NEAR Shoemaker: The Near Earth Asteroid Rendezvous Space Probe

The NEAR Shoemaker

Let us have a look at the NEAR Shoemaker. “Deep down, the only idol, the only God that I respect is time, it is obvious that I can only do myself pleasure or profound harm in relation to him. I knew that this poplar would last longer than I did, that this hay, on the other hand, would have wilted before me; I knew that I was expected at home and also that I could easily have stayed under this tree for an hour. I knew that any haste on my part would be as foolish as any slowness. And this for life“.

The obstacle time, the slow time, its rejection as well as its appreciation, but also, more often, the neutrality, undergone or accepted, with regard to him, recurring themes in the work of Françoise Sagan could not, any better, summarize the existence of Eugene Merle Shoemaker whose time of existence, certainly undergone in this case, has, amusingly or dramatically according to the spirits, employed itself to recall the link, coarse, which it maintained, with the surprise, the disappointment of the surprise.

Deceased at the age of sixty-nine, at the beginning of the Indian summer of his life according to Edwin Shneidamn, following a car accident during a trip in search of asteroid impacts in Australia, “Gene” Shoemaker is, in the collective imagination, mainly known to be the only “being” to have had the privilege of resting on the Moon after his death, the ashes of his remains having been sent in 1999, as a tribute, by wish of NASA and his descendants.

A gifted spirit turned astrophysicist and engineering geologist, Dr. Shoemaker contributed during his lifetime to the creation of the field of “astrogeology” by establishing the Astrogeology Research Program at the U.S. Institute of Geological Surveys in 1961, of which he was the first director. In particular, he was strongly involved in the “Ranger” missions to the Moon, which ended up revealing that the Moon was covered with impact craters of various sizes.

The co-discovery, in 1933, of the comet bearing its name “Shoemaker-Levy 9”, as well as the followup of the latter, completed the “highlighting” enterprise, to all and sundry, started in the previous years.

It’s on the strength of this record of service that he joined the “Discovery” program, launched in 1992 by NASA Administrator Daniel S. Goldin. This program was launched to enable “more frequent, cheaper, efficient” space missions with a spectrum of “skills” extending from robotic exploration of the solar system to the identification of exoplanets, using the now famous Kepler telescope.

The robotic exploration of the solar system, a prerogative of the “Discovery” program, as stated earlier, notably revolved, among many other missions, around the study of asteroids. The interests in the study of asteroids, formerly known as “sky’s vermin” are – both scientifically and economically – considerable. Thus, in astronomy, as Patrick Michel, a French astrophysicist and director of research at the CNRS, reminds us in an interview with Le Monde, “The study of asteroids gives the recipe for the formation of planets”.

Indeed, asteroids have the advantage – unlike the materials that formed the planets – of not having been heated, or only slightly, and therefore not having been chemically transformed, thus keeping the memory of the initial composition of the solar system. It is also thanks to elements found in meteorites, which are asteroids that fell to Earth, that we have been able to date the Solar System to 4.567 billion years ago.

In addition, they could, in the future, enlighten us on the origin of life. Indeed, it is envisaged, by the scientific community, that asteroids may have brought back the necessary ingredients – water and organic matter – for the creation of life. Antonella Barucci, an Italian astronomer, explained in an interview with Le Point that: “carbonaceous chondrite-type meteorites – found on Earth and originating mostly from asteroids – have exactly the same deuterium/hydrogen ratio as the water in our oceans and rivers”.

In a more pragmatic lens, studying asteroids could also allow us to improve the means of “planetary defense”. Indeed, many asteroids have an orbit that brings them dangerously close to the planet Earth. If it seems complicated to systematically destroy them, studying them could allow us, however, to learn how to deflect them. Patrick Michel explained, again, that “if the fall of an asteroid is the least likely natural disaster, it is also the only one that can be predicted and avoided… if we give ourselves the means”.

Moreover, from an economic point of view, it is estimated that one cubic kilometer of type M asteroid, i.e. metallic, contains seven billion tons of iron, one billion tons of nickel, and enough cobalt to satisfy world consumption for three thousand years. Finally, in a distant future, the latter could constitute space bases – self-sufficient due to the presence of mining resources – within the solar system. Moreover, thanks to their low mass and thus their low gravity, the energy spent to leave them would be much less consequent. Now that the time to dive deeper in the mission itself has arrived, let’s take a, quick, moment to have a look at the asteroid constituting its core.

The EROS asteroid, whose exploration was the core of the Near Shoemaker mission, was known to be at the time, the second largest known asteroid representing roughly the size of the Caribbean Island country of Barbados. This asteroid, whose first terrestrial approach was recorded in 1931, is also known to have been the first asteroid to have its shape visually determined and was notably at the heart of a pioneering legal action in this matter. Indeed, eleven months before the landing of the Near Shoemaker probe on the asteroid Eros, Gregory Nemitz, CEO of Orbital Development, a company located in the town of Twin Falls, Idaho, attempted to assert his ownership of the “asteroid433 Eros” by taking legal action against NASA and the U.S. government. The legal action was seated on the recognized and affirmed common law principle of the validity of pre-possession recognition.

During an interview given to the SPACE.com website, Gregory Nemitz said regarding this legal action “Everybody knows that possession is nine-tenths of ownership”. Adding to it, in an attempt to shed some light about his actions, he declared in a meeting filled with School of Mines attendees “The primary purpose of the lawsuit was to get an official determination from the U.S. government about property rights in space. The secondary goal was to move forward the international conversation about that topic” Even if, in the end, the lawsuit resulted in a “motion to dismiss”, with both of the Federal Court and the Court of Appeal declining to consider the motion on the grounds of “lack of a cognisable legal theory”, it did end up allowing the asteroid Eros to go down in history as the first space feature for which recognition of possession was sought. To everyone’s surprise, the anchoring in history of the EROS asteroid would end up strengthened, again, thanks to a mission, which became NEAR, conceived in the mid-1980s.

The question that the NEAR mission, inaugurating the “Discovery” program set up by NASA, as mentioned above, proposed to resolve was based on the assumption that at the time of the launch of the project, no asteroid had yet been visited by a spacecraft. It is, with this in mind, that the NEAR probe, renamed “NEAR Shoemaker” in homage to the tragically deceased doctor, saw the light of day with the objective of measuring the general properties of the asteroid Eros as well as its surface and internal proportions.

This project with an initial titanic cost of six hundred and fifty millions of dollars, revised however downwards, two hundred and ten millions of dollars, to adhere to the low-cost policy of the “Discovery” project became, on February 14, 2000, the first project allowing a space object to enter the orbit of an asteroid. This entry, initially planned for January 1999, had however been delayed due to a problem inherent to one of the three maneuvers enabling it to catch up with its target and get closer to it (which notably caused a failure of the probe’s motor as well as a momentary loss of contact with the craft). Chance of fate, the failure, corrected, allowed the scientists in charge of the project to choose as a new date the 14 of February 2001, February 14 related to Valentine’s Day and chosen in reference to the asteroid, taking its name from the Greek god of love, Eros.

During a whole year spent in the orbit close to the asteroid (between five and fifty-six kilometres), “NEAR Shoemaker” allowed to elaborate databases, provided in innumerable fields, such as the mass of the object, its structure, its gravity, its magnetic field… Among the numerous discoveries made, some of them proved to be more fundamental than others, in particular the discovery that “the surface of Eros had both very smooth, flat areas and regions covered with large boulders. NEAR found that Eros, unlike the planets of the solar system, had not undergone extensive melting and differentiation into distinct layers”. To get to the end of this mission, the probe was equipped with “an X-ray/gamma ray spectrometer, a near infrared imaging spectrograph, a multi-spectral camera fitted with a CCD imaging detector, a laser rangefinder, and a magnetometer”, the total mass of the instruments being estimated to fifty-six kilograms and requiring a eighty-one watts power source to function normally. Moreover the NEAR tracking system also allowed a radio science experiment to be held, experiment used to estimate the gravity field of the asteroid.

It’s on the strength of these numerous observations, added to the encounter, 1212 km away, of the asteroid “Mathilde” on June 27, 1997, that the probe’s mission unofficially ended on February 12, 2001. Unofficially, indeed, because on this February 12 the probe survived a landing on the surface of EROS, a landing not foreseen in the initial plans. During this “extra mile” made by the probe, the latter allowed, even beyond the objectives of its mission, both to send photographs of objects as small as a centimetre during its descent and to allow the collection and sending of scientific data on the composition of the surface of the asteroid.

Closing its final chapter, on February 28, 2001, communication with the “NEAR Shoemaker” probe ended, although an unsuccessful attempt to re-establish contact took place on December 10, 2002, killing two birds with one stone by engraving the name, for eternity, of the asteroid and the deceased scientist in the scientific collections, and more importantly, in the collective imagination.

This article was written by Cloé DANIEL, Mikhael TORRES, Yannis KHENNANE, Léa DETURCHE, M’hamed BENNOUNA and Jean-Pierre MENDY (Paris-Saclay).