Appeal by Astronomers

Safeguarding the Astronomical Sky (IT)

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This is an international appeal by professional astronomers open for subscription to ask for an intervention from institutions and governments.

Astronomical observations from the ground can be greatly harmed by the ongoing deployment of large satellite fleets in preparation for the next generation of telecommunications.

For centuries the astronomical observations from the ground have led to exceptional progress in our scientific understanding of the Laws of Nature. Currently, the capability of astronomical instrumentation from the ground is endangered by the deployment of satellites fleets.

Through this international appeal and following the same concerns expressed by the International Astronomical Union, IAU [1] and other institutions, we raise a formal request for greater effective protection and safeguard for professional astronomical observations from the ground, guaranteeing the right to observe a sky free from unnecessary artificial polluting sources.

In particular, all the signers, astronomers and collaborators wish to manifest humanly and personally their worry and contrariety to the sky coverage produced by artificial satellites, which represent a dramatic degradation of the scientific content for a huge set of astronomical observations.

The sky degradation is not only due to light pollution in the sky near cities and the most populated areas, but it is also due to artificial satellite fleets crossing and scarring observations with bright parallel streaks/trails at all latitudes.

Astronomers are extremely concerned by the possibility that Earth may be blanketed by tens of thousands of satellites, which will greatly outnumber the approximately 9,000 stars that are visible to the unaided human eye. This is not some distant threat. It’s already happening. The american private company SpaceX has already put 180 of these small satellites, collectively called Starlink, in the sky and plans to constellate the whole sky with about 42,000 satellites (placed at three different quota: 340km, 550km and 1150km). Thus, together with other telecommunication space projects in the near future (i.e. the English OneWeb, the Canadian Telesat, the American Amazon, Lynk and Facebook, the Russian Roscosmos and the Chinese Aerospace Science and Industry corp), there could be over 50,000 small satellites encircling the Earth (at different altitudes) for various telecommunication purposes but mainly delivering internet.

These new satellites are small, mass-produced, and orbit very close to the Earth with the intent to provide speedy internet connection with low-latency signals. But that closeness (~340Km) also makes them more visible, and brighter in the night sky especially when lighted by the Sun (satellites launched by SpaceX, 180 at the present day, are brighter than 99 percent of the population of objects visible by the Earth orbit ).

The current total number of cataloged objects in Earth orbit is less than 20,000 among spacecrafts, rocket bodies, fragmented mission and other related debrids, so with only the nominal Starlink fleet the total number of orbiting objects will triple (see pictures).(*)

In the mid and long term, this will severely diminish our view of the Universe, create more space debris, and, deprive humanity of an unblemished view of the night sky. It has been computed that most of these satellites will be visible to the naked eye (with a brightness between the 3rd and 7th magnitude particularly in the time after sunset and before sunrise, reaching the brightness of the stars in the Ursa Minor constellation (e.g. there are only 172 stars in the whole sky exceeding the expected brightness of Starlink satellites). Thus with 50k satellites the “normality” will be a sky crowded with artificial objects (every one square degree of the sky will have a satellite crawling in it along the whole observing night).

Not only observations with wide-field survey telescopes will be damaged (e.g. LSST [2] capable to scan and perform a survey of the entire sky in three nights or VST [3] with its 268MegaPixels camera and a FOV of 1 square degree or Pan-STARRS [4] with its FOV of 7 square degrees and 1.4 Giga pixels camera, …), but also deep/long exposures with small-field facilities will be unavoidably impaired, see picture and [7].

Considering that large area astronomical observations and sky survey are commonly used in NEO and asteroids monitoring and research related projects to guard the Earth planet from potential impact events, such satellite constellations could negatively impact on the ability to prevent and warn the whole humankind.(*)

Few starlink satellites visible in a mosaic of an astronomical image (NSF’s National Optical-Infrared Astronomy Research Laboratory/NSF/AURA/CTIO/DELVE)

This light pollution is extremely damaging for astronomical observations at all wavelengths. The recent attempt to use non-reflecting paint on the body (i.e. not the solar panels which represents 75% of the reflecting surface) of one of the Starlink satellite (n.1130 DARKSAT), see [8], even if their brightness would reduce to zero (which is impossible since the solar panels, which represent 3/4 of the reflective surface, would remain uncovered), the degradation for scientific observations will remain high for two reasons: 1) the stars and other objects in the universe will be eclipsed, therefore harming time-dependent (variability) studies, and,  2) the reflectivity of surface depends on the observational wavelength, so what becomes dark in one part of the spectrum (e.g. visible) remains bright or shines in other parts of the spectrum  (e.g. infrared or radio).(**)

It should also be noted that during nominal service operations SpaceX expects to dismiss and replace from 2,000 to 8,000 Starlink satellites every year, disintegrating them in the lower atmosphere, with all related issues.(*)

What is not widely acknowledged is that the development of the latest generation telecommunication networks (both from space and from Earth) already has a profound impact on radio-astronomical observations (at all sub-bands): with LEO satellite fleets it is feared that the situation will become unbearable.

In particular, low Earth orbit satellite’s spectral windows identified to communicate with earth stations in the Ku (12-18GHz), Ka (27-40GHz) and V (40-75GHz) bands will overlap with the nominal radio-astronomy bands and so will interfere with ground radio telescopes and radio interferometers, making the radio detectors enter in a non-linear regime in the K band (18.26.5GHz) and in Q band (33-50GHz). This fact will irreparably compromise the whole chain of analysis in those bands with repercussions on our understanding of the Universe, or even, making the astrophysics community blind to these spectral windows.

To aggravate the matter, with the current technological development, the planned density of radio frequency transmitters is impossible to envisage. In addition to millions of new commercial wireless hot spot base stations on Earth directly connected to the ~50,000 new satellites in space, will produce at least 200 billion of new transmitting objects, according to estimates, as part of the Internet of Things (IoT) by 2020-2022, and one trillion of objects a few years later. Such a large number of radio-emitting objects could make radio astronomy from ground stations impossible without a real protection made by countries’ safe zones where radio astronomy facility are placed. We wish to avoid that technological development without serious control would turn radio astronomy practice into an ancient extinct science.


We, astronomers subscribing to this appeal state THERE IS NO MORE TIME TO DISCUSS, IT IS TIME TO ACT!


  1. to be committed to provide legal protection to ground astronomical facilities in all of the available observation electromagnetic windows.
  2. to put on hold further Starlink launches (and other projects) and carry out an accurate moratorium on all technologies that can negatively impact astronomical observations from space and from the ground, or impact on the scientific, technological and economic investments that each State engages in astrophysical projects.
  3. to put in place a clear evaluation of risks and predictive impacts on astronomical observatories (i.e. loss of scientific and economic value), giving stringent guidelines to private individuals, societies and industries to plan satellite investments without clearly understanding all of the negative effects on outstanding astronomical facilities.
  4. that the US Federal Communications Commission (FCC) and any other national agency be wary of granting permission to ship non-geostationary low-orbit  satellites into orbit or alternatively to limit the authorization of only satellites  being above the airspace of the “home country”.
  5. to demand a worldwide orchestration, where national and international astronomical agencies can impose the right of veto on all those projects that negatively interfere with astronomical outstanding facilities.
  6. to limit and regulate the number of telecommunication satellite fleets to the “strictly necessary number” and to put them in orbit only when old-outdated technology satellites are deorbited, according to the Outer Space Treaty (1967) – the Art IX [5], and the United Nations Guidelines for the Long-term Sustainability of Outer Space Activities (2018) – guideline 2.2(c) [6], requiring the use of outer space be conducted “so as to avoid [its] harmful contamination and also adverse changes in the environment of the Earth” and […omissis…] risks to people, property, public health and the environment associated with the launch, in-orbit operation and re-entry of space objects”.


All of these requests come from the heartfelt concern of scientists arising from threatens to be barred from accessing the full knowledge of the Cosmos and the loss of an intangible asset of immeasurable value for humanity. In this context, all co-signers of this appeal consider ABSOLUTELY NECESSARY to put in place all possible measures to protect the night sky right also on the legal side. It would be desirable to adopt contingent and limiting resolutions to be ratified with shared international rules, which must be adopted by all space agencies to ensure protection for astronomical bands observable from the ground. All of this to continue to admire and study our Universe, for as long as possible.


[1]  https://www.iau.org/https://www.iau.org/news/announcements/detail/ann19035/?lang

[2]  https://www.lsst.orghttps://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory

[3]  https://www.eso.org/public/https://en.wikipedia.org/wiki/VLT_Survey_Telescope

[4]  https://panstarrs.stsci.edu/

[5]  https://www.unoosa.org/oosa/en/ourwork/spacelaw/treaties/introouterspacetreaty.html

[6]  https://www.unoosa.org/res/oosadoc/data/documents/2018/aac_1052018crp/aac_1052018crp_20_0_html/AC105_2018_CRP20E.pdf

[7] Simulated prediction of “only” 12k Starlink satellites in the sky: https://youtu.be/LGBuk2BTvJE and https://www.youtube.com/watch?v=z9hQfKd9kfA

[8] Visualization tool to find, plot and search satellite orbits: https://celestrak.com/cesium/orbit-viz.php?tle=/satcat/tle.php?INTDES=2020%2D001&satcat=/pub/satcat.txt&orbits=20&pixelSize=3&samplesPerPeriod=90

This appeal/petition can be signed by professional Astrophysicists & Astronomers, Technologists/Engineers , Collaborators & PHD Students involved in professional astronomical observations.

Note that (*) Such a sentence was added the 13/01/2020.

Note that (**) Such a sentence was added the 16/01/2020.

To sign/subscribe this appeal/petition you can follow this link.

Next Step?… legal action!

In this bad situation for astronomy, our task is clear: we are scientists and therefore we must analyze the phenomenon with the greatest possible accuracy and scientific rigor.

There are different international stakeholder players, so we need to consolidate collaborations among colleagues in order to analyze the problem quantitatively.

It is clearly needed to collect existing informations on the problem, without minimize issues to astronomy related to satellites’ constellations.

NO alarmism… only realism!

After the astro-amateur Thierry Legault , see here: https://astronomersappeal.wordpress.com/2020/02/09/darksat-not-so-dark/

Other non-professional astronomers (the Italian UAI) start the evaluation of light pollution caused by satellites: https://www.uai.it/sito/news/uai-inquinamento-luminoso/al-via-uai-satmonitor-il-programma-per-la-misura-e-la-valutazione-degli-effetti-dei-satelliti-commerciali-sulle-attivita-astrofile/

What is currently totally missed by international institutions is an OPEN CALL on the main ground based facilities for observational campaign to characterize the phenomenon in its very first phase.

We must bitterly note that the international astronomical community without mitigating circumstances is failing in regards timing and odds of intervention by continuing to focus on the predictions of a sure damage and never to avoid it.

How much time could last the work to raise up a scientific rigorous prediction of the damage caused by SpaceX and OneWeb to professional Astronomy?

We can try to make a prediction: that time will be greater than what will be necessary by companies to startup satellites and provide to the whole mankind the internet service from the space. This will help the public opinion to totally “put aside” the ground based astronomy with all related claim and requests!

This is an EPIC FAIL for all of us: “while the astronomy community is talking and discussing on the “decimal precision” about the suffered damage, the Telecommunication Industry is deploying his pieces on the chessboard to checkmate Science in few steps“.

For this reason we are moving orthogonally to the scientific government bodies hoping to sue a legal action with the assistance of a US legal consulting firm, to put on hold satellites’ deployment in the bud: the firm is studying the case and in few days it will propose a legal strategy of intervention.

So in few days we will receive serious requests coming from out legal firm and we will need open contributions from everybody for a fast and incisive response.

It is difficult but we need to do! Together.

Starting Local Initiatives

In these days we are going to send our first email to each subscribers.

This POST contains the content of the email that we are sending to you, in total transparency.

Unfortunately the maximum amount of email allowed to be send by google is 500, so, because we are thousands, we are evaluating different alternatives for manage and send newsletter and mailing list in respect of our commitment and the appeal signatories privacy. We apologize immediately if it will happen to send more than one email to the same recipients (please don’t mark as a spam!)

From the next week will be opened voluntary adhesions to our TTT, “think tank team”, to seriously quantify the damage to professional astronomy starting from radio astronomy and then extending it to all the bands for which significant investments have been made by nations to implement ground-based astronomy facilities.
This is the starting point for legal action to safeguard our profession.

Please SHARE this email with your contacts.

Here is the email text (DOWNLOAD):



As attachment to the email is the open-letter to instituttions (DOWNLOAD):

links: they talk about us!






Does SpaceX accelerate launches for us?



IAU – 2nd Statement and Astronomers' Appeal initiative

At the following link it is possible to read the 2nd statement of IAU related to the Impact of Satellite Constellations on Astronomy:



As we can read the IAU, which is the greater astronomical association in the World, currently is performing studies and investigations on the impact of mega-constellations.


From the text we see how all reported simulations are still greatly underestimating the amount of satellites that will actually be launched into orbit. We don’t understand why, but we also note how the press release is too-much focused on the impact to the naked-eye visibility and not so much to professional astronomical issues and optical observations.

A dedicate paragraph point is even dedicated to the bright phase of “strings of pearls” in the sky after the launch (during the displacement of satellites in orbit), minimizing this effect because of the limited time before these satellites raise in the stable orbit, but in the statement is forgotten to say that this period lasts about one month and considering the replacement strategy in 42k LEO Constellations the amount of satellites deorbited & substituted could reach about ~8000 satellites per year so that in operational mode each days there will be more than 300 satellites moving to reach their stable orbit and producing those disturbing pearls.

So IAU takes care to write 4 point statements on the impact to naked eyes observations, but only one point for professional observations without entering too much in depth of the problem; we therefore quote the statements regarding the professional astronomical observations in the visual bands:

Apart from their naked-eye visibility, it is estimated that the trails of the constellation satellites will be bright enough to saturate modern detectors on large telescopes. Wide-field scientific astronomical observations will therefore be severely affected. For instance, in the case of modern fast wide-field surveys, like the ones to be carried out by the Rubin Observatory (formerly known as LSST), it is estimated that up to 30% of the 30-second images during twilight hours will be affected. Instruments with a smaller field of view would be less affected. In theory, the effects of the new satellites could be mitigated by accurately predicting their orbits and interrupting observations, when necessary, during their passage. Data processing could then be used to further “clean” the resulting images. However, the large number of trails could create significant and complicated overheads to the scheduling and operation of astronomical observations.

What IAU states is that the ONLY visible satellites in the dark sky can impact on professional astronomical observations, but this is not correct, since the whole sky is used to perform astronomical optical observations and calibration. In particular to flattening the dark sky images it is necessary to takes low-exposures images (fast) at the twilight (sundawn or sunset) in order to stack these images and create a calibration MASTER-FLAT image. This has to be done for each filter foreseen to be used in the following observing night. Thought some relevant stars in images can be masked the presence of LEO Starlink satellites (at 340Km altitude) will affect the flat fielding acquisition making impossible to correct for defects and flat images. This will irreparably affect all scientific content of optical images even when the observer is enough skilled to avoid any trail in the dark-sky deep-field image: with 50k satellites it will become impossible to obtain good calibration images at twilight to analyse and reduce scientific images.

MOREOVER we state that is totally missed the impact on radioastronomy!

More urgent is to evaluate the impact on radio astronomy, but it is revealed that “The focus of this Statement has been on the optical wavelengths. This is not to underplay the effect on the radio and submillimetre wavelength ranges, which is still under investigation“… so let’s wait the 3rd statements hoping that it will come before the Congress in October 2020.

Finally we must note that all effort of IAU from the beginning of the Constellations affair is concentrated on the mitigation and minimization of issues and damages, it never talks about the prevention of such damage.

In the meantime telecommunication companies are launching their fleets and in few months they will acquire the legal right to operate regardless the impact on our profession. If companies would take care of astronomical safeguard they would stop launches and wait the darksat experimental evaluation, but this has not happened nor anybody ask them to ***put on hold*** further launches. Moreover we note that other 60 “not darkened” satellites were launched few days ago.

Not only SpaceX also OneWeb is launching satellites: see this recent NewYorkTimes Article:


It is time to start the second phase of the Appeal… all subscribers together to stop further launches!

In few minutes you will receive our first mail from to the contact provided in the signature module. Let’s go on!

DARKSAT … not so dark!

Appeal subscribers should find of interest that the french satellite imager Thierry Legault has shown that the darksat Starlink satellite is not that dark at all.

Now that it is clear to everyone that all months passed to negotiate a solution with SpaceX did not produced any effect to the satellite albedo: the experimental DARKSAT impacts on astronomical observations in the same way of others!

Since nobody has even bothering to stop the subsequent launches.
It is obvious that it is necessary to move to an urgent inhibition lawsuits.

There is NO time to wait, no time to lose!

From Jeremy Tregloan-Reed comment, we report “not to lose hope yet”:

“from what we can tell the non coated side is pointing to Earth while it is still manoeuvring into position and the antenna is on the non-coated side. Once it reaches its 550km orbit, the dark coated side should then face the Earth. We will then be performing observations to determine the true change in brightens…. “

and more:

“Using the telemetry data from NORAD (https://celestrak.com/NORAD/elements/supplemental/starlink.txt), Darksat currently has an altitude of ~480km. We have been seeing on average an increase of 10km per day, so it should reach its nominal orbit in a week. However, the satellite telemetry is updated every eight hours so things can change as Space X has not disclosed the details.”

So we can argue few points:

  • the dark painting is not over the whole body of satellites but only in one face of it
  • during (the very long >1month) displacement on the final orbit (e.g. 550km) the satellites will shine as other not covered satellites
  • in the nominal operations are foreseen about 8000 satellite-replacements every year so that each day ~20-25 satellites will deorbited ( in one month 140-200 satellites replaced).

So, regardless on dark coating, each month hundreds of satellites will always shine in sky without brightness reduction!

The real question is: “if we have to wait for the final configuration of DARKSAT in order to evaluate its “right” albedo in the final configuration, WHY SPACEX does not wait to send further saltellites in orbit? Maybe the company knows that 3/4 of the reflecting surface are solar panels that can not be covered?

Latest NEWS: the celestrak DB site do reveal today that last 60 Starlink Satellites now communicate each other so that the total amount of SpaceX fleet in orbit is currently 240 unities.

Please check the AAS Press Conference (of 8 Jan 2020) about Satellite Constellations.

The Astronomers' Appeal mentioned on LeMonde and other news on satellites' constellations

The French Journal Le Monde pubblished yesterday a detailed article on our appeal, with all astronomical concerns/issues related to satellites’ constellations form the professional astronomy.

Here is the link: https://www.lemonde.fr/blog/autourduciel/2020/02/06/le-projet-starlink-delon-musk-menace-la-recherche-astronomique/

In the meantime a second satellites constellation, OneWeb ( UK project ) has started launches of satellites. One Web plans for 5,260 satellites and intends to launch 30 satellites at a time every three/four weeks beginning in the first months of 2020. One web will start the service as soon as the first 300 satellites are in orbit (approximately in late 2020). The 6th February at 4:42 p.m. EST (2142 GMT) from Baikonur, 34 OneWeb Satellites were launched by the Soyuz Rocket and they will be displaced at about 1,200 km altitude. Such an altitude means that OneWeb satellites will be visible up to 8th magnitude all night long.


Very soon you will receive the Letter model to send to your institute, agencies and local government to arise awareness on the problem and ask for a legal intervention to stop and put on hold further launches.

Stay tuned…

satellites news (03feb2020)

The 29th January other 60 Starlink satellite were launched in orbit but in the CelesTrack database are notified as “LOST”. What does it means?

Did Saltellites disintegrate in launch?

Do they still have to be turned-on before to be displaced in orbit?

What is the probability of running into kessler syndrome if a subset of 60-satellites would explode in LEO after the lunch?

NOTE that no oather DARKSAT were launched in this Falcon-X shipment:
this is highly indicative of the lack of attention SpaceX has towards the astronomical community.

We reached

+1500 signatures

of astronomers to the appeal!

It is time to start with requests to institutions, agencies and governments.

Very soon all subscribers of the appeal will receive a message from us with a dedicated text to send to the subscribers’ institute, agencies and government commissions to request urgent and incisive action in order to stop further satellites deployment.

Let’ s remember that with Satellites’ Constellations such pictures,

OF Gianluca Licausi,

could became a memory from the past…

With SpaceX & Starlink Satellites forget the night sky, not only for astronomers! (Courtesy and copyright, Gianluca Licausi )


update 1st milestone: 1000+ subscribers

The number of subscribers is increasing hour by hour. We thank you for your energy and good comments received.
Very soon a page will be posted with all the comments collected in these three weeks.

The first 1280+ signatures (at the time of writing) will be sent to international agencies, affiliated institutes and national governments in few days.
The full description paper

(LINK: here )

has been submitted to the arXiv Astro-ph Archive in order to enlarge the astronomers protest-base.

In this moment we ask for a choral action to raise awareness of the problem at one’s own institutions and local governments.

Note that any institution that owns ground-based astronomy facilities and has existing projects in place, being damaged by the deployment of the Starlink satellites, it will suffer a loss of value of the infrastructure investment made (most of all public financed money), which would represent a great economic damage. Therefore, individual institutions and governments must calculate the economic damage suffered and act through legal channels trying to prevent the damage, rather than asking for compensation.
The task of each subscriber of the appeal is to send this formal request to their institutions and governments to take a self-defense legal action to put in hold further satellite launches pending verification of the effective legitimacy of the F.C.C. in authorizing such a huge commercial deployment, regardless on rights of near and far nations.

Some protest actions have already been planned in US, waiting for other countries to come.
We also need to raise the level of attention by involving TV, newspapers and magazines as much as possible.

Soon we will prepare an “OPEN LETTER” to send to your local ground-based project stakeholder institutions, agencies and governments. We will invite you to send this letter in order to make your instiutions aware of the problem and take action for self-defending.

Note that it is not possible to understand if the launch of other 60 satellites from Cape Canaveral by Falcon-X rocket planned for the 21th January 2020 was accomplished or not, since the celstartrack orbiting satellites database counts only of about 180 Starlink satellites in orbit.

This is the moment of action.

With your help we can make a difference, or, at the very least, make ourselves feel right.

News from SpaceX and Starlink satellites: the 20th January 2020 other 60 satellites in orbit

As announced here, International Astronomical Union has put in place a huge effort to negotiate and mitigate issues coming from the deployment of large fleets of LEO satellites, and one solution in order to mitigate at least the luminosity brightness was identified with a special coating for one of the last 60 Starlink satellites launched. This testing satellite is called DARKSAT and can be searched in the CelesTrack site: https://www.celestrak.com (searching for starlink as Name-keyword).

From the celestrak.com it is possible to search for starlink satellites and find when the fleet is over the country. This will help to understand how much the starlink fleet will be visible during the whole nights. For the first 180 satellites the expected quota is 340Km so the contribution of luminosity trails will be prominent in few hours near twilight. Note the DARKSAT where a special coating is placed in order to limit reflectivity.

We encourage to use this tool using the slide timing-bar in order to identify a good time for satellite observation (in your region) and check the darkening factor of DARKSAT compared to non-obscured satellites.


If you are able to take a picture of the satellites please send it to me (with these observation data: place, date, observing time, exposure time and possible filter).

I will check darkening factor and interact with IAU, to understand if forecasts are met.

Considering the darkening testing of these week,

it is really not clear why SpaceX , especially considering its willingness to avoid damage to astrophysics, does not want to wait for the results of these tests, by putting the launches on hold

and in particular

Why IAU does not claim/demand a precautionary stop for the launches?

The 20th January 2020 it is planned another Starlink launch to put in orbit 60 starlink satellites from the Cape Canaveral Air Force Station. After this further displacement the total SpaceX satellites in orbit will reach a total of 240.

We remind that to turn on the system at least 420 satellites are needed, while to provide the first telecommunication service SpaceX will need of <1000 satellites.

If no international entity will stop this displacement the right of the private company SpaceX will become acquired at the beginning of March 2020.

There is no more time to wait: it is the time to act!

How the international astronomical community could mobilize in order to stop further Starlink launches?

1 Sue in court for luminous pollution not taken into account by US F.C.C.: The FCC’s lack of review of these commercial satellite projects violates the National Environmental Policy Act, NEPA, which obligates all federal agencies to consider the environmental impacts of any projects they approve. So in the most basic sense, SpaceX’s satellites displacement authorization would be unlawful.

2 Legal site: lack of jurisdiction and jurisprudence of US F.C.C. to authorize not geostationary satellites over other states and nations.

See this interesting article: https://www.scientificamerican.com/article/the-fccs-approval-of-spacexs-starlink-mega-constellation-may-have-been-unlawful/

Please share and subscribe this APPEAL:


Appello degli Astronomi


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(la frequenza di aggiornamento del contatore potrebbe subire dei ritardi)

Per sottoscrivere seguire questo link.

Questo accorato appello proviene dagli astronomi di tutto il mondo per chiedere un intervento efficace da parte delle istituzioni e dei governi.

Le osservazioni astronomiche da terra verranno gravemente danneggiate dal dispiegamento in corso di grandi flotte di satelliti per garantire il funzionamento delle future tecnologie di telecomunicazioni.

Da secoli le osservazioni astronomiche da terra hanno portato progressi eccezionali nella nostra comprensione scientifica delle Leggi della Natura. Attualmente, le capacità della strumentazione astronomica da terra è messa in pericolo dall’ insistente dispiegamento di flotte di satelliti per telecomunicazioni.

Attraverso questo appello internazionale e dando seguito alle medesime preoccupazioni espresse dall’Unione Astronomica Internazionale, IAU [1] e da altri soggetti istituzionali, solleviamo una serie di richieste formali in merito ad una maggiore tutela e salvaguardia per le osservazioni astronomiche professionali da terra, garantendo agli astronomi, il diritto di osservare un cielo libero da inutili fonti di inquinanti artificiali.

Nello specifico tutti i firmatari astronomi, associati e collaboratori, desiderano manifestare umanamente e personalmente la loro preoccupazione e la loro contrarietà inerente la copertura del cielo prodotta dai satelliti artificiali, che degradano drammaticamente il contenuto scientifico di una vasta gamma di osservazioni astronomiche.

Infatti non vi è solamente l’inquinamento luminoso del cielo dovuto al disperdersi della luce proveniente dalle città e alle aree più popolate del pianeta, ma dovuto anche alle flotte di satelliti artificiali, che attraversano e segnano irrimediabilmente le osservazioni con strisciate/scie parallele molto luminose a tutte le latitudini.

Gli astronomi sono estremamente preoccupati per la possibilità che la Terra possa venire coperta da decine di migliaia di satelliti, che supererà notevolmente le circa 9000 stelle, che sono visibili ad occhio nudo. Purtroppo questa non è una minaccia lontana o la prospettiva di un futuro lontano, ma sta già succedendo ora. La compagnia privata americana SpaceX ha già messo in cielo 180 di questi piccoli satelliti, chiamati Starlink, e prevede di costellare l’intero cielo in totale con circa 42.000 satelliti (a tre differenti quote: 340km, 550km e 1150km). Pertanto, insieme ad altri progetti spaziali di telecomunicazione previsti per il prossimo futuro (ovvero OneWeb da UK, Telesat dal Canada, Amazon, Lynk e Facebook dagli USA, Roscosmos dalla Russia e quello della corporazione aerospaziale ed industriale cinese), potrebbero esserci oltre 50.000 piccoli satelliti, che orbiteranno intorno alla Terraa a differenti altitudini con differenti obiettivi connessi all’ industria delle telecomunicazioni e che forniranno principalmente Internet da satellite.

Questi nuovi satelliti sono piccoli, prodotti in serie e orbiteranno molto vicino alla Terra, in modo da fornire una connessione Internet veloce con segnali a bassa latenza. Ma tale vicinanza (~340Km di altitudine), quando illuminati dal Sole, li renderà anche più visibili e più luminosi nel cielo notturno (infatti già oggi gli attuali 180 satelliti Starlink, sono più luminosi del 99 percento della popolazione di oggetti visibili dall’orbita terrestre).

Da notare che il numero di oggetti artificiali attualmente catalogati (e visibili) in cielo non supera il numero totale di 20mila, tra oggetti funzionanti e detriti fluttuanti, quindi con i soli satelliti Starlink questo numero totale verrà triplicato (vedere Figure). (*)

Nel medio e lungo termine, ciò ridurrà drasticamente la nostra visione dell’Universo, creerà più detriti spaziali e priverà l’umanità di una visione incontaminata del cielo notturno. È stato calcolato che molti di questi satelliti saranno visibili ad occhio nudo (con una luminosità compresa tra la 3a e la 7a magnitudine apparente, ovvero raggiungendo la luminosità delle stelle nella costellazione dell’Orsa Minore e superati in luminosità solo di 172 stelle in tutto il cielo!). Saranno estremamente più luminosi nelle ore immediatamente successive al tramonto del Sole e comunque, con 50mila satelliti, la “normalità” sarà un cielo affollato di oggetti artificiali (un satellite in ogni grado quadrato di cielo, che provocherà strisciate vanificando e compromettendo le osservazioni per tutta la notte).

Ovviamente non saranno danneggiate solo le le osservazioni con i telescopi a grande campo (ad esempio LSST [2] o VST [3] o Pan-STARRS [4], …), ma risulteranno danneggiate anche le pose profonde e quelle a campo ridotto, vedere immagine e [7].

Essendo le osservazioni/surveys astronomiche a grande campo del cielo comunemente utilizzate nei programmi di monitoraggio/ricerca di NEO e potenziali oggetti da impatto per la Terra, risulta importante segnalare come queste costellazioni satellitari potrebbero compromettere le capacità di prevenire ed avvisare l’ intera umanità dai rischi di potenziali impatti. (*)

Alcuni satelliti Starlink visibili nel mosaico di una immagine astronomica (NSF’s National Optical-Infrared Astronomy Research Laboratory/NSF/AURA/CTIO/DELVE)

Questo inquinamento luminoso è estremamente dannoso per le osservazioni astronomiche a tutte le lunghezze d’onda. Il recente test di utilizzare una pittura oscurante/antiriflesso sul corpo di uno dei satelliti Starlink (n.1130 DARKSAT), anche qualora si riducesse a zero la loro luminosità (cosa impossibile poiché i pannelli solari, che rappresentano 3/4 della superficie riflettente, rimarrebbero non uscurati), il degrado alle osservazioni scientifiche rimarrà comunque elevato per due motivi: 1) le stelle e altri oggetti nell’universo verranno comunque eclissati, alterando quindi la tempistica negli studi di variabilità, e 2) la riflettività della superficie del satellite dipende necessariamente dalla lunghezza d’onda osservativa, quindi ciò che diventa scuro in una parte dello spettro (ad esempio il visibile) rimane luminoso (o risplende) in altre parti dello spettro (ad esempio infrarossi o radio); inoltre una superficie più oscurante significa anche maggior cattura del calore solare con conseguente reirradiamento nell’ IR.(**)

Da notare inoltre che una siffatta flotta di satelliti a bassa orbita non geostazionari prevede, a regime nominale di funzionamento, un tasso di sostituzione da 2000 a 8000 satelliti Starlink l’ anno, i quali verrebbero irrimediabilmente lasciati disintegrare nella bassa atmosfera terrestre, con tutti i rischi e le conseguenze del caso. (*)

Di rilievo inoltre il fatto che lo sviluppo delle reti di telecomunicazione di ultima generazione (sia dallo spazio sia dalla Terra), già influenza profondamente le osservazioni radioastronomiche (in tutte le sottobande osservative): con le flotte di satelliti LEO si teme che la situazione diventerà insopportabile.

In particolare le finestre spettrali dei satelliti in orbita terrestre bassa designate per fornire i servizi e comunicare con le stazioni terrestri nelle bande Ku (12-18 GHz), Ka (27-40 GHz) e V (40-75 GHz) si sovrapporranno inevitabilmente alle bande nominali di radioastronomia e quindi interferiranno con radiotelescopi e radio interferometri a terra, alcuni dei quali già oggi entrano in regime non lineare (ovvero si saturano) nella banda K (18,26,5 GHz) e nella banda Q (33-50 GHz). Questo fenomeno compromette costantemente (e comprometterà ancora di più) l’intera catena di analisi in quelle bande con inimmaginabili ripercussioni sulla nostra comprensione dell’Universo, o addirittura, rendendo la comunità astrofisica cieca in queste finestre spettrali.

Ad aggravare la questione, con l’attuale sviluppo tecnologico, è impossibile prevedere esattamente la densità pianificata dei trasmettitori di radiofrequenze: le milioni di nuove stazioni base wireless, hot spot commerciali sulla Terra collegate direttamente ai futuri ~50.000 nuovi satelliti nello spazio, produrranno, secondo le stime, almeno 200 miliardi di nuovi oggetti trasmittenti nel contesto dell’Internet of Things (IoT) entro il 2020-2022 e qualche trilione di oggetti solo pochi anni dopo. Un numero così elevato di oggetti, che emettono nel radio potrebbe rendere impossibile la radioastronomia dalle stazioni terrestri senza una reale protezione, creando vere zone di rispetto nei paesi, in cui sono collocate le strutture di radioastronomia. In sostanza, desidereremmo evitare che lo sviluppo tecnologico senza un serio controllo trasformi la pratica della radioastronomia in un’antica scienza estinta.


Noi, astronomi sottoscrittori e firmatari di questo appello proclamiamo che NON C’È PIÙ TEMPO PER TERGIVERSARE, MA È GIUNTO IL MOMENTO DI AGIRE!


  1. di impegnarsi a fornire protezione legale per le strutture astronomiche da terra in tutte le finestre elettromagnetiche di osservazione disponibili.
  2. di mettere in attesa ulteriori lanci di Starlink (e altri progetti) e attuare un’accurata moratoria su tutte le tecnologie che possono avere un impatto negativo sulle osservazioni astronomiche dallo spazio e da terra, o sugli investimenti scientifici, tecnologici ed economici che ciascuno Stato si impegna in astrofisica progetti.
  3. di mettere in atto una chiara valutazione dei rischi e degli impatti predittivi sugli osservatori astronomici (vale a dire la perdita di valore scientifico ed economico), fornendo linee guida rigorose a privati, società e industrie per pianificare investimenti satellitari senza comprendere in modo trasparente tutti gli effetti negativi su strutture astronomiche esistenti e/o funzionanti.
  4. di diffidare la Federal Communications Commission (FCC) degli Stati Uniti e qualsiasi altra agenzia nazionale dal concedere l’autorizzazione a spedire in orbita satelliti non geostazionari a bassa orbita o, in alternativa, a limitare l’autorizzazione ai soli satelliti che si localizzino sopra lo spazio aereo del “paese di origine”.
  5. di richiedere/pretendere un’orchestrazione mondiale, in cui le agenzie astronomiche nazionali e internazionali possano imporre il diritto di veto a tutti quei progetti, che interferiscono negativamente con le strutture astronomiche esistenti.
  6. di limitare e regolare nel numero (ed il numero) di flotte satellitari di telecomunicazione riducendole al “numero strettamente necessario” per il loro funzionamento e metterle in orbita soloed esclusivamente quando i satelliti tecnologici obsoleti vengano preventivamente deorbitati, secondo il Trattato sullo spazio esterno (1967) – Art IX [5], e le Linee guida delle Nazioni Unite per la sostenibilità a lungo termine delle attività spaziali esterne (2018) – linea guida 2.2 (c) [6], che impone l’uso dello spazio esterno “in modo da evitare la [sua] contaminazione dannosa e anche cambiamenti avversi nell’ambiente della Terra “e [… omissis …] rischi per le persone, le proprietà, la salute pubblica e l’ambiente associati al lancio, al funzionamento in orbita e al rientro di oggetti spaziali”.


Ci teniamo a manifestare che tutte queste richieste provengono da una sincera ed accorata preoccupazione da parte di noi scienziati circa la minaccia che venga preclusa la piena disponibilità ed accesso al Cosmo assieme alla perdita di un bene immateriale di valore incommensurabile, sebbene intangibile per l’umanità, che rappresenta la consocenza della Natura.

In questo contesto, tutti i firmatari di questo appello ritengono ASSOLUTAMENTE NECESSARIO mettere in atto tutte le misure possibili per proteggere il cielo notturno, anche dal punto di vista giuridico, adottando risoluzioni contingenti e limitanti per paesi ed agenzie, da ratificare tramite norme internazionali condivise ed adottate da tutte le agenzie spaziali mondiali, per assicurare la protezione delle bande astronomiche osservabili da terra e continuare ad ammirare e studiare il nostro Universo per sempre.


[1]  https://www.iau.org/https://www.iau.org/news/announcements/detail/ann19035/?lang

[2]  https://www.lsst.orghttps://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory

[3]  https://www.eso.org/public/https://en.wikipedia.org/wiki/VLT_Survey_Telescope

[4]  https://en.wikipedia.org/wiki/Pan-STARRS

[5]  https://www.unoosa.org/oosa/en/ourwork/spacelaw/treaties/introouterspacetreaty.html

[6]  https://www.unoosa.org/res/oosadoc/data/documents/2018/aac_1052018crp/aac_1052018crp_20_0_html/AC105_2018_CRP20E.pdf

[7]  Simulazioni di come “soli” 12mila satelliti Starlink popoleranno il cielo stellato: https://youtu.be/LGBuk2BTvJ e https://www.youtube.com/watch?v=z9hQfKd9kfA

[8] Tool di visulizzazione delle orbite dei satelliti ricercati: https://celestrak.com/cesium/orbit-viz.php?tle=/satcat/tle.php?INTDES=2020%2D001&satcat=/pub/satcat.txt&orbits=20&pixelSize=3&samplesPerPeriod=90

Nota Questa frase (*) è stata aggiunta il 13/01/2020.

Nota Questa frase (**) è stata aggunta il 16/01/2020.

Questo appello/petizione può essere firmata (solo da astrofisici, tecnologi, collaboratori, associati ed studenti, che si occupano di osservazioni astronomiche professionali) al seguente link.

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