Shielding Disintegrates

Fragments of carbon. Heat shields strike the atmosphere at high speed. Friction causes the shield to shed layers. This loss of material is spallation. Spacecraft face heat during the descent to the soil.

Technicians in white suits calibrated every sensor to protect the pilots. I was like witnessing the quiet intensity of the room as the vacuum pumps hummed.

NASA Engineering and Safety Center analysts use mass spectrometry for the data. This technique counts the particles in the plasma flow. Study the results.

Oxygen atoms collide with the carbon surface. This reaction creates carbon monoxide. The heat shield thins as the gas environment changes.

Logic dictates the design. But here’s where it gets weird, the air pressure ejects larger chunks of material than the chemical reactions alone.

The HYMETS facility simulates the fire of entry.

Scientists observe the erosion while the air hits the shield. The material holds. The velocity of the descent turns the surrounding air into a soup of atoms that strips the carbon from the craft one molecule at a time until the shield becomes a thin layer of protection.

Extra Perk

Entry models now include kinetic energy updates.

These formulas predict the path of every fragment. New carbon composites undergo testing in the plasma jet to ensure the safety of the next generation of explorers. Sensors embedded in the hardware transmit data through the heat of the plasma.

The Quiz

1. If a shield never eroded during descent, would the spacecraft survive the landing?

2. Does the creation of carbon monoxide gas provide a benefit to the vehicle structure?

Hypothetical Answers

1. No, because the erosion process carries away the heat; a static shield would melt the internal cabin.
Read: Ablative Thermal Protection Systems, NASA Technical Reports

2. Yes, the gas creates a boundary layer that acts as a buffer between the craft and the friction of the atmosphere.
Read: Mass Spectrometry in Plasma Analysis

Note: The information in this article was first published in “NASA”.