A penetrometer is a device to test the strength of a material such as soil. There are many types of penetrometer. They are usually round or cone shaped. The penetrometer is dropped on the test subject or pressed against it and the depth of the resulting hole is measured. The measurements determine whether the soil is strong enough to build a road on. Scientists also use a penetrometer to measure how much moisture

Moisture

Humidity is the amount of moisture the air can hold before it rains. Moisture refers to the presence of a liquid, especially water, often in trace amounts...

 is in soil. Penetrometers are used on space probes such as the Cassini–Huygens probe, to measure the amount of moisture in soil on other planets.

External links

• University of Arizona document, "An impact penetrometer for a landing spacecraft."
• Picture of a penetrometer from the European Space Agency (ESA)