Space Sunday: starships, dishes and microbes

A stunning image of Starship SN9 standing on the Boca Chica launch platform framed by a low Sun. Credit: Mary “BocaChicaGal”

In December 2020, and following the not-quite-successful flight of Starship prototype SN8, SpaceX suffered what might have been a further setback in their flight test plans for the Starship vehicle, when prototype SN9 toppled sideways whilst in the stacking facility at the company’s Boca Chica, Texas, construction and flight test centre (see: Space Sunday: the flight of SN8 and a round-up).

However, the vehicle was quickly righted and following examination, work commenced on repairing / replacing the damaged elements (notably one of the forward aerodynamic surfaces). This work proceeded at a surprising pace; so much so that on December 22nd, 2020, it was delivered to he Starship launch platform.

Since then work has continued at the same rapid pace, such that within the two weeks since its arrival on the stand, SN9 has completed the majority of its pre-flight checks that took around 2 months to complete for SN8. These included initial fuel tank pressurisation tests using inert liquid nitrogen (to test the tanks and structure for leaks), partial and fuel test fuelling operations, vent system tests, testing of the reaction Control system (RCS) thrusters that help maintain the vehicle’s orientation in the atmosphere and will provide manoeuvring capabilities in space, and even a full static fire test of the vehicle’s three Raptor engines, which took place on January 6th.

SN9 static fire engine test. Credit: Mary “BocaChicaGal”

Two tests were skipped in the process – but this is seen as not so much because the company is trying to make up for any “lost time”, but rather the result of growing confidence in the process of taking a prototype vehicle from fabrication to test flight. However, while the engine firing was successful, it was somewhat shorter than those for SN8 – the Raptors fired for less than 2 seconds – so it is not clear whether or not an issue was encountered, forcing a premature shut-down.  If this is the case, then it might be that further static fire tests may be announced ahead of any flight; if the brief firing was intentional, then it is possible a flight test could come within the next week or so.

As it is, the exact date of any actual flight test for SN9  – which will seek to repeat the 12.5 km altitude reached by SN8, but hopefully follow it with a successful landing – hasn’t been confirmed. However, to avoid a repeat of the SN8 crash, SpaceX CEO Elon Musk confirmed that the Methane header tank – a smaller tank designed to feed fuel to the Raptor motors during the landing sequence  – for SN9 and at least some of the prototypes that follow it will be “pressed” with helium (this is, helium will be forced into the tank in order to force the methane out and to the engines) in order to avoid any pressurisation issues. However, it is not clear if this will be the permanent solution to the problem, or an interim update to allow test flights to continue whilst SpaceX develop a more permanent solution to the problem.

A diagram showing Starship and Super Heavy prototype development. On the left, SN9 is complete, and awaiting its flight. SN10 is awaiting Raptor motor installation and the attachment of its aft flaps, and SN11 has yet to have its upper sections installed and is awaiting its tail flaps and motors. All of the major hull elements of SN12 have been fabricated but have yet to be assembled. The diagram also show the assembly of SN15, which is will in advance of SN13 and SN14, while to the right is the status (as of January 9th) of the first Super Heavy prototype. Credit Brendan Lewis

At the same time as pre-flight tests have been continuing with Starship SN9, work has been continuing with a number of further prototypes. SN10 very close to completion, with just engines and aft aerodynamic flaps to be mounted, and SN11 will be receiving its upper sections in the coming week. Further down the chain, SN15 is also progressing, as is SN16. These will likely be the first two prototypes fully fitted with the thermal protection system used to safeguard the vehicle’s hull during atmospheric entry. This doesn’t necessarily mean either will make an orbital flight – SpaceX will doubtless want to text how the entire thermal system holds up under atmospheric flight prior to committing to an orbital attempt.

However, work currently appears to be on hold for vehicles SN13 and SN14, and SN12 has yet to be stacked. Whether these vehicles will be completed remains to be seen: Musk has previously indicated that the SN15 vehicle and beyond will include “significant upgrades” compared to earlier vehicles, so it is possible SpaceX may opt to skip from SN11 to SN15 in the flight test programme.

An image demonstrating the relative size of SpaceX vehicles and the shuttle. Left: the Crew Dragon – capable of flying up to 7 into LEO; right: a starship vehicle with a shuttle orbiter alongside. The orbiter could carry up to 7 into LEO with up to 28 tonnes of cargo. Starship can carry up to 100 people + cargo or up to 100 tonnes (cargo variant) to LEO. A Tesla 4×4 and human are included for scale. Credit: Dale Rutherford

Puerto Rico Governor  Supports Rebuilding Arecibo

The outgoing governor of Puerto Rico, Wanda Vázquez Garced, signed an executive order on December 28th, 2020 backing the rebuilding of the 305-m diameter Arecibo radio telescope that collapsed in November 2020 (see:  Space Sunday: returns and a collapse).

The order states that US $8 million is to be “assigned and allocated” for removing the debris of the collapsed telescope and “remedial environmental” work be completed at the site. It further states that the Puerto Rico government wishes to see the development of a telescope with a larger effective aperture,  wider field of view and a more powerful radar transmitter to replace the original, thus providing the nucleus of “a world class science and education facility”.

Arecibo as it was: visible is the main dish with the central receiving platform suspended over it via the three towers. Credit: NASA

However, things are not as clear cut as this. For one thing, the construction of a new telescope is liable to cost more than ten times the funding stated in the order. It’s also not clear where the $8 million will come from; the order only suggests it could be provided through “state, federal and private sources (including public-private partnerships and state-federal partnerships)”.

More particularly, Arecibo is not under the funding auspices of the Puerto Rican government, but rather that of the National Science Foundation (NSF), which it turn is funded directly by the US government. Thus far, the NSF has not committed to any rebuilding / replacement at the site, nor have any funds been allocated by Congress in the 2021 federal budget – although the NSF has been directed to prepare a study / report on the telescope’s collapse, the clean-up operation and to determine whether a replacement / comparable facility should be established at the sit, together with the associated costs for doing so.

After the fall: the telescope after the collapse of the receiving platform (the wreckage of which can be see to the right of the disk. Also clearly visible is the scar where the collapsing platform and cables tore through the disk. Credit: NASA
NSF has a very well-defined process for funding and constructing large-scale infrastructure, including telescopes. It’s a multi-year process that involves congressional appropriations and the assessment and needs of the scientific community. So, it’s very early for us to comment on the replacement.

– Ralph Gaume, director of NSF’s Division of Astronomical Sciences

India Determined to Become Major Space Player

In my first Space Sunday for 2021, I noted that India plans to make an uncrewed launch of its Gaganyaan capsule system before the end of 2021. On  January 4th, the Indian Space Research Organisation (ISRO) gave further details on its plans for 2021 and beyond, as the country seeks to become a major player in space-based activities.

The announcement is the start of a decadal plan for India’s operations in space that encompasses all ISRO facilities and assorted national science and educational centres in a series of wide-ranging  programmes that include:

  • Launch vehicles: a new heavy lift launch vehicle and a reusable launcher.
  • New propulsion systems, including a semi-cryogenic upper stage capable of delivering 5.5 metric tonnes to geosynchronous transfer orbit; an electric propulsion system suitable for deep-space science missions and more “environmentally friendly” booster propulsion options.
  • The on-going development of the Gaganyaan human spaceflight capabilities (the first crewed launch of the system is expected in 2022). Together with the development of orbital habitats with regenerative life support systems.
  • Advanced science missions, the development of assorted orbital satellite capabilities including communications and broadband delivery and Earth observations platforms.
  • The commissioning of a new launch site at Kulasekarapattinam, situated in the southernmost part of the Indian subcontinent, for government and private sector launches.

The Case for Life on Enceladus

A team from researchers from the University of Texas, San Antonio and the Southwest Research Institute (SwRI), Arizona, have used computer modelling and data gathered by the NASA Cassini mission to  try to determine whether or not Saturn’s moon Enceladus might support basic life forms.

Thanks to Cassini, we already know that Enceladus is home to a subsurface global ocean that is home to  molecular hydrogen, a potential food source for microbes. This was detected in the plumes from erupting geysers on the surface of the moon. Now the new study suggests that the ocean of the moon could well contain a variety of chemicals and processes that could, when combined, support a diverse community of microbes.

The microbes are most likely most likely fed by oxidants descending from the upper levels of the ocean, and by reductants rising from hydrothermal activity in the moon’s core. Both of these, in the right balance, can kick-start basic and microbial life, providing food and energy, whilst providing conditions in which further chemical compounds microbes could use to survive. The researcher’s modelling demonstrates that the likely conditions within Enceladus are within the parameters for that balance to be met and for the necessary interactions to help create other compounds.

The case for life on Enceladus. Credit: UoT / SwRI

In fact, the modelling revealed that the conditions within the Enceladus ocean could support  multiple pathways by which life could develop within the moon’s ocean. In particular, it showed that oxidant production and oxidation chemistry could contribute could supply sufficient “food” that, with the energy (heat) emanating from within the moon’s core is capable of supporting ” a metabolically diverse microbial community on Enceladus”.

That doesn’t mean there is life within Enceladus, but it does lift the case for a mission to the moon to examine what is going on there through the collection of samples from the geyser plumes.

Now that we’ve identified potential food sources for microbes, the next question to ask is ‘what is the nature of the complex organics that are coming out of the ocean? This new paper is another step in understanding how a small moon can sustain life in ways that completely exceed our expectations.

– SwRI Program Director Dr. Hunter Waite

Just such a mission was proposed in 2015 – the Enceladus Life Finder (ELF). This was originally put forward for funding in 2015 as a part of NASA’s Discovery programme, but failed to get selected. It  was again put forward in 2017 for funding under NASA’s New Frontiers programme, but again was not selected. Were it to be approved, ELF would orbit Saturn and make multiple passes over Enceladus and through the geyser plumes to seek amino acids, the building blocks of proteins,  analyse fatty acids, and determine whether methane (CH4) found in the plumes could have been produced by living organisms.