How long does it take a planet to form – millions of years? Well, how about a moon – about the same? What if I told you the core of our Moon may have been formed in less than 6 hours? It sounds unlikely, but the idea was first proposed in 2022, and it has now got a degree of further backing.
To explain: the current broad theory is that the Moon was formed fairly shortly after Earth – around 100-150 million years after -, some 4.5 billion years ago as a result of a collision between proto-Earth and a body scientists call “Theia”, thought to be the size of Mars. The theory is that whilst Earth was dealt a glancing blow, Theia was utterly ripped apart due to a mix of the impact and Earth’s gravitational influence, resulting in a debris cloud which orbited the Earth and gradually – over further millions of years – accreted to form the Moon.
However, such a theory doesn’t account for why rocks returned to Earth by Apollo are, in isotopic terms, very similar to those of Earth’s mantle that they might well have formed here. Whilst some debris from Earth might have been cast off in a collision with Theia, by rights the lunar rocks should carry isotopic signatures largely different to those of Earth’s mantle.
In 2022, NASA funded research at Durham University’s Institute for Computational Cosmology in the UK to try to model how such a collision between proto-Earth and Theia might have resulted in the Mon’s formation. The several hundred simulations run by the ICC suggested that whilst the collision between Earth and Theia most likely gave rise to the Moon, it likely took place a lot sooner after proto-Earth had formed: around 60 million years after, rather then between 100-150 million years after.
Such a time period would mean that both bodies would be much hotter than in the 100-150 million year period for the collision, and this would result in two things: much of Theia would likely remain intact and sink to Earth’s molten core and considerably more of Earth’s molten mantle would be “splashed” into the space along with the rest of Theia.
Most interestingly, the ICC study suggested that contrary to common thinking, the debris cloud would have sufficient enough velocity imparted to it that it would start out dense enough and rotating about itself fast enough to coalesce extremely rapidly and without being ripped apart by Earth’s gravity. And by rapidly, the ICC suggested the core of the Moon could have formed within a day of the collision – if not in hours.
Now the Southwest Research Institute (SwRI) and the University of Arizona – two of the most globally-respected space research institutes – have published a study which, whilst acknowledging some of their modelling accounts for the Moon forming over a much more extended period of at least hundreds of thousands of years, very strongly supports the ICC’s simulations for a very rapid formation of the lunar core – potentially in as little of 5 or 6 hours after Theia’s destruction.
There is just one slight wrinkle with both the SwRI and ICC studies however: while both allow for material from Earth to form a proportion of the Moon’s make-up, they don’t explain why lunar surface rocks – even allowing for early volcanism on the Moon throwing up material from deep within it which might have originated from that collision debris cloud – are so very similar to Earth’s mantle rocks. As such, there is still more to learn about how the Moon as we know it today came to be. But the idea that its core came into existence in mere hours is intriguing.
Rocket Lab Launches GAO Protest
Earlier in September, NASA awarded a US $700 million contract to Blue Origin to build the Mars Telecommunication Network (MTN) – which despite having “network” in the name, is in fact a single satellite. The spacecraft is intended to be NASA’s next generation communications relay between missions operating on and around Mars and Earth.
Blue Origin had submitted a proposal for MTN in competition with New Zealand / US Rocket Lab – and the latter has now lodged a formal protest with the US Government Accountability Office (GAO) over how the contract was awarded.
On the surface, there is much that is puzzling about the decision to go with Blue Origin:
- Blue Origin has never actually built a satellite; Rocket Lab not only builds satellites for customers, it currently has two satellites en-route to Mars forming the NASA Escapade mission.
- Blue Origin has no experience with communications satellites other than launching them. Rocket Lab has built (and initially operated on behalf of clients) no fewer than eight communications satellites to date.
- Rocket Lab has a reputation for delivering satellites on-budget and on time. Blue Origin has no such reputation.
- Rocket Lab proposed developing, building and delivering MTN by 2028; Blue Origin is targeting 2030.
- Blue Origin proposes using their Blue Ring orbital vehicle as the MTN satellite “bus” (providing power, propulsion, etc.), although this has yet to fly beyond a demonstrator version. Rocket Lab already has a proven satellite bus in the form of Photon with, at the time of writing, three successful operational missions under its belt in addition to demonstrator flights.
The only significant advantage Blue Origin had going into the bid process was their New Glenn booster which, despite the NG-4 mishap, has successfully flown 3 times and is fully capable of delivering MTN to Mars. Rocket Lab would have to rely on their upcoming Neutron rocket, which has yet to fly.
In protesting the NASA decision to go with Blue Origin, Rocket Lab cites inconsistencies with the eligibility criteria for bids, as mandated by Congress in providing NASA with the MTN budget. However, the company has, understandably, refused to air what these inconsistencies might be in the court of public opinion.
For Blue Origin, this is very much a case of the shoe being on the other foot. In 2021, the company filed a protest with (initially) the GAO and then later in federal court, over NASA’s decision to both allow SpaceX form a late entry bid for the agency’s lunar Human Landing System (HLS) vehicle, before awarding the contract to SpaceX whilst denying a second HLS contact as agreed (a decision later reversed by Congress). Blue Origin ultimately lost both the GAO protest and the court case.
Whether Rocket Lab will go so far as federal court should GAO refuse to take action on the contract award remains to be seen. But contrary to social media sentiment against Rocket Lab, as noted above, the company does have some good standing on which to protest the decision.
Video Updates
Roman Grace Telescope
As the Nancy Grace Roman Space Telescope (or more simply, the Roman Space Telescope or RST) continues towards its rendezvous with a halo orbit around the Sun-Earth L2 position, let’s take time to look at the two primary instruments on the observatory and how they work by means of two short videos from NASA published a few years ago.
In the first, the CGI – or Coronagraph Instrument – and its ability to reveal the light of distant exoplanets to us is explored. In short, this instrument will enable scientists will be able to see the visible light reflected by planets that are older, colder, and in closer orbits than the hot, young super-Jupiters we’ve thus far been able to detect. CGI will conduct a series of pre-planned observations for a total of three months spread across the mission’s first year-and-a-half of operations.
The Wide Field Instrument (WFI) will enable RST to capture images of deep space around 100 times larger than those captured by the Advanced Camera on the Hubble Space Telescope. The WFI uses a total of 18 4K sensors and a short focal length for its images, and will be able to image and catalogue 50 times as much sky in its 5-year primary mission as Hubble covered in its first 30 years of operation. RST will thus carry out a complete sky survey 1,000 times faster than Hubble but with the same sensitivity and infrared resolution.
BepiColumbo: 8 Years in Under 5 Minutes
In my previous Space Sunday article, I wrote about BepiColombo, the joint European Space Agency (ESA) / Japan Aerospace Exploration Agency (JAXA) mission to Mercury, which is now – after eight years, nine billion kilometres and nine planetary fly-bys – soon to enter orbit around Mercury.
A couple of days after that article, ESA released a short video compressing the journey down to less than 5 minutes. The film has been made from images captured by the 3 monitoring cameras (M-Cams) mounted on the Mercury Transfer Module (MTM) used to provide propulsions and power to the spacecraft throughout its journey, and which – as I reported – has now been successfully jettisoned, its job done.
The 3 M-Cams were designed to monitor elements of the Mercury Planetary Orbiter (MPO), the main science vehicle being transported to Mercury by MTM. As such, they have fixed fields of view, reflected in the video below. Within it, and on the left are images from M-Cam 1, monitoring the solar array; in the centre are images from M-Cam 2, monitoring the instrument booms, and on the right, M-Cam 3, monitoring the MPO’s high-gain communications antenna.
Whilst fixed in position, all three cameras also caught sight of Earth, Venus and Mercury during the mission’s fly-bys, and the video present all nine in the following order:
- 0:38: Earth fly-by, April 10, 2020; visible as a white crescent on M-Cam 3 (right side images) as the spacecraft passed around the night side of the planet.
- 1:11: 1st Venus fly-by, October 15, 2020; initially visible as a small disk on M-Cam 3, then moving to larger disk on M-Cam 2 (centre).
- 1:24: 2nd Venus fly-by, August 10, 2021; briefly visible on M-Cam 1 (left) before filling M-Cam 2’s field of view and then “looping” (due to vehicle reorienting itself) and diminishing in M-Cam 3’s view.
- 1:32: 1st Mercury fly-by, October 1, 2021; visible in M-Cam 2 and then M-Cam 3.
- 1:48: 2nd Mercury fly-by, June 23, 2022; predominantly visible on M-Cam 2.
- 2:15: 3rd Mercury fly-by June 19, 2023; initially visible on M-Cam 1 during the approach phase, then on M-Cam 3 as the spacecraft departs.
- 2:41: 4th Mercury fly-by, September 4, 2024; near-continuous view of departure, M-Cam2 and M-Cam 3.
- 2:55 and 2:58: 5th Mercury fly-by, December 1, 2024; initially and briefly visible across the bottom of M-Cam 2 during approach, then briefly visible on M-Cam 2 and 3 at long-range during departure.
- 3:02: 6th Mercury fly-by, January 8, 2025; initially visible moving across M-Cam 1 and M-Cam 2 at a distance, then more closely in both cameras with overlapping images.
Note that the MTM camera did not have shutter, so there are occasions when white streaks appear on some images (notably M-Cam 3). Also not the changing levels of light on things like the solar array and instrument booms is the result of the spacecraft’s changing orientation relative to the Sun, while the high gain communications antenna can clearly be seen in motion on M-Cam 3’s images as it maintains a fix on Earth whilst the spacecraft periodically re-orients itself for things like engine burns and cooling.
Inara Pey: Living in a Modemworld 