After an extraordinary journey spanning seven years and covering a distance of nearly 4 billion miles, NASA’s OSIRIS-REx spacecraft made a gentle landing in the Utah desert on the morning of September 24, 2023, carrying a priceless cargo. The spacecraft successfully retrieved a sample from the asteroid Bennu, amounting to roughly half a pound of material collected from the 85 million-ton asteroid (77.6 billion kg). This precious payload will provide invaluable insights into the formation of our solar system, particularly in determining whether asteroids like Bennu contain the essential chemical building blocks for life.
The cost of NASA’s mission was initially budgeted at a staggering $800 million but is now estimated to reach around $1.16 billion, making the sample’s price tag come to approximately $132 million per ounce or $4.7 million per gram. However, while this may seem exorbitant, there are even more astronomical costs associated with other materials used in scientific research.
As an astronomy professor with a fascination for extraterrestrial specimens, I regularly employ Moon and Mars rocks in my teaching and maintain a humble collection of meteorites. It never fails to astound me that I can hold in my hand an object that is billions of years old and originated from billions of miles away.
To put the price of these space rocks into perspective, Moon rocks collected during the Apollo program from 1969 to 1972 brought back a total of 842 pounds (382 kg) of lunar samples at an overall cost, adjusted for inflation, of $257 billion. This equates to a relative bargain of $19 million per ounce or $674,000 per gram. The Apollo program, of course, had the added value of showcasing technological advancements in human spaceflight.
Looking ahead, NASA’s upcoming Mars Sample Return mission, scheduled for the early 2030s, aims to retrieve 30 sample tubes with a combined weight of one pound (450 g) to investigate potential traces of ancient life. However, due to the mission’s complexity involving multiple robots and spacecraft, the cost of bringing back these samples could reach a staggering $11 billion. This would place the price at $690 million per ounce or $24 million per gram, significantly surpassing the unit cost of the Bennu samples by a factor of five.
Interestingly, some space rocks come completely free of charge. Every day, approximately 50 tons of free samples from the solar system rain down on Earth. Most of these meteoroids burn up upon entering the atmosphere, but those that survive and reach the ground are known as meteorites, with the majority originating from asteroids. Identifying and retrieving meteorites can prove challenging, as they often resemble regular rocks to the untrained eye.
The most common meteorites, known as chondrites, can be purchased online for as little as $15 per ounce or 50 cents per gram. Chondrites differ from ordinary rocks due to the presence of round grains called chondrules, which formed as molten droplets in space during the birth of the solar system 4.5 billion years ago. Iron meteorites, on the other hand, possess a dark crust caused by atmospheric melting upon entry and an internal pattern of long metallic crystals. These specimens can cost up to $50 per ounce or $1.77 per gram. The rarest meteorites, known as pallasites, are stony-iron meteorites infused with the mineral olivine. When cut and polished, they exhibit a translucent yellow-green color and can command prices exceeding $1,000 per ounce or $35 per gram.
Although relatively rare, a handful of meteorites originating from the Moon and Mars have made their way to Earth. Approximately 600 have been confirmed as lunar in origin, with the largest specimen, weighing 4 pounds (1.8 kg), selling for about $4,700 per ounce or $166 per gram. About 175 meteorites have been identified as originating from Mars, with a purchase price of around $11,000 per ounce or $388 per gram.
Determining the source of meteorites is possible by examining their landing trajectories to trace them back to the asteroid belt or by comparing their composition to different classes of asteroids. Lunar and Martian rocks can be identified based on their unique geology and mineralogy. However, the drawback of these “free” samples is that their origin within the Moon or Mars remains unknown, limiting their scientific value. Moreover, they become subject to contamination as soon as they touch Earth’s surface, making it difficult to discern whether any microorganisms found within them are truly extraterrestrial.
Moving beyond space rocks, other elements and minerals command high prices due to their scarcity. Simple elements found in the periodic table, such as carbon, iron, aluminum, and even mercury, have relatively low costs. Precious metals like silver fetch $14 per ounce or 50 cents per gram, while gold demands a price of $1,900 per ounce or $67 per gram. However, the prices skyrocket when it comes to rare radioactive elements, with polonium-209 topping the list at a colossal $1.4 trillion per ounce or $49 billion per gram.
Gemstones can also carry hefty price tags. Top-quality emeralds fetch prices ten times that of gold, while white diamonds are a hundred times more expensive. Some diamonds possess a boron impurity, giving them a brilliant blue hue. These blue diamonds, found in only a few mines worldwide, can cost up to $550 million per ounce or $19 million per gram, rivalling the cost of the upcoming Mars samples. It is worth noting that an ounce of diamond weighs around 142 carats, but such large gemstones are extremely rare.
One of the most expensive synthetic materials is a minuscule carbon cage containing a trapped nitrogen atom. These carbon cages, known as endohedral fullerenes, exhibit exceptional stability and can be used in atomic clocks for timekeeping. The cost of these highly specialized materials is a staggering $4 billion per ounce or $141 million per gram.
Yet, the pinnacle of exorbitance resides in antimatter, an incredibly scarce substance in nature due to its characteristic of instantly annihilating upon contact with regular matter, releasing radiation. The particle accelerator at CERN can produce around 10 million antiprotons per minute, which may sound like an immense quantity. However, at this rate, it would require billions of years and cost a mind-boggling sum of one billion billion ($10^18) dollars to generate a single ounce, equivalent to $3.5 x 10^16 per gram. Thus, the development of warp drives powered by matter-antimatter annihilation, as depicted in “Star Trek,” will have to remain a futuristic fantasy.
In conclusion, while NASA’s mission to retrieve a sample from the asteroid Bennu carries a hefty price tag, it pales in comparison to the costs associated with other materials used in scientific research. Space rocks and meteorites provide valuable insights into the formation of our solar system, but they often come with a significant price. Ultimately, it is our insatiable curiosity about the universe and our quest for knowledge that keeps us on a constant journey of exploration.
This article was authored by Chris Impey and originally published on The Conversation, an independent, nonprofit news site committed to disseminating ideas from academic experts. Chris Impey receives funding from the National Science Foundation.
