Help Shape the Future of Space Exploration

Join The Planetary Society Now  arrow.png

Join our eNewsletter for updates & action alerts

    Please leave this field empty

Headshot of Emily Lakdawalla

Pretty Picture: ISS in the X-band

Posted by Emily Lakdawalla

04-03-2010 8:40 CST


This is from the "Just Plain Cool" department: a picture of the International Space Station taken in microwave radar. The specific radio wavelength involved is the X-band, radio with wavelengths of a few centimeters. (I've noticed some bloggers incorrectly reporting this image as being taken in "X-rays," which is quite a different animal entirely, waaaaay shorter wavelength than visible light and not a very friendly wavelength to be irradiating astronauts with; microwave radar is waaaay longer wavelength than visible light and of no consequence to astronaut health.) For comparison, I'm also posting an image of the ISS taken with a plain old optical camera just a couple of months later.

ISS in the X-band

German Aerospace Center (DLR)

ISS in the X-band
On March 13, 2008, the International Space Station (ISS) passed across the field of view of Germany's remote sensing satellite, TerraSAR-X, at a distance of 195 kilometers.

In contrast to optical cameras, radar does not "see" surfaces. Instead, it is much more sensitive to the edges and corners which bounce back the microwave signal it transmits. Unless they are directly facing the radar spacecraft, smooth surfaces such as those on the ISS solar and radiator panels, do not reflect a strong signal to the detector, so they appear dark. Yet the bright spots outlining edges and corners clearly show the shape of the ISS. The central element on the ISS, to which all the modules are docked, has a grid structure that presents a multiplicity of reflecting surfaces to the radar beam, making it readily identifiable. This image has a resolution of about one meter.

The main reason I'm posting this picture is because it's a picture of a pretty familiar object -- the Space Station -- in an unfamiliar part of the electromagnetic spectrum. I post images here all the time in wavelengths longer than the human eye can see, and it's tempting to assume that images of the same places will look pretty much the same in visible wavelengths. But the photo above shows how simultaneously familiar and strange a well-known object looks in radar, reminding me that my instincts in interpreting what I see in radar images of places like Titan, Venus, and the Moon may not always be reliable.

A final note about this image -- I first learned about it via DLR's Twitter feed. I'm finding it easier to get news about European missions via Twitter than more traditional means!

See other posts from March 2010


Or read more blog entries about:


Leave a Comment:

You must be logged in to submit a comment. Log in now.
Facebook Twitter Email RSS AddThis

Blog Search


Our Curiosity Knows No Bounds!

Become a member of The Planetary Society and together we will create the future of space exploration.

Join Us

Featured Images

Tethys in enhanced color: south pole and southern Ithaca Chasma
Tethys' anti-Saturn side
Dione in true color
Cometary Interloper
More Images

Featured Video

Intro Astronomy 2015. Class 8: Galilean Satellites, Saturn System

Watch Now

Space in Images

Pretty pictures and
awe-inspiring science.

See More

Join the New Millennium Committee

Let’s invent the future together!

Become a Member

Connect With Us

Facebook! Twitter! Google+ and more…
Continue the conversation with our online community!