in proportion, this means that SOFIA detected the equivalent of one third of a litre of water trapped in a cubic metre of lunar surface material – which is actually a lot.  If the SoFIA findings hold true for all of the surface material within the sunlit parts of the Moon, it means there a potentially a lot of water to be had;  but whether or not it is actually accessible or have any significant bearing on human activities on the Moon is open to debate. Certainly, it is unlikely to have any significant impact on America’s Project Artemis, despite claims otherwise.

Simply put, the water molecules detected within Clavius are most likely bound in glass beads that resulted from micrometeoroid impacts. As such, it is nowhere near as potentially accessible as the water ice in the south polar region craters, and it is going to need relatively intensive processing in order to be properly extracted and turned into usable water – and the kind of heavy engineering required to achieve this at scale isn’t going to be available for use on the Moon any time soon, and may not even been cost-effective even when it is.

Clavius crater as seen by NASA’s Lunar Reconnaissance Orbiter (launched in 2009 and still operational). Note that is this image, north is at the bottom. Credit: NASA

Nevertheless, the discovery is important for our understanding of the Moon and our longer-term exploration of the lunar surface. It might also mean a new lease of life for SOFIA. whilst not mentioned in the release, NASA had sought to quietly terminate the 10-year-old telescope in 2021, citing it’s “lack of scientific output”.

Continue reading “Space Sunday: water on the the Moon; asteroids & comets”

Space Sunday: asteroid sampling & starship building

Kissing an asteroid: the sample head of TAGSAM, the sample gathering mechanism on NASA’s OSIRIS-REx makes contact with asteroid Bennu on October 20th, 2020. Credit: NASA

In my previous Space Sunday update, I covered the (then) upcoming attempt by NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) to snag samples of material from the surface of asteroid 101955 Bennu, a carbonaceous near-Earth asteroid.

The attempt was successfully made on Tuesday, October 20th – although just how successful it was did not become apparent until a few days later, when mission engineers realised they now had a slight problem.

The mission required OSIRIS-REx slowly descended from its close-in altitude of 770m, a sample gathering called TAGSAM (Touch-And-Go Sample Acquisition Mechanism) extended beneath it. This was intended to make very brief contact with the surface of Bennu, absorbing the spacecraft’s momentum in springs, and allowing it to fire a nitrogen jet to blast material up from the asteroid some of which would hopefully be caught in the arm’s sampler head, prior to the arm “pushing off” from Bennu once more, allowing OSIRIS-REx to gently back away to a point where it could examine what it has gathered.

OSIRIS-REx: the sample-gathering operation. Credit: NASA

The entire operation was scheduled to take some 4.5 hours from start to back-away and parking. The event was live-streamed, but due to the current distance between Earth and Bennu, those on Earth were witnessing events 18.5 minutes after they had actually occurred. This also meant the entire operation was carried out autonomously, the software controlling it having been previously uploaded to the satellite.

OSIRIS-REx, following Bennu’s rotation about its axis, struck the asteroid a metre one metre away from its intended contact point, which lay within a shallow crater on Bennu that has been christened “Nightingale”. It remained in contact with the surface for 6 seconds – very slightly longer than had been anticipated.

The moment of contact for TAGSAM – and of actually smashing through the surface material on Bennu (film speeded up). Credit: NASA

Whilst there was a camera on the robot arm recording the operation, the footage could not immediately be sent back to Earth. Instead, mission controllers relied on the telemetry OSIRIS-REx did immediately transmit back to Earth. This revealed that everything had apparently gone as planned: TAGSAM made contact, the gas was fired and regolith (surface material blasted upwards. The telemetry then confirmed OSIRSIS-REx was backing away from the asteroid towards the point where analysis of the amount of captured material could be carried out.

This was transcendental. I can’t believe we actually pulled this off. The spacecraft did everything it was supposed to do. Even though we have some work ahead of us to determine the outcome of the event, this was a major accomplishment for the team. I look forward to analysing the data to determine the mass of sample collected.

– OSIRIS-REx Principal Investigator Dante Lauretta

Then came the first of the surprises.  When the video footage captured by the TAGSAM arm camera was received and processed (above right) on October 21st, it revealed that the sample head hadn’t so much touched the surface of Bennu as smashed straight through it to an estimated depth of almost 50 centimetres – and in doing so, had pulverized a rock roughly 20 cm across which, when first viewed in the footage, caused the mission team to worry it might prevent sample gathering and damage the sample head.

The next step in the operation was to analyse the state of the sample head once TAGSAM had been returned to its stowed position against the spacecraft. To do this, one of the star tracker cameras used for navigation was tasked to capture an image of the sample head. When this was returned to Earth, mission staff had a second surprise: the sample head was “leaking” material.

Following the sample gathering operation, a Mylar diaphragm should have rotated over the opening of the sample head to seal any material gathered inside it – but the star tracker camera revealed this had failed to sit correctly, and a small cloud of material was forming around the sample head as it persistently “leaked” out. Given the force of the contact with Bennu, the mission team realised that, rather than just collecting 60 grams of material, the sample head had likely been filled to capacity, preventing the Mylar cover from correctly sealing it.

A small but growing cloud of material gathers around the TAGSAM sample head on OSIRIS-REx following a sample gathering operation that likely overfilled the sample containment area, preventing a Mylar diaphragm (the white semi-circle, visible in the middle of the circular sample head) from sealing the cavity. Credit: NASA

With material slowly but steadily escaping, the decision was been taken to cancel the attempt to estimate the amount of material gathered, and instead move to transferring the sample head to the Sample-Return Capsule (SAC). This is the unit that will return the sample to Earth when OSIRIS-REx return here in 2023. As the SAC is sealable, moving the sample head there as soon as possible – in this case, October 27th – will ensure the remaining material from Bennu is preserved.

In the meantime, and while OSIRIS-REx cannot start on its return to Earth until March 2021, the decision has been made not to return the vehicle to a low-level “hover” orbiting Bennu, but to instead allowing it to continue away from the asteroid at around 44 metres per hour until it reaches a more extended orbital position.

Continue reading “Space Sunday: asteroid sampling & starship building”

Space Sunday: OSIRSIS-REx: sampling an asteroid

An artist’s impression of NASA’s OSIRIS-REx above the asteroid Bennu,with Earth added in the background for dramatic effect. Credit: NASA Goddard

After a period of delay, NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) is due to attempt the collection of a 60 gram (2.1 oz) sample from the surface of 101955 Bennu, a carbonaceous near-Earth asteroid, on Tuesday, October 20th.

Originally scheduled for August 2020, the attempt to gather the sample requires the space craft to slowly descend to within “touching” distance of the asteroid using a robotic arm. If successful, the sample gathering will open the door for OSISRIS-REx to complete the remainder of its mission before making its way back to Earth where the sample can be analysed.

Launched in September 2016, OSIRIS-REx is one of two such asteroid sample return missions currently in progress, the other being Japan’s Haybusha 2 mission (the original Hayabusha mission also returned samples from an asteroid – but they only amounted to around 1 milligram of material).

Having been launched well ahead of OSIRIS-REx, Hayabusha 2 is actually on its way back to Earth from asteroid 162173 Ryugu, with which it rendezvoused in June 2018. It spent 18 months surveying the asteroid, depositing four micro-rovers on its surface before gathering samples blown off of the asteroid by the force of a kinetic impactor (think bullet), allowing it to collect a mix of surface and sub-surface material. Currently, Hayabusha 2 will deliver its cargo back to Earth during a fly-by on December 6th, 2020, after which it may be tasked with a further sample return mission.

Image sequence showing the rotation of Bennu, captured by OSIRIS-REx at a distance of around 80 km. Credit: NASA Goddard

OSIRIS-REx reached it’s target, Bennu, at the very end of December 2018 and has spent most of the intervening time studying the asteroid in detail. Both Bennu and Ryugu are of interest to scientists for a number of reasons: they are both part of a class of asteroids that are believed to have been around since the formation of the solar system, and so they could help us learn more about that period.

Both are also in the Apollo asteroid group, meaning they routinely cross Earth’s orbit, and thus present a potential collision risk, and at 1 km diameter for Ryugu and just under 1/2 a km for Bennu, an impact from either would not be a Good Thing for Earth. So, another reason for sampling them is to determine their composition (and by extension, allow us to draw conclusions about the composition of other large Apollo asteroids) that may help make a determination of how to deal with them should that threat of impact become real (in fact, there is a chance that Bennu in particular might impact Earth between 2175 and 2199).

Finally, samples from both might offer clues as to how life-forming materials reached the surface of Earth.

Bennu has proven particularly intriguing for scientists. For one thing, it has proven to be entirely unlike anything that had been anticipated; rather than being relative smooth, with crater pits and sand-like regolith (surface material), Bennu revealed it is a boulder-strewn place with rocks in places comparable to mountains relative to its size, many of them placed so closely together, any attempt to gather samples near them would like result in a loss of the vehicle. This required a more extensive survey to determine potential sample sites, with five initially being identified, before these were narrowed to two, the primary, Nightingale, and a back-up.

This image, captured by OSIRIS-REx shows the Nightingale sample gathering crater surrounded by large boulders. The silhouette of the spacecraft (which is about the size of a van – excluding the solar panels and has a mass of just over 2 tonnes) added for comparison. Credit: NASA Goddard

The asteroid also demonstrated it can emit plumes of material from within itself when in the “warm” part of its 1.2 year orbit around the Sun. However, one of the most surprising discoveries was the identification of six bright boulders on the asteroid’s surface which, when subjected to spectroscopic analysis, revealed themselves to be of the same materials as boulders on Vesta, the second-largest asteroid in the solar system, surveyed by the NASA / ESA Dawn mission.

It’s believed that the presence of these rocks indicates that Bennu started life as part of a larger body – an asteroid or planetesimal – within the asteroid belt beyond Mars, where it was in collision with a fragment of Vesta, depositing material from the latter on its surface. That event, or another similar collision, led to a “catastrophic disruption” within Bennu’s parent, creating Bennu itself and sending it on its way into the inner solar system to be caught in an orbit much closer to the Sun.

The asteroid has also revealed itself to be particularly rich in carbon-bearing material, which can tell us how much water it may have contained (and how much might still be present as sub-surface ice). What is particularly interesting here is that many of the boulders on Bennu contain mineral veins composed of carbonate – which on Earth often precipitates from hydrothermal systems that contain both water and carbon dioxide. Some of these rocks are located around the Nightingale sample  recovery area. The presence of such carbonate strongly suggests that Bennu’s parent body, whether asteroid or small planetary body,was likely hydrothermally active. This has in turn given rise to the prospect that any sample returned by OSIRIS-REx might contain organic material.

Continue reading “Space Sunday: OSIRSIS-REx: sampling an asteroid”