The story of Hitomi: a spacetime twist

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Four years ago, these days, I was living in Japan, and the Hitomi satellite was disintegrating in the sky along with my dreams of calibrating astronomical data never seen before.

Hitomi before launch, photographed in the Tsukuba space center, Japan.
Image of the launch of the Hitomi satellite from the Tanegashima Space Center on February 17, 2016.

Hitomi means pupil. The black of the pupil, where the light enters.

Designed to detect cosmic X-rays with a much higher resolution than that of the best existing telescopes, launched from the Tanegashima Space Center on February 17th 2016, on the night between March 26th and 27th 2016 Hitomi disintegrated in the sky while whirling and spinning on itself, out of control.

Infrared images of what remains of the Hitomi satellite, taken on April 2, 2016 by the Japanese telescope Subaru: in addition to the main body of Hitomi, various pieces of a few meters in size can be distinguished.

The news of the disintegration in orbit did not immediately reach Earth: the fate of Hitomi, for us humans, remained unclear for about a dozen days and a dozen semi-sleepless nights. It was clear that the satellite was abnormally spinning on itself, having completely lost its “cosmic orientation“.

Images filmed by terrestrial cameras were showing the satellite traveling in an uncontrolled manner, appearing similar to a bizarre, confused shooting star.

The satellite had probably broken, but perhaps not in an unrecoverable way.

This image has an empty alt attribute; its file name is Screen-Shot-2020-03-30-at-8.46.43-PM.png
Photograph of the JAXA monitor with Hitomi’s scientists telling us the latest updates on the satellite situation. It was clear that the satellite was spinning on itself without control, and that it had broken: but in how many pieces? Maybe the solar panels were still intact ..?

On 29 March 2016 I was interviewed by Marco Malaspina of Media INAF, and the YouTube video below (in Italian, sorry!) faithfully reports the atmosphere I was breathing in those days: trust and hope, which would have been irreparably broken by the laws of physics a few days later.

A story as crazy as it is real, that of Hitomi; a chain of cosmic contingencies (space is hard!) and human errors crowned by the fatal, almost-comic one in the drama: a ‘ ‘ sign instead of a ‘ + ‘ sign!

A push in the wrong direction to the already confused satellite and … CRACK!

Centrifugal force in action on 2.7 orbiting tons that make unbalanced turns, and together with the satellite the scientific projects and visions of dozens and dozens of astronomers of all ages and of all nations are broken — but especially Japanese, Dutch, Americans, Swiss, Canadians — and scientists who worked there, and students who studied there. In short, a lot of science lost, evaporated.

Set of corporate logos of all the Space Agencies, Universities, Research Centers, Companies, Industries involved in the construction of Hitomi.
JAXA managers update us on the status of Hitomi. Game over: the satellite broke, it lost its solar panels, and there is no way to recover it. Sorry!

Before disintegrating, Hitomi left us the best X-ray “energy spectrum” that humanity has ever seen: its gaze on the cosmos has been unprecedented.

Observing the Universe with Hitomi was like wearing clean glasses for the first time, after decades: but a few hours later, those glasses broke. To say that we were left with a bitter taste is a severe understatement.

X-ray spectrum of the Perseus Cluster. In red the X-ray spectrum visible from the largest orbiting X-ray telescope, XMM-Newton. In black the X-ray spectrum visible by Hitomi. What for XMM-Newton seemed to be “broad hills” around 6.5, 6.8, 7.7 keV, are revealed by Hitomi to be a set of narrow and well-defined signals, rich in information.

Still, a few terrestrial revolution later, I can say that Hitomi has been one of my greatest masters, and I thank his lost bits much more often than I could have imagined four years ago.

Four years ago, I was saying, I was living in Japan: alone, in a studio flat in the Japanese aerospace exploration agency JAXA, outside Tokyo. I mostly ate algae, sushi, shrimp, eggs, soups, rice, miso, and beer.

Photograph of the building of the Japanese Aerospace Research and Exploration Institute (JAXA) where I was staying in Sagamihara, west of Tokyo.

I had been sent to Japan for a month on behalf of SRON (the Space Research Institute of the Netherlands), involved at the forefront of the Hitomi project, to help calibrate the Soft X-ray Spectrometer (SXS): a revolutionary instrument in the field of high energy astrophysics, X-rays in particular; it was the SXS who had supplied Hitomi with those fantastic “new X-ray glasses“.

Photograph of the SXS, Soft X-ray Spectrometer, the technological gem aboard Hitomi.

All this has never happened: with Hitomi broken in orbit, the need for my scientific contribution suddenly evaporated. Back in the Netherlands all alone and all sad, there had been no meeting to take stock of a situation that no longer existed: we went from meetings over meetings, precisely planned meetings, maniacally projected into the future week after week, day after day , to … nothing.

Nothing, niente, nada de nada.

The frustration of understanding that we couldn’t see the long-awaited black hole data for the next five or ten or twenty years, applied to the cosmic nothingness that surrounded me, fermented a creative impetus that kicked off a series of events that led me, a few years later, to live in another country, in love, married, detoxified, at the head of my own project, and to travel the world to talk about black hole winds, up to Ethiopia. Oh, spacetime!

It was April 12, 2016; there were only a few days left for my return trip to Europe, and for several days I had been living in cosmic nothingness, made of no data; no bright future perspectives; or rather: no future perspectives.

In my job I was caught in a bottleneck: still too young by age to compete for senior positions, and already too old academically to compete for junior positions. My fourth postdoc contract was about to expire, and from the present and future perspectives the big, sparkling piece had just vanished: Hitomi.

That April 12 I put a point in the present.

Partly like a game (kind of a puzzle), partly for fun (drawing black holes like comics), partly for frustration (“we won’t see new data for the next 5-10 years!” — Mantra-like), with the help and the encouragement of Chris Done — professor at Durham University and a giant in the field of black hole physics; also a guest at JAXA to collaborate on the development of Hitomi, and companion in those days of sushi and hopes and disillusions — I started to summarize everything we knew until then from the observational point of view on supermassive black holes that reside at center of galaxies (called active galactic nuclei, AGN) on a giant whiteboard in a giant classroom on the ninth floor of the JAXA.

I wanted to understand what we could say we had understood, as astronomers, until then, about supermassive black holes and the winds that can be generated near them.

In particular: what different types of wind do you expect for different supermassive black hole “diets”? Is there a (relatively) simple way of explaining the vast phenomenology of AGNs, simply by considering different diets (fat or slim black holes, who eat little or eat a lot)?

The JAXA whiteboard full of scientific doodles summarizing our knowledge of supermassive black holes from the point of view of X-rays and ultraviolet rays, in the spring of 2016. Three years and five months later, the article was printed in “Astronomy & Astrophysics”.

Two months later, this whiteboard had become a rickety draft article; four months later Daniel Proga enthusiastically entered the project; a year and a half later the article was rejected by the journal to which we had proposed it for publication, I was left unemployed, Chris left the project.

But as they say: “Nevertheless, she persisted” – or also: “She was just extremely stubborn”.

Rearranged the article together with Daniel, we changed format and journal; in July 2018 we resubmitted the article, which on 11 April 2019 was officially accepted for publication in Astronomy & Astrophysics, where it appeared in September 2019.

In the meantime, the scientific basis of the article had served me as an anchor to win funding for a senior project, that supports me so far.

What would have happened if Hitomi hadn’t broken?

Surely I could have already known better how supermassive black hole winds behave, very close to the event horizon.

My scientific career would have received a significant upward impulse, a consequence of the countless articles with revolutionary scientific results that would have resulted from the new Hitomi observations (indeed, a single observation with SXS gave birth to a dozen scientific articles…).

I would probably be working in Japan, or in the Netherlands, where I was postdoc at the time of Hitomi. I would be very fat, very sad, very lonely. I would be working for someone who would be working for someone who would be working for someone, on a strict hierarchical scale — probably inevitable when it comes to supporting the development of great scientific missions.

All those scientific articles were never born, yet a single stubborn article born out of nowhere allowed me to win a grant of the Comunidad de Madrid, thanks to which I have been the head of myself for almost a year, as I will be for the next three . Thanks to this project I am being able to refine the theoretical-observational scenario for the black hole winds that I described in the article with Daniel.

In the meantime, I collaborate with independent researchers, conducting exciting research on a completely new cosmic phenomenon: quasi-periodic eruptions of X-rays, QPE.

I live in a sunny country, where people laugh a lot, I am in love, married, slim, fit, detoxified, I eat well, without butter, at night I don’t drink beer – I actually became allergic to alcohol! – but chamomile, I work in the most beautiful research center I’ve ever seen, where they control the programs of the largest space telescopes that we scientists use, and where I can also grow my own tomatoes and zucchini.

I still don’t know how exactly black hole winds behave very close to the event horizon, but I’m trying to learn not to be in a hurry.

These are the main lessons learned from the Hitomi experience. This is the last slide of a public presentation that I held in Utrecht, the Netherlands, where I lived for another 23 months after returning from Japan.

  • it is necessary to know well, and to apply well, the basic math;
  • don’t make plans;
  • alternatives must be left open;
  • sleeping well is immensely important.

Hitomi taught me mainly not to make plans: to take advantage of the natural course of events as much as possible, since the big plans can change, break, even evaporate suddenly.

We are experiencing a season where small or large Hitomis have broken for all of us.

My advice is to accept what happened as a test, a space-time challenge. Collect all the pieces you own, look at them well, observe them one by one, and create everything possible with what you already have, with everything you already have available. Put this “everything possible” to ferment, and follow its natural evolution in the near future, with confidence.

Being able to scramble and rearrange spacetime from scratch is an opportunity that does not happen in every life.

Published by marghezz

Astronomer, human of planet Earth investigating supermassive black holes.

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