Near Earth Probes (NEPs)

Sadly, the visionary radio astronomer Frank Drake passed away on September 2, 2022. When the Breakthrough Listen initiative was announced in London on July 20, 2015, I had the privilege of sitting next to Frank for four hours during a banquet dinner preceding a panel discussion about the Search for Extraterrestrial Intelligence (SETI). Frank pioneered radio SETI with Project Ozma in 1960, two years before I was born. For the sixty-two years that have elapsed since then, the SETI effort focused on the search for radio or laser signals from distant civilizations.

This traditional SETI approach is equivalent to waiting for a ringtone on our phone. To receive an electromagnetic signal, we need the sender to transmit it exactly a light-travel-time ago with similar communication technologies to those we developed over the past century. This runs the risk of not detecting any transmission since the senders may have sent their signals billions of years ago, as their parent stars formed before the Sun.

The likelihood for a phone call is highly uncertain, as Frank quantified in his famous Drake equation. With no ringtone from our phone, we kept reflecting on Enrico Fermi’s question: “Where is everybody?

Gladly, there is an alternative search method. It involves checking for physical packages in our mailbox. Even if radio-transmitting civilizations are dead by now, their packages might have piled up in our cosmic neighborhood since these packages move slowly and are bound by gravity to the Milky Way disk.

Over the past year, NASA and the US Intelligence agencies encouraged the scientific community to study the nature of Unidentified Aerial Phenomena (UAP) near Earth. Their request inspired the Galileo Project at Harvard University, which follows the alternative path to traditional SETI. The time is ripe for academia to engage more broadly with the new All-domain Anomaly Resolution Office (AARO) in an effort to explain the unknown nature of an unusual subclass of Near-Earth Objects (NEOs). When asked whether the Galileo Project relates to my day job as an astronomer, I replied positively since astronomy is engaged in the analysis of telescope data and the objects we seek with the Galileo Project telescopes could have originated at great distances.

At a recent panel discussion, I was asked: “If a spaceship landed in your backyard, would you board it?” My answer was a resounding yes. But I also quoted my wife, who told me a decade ago: “If you decide to go ahead, I want you to do two things before boarding the spaceship: please leave the car keys with me and ask them not to ruin the lawn at lift off.” In view of recent economic and societal turmoil, I asked my wife again the same question. Interestingly, she updated her answer: “If you go ahead, please turn off the lights. I will join you.” Most of my colleagues are absolutely certain that they will never leave Earth. Oscar Wilde already acknowledged these differing views by stating: “We are all in the gutter, but some of us are looking at the stars.”

Most likely, we will never be offered a ride to exotic interstellar destinations for the same reason that ants on the sidewalk are not offered rides by bikers who traveled from far away. In fact, the bikers might barely notice these ants. Moreover, the bikers’ language, technological equipment, and intellectual aspirations are entirely foreign to the rituals of an ant colony. It is pure fantasy for the ants to imagine that the bikers would say: “take us to your leader,” as it is for Neil de Grasse Tyson to expect having dinner with extraterrestrials in New York City.

Could we identify an encounter with something that we cannot comprehend? Absolutely. The search technique is straightforward: the object should not resemble familiar entities. These include natural objects like insects, birds, thunderstorms or rocky meteors, and human-made objects like drones, weather balloons, bullets, artillery shells, missiles, airplanes, and satellites. There is no need for us to reverse engineer the objects we detect. They could inspire the awe experienced by a cave dweller while looking at an airplane. We should keep in mind that the airplane does not need to violate the laws of physics in order to signal a technological gap relative to the cave dweller. Similarly, UAP could comply with known physics and still represent an unfamiliar technology.

New physics is a high bar that should only be contemplated when the data demands it without a reasonable doubt. Any new physics must be universally accessible and reproducible through experimental data on multiple systems. In fact, we might harness it ourselves after fully understanding how it works. Here lies a business opportunity for technology entrepreneurs.

If functional devices arrived at Earth, their manufacturers were likely far more technologically advanced than we are. Our current interstellar probes will take tens of thousands of years before they exit the Oort cloud of the Solar system and enter interstellar space. Future light sail technologies, inspired by Breakthrough Starshot, could enable interstellar travel at a higher speed.

Near-Earth Probes (NEP) are a new subclass of NEOs that could be equipped with artificial intelligence (AI). Should we be worried about the risk from the unknown? Not at all. If the unknown wanted to harm us, it would have done so long ago. We should collect scientific-quality data and use our best AI systems to interpret it.

The task before us is to humbly study any new evidence on NEP. The reality in interstellar space remains the same irrespective of what is popular on social media or in academia. Let us be as open minded as students on their first day in class. This is the true legacy of Frank Drake.


Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He chairs the advisory board for the Breakthrough Starshot project, and is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021.



Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
Avi Loeb

Avi Loeb


Avi Loeb is the Frank B. Baird Jr Professor of Science and Institute director at Harvard University and is the bestselling author of “Extraterrestrial”.