October brought about two small but tasty bites of space news: organic compounds floating on Enceladus and cosmic threads of hydrogen connecting galaxies.
Enceladus, a Saturn moon, has been in the exobiology crosshair for some time now because of its ocean. Astrophysicists had been hopeful about that saltwater sea, liquid under an ice crust, perhaps containing chemical building blocks of life. And, bingo, it was found that molecules with nitrogen and oxygen, i.e. possible amino-acid ingredients, are floating in it.
The molecules were found in jets escaping from cracks in the ice, which spacecraft Cassini passed through back in 2008. Cassini data sure take a long time to work through – and who knows if the life cocktail might not have already started mixing in the distant dark sea by now :p
As about hydrogen, it doesn’t only make up burning spheres in the sky (yes, this is stars), but it’s also believed to mostly roam between galaxies. More precisely, it’s believed that huge elongated hydrogen clouds spread through universe and where they intersect galaxies form. And now these gaseous threads were seen for the first time.
The European Southern Observatory’s Very Large Telescope squinted at a cluster with many young galaxies. What it looked for was a web of hydrogen filaments faintly illuminated by galactic light. This is indeed what it saw, with the galaxies forming where the filaments cross. If more observations of this kind come in their faint shine will confirm a lot of the current theories about how cosmic objects emerged slowly in the millions of years following the big bang.
That's not all. Since this month was particularly quiet, I thought I’d take the chance for something different: to amend two things that the Ph-word wrote about incorrectly in the past (and which also have some gossip value, of course).
So, in September
the hot topic was the tardigrades now hibernating on the moon, after spacecraft Beresheet crashed on it. The mistake in that story was that the crash and the subsequent “colonization” actually took place in April. The fun is that the tardigrades part became publicly known in August, only after Wired magazine found out about it.
Yes, this means that the agencies who sent a life form to moon kept this fact a secret – or, perhaps, it was meant as a future surprise?
Then, in May of last year the Ph-word had an overview of the epic history of gravitational wave discoveries by LIGO and Virgo experiments. Now this will get a bit more technical. The takeaway is that there are three points of skepticism around LIGO, not really about its overall results but rather about the standards involved in its work, that make the story somewhat less epic.
First is the treatment of “noise”, i.e. the sources of potentially fake signal, something that plagues every experiment. For this reason the proper treatment of noise is among the first things that every experiment shows publicly that they are doing correctly. However, ever since the start of its operations there has been concern about whether LIGO is lagging in this sector. As time went by more relevant studies were made public – but the concerns were only dispelled de facto thanks to the event of August ’17.
Which brings us to the second point – the event of August ’17. Back then LIGO caught a gravitational signal, it cross-checked it with Virgo which permitted the rough localization of its source in the sky, and then it notified observatories around the world which were able to observe the accompanying light in a distant galaxy. This sure showed that the experiments know what they are doing with their data.
Only that the sequence of events didn’t happen in this order.
LIGO comprises two detectors. One of them did get the signal but the other one didn’t, because it looked like a glitch (precisely the kind of problem people had been skeptical about). Fortunately the orbital telescope Fermi also caught a gamma-ray burst from the same source, it told LIGO, and only then was the glitch cleaned and the other observatories notified. So, LIGO and Virgo located correctly indeed the region of the sky using their measurements, but it was Fermi’s contribution that turned this into the “unprecedented triumph” that I (incorrectly) wrote.
And then there is the third point. This is about the most famous plot coming from LIGO, showing their first gravitational wave detection in September ’15. The issue arose in October of last year, when New Scientist magazine revealed that this plot was to some unknown extent drawn by humans, instead of being the product of computerized analysis. That’s a really unusual event for scientific publishing, and when it happens it is mentioned explicitly. Not mentioning it for three years until reporters find out can be called extremely unusual, especially if in the meantime that plot helped landing a Nobel prize.
Well, when someone is pretty good at something it’s probably a pity to try and show that they are dazzlingly good at it, as the ancient chinese proverb would have it.