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View of the plume emanating from Didymos, Dimorphos and Dimorphos following the intended impact of the Double Asteroid Redirect Test, or DART mission, in this image acquired by ASI’s LICIACube satellite just before closest approach to the Dimorphos asteroid on September 26, 2022. | Photo credit: Reuters
Launched in 2011, NASA’s The NEOWISE Mission It was active in Earth’s orbit until the end of last week. It detected more than 3,000 satellites near earth objects or NEOs — asteroids or comets whose orbits could bring them close to Earth, even if there is a chance of a collision. NEOWISE was switched off on Aug. 8.
Surveying the population of NEOs is central to the emerging concept Planet DefenseThat is, understanding and reducing the risk of collisions with large asteroids that could cause significant damage to Earth.
NEOWISE has made fundamental contributions to establishing the knowledge base for planetary protection, and of the 3,000 objects it has studied, more than 200 are objects we did not previously know about.
Now at the end of the mission, and after being ordered by NASA to shut itself down, NEOWISE will re-enter Earth’s atmosphere before the end of this year. What options does this leave us with to protect our planet?
From astrophysics to planetary protection
NEOWISE began as a separate mission, simply called WISE (Wide-field Infrared Survey Explorer) It was designed to study infrared radiation From distant galaxies in the universe.
Infrared means “beyond red” – infrared light is slightly beyond the red end of the spectrum of colours that humans can see. We know infrared radiation better as the heat coming from the sun, for example, or from radiators keeping us warm in winter.
When the coolant on the WISE mission ran out and these sensitive observations of galaxies could not be carried on, NASA granted a mission extension under the name NEOWISE. They realized that the telescope system was still sensitive enough to detect asteroids and comets that came close to Earth and the Sun, giving off a very strong infrared signal.
NASA has an extraordinary history of squeezing extra life out of spacecraft. Missions that are completedIn this case, NEOWISE represented a whole second life in an entirely different field of research.
How do we protect the Earth now?
Along with discovering and studying thousands of NEOs, NEOWISE laid the foundation of knowledge that has informed a new, dedicated planetary defense mission. NEO Surveyor Will be launched in 2027.
NEO Surveyor aims to discover about two-thirds of all NEOs larger than 140 metres in a five-year baseline survey. This is a major step toward fulfilling the mandate The United States Congress has authorized NASA to: Discovering 90% of all NEOs in this size range.
If these asteroids hit Earth, they could cause massive loss of life, provided the impact falls on a major metropolitan area.
You might think this is a bit risky – shutting down NEOWISE three years before launching NEO Surveyor. What if one of these big asteroids comes our way in the next few years?
The risks are very low, as estimates suggest that asteroids with a diameter of 140 metres hit Earth about every 20,000 years. So, we would have to be very unlucky if an asteroid hit Earth in any three-year period, especially in a location, to cause significant damage. Only about 3% of the Earth’s surface is hit by an asteroid. The urban areas are occupied,
NASA doesn’t really have any choice but to end NEOWISE. The Sun’s 11-year activity cycle causing turbulence in the Earth’s upper atmosphere, Ionospherethickening. NEOWISE is flying through this ionosphere and can’t raise its orbit, so the ionosphere is essentially pulling NEOWISE back to Earth.
Construction of NEO Surveyor begins in 2023, so a 2027 launch is impressively fast, closing the gap between NEOWISE and NEO Surveyor.
NEOWISE is scheduled to enter Earth’s atmosphere before the end of the year, but we don’t know exactly when that will happen.
Weighing about 700 kilograms, some part of NEOWISE is likely to hit the Earth’s surface. It is expected to stay away from populated areas in the process – as a result of some recent re-entry events Space debris is falling very close to populated areas,
An asteroid is coming! What’s next?
Knowing about an asteroid that’s about to hit Earth is one thing. Doing something about it is quite another.
A major step toward planetary protection was taken two years ago, when DART Mission One approached an asteroid, collided with it and changed its trajectory. This showed that it is possible to change the path of asteroids, which could be used to protect the Earth from collisions in the future.
Predicting potential Earth impacts as far in advance as possible, preferably years in advance, gives DART-style technology approaches a chance.
NEOWISE’s pioneering work, and the upcoming extensive observations of NEO Surveyor, will add a wealth of information to our scientific repository that will never become out of date and will potentially form the basis for planetary protection for hundreds of years into the future.
This article is republished from The Conversation under a Creative Commons license. Original article,
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