Final answer:
The NASA Spaceguard Survey discovers and tracks near-Earth asteroids to assess impact risks, and as of 2021, it has found over 98 percent of hazardous asteroids larger than 1 kilometer.
Step-by-step explanation:
The NASA Spaceguard Survey is a program designed to locate and track asteroids and comets that could potentially pose a threat to our planet.
Initiated in the 1990s, the survey involves using several small yet sophisticated wide-field telescopes to scan for potentially hazardous asteroids (PHAs). By 2021, the Spaceguard Survey had successfully discovered over 98 percent of the hazardous near-Earth asteroids larger than 1 kilometer, ensuring that none of these pose any danger to Earth at present.
However, the discovery of objects not yet found continues, as each asteroid identified can be evaluated for future risk. The search is further supported by additional equipment; the Vera Rubin Telescope is set to enhance the full-sky scanning, and a space-based search telescope is under development.
In the context of life-and-death undertakings by astronomers, the Spaceguard Survey holds significant importance with its potential to prevent a catastrophic impact on our planet. Technologies to defend against these threats are also being explored, exemplified by the DART mission which aims to test the deflection of asteroids.