Problems with the Richter scale

The major problem with Richter magnitude is that it is not easily related to physical characteristics of the earthquake source. Furthermore,there is a saturation effect near 8.3-8.5, owing to the scaling law of earthquake spectra, that causes traditional magnitude methods to yield the same magnitude estimate for events that are clearly of different size. By the beginning of the 21st century, most seismologists considered the traditional magnitude scales to be largely obsolete, being replaced by a more physically meaningful measurement called the seismic moment which is more directly relatable to the physical parameters, such as the dimension of the earthquake rupture, and the energy released from the earthquake. In 1979 seismologists Tom Hanks and Hiroo Kanamori, also of the California Institute of Technology, proposed the moment magnitude scale , which provides a way of expressing seismic moments in a form that can be approximately related to traditional seismic magnitude measurements.

Population control

Population control is the practice of curtailing population increase, usually by reducing the birth rate. Surviving records from Ancient Greece document the first known examples of population control. These include the colonization movement, which saw Greek outposts being built across the Mediterranean and Black Sea basins to accommodate the excess population of individual states. An important example of mandated population control is China's one-child policy, in which having more than one child is made extremely unattractive. This has led to allegations that practices like infanticide, forced abortions, and forced sterilization are used as a result of the policy.
In ecology, population control is on occasions considered to be done solely by predators, diseases, parasites, and environmental factors. At many times human effects on animal and plant populations are also considered. Migrations of animals may be seen as a natural way of population control, for the food on land is more abundant on some seasons. The area of the migrations' start is left to reproduce the food supply for large mass of animals next time around. See also immigration.

NASA spaceflight missions

NASA has had many successful space missions and programs, including over 100 manned missions. The many notable manned missions have been from the Apollo program, which were a sequence of missions to the moon, and included the achievement of the first man to walk on the moon, during Apollo 11. The Space Shuttle Program has also been a huge success with, despite the loss of two of the Space Shuttles, Challenger and Columbia which resulted in the deaths of their entire crews. The Space Shuttles were able to dock with the space station Mir while it was operational, and are now able to dock with the International Space Station - a joint project of many space agencies. NASA's future plans for space exploration are with the Project Constellation.

There have been many unmanned NASA space missions as well, including at least one that visited each of the other 7 planets in our solar system, and four missions that have left our solar system. There has been much recent success with the missions to Mars, including the Mars Exploration Rovers, and the Mars Reconnaissance Orbiter.