Assessing the Sampleability of Bennu's Surface for the OSIRIS-REx Asteroid Sample Return Mission.

Area of Science:

• Planetary Science
• Astrogeology
• Space Mission Engineering

Background:

• NASA's OSIRIS-REx mission aimed to collect samples from asteroid Bennu.
• Selecting a suitable sampling site was difficult due to Bennu's surface composition, lacking fine-grained regolith deposits.
• The Touch-and-Go Sample Acquisition Mechanism (TAGSAM) has specific particle size requirements for sample collection.

Purpose of the Study:

• To develop and describe the Sampleability Map for asteroid Bennu.
• To aid in selecting optimal candidate sampling sites for sample collection.
• To estimate the probability of successfully collecting sufficient sample mass.

Main Methods:

• Constructed a Sampleability Map using a numeric score based on surface properties.
• Developed an algorithm derived from laboratory testing of TAGSAM performance.
• Evaluated sampleability at global and site-specific scales using mission data.

Main Results:

• The Sampleability Map quantified surface compatibility with the TAGSAM.
• The algorithm predicted sample collection based on particle size distribution and TAGSAM head tilt.
• Global assessment identified and avoided areas with large boulders, while site-specific analysis refined collection predictions.

Conclusions:

• The Sampleability Map was crucial for overcoming challenges in site selection on Bennu.
• The rigorous assessment provided confidence in choosing the best sample collection site.
• This approach enabled the successful collection of hundreds of grams of asteroid material.