Tag Archives: Galileo

Europe’s GPS-type constellation Galileo down

For as yet unexplained reasons, Europe’s entire Galileo constellation of GPS-type satellites has been out-of-operation for the past four days.

The European GNSS Agency (GSA), the organization in charge of Galileo, has not published any information in regards to the root of the outage, which began four days ago, on Thursday, July 11. On that day, the GSA published an advisory on its website alerting companies and government agencies employing the Galileo system that satellite signals have degraded and they “may not be available nor meet the minimum performance levels.” The agency warned that the Galileo system “should be employed at users’ own risk.”

The GSA published a more dire warning on Saturday, July 13, when it said that Galileo was experiencing a full-service outage and that “signals are not to be used.”

I cannot imagine any technical problem on the satellites themselves that would cause them all to fail at the same time. Instead, this appears to be some form of sabotage, a variation of the recent Russian tactic of disrupting GPS in areas they consider sensitive.

It also may explain the announcement yesterday by French president Macron that France is going to create its own space command.

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Historian discovers long-lost original of Galileo letter

An historian doing different research in the library of Great Britain’s Royal Society has accidentally discovered a long-lost original of a letter by Galileo that might clarify the events surrounding his eventual trial with the Inquisition.

The seven-page letter, written to a friend on 21 December 1613 and signed “G.G.”, provides the strongest evidence yet that, at the start of his battle with the religious authorities, Galileo actively engaged in damage control and tried to spread a toned-down version of his claims.

The question that has been bothering historians for hundreds of years is whether the letter, used as evidence against Galileo during his inquisition trail, was doctored by the inquisition or Galileo. During the trial Galileo presented a milder version that he claimed was the original. This original, with corrections in Galileo’s hand, suggests it was he that did the rewrite.

The story of how postdoctoral student from Italy, Salvatore Ricciardo, found it in a British library however is as interesting:

Ricciardo uncovered the document when he was spending a month this summer touring British libraries to study any handwritten comments that readers might have left on Galileo’s printed works. When his one day at the Royal Society was finished, he idly flicked through the online catalogue looking for anything to do with Castelli, whose writings he had recently finished editing.

One entry jumped out at him — a letter that Galileo wrote to Castelli. According to the catalogue, it was dated 21 October 1613. When Ricciardo examined it, his heart leapt. It appeared to include Galileo’s own signature, “G.G.”; was actually dated 21 December 1613; and contained many crossings out. He immediately realized the letter’s potential importance and asked for permission to photograph all seven pages.

“Strange as it might seem, it has gone unnoticed for centuries, as if it were transparent,” says Giudice [Ricciardo’s doctoral supervisor]. The misdating might be one reason that the letter has been overlooked by Galileo scholars, says Giudice. The letter was included in an 1840 Royal Society catalogue — but was also misdated there, as 21 December 1618.Another reason might be that the Royal Society is not the go-to place in the United Kingdom for this type of historical document, whose more natural home would have been the British Library.

The historians are now trying to trace how long the letter has been in the Royal Society library, and how it arrived there. They know that it has been there since at least the mid-eighteenth century, and they have found hints in old catalogues that it might even have been there a century or more earlier. The researchers speculate that it might have arrived at the society thanks to close connections between the Royal Society and the Academy of Experiments in Florence, which was founded in 1657 by Galileo’s students but fizzled out within a decade or so.

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Europa water plume detected in old Galileo data

Using old Galileo data and new techniques of analysis scientists have uncovered a water plume on Europa that the spacecraft flew through in 1997.

Over the course of 5 minutes, spikes the spacecraft recorded with its magnetic and plasma sensors reflected the alterations that a veil of ejected water, from one or many vents, could cause in a region matching the telescope observations, they report today in Nature Astronomy. This indicates that a region of the moon potentially 1000 kilometers long could host such activity, though it is impossible to say whether this is a single plume or many, like the complex system of fractures and vents seen on Enceladus. Indeed, on its own, this evidence was too weak to tie to erupting water in a 2001 study describing it, the authors add, but it fits well with the Hubble and modeled evidence.

As indicated by the quote above, the result has a lot of uncertainty.

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Scientists catch a big volcano eruption on Io

Scientists reviewing twenty year old data from the Galileo orbiter that studied Jupiter and its moons in the 1990s have identified the most intense volcanic eruption yet found on Io.

While looking through the NIMS temperature data, Davies and his colleagues spotted a brief but intense moment of high temperatures that cooled oddly quickly. This signal showed up as a spike in heat from a region in the southern hemisphere called Marduk Fluctus. First, the researchers saw a heat signal jump to 4–10 times higher than background, or relatively normal, levels. Then just a minute later, the signal dropped about 20%. Another minute later, the signal dropped another 75%. Twenty-three minutes later, the signal had plummeted to the equivalent of the background levels.

This signature resembled nothing Davies had seen before from Io. The lava flows and lava lakes are familiar: Their heat signals peter out slowly because as the surface of a lava flow cools, it creates a protective barrier of solid rock over a mushy, molten inside. Heat from magma underneath conducts through this newly formed crust and radiates from Io’s surface as it cools, which can take quite a long time.

This new heat signature, on the other hand, represents a process never before seen on Io, Davies said: something intense, powerful, and—most important—fast.

There’s only one likely explanation for what the instruments saw, explained Davies, whose volcanic expertise starts here on Earth. Large, violent eruptions like those seen at Stromboli are capable of spewing huge masses of tiny particles into the air, which cool quickly.

The article makes it sound like we’ve never seen this kind of eruption on Io before, which isn’t really true. Such eruptions have been imaged, but this is the first time that infrared data of their temperature spike was captured, thus confirming its nature.

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Europe’s continuing problems with Galileo GPS

A look at this week’s failed Soyuz launch and the continuing problems Europe has had building its Galileo GPS satellite constellation.

The program has had a series of problems and failures, which this most recent launch only helps highlight.

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Arianespace and ESA sign contract for three launches

Arianespace and the European Space Agency (ESA) signed a contract on Thursday for the Ariane 5 rocket to launch 12 more of Europe’s Galileo GPS satellites on three launches.

This contract is a perfect example of European pork. Europe’s Galileo system might provide competition to the U.S. GPS and Russian Glonass systems, but I am not sure what additional capabilities it provides that will convince GPS users to switch to it. Instead, building it provides European jobs, while using the Ariane 5 rocket to launch it gives that increasingly uncompetitive rocket some work to do. In fact, this situation really reminds me of the U.S. launch market in the 1990s, when Boeing and Lockheed Martin decided that, rather than compete with Russia and ESA for the launch market, they instead decided to rely entirely on U.S. government contracts, since those contracts didn’t really demand that they reduce their costs significantly to compete.

Europe now appears to be heading down that same road.

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Eddi Reader – Galileo

An evening pause:

Galileo fell in love as a Galilean boy
And he wondered what in heaven, who’d invented such a joy.
But the question got the better of his scientific mind
And to his blind and dying day
He’d look up high and love and sighed and sometimes cried,
Who puts the rainbows in the sky?
Who lights the stars in the night?
Who dreamt up someone so divine?
Someone like you and made them mine?

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