A New Search Strategy for SETI

We all imagine that advanced civilizations in our Milky Way Galaxy will build spacecraft to travel among the stars, à la Star Wars and Star Trek.  Unfortunately, the laws of physics conspire against interstellar travel.  The two problems are time and energy.

Let’s consider a trip in a car-sized spacecraft from Earth to Alpha Centauri, traveling at 50% the the speed of light. Sad to say, the trip will take 9 years, and 18 years round trip. Along the journey you’ll find no rest stops, Starbucks, nor pizzerias, never mind a pharmacy or Apple repair store.

Worse, the needed propulsion energy of your craft is gigantic. Kinetic energy is given by the equation, 1/2 the mass of the craft multiplied by its velocity squared (Energy = 1/2 mass vel^2).  This basic physics  shows that the needed propulsion energy is 3 trillion kilowatt-hours.  This is 1000x the total electricity energy used in New York city during a full year – a daunting amount of energy to acquire and control. Carrying the required propellant mass makes matters even worse.

To save energy, you might propel your ship to only 1/10 light speed toward Alpha Centauri. At this snails pace, the two-way trip now takes 90 years. Few people want to spend a century in the cold, darkness of space, confined to a VW Golf.  Oh, and an additional problem is that interstellar dust particles and cosmic rays will hit your craft at more than 1/10 the speed of light, puncturing holes, causing cancer, and damaging equipment. (See, you’ll need that Apple genius bar.)  Advanced civilizations might do a few trips like this, but the daunting energy and time becomes unappealing.

There’s a better way to explore the Galaxy.  You can build small, inexpensive robotic probes, similar to our Pioneer and Voyager spacecraft.  Low mass and traveling at a slow speed of, let’s say, 1/100 the speed of light, they will require little energy.  The long travel time to the nearest star is not a problem for a machine. It simply takes a few centuries, which is a blink in Galactic time and brief compared to the half-life of nuclear fuel.  Civilizations can easily send probes to thousands of stars in their neighborhood, equipped with cameras and transceivers that transmit pics (including selfies) back home. 

Our home Milky Way Galaxy may be populated by millions of these robotic probes, sent to many stars for in situ reconnaissance.  Our home Solar System may contain one.  A network of such probes may be optimized by spacing some “repeater nodes” by less than a light year, minimizing the attenuation of signals by the inverse square law. Communication beams may enjoy privacy, high bit rate, and minimal energy usage by using the tight beams of lasers – ultraviolet, optical, or infrared. Indeed, laser beams and repeaters are already widely used by human-made satellites orbiting Earth.

We may detect extraterrestrial probes in the Solar System two ways.  They will reflect sunlight, as do all satellites.  Glints caused by specular reflection off flat, metallic surfaces will make especially bright glints.  We should search for glints coming from probes orbiting the Earth or the Sun.  Also, probes will be receiving and emitting transmission beams that broaden like flashlight beams, overfilling their intended target receiver, allowing us to detect the spill-over light that travels onward (forever).   Our telescopes can search for this laser spill-over light.

We have a new opportunity to search for advanced technology in the Galaxy.  Rather than hunting for the inhabitants of civilizations, we should hunt for their “Voyagers”, by their glints and lasers.

Thanks to Beatriz Villarroel, John Gertz, Ben Zuckerman, and Lawrence Krauss for many of the ideas here.

G. Marcy,

VASCO and Director of Space Laser Awareness

A New Search Strategy for SETI

International Rising Talents 2022

Dear all,

Some of you might remember that I received the L’Oreal-UNESCO For Women in Science national prize 2021 in Sweden for the VASCO project.

This year (2022), I was lucky to be selected as one of 15 early-career scientists worldwide for an L’Oreal-UNESCO For Women in Science International Rising Talents prize, in a ceremony (or actually two!) that happened in Paris in June 2022. I feel incredibly honoured.

I want to express a strong gratitude to all members in the VASCO team, and all the citizen scientists who are involved in this research. This prize belongs to you.

Thank you.

International Rising Talents 2022

How an idea is born

Today is the International Day of Women in Science. It’s a special day, celebrating the enormous progress we have made to make it possible for women to work in science. I’m incredibly grateful for the many opportunities we have to make our dreams come true. In March 2021, I was awarded the L’Oreal-UNESCO For Women in Science prize in Sweden for the VASCO project, which I feel incredibly honored for. This prize belongs to everybody in the VASCO project, as it’s a common endeavour we embarked upon.

In the light of this day, I have decided to open up a bit about myself and finally answer a question that I frequently have received since I started my first searches for vanishing stars: ”How did you come up with the idea to search for vanishing stars?” I have kept the details for myself, even though I mentioned it sometimes. Nevertheless, telling the details might illustrate how the mind process behind a scientific idea works and how an idea might appear ”out of nothing”.

The idea goes well back in time. When I was younger, I used to write a bit in my free time. In Swedish. Small things: short stories, poems, nothing particularly serious, nor things I normally ever share. I did so also in the end of my undergraduate studies and the beginning of my PhD times. It was also in this time period, when I was working on a small fable about a quasar that was pondering about his cosmic life. Nevertheless, eventually came the moment in the fable when the poor quasar fell through a macroscopic wormhole and ”vanished”. After reaching the end of the story writing, I just could not let go of the thought: had any scientist ever searched for objects that vanish?

Some months after this, I decided to make a Skype call to one of the leading persons behind a major astronomical survey. I asked if the survey could make a second round of photometry and get spectra of the entire sky so that I could have perfectly homogenous data for looking for vanishing objects. The professor smiled at me, and explained it was a major undertaking that most likely would not happen for some time. So I let go of the idea of looking for vanishing objects, but I could not forget it.

Sometimes, all what one needs is the right moment. A few years had passed when I learned about the existence of the US Naval Observatory Catalog (USNO), which had mapped the sky in the 1950s. I immediately saw the opportunity to perform the study I was interested in: the search for vanishing objects, as crazy as it seems. I still wondered about the possible existence of wormholes and undiscovered new physical phenomena related to vanishing objects. Soon, however, I learned that there were serious astronomical efforts, rooted in serious astrophysics, to look failed supernovae. Failed supernovae can be found by looking for a star that vanishes. It was also at that moment I understood the possible connection to searching for extra-terrestrial intelligence.

This little bit describes how a simple idea was born out of nothing. Today, with the VASCO project, we focus on looking for everything that makes an object observationally ”vanish” – or just go subluminous. We know what we are looking for, but we will always be careful with conclusions when we find an interesting anomaly, because in the end, many anomalies have mundane explanations.

Finally, for the curious reader, I give away a small bit of myself and attach the untitled fable at the bottom of the blog post.

How an idea is born

L’oreal-UNESCO For Women in Science prize 2021

Dear friends of VASCO,
As a news, I would like to tell that on the 8th of March 2021,
I, as the principal investigator of VASCO, have been awarded the L’Oreal-Unesco
prize For Women in Science 2021 in Sweden.

Links can be found here:


I’m very grateful for this important recognition, and make a cheers with all collaborators and friends of the project.

Best from,
Beatriz Villarroel.

@Karl Nordlund 2021
L’oreal-UNESCO For Women in Science prize 2021

VASCO citizen science

Dear friends,

The Corona virus is spreading all over the world. Many institutes have been physically closed, so that we all have to work on distance (while the Internet works). The situation is hard everywhere.

In the last months, we have been working on preparing the citizen science project. In particular our IT experts, led by Kristiaan Pelckmans, have made a fantastic work in making it happen through the development of the citizen science interface and infrastructure. Our plan was to start up the citizen science project with a number of schools and amateur societies in order to test our project design and see what kind of results that we get. Unfortunately, with the corona outbreak we cannot follow this path now as many schools have closed.

We therefore are opening up the citizen science project in its experimental stage to everybody to participate. All you need, is a web browser. We hope you will enjoy it. 

The link to the citizen science project, in English and French, can be found here:


A short video greeting from myself, can be found here:


Stay safe and healthy!


VASCO citizen science