File:Iridium clad GPHS pellet.jpg

No higher resolution available.

Iridium_clad_GPHS_pellet.jpg ‎(222 × 222 pixels, file size: 15 KB, MIME type: image/jpeg)

This is a file from the Wikimedia Commons. Information from its description page there is shown below.
Commons is a freely licensed media file repository. You can help.

Summary

DescriptionIridium clad GPHS pellet.jpg	English: Pu-238 fuel pellet in its protective iridium metal cladding, as used in the General Purpose Heat Source (GPHS). The photograph shows the equatorial tungsten arc weld and the iridium frit-vent at the pole, which releases helium from the alpha decay of plutonium.
Date	26 February 2012
Source	http://solarsystem.nasa.gov/rps/types.cfm
Author	U.S. Federal Government

Licensing

	This file is in the public domain in the United States because it was solely created by NASA. NASA copyright policy states that "NASA material is not protected by copyright unless noted". (See Template:PD-USGov, NASA copyright policy page or JPL Image Use Policy.)
	Warnings: Use of NASA logos, insignia and emblems is restricted per U.S. law 14 CFR 1221. The NASA website hosts a large number of images from the Soviet/Russian space agency, and other non-American space agencies. These are not necessarily in the public domain. Materials based on Hubble Space Telescope data may be copyrighted if they are not explicitly produced by the STScI.[1] See also {{PD-Hubble}} and {{Cc-Hubble}}. The SOHO (ESA & NASA) joint project implies that all materials created by its probe are copyrighted and require permission for commercial non-educational use. [2] Images featured on the Astronomy Picture of the Day (APOD) web site may be copyrighted. [3] The National Space Science Data Center (NSSDC) site has been known to host copyrighted content. Its photo gallery FAQ states that all of the images in the photo gallery are in the public domain "Unless otherwise noted."