The threat of Starlink

This is the English adaptation of the article I published in the Spanish science communication website yesterday, Tuesday 4th June 2019, which was an extended version of the article I wrote for my weekly section “Zoco de Astronomía” in Diario Córdoba last Sunday, 2nd June 2019.

If the light reflected by satellites is not limited, the new “satellite constellations” such as Starlink may not only be a problem for the scientific observations of professional astrophysicists and amateur astronomers but they will also induce a loss for our society, as we could have more satellites than stars visible to the naked eye anywhere in the world during several hours during the night.

For generations and generations we human beings have looked to the heavens and left in them our illusions, hopes, aspirations, goals, even searched for our own origins. The contemplation of a completely starry sky awakens all kinds of feelings in the human being, has defined us as people, as cultures and as societies. Being under a sky full of stars on a moonless night is really one of nature’s greatest spectacles we can enjoy. An unique show that, little by little, we are losing.

First it was the light pollution. As cities grew and technology was able to produce electricity cheaply, we began to shine irresponsibly. It is incredible how little aware we are of the problem of light pollution: billions of euros are lost every year around the world illuminating the sky, something that has as ominous consequences the impact on the environment and human health, in addition to erasing at a stroke until 95% of all the stars we could see in the sky. This generation, the one that is growing now, is the first one in all history that has not been able to enjoy a dark starry sky. Sadly, in many large cities of the civilized world children believe that the true color of the night is orange (or blue, after the introduction of the terrible lighting using LEDs).

These days we are starting to be aware of a new threat to enjoy the starry sky. This thread is global, and not local as the light pollution is. After all one “can  escape” from the light pollution, even for a few days, taking refuge in dark places in the middle of the countryside, on the tops of mountains, in the middle of the ocean, on deserted islands or in the middle of the desert. But we could not escape this new threat if it materializes.

On Thursday, May 23, 2019, the US private space company SpaceX , led by the famous Elon Musk , launched a group of 60 satellites in low Earth orbit . This group of satellites is the first of a super satellite complex (also referred to as a “constellation“) known as Starlink . In the next few years, SpaceX has planned many more launches of these individual satellites, perhaps even surpassing 12,000 units in a decade. The goal of Starlink is to get internet service to everyone at a low cost. But these satellites, which have solar panels and metal surfaces, are visible to the naked eye. Since the launch of these 60 Starlink satellites have been seen by hundreds of thousands of people. These sightings have unleashed the controversy: the satellites are much brighter than expected.

(a) Coverage of the Starlink constellation. (b) Starlink satellites. (c) Starlink satellites prior to being released by the second stage of Falcon 9. (d) Image of the group of galaxies NGC 5353 with the diagonal traces of the Starlink satellite group crossing the field of view, as observed on Saturday 25 of May. Credits: (a) Mark Handley, (b, c) Space X (d) Victoria Girgis, Lowell Observatory.

How bright? It depends on the specific moment, but on some occasions they can equal the brightness of the brightest stars, with flashes that exceed the brightness of Sirius, the brightest star in the night sky. There are internet pages and apps that let you know what artificial satellites can be seen from a particular place on a particular night. Searching for the passage of the International Space Station (ISS) is quite common, for example, and usually like everyone. But the problem here is that there would be 12,000 satellites up there: although the space around the Earth is large, it is not so large, and there will always be tens or hundreds of satellites visible at a particular moment of the night. So much that the worst estimations indicate that there might be more satellites moving through the sky than fixed stars that we can see with the naked eye in urban areas.

Some astronomers have tried to make calculations to account for the problem. For example, the Dutch astrophysicist Cees Bassa accounted for only 1,600 satellites (the first phase of the Starlink constellation), estimating that in places with latitudes equal to that of London (52 degrees north) there would always be 84 satellites visible at any time, of which 15 would be easily visible, especially in the summer months when the sun does not fall much over the horizon. The visibility of satellites is worse in the hours close to sunset or sunrise. With 12 thousand satellites he estimated that between 70 and 100 satellites would be visible from any point of the sky for much of the night. Of course, the exact brightness of these satellites once they are in their final orbit is still unknown, but right now it is feared that many of them can be really as bright as the stars that are seen from places with high light pollution.

Graph showing the number of Starlink satellites visible in latitudes of 52º (London). It assumes 7500 satellites at 340 km altitude, with 75 orbital planes, each with 100 satellites. Only satellites that have a height greater than 30º above the horizon are included. The horizontal axis collects the time of day and the vertical axis the day of the year. The green and red stripes show the sunrise and sunset, respectively. The color yellow corresponds to 40 satellites, the color black to 0 satellites. Following this figure there would be an average of 40 satellites illuminated at any time in the hours around twilight, and all night in the months near the summer solstice (June and July). Credit: Cees Bassa.

Amateur astronomers are screaming blue murder. And many professional astrophysicists too. Some have had curious interactions with Elon Musk, who in this case does not seem to be setting a good example because he has helped spread bad information. For example, in a tweet he said that “the ISS looks very bright because they turn on the lights“, something that is completely false because it simply reflects the light of the Sun, just as Starlink’s satellites do.

In addition to the loss of the starry sky to the general public, the large increase in artificial satellites in low Earth orbit is a huge problem no longer to amateur astronomers (they are used to occasionally have “traces” of artificial satellites in their photos, but this is corrected by obtaining many photos and averaging when stacking) but to professional astrophysicists. Astrophysical images are often “deep ” (exposures of many minutes, sometimes an hour) but few (2 – 5 images per target), so the “clean” data would be much more complicated. And to this we have to add that the many calibration images (for example, “flatfields“), that are fundamental for the correct scientific use of the data, would also be affected, and it is necessary to invest more time than is currently used in these shots. calibration to make sure they are valid.

In the coming years new telescopic installations will be inaugurated. Some of them are costing a lot of money and are thought to take images in very large fields of the sky. For example, the Large Synoptic Survey Telescope (LSST) will be capable of mapping the entire sky in only 3 nights. Nonetheless, this early morning LSST has issued a statement notifying that, after a preliminary study, the impact of the satellites of the Starlink constellation would be very small for LSST. That is because the algorithm that combines individual frames (3 of them) into a final scientific image should be able to eliminate the satellite traces.

But it is not only the large telescopes: there are dozens of “modest” professional telescopes (say, between half a meter and 4 meters in size) that perform fundamental scientific work, for example, the hunting of asteroids and comets or the search for supernovas. All these scientific observations would also be affected by satellite traces.

Another problem added: the radio-interference that the satellites would cause in radio telescopes . This is something well known by professionals and difficult to quantify until the satellites are actually there. One of the most ambitious international projects is precisely the SKASquare Kilometer Array“, a network with thousands of radio telescopes that will be installed between South Africa and Australia. If constellations of satellites like Starlink are not careful in limiting the frequencies in which they emit and receive they could greatly limit the huge investment in technical and human capital that is being used in SKA. Several professional radio astronomy organizations, including the NRAO ( National Radio Astronomy Observatory, USA ), have issued statements insisting that SpaceX has been in contact with them to minimize the impact of radio interference on scientific observation, delimiting “exclusion zones“. These are frequency ranges that should not be used in satellites, to minimize the impact on astrophysical tasks from the ground. But this does not have to be the case in constellations of satellites launched by other companies or other countries.

Here we also have to insist on something else: we do not need to go into space for doing astronomy (as indeed Elon Musk himself suggested): many of these installations (telescopes of class 30 meters and radio interferometers such as the SKA) are only possible on Earth, at least with the current means and budgets. In addition, satellites in low orbit also interfere with the work of space telescopes such as the HST ( Hubble Space Telescope )! It is not common yet, but it is detected in some shots of the HST the passage of artificial satellites as “defocused strokes” .

Early this week, the International Astronomical Union (IAU) issued a statement precisely warning of this problem, notifying that “we still do not understand well the impact of thousands of these satellites visible throughout the night sky and, despite their good intentions, these constellations of satellites can threaten [astronomical observations in optical and radio] In the same statement, the IAU asks all the companies involved and legislators to work together with the astronomical community to understand the real impact that satellite constellations may have and thus eliminate or at least mitigate their impact on scientific work and exploration. space.

Indeed, many of us do not expect to suspend these space projects, but we hope that satellite companies take this problem into account, in order to minimize the reflectivity of the satellites and the frequencies in which they operate, and to legislate correctly so that this actually happens. It is no longer just SpaceX: several international companies want to launch their own satellite constellations in the near future, reaching more than 50,000 in just a couple of decades.

In 20 years or so, the children of our world will might see the sky as an orange glow where hundreds of bright spots are continuously moving, losing forever the real beauty of the night sky. And they will not be able to escape from this pollution: it does not matter where you are on Earth, far or near cities, if you’re lost in a desert, in the middle of the ocean or in an astronomical observatory:  there could be dozens or hundreds of satellites moving through the sky almost at any moment. Goodbye to the romanticism of Astronomy and identifying the constellations in the sky. Goodbye to a society and young people marveling at the beauty of a dark sky full of stars. They might get the best internet connection, but they will be losing what once it made us dream with the stars.



Twitter helping in a busy week

You might or might not know that I’ve been trying to be very active in my favorite social media network, Twitter, for the last years. I joined Twitter in 2011 just to promote my Spanish blog “El Lobo Rayado“, that is why my username still is @El_Lobo_Rayado (*)

In some way, micro-posting in Twitter has had a huge impact on the way I do science communication. For example, I used to write long posts in my Spanish blog explaining or discussing astronomy news, but now I do that in Twitter, and almost everything in English. Twitter drastically changed my presence in the web, also helping me to promote science communication events, and at the same time contacting very interesting people.

Social media and science communication have evolved A LOT between 2011 and 2019, that’s for sure.

Twitter has been increasingly popular for researchers, astronomers in particular, and a bit of “networking” is also done there. Conferences usually have a hashtag to follow, sometimes even a full twitter account, and that has been my way of capturing and summarizing the talks, sometimes providing comments or discussions to the topics that were discussed. And even, I must confess, writing Twitter posts including some photos of the talk is now the way I’m taking notes during the Conference.

I’m doing that using threads, that is, connecting all my tweets one after the other. Some people of Twitter use threads to tell a story as if it was a post in a conventional blog… but breaking the post in many (10-50 or even more) independent tweets. I don’t like that. In my personal opinion, if you want to tell that much, just write a post in a blog and provide the link in a single tweet! But that is my humble opinion, I can understand that other people DO LOVE to write threads (and even they first prepare them in a separate document to know how many tweets are needed and/or schedule the individual tweets seeking the highest impact).

What was missing? Compiling all those tweets in an easy way! If you are familiar to Twitter you know that, after some few days (it depends on how active you are) it is not that easy to find a particular tweet. In the past we had Storify to collect tweets, not necessarily from the same account. It was quite good, although it involved a bit of extra work compiling tweets and sorting them. But Storify was closed a year ago (and with that some of us lost plenty of useful information, as the tens of #AskAAO sessions we used to have in the old “Australian Astronomical Observatory”).

Luckily recently a new tool came into play to help us with that. It is the Thread Reader App, that allows the user to get a full post compiling all the tweets in a thread. How to do it? Easy: just send a tweet to @threadreaderapp at the end of your Twitter thread including the word “unroll“… and magic happens!

And that is what I’ve done today to compile my tweets of Monday and Tuesday… busy as I’m both attending the “ASTRO-3D Science Meeting 2019#A3Dscimeet19 AND helping in the international science communication festival “Pint of Science#PintAU19 #Pint19AU in the evenings…

Here they are the posts with all my tweets during the week:

I have to say… I should be at the #A3Dscimeet19 right now but I had some few “urgent” things to do at the university, and later I got some few emails and… well… here I am in my office writing this.

But I’ll update it later with today’s thread. Done!

(*) I say “still” because I’m seriously considering changing it to a “more English-speakers friendly” username…


The Galaxy and me

The Galaxy and me

The Anglo-Australian Telescope, The Emu in the Sky (The Milky Way), the Southern Cross, Carina Nebula, Large Magellanic Cloud, Jupiter, Saturn… and me! Single 15s shot using a CANON 5D Mark III with a 14mm lens at f2.8, 1600ISO. Photo taken at 1.15am AEST, Saturday 6th April 2019.

Full resolution image in my Flickr.

Credit: Ángel R. López-Sánchez (Australian Astronomical Optics, Macquarie University).

Podcast “Astronomía para Principiantes” in SBS radio Australia in Spanish

Since the beginning of 2016 I collaborate with  SBS Radio Australia en español (SBS Radio Australia in Spanish) with a section about Astronomy. The idea came from the journalist Anna Sagristà who, after interviewing me for the section “Latinos in Australia” (*), invited me to have an informal conversation of ten minutes about some Astronomy facts of interesting news.

That was the birth of “Astronomía para Principiantes” (Astronomy for Beginners), a monthly section on SBS Radio Australia in Spanish, that I also upload as a podcast in iVoox.

It is redundant to say that this podcast is in Spanish, but it is conducted in Australia, and that is why I think it is convenient I talk about it in this blog, as one of the many science communication activities I do in this country.

With the return of Anna to Spain in mid-2016, it is my friend the journalist Rocío Otoya who has been conducting the section.

Astronomy for Beginners is usually released on the last Sunday of every month.
The most recent episode (number 31) was aired on Sunday, 31st March 2019 and it was dedicated to the Milky Way and its “weight”. However, on my iVoox channel I have uploaded so far only to Episode 23 (ApP23: The Blue Blood Supermoon, January 28, 2018). I’ll be uploading the rest of episodes during the next weeks.

Besides publicizing this science communication podcast in Australia, I’m compiling here the list with all the episodes of “Astronomía para Principiantes” that are published in iVoox:

I added one of the “special episodes” on the first detection of gravitational waves, I should upload the other two that we recorded (one on “Estrella Cervantes” and the aforementioned interview on the SBS section “Latinos in Australia”).

I will update this entry when I publish new episodes.

I hope you like it! Some English-speakers have told me they use it for practicing their Spanish, which is always a good thing!

(*) I am not responsible for the title given to this interview …

Visiting the Macarthur Astronomical Society

Yesterday I was visiting my friends at the Macarthur Astronomical Society (MAS), which is based in Campbelltown, at the south of Sydney. I have had the privilege of visiting them several times in the last years, where I talked about different aspects of Astronomy, from the “Light of the Universe” to the “Colour of the galaxies” till “Amateur Spectroscopy“.

This time I was presenting my very own research, the Hi-KIDS project (the “HI KOALA IFS Dwarf galaxy Survey“, that I have to eventually publicize here too.

My talk was entitled “Dissecting Dwarf Galaxies with The AAT“. The abstract  was:

Dwarf galaxies provide fundamental clues about galaxy origin and evolution. Many of them have irregular shapes and have processed little their gas, although they possess many old stars born billions of years ago. Still, many dwarf galaxies are very gas-rich and are currently forming stars, sometimes in a spectacular way. With these new observations using the powerful KOALA+AAOmega instruments at the 3.9m Anglo-Australian Telescope we are “dissecting” these dwarf galaxies to characterize the properties of the gas and the stars within them. Combining these new data with deep radio observations at 21 cm of the diffuse, cold gas within and surrounding these dwarf galaxies we will get a better understanding of the local and global star-formation processes in galaxies, the feedback of the newborn stars into the galaxies, the importance of inflows and outflows of gas, and the chemical evolution of nearby dwarf galaxies.

You can find some photos of the talk in the Facebook webpage of the Macarthur Astronomical Society.

I have to say that this is a very welcome audience and that I have always enjoyed a lot the visit to MAS. They have an invited speaker almost every month, getting many Australian (and overseas) astrophysicists to talk to them. You can have a look to the full list in the MAS webpage.

Thanks for having me and see you in another astronomy event or talk soon!

Intriguing Wolf-Rayet star discovered

A new, very intriguing Wolf-Rayet star has been discovered in the Milky Way. Actually it is a massive triple star system. It has been nicknamed Apep after an ancient Egyptian deity, this may be the first ever gamma-ray burst progenitor found.

The research has been mainly conducted at the University of Sydney using data from the Anglo-Australian Telescope (AAT) and ESO’s Very Large Telescope. The announcement was made public yesterday in several media releases by the European Southern Observatory and the University of Sydney, following the publication of the research paper in Nature Astronomy.

Image of Apep captured in the thermal infrared with the VISIR camera on the European Southern Observatory’s VLT telescope in Chile. Credit: Professor Peter Tuthill/ESO.

Earlier this week I was contacted from a journalist from The Age, Liam Mannix, who wanted to talk to me as “expert of Wolf-Rayet stars who has not participated in this research”. He called me and I spent 20 minutes to half an hour explaining what Wolf-Rayet stars are, the few of these stars known in our Galaxy (~600s) as they are the descendant of the most massive stars (and these are quite rare), and more. Of course, this conversation was latter summarized in a line in the article that he prepared:

Systems like this are very, very rare,” says Angel Lopez-Sanchez, an astrophysicist at Macquarie University who studies Wolf-Rayets and was not involved in the research. “It is a very exciting finding.”

But in any case I’m very happy I had this conversation with Liam and that I could contribute at least to the dissemination of this nice work.

Eclipse of the body

This is the translation and adaptation to English of my article “Eclipse de cuerpo“, originally published on Sunday, 21st Oct 2018 in the Supplement “El Zoco” of  the newspaper Diario Córdoba. This article summarizes my experience after being diagnosed by the Guillain-Barré Syndrome. I’m still recovering from this, as plenty of rehabilitation and gym are needed. So you are still wandering why I have not answered your email… well, that it is! Thanks a lot for all your support during these hard times.

During the second week of July I was in my natal city, Córdoba (Spain), giving talks at the University of Cordoba within the activities of its Foro Único (which I have the privilege of being part of since its creation) together with the Scientific Culture Unit of the University of Córdoba (“Unidad de Cultura Científica de la Universidad de Córdoba“) and the Astronomical Association of Córdoba. At the same time, I was finishing preparing my contributions (including an invited talk in a plenary session) for the Astronomy Conference and Science Meeting organized every two years by the Spanish Society of Astronomy (“Sociedad Española de Astronomía”) and held in Salamanca (Spain) the following week . These activities promoted not only the dissemination of my scientific work but also the need to inform society about the astronomical discoveries we as researchers are doing.

Without expecting it, and in just four days, from lectures, nice walks, talks, “tapas” and meetings with collaborators, scientists, astronomers and friends in Córdoba, I had to be admitted to the Intense Care Unit (ICU) of the Reina Sofía University Hospital with an induced coma and with the body paralyzed almost entirely. I had been affected by the Guillain-Barré syndrome.

This ill-fated and terrible neurological disease, of which some details are still unknown as to why exactly it does occur, is an autoimmune disorder in which the antibodies generated to attack a virus also attack the nervous system. Consequently the nerves can not send the signals effectively and the muscles lose their ability to respond. This leads to the paralysis of legs, arms, hands and feet, the inability to have sensations such as pain, cold or heat, and even the paralysis of the digestive, excretory and respiratory systems. Although Guillain-Barré syndrome only occurs in 1-2 cases per 100 thousand people per year, its death rate is around 7.5%, usually as a result of respiratory failure induced by paralysis.

Fortunately I was in Córdoba, where one of the best hospitals in Spain (and I would add of Europe or even the whole world) is located. The professionals at the Hospital Universitario de Reina Sofía not only diagnosed the disease quickly, but they did an exhaustive follow-up of everything that was happening to me. The treatment (plasmapheresis, that is, “filtering” the blood to extract the plasma, leaving only the red blood cells, white blood cells and platelets, which did return to the body), the speed of taking me to the ICU to intubate, feed me and make me eliminate my waste, and the rehabilitation from day zero were key to recovery.

Me at the UCI at Hospital Universitario Reina Sofía on 3rd August 2018, just after the doctors removed the breathing tube.

Me at the UCI at Hospital Universitario Reina Sofía on 3rd August 2018, just after the doctors removed the breathing tube.

In 10 days I was able to breathe again for myself and talk (I do not recommend being fully conscious and not being able to communicate). In 3 weeks I was able to use my mobile phone again, write and feed myself. In just a month and a half I was able to walk again, with help. A month ago, on Sep 19th, at the insistence of the Australian insurance (as I do not quote in the Spanish social security all the hospital expenses were charged to my Australian travel insurance), I returned to Sydney. Three months later I start to see it as a bad dream, I have returned to work and I have a completely normal life, only that I still have a lot of muscle to recover (I lost almost 15 kilos of weight) and I still get fatigued more than usual. In another 3 months I hope to be fully recovered.

In total I spent 19 days (three of them unconscious) in the ICU of Reina Sofía and another two weeks more in plant, plus one month going daily to rehabilitation, where day by day the team of doctors, nurses, physiotherapists, assistants, caretakers and others showed excellent treatment both professionally and personally.

Me with some of the doctors, nurses, and specialists at Hospital Universitario Reina Sofía who helped me to recover so fast! This was taken on 6th September 2018, when I was starting to walk a bit (the walking frame I was still using by then is not seen in the photo).

That’s why my first Astronomy article this season, and the first science or outreach article I write after returning to work this third week of October (three months after the start of the illness) is dedicated to the exceptional staff of Reina Sofía. I do not want to give a long list of names for fear of leaving many people behind, but I insist that I do not have enough words of thanks to each and every one of them. It is something that should make us feel very proud to Cordoba, and we should support at all times to continue to make the impressive medical and research work that takes place at the Hospital Universitario de Reina Sofía.

It happened that, being in the phase of improvement at the end of July but still in the ICU, there was a total lunar eclipse visible from Europe and Asia. This lunar eclipse in the middle of summer delighted amateur astronomers and the general public, who enjoyed this beautiful celestial spectacle that does not need a telescope to be observed. A total lunar eclipse  occurs when our satellite enters into the shadow of the Earth. The phantom color between orange, red and black that the Moon acquires is a consequence of the light refracted by the Earth’s atmosphere. The poets can say that we are seeing all the sunsets and sunrises that are happening on Earth at that moment. From Spain the total phase occurred shortly after the departure of the full moon over the eastern horizon, which left beautiful prints of our red satellite next to monuments or mountains. It also proliferated through social networks multitude of “fake photographs” made as assemblies (I was shown one of the Roman Bridge in Córdoba with a full moon eclipsed so big that to have been real our satellite should be 20 or 30 times closer to Earth than it actually is!) .

Total Lunar Eclipse on 27th July 2018 seen from Córdoba, Spain. Credit: Paco Bellido.

Here I compile the wonderful shots that the astrophotographer Paco Bellido took from Córdoba showing the moon completely eclipsed (below left) and two shots of the eclipse when the moon was leaving the Earth’s shadow.

This lunar eclipse occurred on July 27 and I missed it (unfortunately, the window of my ICU room did not have the correct orientation). But for this I had suffered an eclipse of the body myself!