Neil deGrasse Tyson hosts astrophysicist and Chuck Nice for a deep dive into asteroid science with Harold Connolly Jr., founding chair and professor of geology at Rowan University and co-investigator on NASA's OSIRIS-REx mission.

The conversation explores how asteroids serve as time capsules from the early solar system, preserving ingredients for life that have remained pristine for 4.567 billion years. Connolly discusses the successful sample return from asteroid Bennu, which brought back over 120 grams of material containing amino acids, organic compounds, and minerals that formed in ancient water-rich environments.

The discussion covers the technical challenges of the touch-and-go sampling mission, the discovery of evaporite minerals indicating past fluid activity, and the broader implications for understanding how life's building blocks may have been delivered to Earth and Mars through asteroid impacts.

OSIRIS-REx Mission: From Acronym to Asteroid Sample Return

OSIRIS-REx stands for Origins, Spectral Interpretation, Resource Identification, Security, and Regolith Explorer - a $2 billion NASA mission to return samples from asteroid Bennu.

The mission successfully collected 122 grams of pristine material using a touch-and-go sampling mechanism that fired nitrogen gas to fluidize surface material into a collection head.

"We had designed originally the spacecraft for big ponds on the surface of really fine-grained material... We got there, we screamed because there were boulders 11 stories high" - Harold describing unexpected surface conditions.

Bennu's Surprising Structure and Sampling Challenges

Bennu is a 'rubble pile' asteroid held together primarily by gravity, rotating retrograde every 4.2 hours with boulders up to 11 stories high on its surface.

The spacecraft penetrated 48 centimeters into Bennu's surface during sampling, much deeper than expected, revealing the asteroid's loose internal structure.

Sample collection nearly failed when stones got caught in the collection flap, causing material to leak out every time the robotic arm moved, requiring emergency early stowage.

Ancient Water and the Building Blocks of Life

Bennu samples contain evaporite minerals including table salt, formed when water-rich solutions evaporated in the asteroid's parent body 4.567 billion years ago.

Scientists have identified 15 of the 20 amino acids needed for life in Bennu samples, including tryptophan - the same compound that makes people sleepy after eating turkey.

"The evaporite minerals that we talked about are the late-stage product of the fluid that moved through, that formed other minerals first" - Harold explaining how organic compounds concentrate with salts.

Phosphorus-rich minerals found in samples provide key nutrients that, combined with carbon and hydrogen, form prebiotic compounds essential for life.

Contamination Concerns and Planetary Protection

NASA considers asteroids non-hazardous for biological contamination since they've been sterilized by solar radiation and cosmic rays for billions of years, unlike Mars samples which require strict protocols.

Neil references The Andromeda Strain by Michael Crichton when discussing his concerns about bringing extraterrestrial samples to Earth, though Harold assures him asteroids pose no biological threat.

Meteorites on Earth become contaminated within days of landing, with microbes beginning to consume them, making pristine space samples crucial for accurate analysis.

Pre-Solar Grains and Cosmic Heritage

Pre-solar grains found in asteroid samples are older than our solar system, originating from dying stars that seeded the molecular cloud from which our solar system formed.

These nanometer-sized grains include diamonds, silicon carbide, corundum (ruby/sapphire), and silicates that survived the solar system's formation and provided 'nutrients' for rocky planet development.

"We are stardust... these grains predate the origin of the solar system and they provided the nutrients, if you will, for the beginning of the formation of rocky materials" - Harold explaining cosmic inheritance.

Bennu's Future Earth Encounter and Planetary Defense

Bennu has a 1 in 2,700 chance of hitting Earth on September 24, 2182, making it a potentially hazardous near-Earth asteroid requiring continued monitoring.

Understanding Bennu's composition helps refine orbital predictions and informs potential deflection strategies, as "that probability also needs to know what's the composition of the asteroid in order to predict well" - Harold.

The 160-year warning provides ample time to develop deflection technology, assuming continued funding for planetary defense programs.

Implications for Life's Origins and Panspermia

Asteroid samples suggest that prebiotic compounds can form abiotically in space, potentially seeding early Earth and Mars with life's building blocks through impact delivery.

Harold argues against panspermia: "If you can make amino acids on rocks in space or in the parent body from which it came, you can make amino acids on Earth without the rock."

The discovery of RNA sugars like ribose in asteroid samples adds another crucial ingredient for life, though the gap between prebiotic compounds and actual life remains unexplained.