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General NEO FAQs
When is the next big impact likely to happen?
It’s all a question of probabilities. As you can see in the table here, small impacts occur relatively frequently, whereas bigger impacts, that is, those that would cause major damage, occur every several thousand to millions of years. However, this impact frequency is just an average. For example, even though the Tunguska impact in Siberia was in 1908, that doesn’t mean that the next 50m asteroid will impact Earth in 3908. It is an average, based on analyses of the known and expected NEO populations. There is no substitute for observation campaigns designed to detect and monitor NEOs.
The planning and implementation of a mission depends on its complexity and the amount of resources available to implement it, as well as the amount of risk that is willing to be accepted for a mission failure. For a mission of this complexity implemented through the standard (e.g. ESA or NASA) processes, a development time of 6-10 years would be normal. However, within the scope of the NEOShield project, a lot of the initial mission design and planning work has already been completed meaning that, if a threat is detected, a mission can be implemented faster. We are now developing and testing critical technologies as part of the NEOShield-2 project, which will further reduce the time required. The exact development roadmap has already been analysed during the initial NEOShield project and is being further assessed during NEOShield-2.
How are NEOs and PHOs tracked and will we see one in time to plan to deflect it?
More recently there have been advances in ground technologies to detect and observe NEOs from Earth, and NEOs and PHOs are tracked mainly through these ground-based observatories. There are networks of mainly optical telescopes, but also radar telescopes, around the world. Amateur astronomers also make a significant contribution to the discovery and tracking of NEOs.
There are some space-based observatories, however there are arguments for funding a new, dedicated, NEO survey spacecraft.
The Minor Planet Center gathers and analyses the new findings.
In general, large NEOs, which are the dangerous ones, are discovered with sufficient warning to prepare for a mitigation method, however some NEOs are not observable, as they may be for example on the other side of the Sun from Earth. This is an argument for a NEO-observation spacecraft that would be placed in an orbit closer to the Sun that could survey all sides of the Solar System.
Is there a risk that the nuclear solution could lead to a weaponization of space?
No. The nuclear solution will only be used if it is absolutely necessary, and if so the mitigation attempt would probably be controlled by a multinational organisation such as the UN. The Space Missions Planning and Advisory Group (SMPAG) is the political structure put into place by the UN to prepare for an international response to a NEO threat, and the NEOShield and NEOShield-2 projects are well represented in this community.
What are NEOs made of?
Asteroids are essentially rocky small bodies. The asteroids are often divided into different classes based on their material composition. Most common are C-type, which are carbon-rich and darker asteroids, and S-type, which are silica rich stony asteroids and slightly lighter. There are also asteroids that have a higher metallic content.
Comets are usually rocky cores with ice around them. It is the melting of this ice streaming behind comets that gives them their well-known tails.
What is the naming convention for Asteroids?
Asteroids and Comets are named by committees of the International Astronomical Union (IAU). The discoverer can suggest a name to these committees.
However, most asteroids only have provisional names. The convention for theses is that the first four digits are the year of discovery, followed by a space, followed by a letter representing the half month within that year in which it was discovered, followed by another letter representing the order of discovery within that half month. If there is a number after the second letter, it represents the number of times that the second letter has been repeated in that half month. For example, 2005 GO21 was discovered in the 7th half month of 2005 (G is the seventh letter), and was the 539th new asteroid named in that half month (21 repetitions of the alphabet and then O is the 14th letter, without “I”).
Why are the total number of NEOs and PHAs different on different websites?
Different organisations use different definitions for both NEO and PHA. The size is usually calculated from the Absolute Magnitude, however this method is often approximate. Also, make sure that you are comparing numbers from the same dates, as new NEOs are always being discovered!
NEOShield and NEOShield-2 Projects FAQs
How long did the NEOShield project last?
The NEOShield project lasted for 3 and a half years and ended in the middle of 2015.
The NEOShield-2 project follows on from the initial NEOShield project. Starting in March 2015, the project will last for ~two and a half years.
Who was involved in NEOShield and who is now involved in the NEOShield-2 project?
Check out our team page for thorough information.