IEEE Spectrum is the flagship publication of the IEEE — the world’s largest professional organization devoted to engineering and applied sciences. Our articles, podcasts, and infographics inform our readers about developments in technology, engineering, and science.
Enjoy more free content and benefits by creating an account
Saving articles to read later requires an IEEE Spectrum account
The Institute content is only available for members
Downloading full PDF issues is exclusive for IEEE Members
Access to Spectrum's Digital Edition is exclusive for IEEE Members
Following topics is a feature exclusive for IEEE Members
Adding your response to an article requires an IEEE Spectrum account
Create an account to access more content and features on IEEE Spectrum, including the ability to save articles to read later, download Spectrum Collections, and participate in conversations with readers and editors. For more exclusive content and features, consider Joining IEEE.
Join the world’s largest professional organization devoted to engineering and applied sciences and get access to all of Spectrum’s articles, archives, PDF downloads, and other benefits. Learn more →
Our robot explorers aren’t always passive observers. In 2005 NASA’s Deep Impact space probe flew past the comet Tempel 1 and fired a projectile at the comet’s icy nucleus. The probe photographed the resulting cloud of dust and ice that expanded into space, and its spectrometers studied the chemical composition of the dust cloud.
If you are viewing this page with an iPad or iPhone, click here to launch the slideshow: