For asteroid protection, observatories across the globe monitor different patches of the sky to discover previously unidentified space objects in the solar system and track the known ones.

The extensive project still continues, but every now and then some small or big space rock makes an uninvited appearance and flies by our planet. This has raised alarms regarding the case of a potential impact.

As the behavior of an asteroid — whether on impact course or not — depends a lot on its mass, NASA is working on a way that could measure the weight of an asteroid passing by Earth. This could help flag asteroids that are a potential threat to those on Earth.

Near earth asteroid
NASA is working on technology to measure asteroid masses. Pictured, a mosaic of asteroid 253 Mathilde constructed from four images acquired by the Near Earth Asteroid Rendezvous (NEAR) spacecraft, June 27, 1997. NASA/JPL

Current observational techniques, which include ground and space-based telescopes, can spot a small space object but analyzing its chemical composition and mass requires more precise data, which, according to the agency, its OpGrav mission could provide.

OpGrav or Optical Gravimetry is a technique where several disposable sphere-like probes would be deployed from a parent spacecraft. The probes would hurl toward the object in question, entering its proximity.

As this happens, the gravity of the object in question would deflect the small spheres from their path. This change in trajectory will be recorded by the camera sensors integrated with the parent spacecraft, which would maintain a safe distance from the rock and go about its job of conducting science observations.

Finally, after the flyby, the data related to the minute probes and science observations will be transmitted back to the teams on Earth. Here, the information will be used to calculate the estimated mass of the asteroid in question.

This, as the agency described, would provide high-resolution data, serving a major upgrade over conventional observational telescopes which do not come anywhere near an asteroid. Moreover, as there are many of these probes, the measurement of the asteroid could also be cross-checked, validated.

Once mass distribution in the asteroid has been calculated, ground teams can combine that information with shape models to predict its density or porosity, which could bolster efforts toward planetary defense and provide more insight into the birth asteroids.

However, it is worth noting that the measurement will depend a lot on the size of the asteroid being studied. According to the agency, if the object is small, the probes will have to be directed more precisely than for bigger asteroids. In fact, the accuracy of OpGrav could be up to 40 percent for small asteroids and around 90 percent for bigger ones.

The prototype for the project, named Small body In-situ Multi-probe Mass Estimation Experiment, is currently in the environmental and functional testing phase, giving the agency an idea of probe deployment and measurement accuracy. But, there is still no word on when it might really take to the skies.