18 July 2011


DAWN. On Saturday, July 16 (my mother's birthday), NASA's robotic spacecraft Dawn became the first spacecraft to penetrate the solar system's asteroid belt, going into orbit around the asteroid Vesta. Dawn (see image above) is scheduled to investigate Vesta from orbit until 2012, when it will divert to the dwarf planet Ceres for a similar orbit and investigation. Dawn's mission is "to study two large bodies in the asteroid belt in order to answer questions about the formation of the solar system.

"Ceres and Vesta were chosen as two contrasting protoplanets, the first one apparently 'wet' (that is, icy) and the other 'dry' (rocky), whose accretion was terminated by the formation of the planet Jupiter .... Ceres is a dwarf planet whose mass comprises about one-third of the total mass of the bodies in the asteroid belt .... Smaller Vesta has experienced significant heating and differentiation. It shows signs of a metallic core, a Mars-like density and lunar-like basaltic flows. Both bodies formed very early in the history of the solar system, thereby retaining a record of events and processes from the time of the formation of the terrestrial planets."

Dawn is the first spacecraft to orbit an extraterrestrial body before continuing under powered flight to a second such body. Previous multi-target mission -- such as the Voyager program -- have instead been planetary flybys. The asteroid belt occupies an orbital space between the orbits of Mars and Jupiter, as shown in the image below (click to enlarge).

GRADE INFLATION. The following news does not surprise me in the least. In A History of College Grade Inflation, Catherine Rampell reports that since 1940, historical data on letter grades awarded by more than 200 four-year colleges and universities in the U.S. reveal that in both public and private schools, higher grades are awarded for work that would have received lower grades in the past .... i.e., grade inflation (see chart below, click to enlarge).

"The authors don't attribute steep grade inflation to higher-quality or harder-working students. In fact, one recent study found that students spend significantly less time studying today than they did in the past. Rather, the researchers argue that .... more generous grading can produce better instructor reviews, and can help students be more competitive candidates for graduate schools and the job market.

" .... More disturbing, they argue, are the potential effects on educational outcomes. 'When college students perceive that the average grade in a class will be an A, they do not try to excel. It is likely that the decline in student study hours, student engagement, and literacy are partly the result of diminishing academic expectations."

Ya think? When I was in high school, an A was awarded for grades between 95-100 percent, a B between 90-94 percent, a C between 80-89 percent, a D between 75-79 percent, and an F anything below 75 percent. Period. When you earned As and Bs, it meant something. Now most schools allow 10 percent for each of the upper four grades, and some schools allow even more. How is lower the bar doing a service to students, or to society? Answer ~ it is not.

Notice something on the graph below ~ until the 1960s, an A grade fell somewhere in the middle of the grade distribution, and Cs were most common. This is what one might expect from a normal distribution (bell-shaped curve). With the advent of grade inflation, As skyrocketed, Bs were stable, but Cs and Ds plunged. Is it any wonder that we have high school and college graduates who don't understand essential math skills; students who have to resort to Google or Wikipedia to learn the facts they should already have absorbed in history, geography, science, or the arts; not to mention students who must struggle to put together a competent research paper? Lowered expectations yield lowered performance, which is precisely why students from the U.S. are falling further and further behind students from other developed countries. Rather than breeding excellence, we are breeding mediocrity.

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