LEARN – What Were the First Asteroid Exploration Missions?
LEARN – What Were the First Asteroid Exploration Missions? https://asteroidday-uploads.s3.eu-central-1.amazonaws.com/wp-content/uploads/2025/11/21111258/Sp3.jpg 512 384 Asteroid Day https://asteroidday-uploads.s3.eu-central-1.amazonaws.com/wp-content/uploads/2025/11/21111258/Sp3.jpg
Learning Objective:
To describe how the first space probes opened the way to explore asteroids up close.
Overview:
A new way of seeing and studying asteroids began thanks to the results of these first missions to asteroids.
Specifics:
Launched in March 1972, Pioneer 10 was the first spacecraft to cross the Main Belt. At the time, scientists were concerned that it might be destroyed in collisions, as little was known about the density of bodies in that region. During the crossing, which began in July 1972, the probe confirmed that the space between the asteroids was vast and that the actual risk of impact was very small.
The probe’s primary target was the planet Jupiter, but it carried several multi-purpose scientific instruments, including a meteoroid and asteroid detector to track particles ranging from nearby clumps of dust to large bodies. Although it did not generate images, the probe passed within 8.8 million kilometres of an unnamed asteroid and of asteroid (307) Nike in August and December 1972, respectively.
Subtitle: Pioneer 10, on its way to Jupiter, was the first probe to cross the Main Belt. (Smithsonian / National Air and Space Museum)
In October 1991, the Galileo probe carried out the first flyby of an asteroid in the history of space exploration. On its trajectory to Jupiter, it passed by (951) Gaspra, an irregular body in the Main Belt with an average diameter of about 12 km.
The closest approach was just 1,600 km, and although this was not originally planned as a primary mission objective, the encounter opened a new era of direct asteroid studies. More than 50 images were obtained, revealing details of asteroid surfaces for the first time. This flyby showed that asteroids are complex and diverse worlds, not mere rocks in space.
Subtitle: Asteroid (951) Gaspra, the first asteroid to be photographed up close by a probe. (NASA / JPL / Galileo mission)
In February 2000, the NEAR-Shoemaker probe entered orbit around asteroid (433) Eros, an elongated body with an average diameter of about 16 km. It was the first time a spacecraft had orbited an asteroid, allowing for prolonged observations. For a year, the probe mapped the surface with cameras, spectrometers, and X-ray and gamma-ray detectors.
Subtitle: Eros was the first asteroid to be the target of a fully dedicated mission. (NASA / JPL / NEAR-Shoemaker mission)
The images revealed a landscape riddled with craters, large blocks of rocks and signs of a violent impact history. The data also showed that Eros is composed of silicates and metals, similar to certain meteorites found on Earth.
The mission had already been considered a success simply for orbiting the asteroid, but an even greater feat was yet to come. In February 2001, NASA commanded a controlled descent to the asteroid’s surface. The probe touched down gently, transmitting scientific data until the very last moment. This landing made NEAR-Shoemaker the first human-made object to physically touch an asteroid.
Subtitle: A close-up of the asteroid Eros by NEAR-Shoemaker. In addition to orbiting it, the probe touched down on the surface, revealing fine details of its terrain. (NASA / JPL / NEAR-Shoemaker mission)
This feat marked a watershed in space exploration, showing that it was possible to reach, study and even land on these small worlds.
See also:
LEARN – How Do We Explore Asteroids?
LEARN – Why Aren’t Asteroids Round?
Missions to Asteroids Exhibition Posters – Commemorative Versions
