Regarding the Spiritron Transfer experiment, Aoko was a bit surprised, since she hadn't expected Marisbury to act so quickly. According to the original timeline, after Marisbury won the Holy Grail War and obtained enough money, it still took him quite a long time to activate Chaldeas. Then, after the equipment from the Atlas Institute arrived, the first Spiritron Transfer experiment was finally conducted—which, incidentally, failed.
Based on the somewhat uncertain information in Aoko's memory, when Chaldea first carried out Spiritron Transfer, the group of Masters who traveled to the past all died in that era. Moreover, that particular time point wasn't even a later Singularity, making the details here quite worth examining.
The so-called Spiritron Transfer is essentially converting the Master's physical entity into a Spiritron (quantum) state, entering a so-called "neither alive nor dead" and "unknown" state (inside a coffin-like box), so that coordinate adjustments can be made on the timeline, thus achieving time travel.
However, here lies the issue: in the Nasuverse, true time travel is encompassed only by magic, primarily the Second and Fifth Magics. The Jewel Magus travels to other points in time by operating through parallel worlds.
As for Aoko Aozaki, she uses herself as the center of the galaxy to search across the universe's space-time, but this method is undoubtedly an evil act that accelerates heat death and destroys the normal temporal order.
But Aoko doesn't care, because the degree of heat death she accelerates is but a drop in the ocean compared to the scale of the universe. Moreover, judging from the fact that she can use part of the Fifth Magic in another world, as long as she figures out the fundamental differences of each universe, even if she somehow manages to blow up the Nasuverse, she can still take her family and escape.
Back to the topic of Chaldea's Spiritron Transfer: according to the above, except for time travel achieved by the Five Great Magics, other means are questionable. In other words, Chaldeas' Spiritron Transfer is, to some extent, a form of cheating.
This is because the first step in Spiritron Transfer is to disassemble the Master inside the transfer chamber, and then reconstruct them at the observed point on Chaldeas. In between, the Master is defined as nothing inside the chamber.
To clarify, humans who have undergone Spiritron Transfer truly experience death and rebirth in the sense of human order. For the Master themselves, they really died. This is also why the Emperor of the Lostbelt called Chaldea's Spiritron Transfer an evil art.
Although Aoko herself won't be entering the chamber for Spiritron Transfer, she is still quite interested in Marisbury's experiment this time, because he mentioned in his letter that the destination is 7th-century Britain—the era in which the legendary King Arthur was active.
In his letter, the Lord of the Department of Astronomy not only filled the lines with flattery and compliments for the major shareholder but also subtly hinted that Aoko should bring Artoria along... It seems he wants King Arthur herself to witness the era she once lived in or perhaps to have a person involved confirm the success of his Spiritron Transfer.
Aoko had no objection to this request; she was also curious about the differences between the Age of Gods and regular history in this world. Although she had fought in the Holy Grail War and seen many Heroic Spirits, those were undoubtedly shadows projected from the past into the present, not the same as truly observing the past.
This kind of ambiguous view of history has always been a hallmark of the Nasuverse. Simply put, this Earth has two surface materials, a front and back. Although history is a single timeline, the stories on it are divided into the Age of Gods and mundane versions. This explains why ordinary people can never find traces of gods through archaeology, yet magi often manage to obtain all sorts of strange holy relics.
...Although she had decided to visit Finis Chaldea, the Department of Astronomy's base still under construction, there was still some time before the agreed date. Aoko decided to first take care of her affairs. After all, as the largest shareholder, even if she didn't show up, that white-haired guy probably wouldn't dare say anything.
After greeting Artoria and Gray, Aoko returned to the University of Tokyo. Her doctoral thesis was nearly finished, and after discussing it with her advisor and publishing it in a core academic journal, she'd likely be able to graduate.
She had already managed to get by with quite a few papers like this before, so she was quite adept at it.
That being said, Aoko's papers were quite substantial. In the fields of integer factorization and primality testing, she could be considered somewhat of an authority. That's also why she could come and go to university as she pleased without being criticized.
As for the topic of her dissertation, Aoko chose a project in the popular field of the RSA public-key cryptosystem. With her traverser foresight, getting a PhD was no problem at all.
Touko also knew about this, but she did not agree to go to Chaldea with Aoko. First, Touko had little interest in the Department of Astronomy's project. Second, she had accumulated quite a bit of work at the Clock Tower that needed her attention.
Lord El-Melloi happened to agree to give Aoko a magic furnace (to be put into the Principle Blood Ring), so Touko would act as a courier this time, bringing the magic furnace back to Japan.
However, Touko's main purpose was to meet up with an informant she had previously arranged. Reportedly, she'd hired a few professional magi to investigate Araya Souren's whereabouts and had made progress. It seemed they might soon be able to flush out and eliminate this deranged monk.
But if you asked Aoko, this was making things unnecessarily complicated, since Araya Souren was still in Japan, just hiding very well. There was no need to involve detectives and parade around the Mage's Association. It just showed that the name of the Third Magician wasn't very useful in Japan.
However, she'd heard that the magus detective Touko hired this time was an old acquaintance, apparently named Kairi Sisigou. In this worldline, he was still running around for his adopted daughter's health, willing to work with even such notorious people as Touko for the sake of money and rare elixirs—a rather lamentable sight.