Today In Science History – July 31

Lunar Prospector

Lunar Prospector spacecraft. The spacecraft impacted the Moon to look for evidence of water ice. Credit: NASA

On July 31, 1999, NASA’s Lunar Prospector mission ended with a dive into the south pole of the Moon.

Lunar Prospector was part of the Discovery Program, NASA’s attempt at creating “faster, better, cheaper” planetary missions. The idea behind the Discovery Program was NASA would propose a mission, outline its goal and set a budget. If an industry, team of students, or government lab felt they could accomplish the task for the money, they could submit their proposal to a review committee. If their proposal met the criteria and was selected, a mission was created.

Lunar Prospector was the third mission in this program. It had a budget of only $63 million and was designed to fly to the Moon and enter into a low polar orbit and conduct experiments. This included an extensive mapping campaign of surface features and their composition, measuring changes in the Moon’s magnetic and gravity fields and studying outgassing events. One important feature Lunar Prospector was hoping to find was water ice deposits.

Lunar Prospector was launched on January 6, 1998. It was a relatively small craft, just under 2 meters in diameter and a little more than a meter tall. It had three booms connected to the central drum that carried the instruments needed for the mission. It arrived at the Moon four days later and entered a 100 km orbit that took it around the Moon once every 2 hours. The orbit was lowered to 40 km to obtain higher resolution images. The final act of Lunar Prospector was to deliberately impact the Moon in the permanently shadowed edge of a crater. It was hoped the impact would cause any subsurface water ice to blast out from the impact area. No evidence of water was detected.

One of the more interesting things about Lunar Prospector was that it carried 28 grams of the remains of planetary scientist and astronomer Eugene Shoemaker. When the spacecraft buried itself in the side of the crater, Shoemaker became the first, and only, person buried on the Moon. Another interesting bit of trivia: the crater Lunar Prospector crashed into was called Shoemaker Crater.

Other Notable Events on July 31

1964 – Ranger 7 spacecraft transmits pictures of the Moon.

Ranger 7's First Picture of the Moon

First photograph from Ranger 7 lunar probe of the surface of the Moon. Credit: Jet Propulsion Laboratory/NASA

The first successful U.S. probe to the Moon, Ranger 7 returned the first pictures of the surface of the Moon. The probe sent back over 4300 highly detailed photographs before impacting the surface. These images would aid engineers to build a spacecraft that could land on the Moon.

Until the success of this mission, the Ranger program was a series of failures. The first two prototypes failed to leave Earth orbit. The third missed the Moon. Ranger 4 ran into it without taking any pictures. Ranger 5 missed the Moon again and Ranger 6’s cameras did not activate.


1923 – Stephanie Louise Kwolek was born.

Stephanie Kwolek

Stephanie Kwolek (1923 – 2014) Credit: Chemical Heritage Foundation

Kwolek is an American polymer chemist who discovered the polymer known as Kevlar. She was working on a project to find a strong, lightweight fiber to use in tires. The liquid crystal solutions she was working with were thick and milky looking and she had difficulty convincing the person in charge of the spinning equipment that the solution would not clog the tiny holes in the equipment. Once they started to spin the solution, the Kevlar fibers easily came out of the machine and were very strong and stiff.

Kwolek was also the person who first came up with the classroom demonstration to produce nylon fibers in a beaker at room temperature.


1918 – Paul Delos Boyer was born.

Boyer is an American biochemist who shares half the 1997 Nobel Prize in Chemistry with John E. Walker for discovering the enzymatic mechanism behind the production of adenosine triphosphate or ATP. ATP is the nucleotide that transfers energy during metabolic processes in cells.

ATP Structure

Structure of Adenosine triphosphate (ATP)

1859 – Theobald Smith was born.

Theobald Smith (1859 - 1934)

Theobald Smith (1859 – 1934)

Smith was an American pathologist and microbiologist who discovered the causes of several infectious parasitic diseases. One of the most important discoveries was the cause of Texas Cattle Fever was linked to a protozoan spread by ticks. This was one of the first cases that definitely showed an insect as an important vector in infection. This line of investigation would be important for other diseases such as yellow fever or malaria.


1800 – Friedrich Wöhler was born.

Friedrich Wohler

Friedrich Wöhler (1800 – 1882). Wikimedia Commons

Wöhler was a German chemist who first synthesized the organic compound urea from inorganic components. This was one of the first processes that invalidated the popular vitalism theory, in which biochemical reactions require biological catalysts or a ‘vital’ spark. He also isolated the element aluminum and discovered a method to create acetylene from calcium carbide.

Leave a Reply