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Tracking Chandra

In case you wondered if Chandra is really up there, take a look at these pictures shot by Gary Emerson with a 25 cm telescope at the E.E. Barnard Observatory. Gary used an astronomical program called "The Sky" to generate the positions of the spacecraft position. First he shot with a wide-angle camera and found Chandra, and then he homed in with the 25 cm telescope. Full Story

See Chandra's current position in relation to the Earth!

Tracking Chandra
CXC in orbit - artist illustration
Artist's illustration of Chandra in orbit. (NGST)
Chandra orbit path
Artist's conception of Chandra's orbit path & radiation belts. (CXC/M.Weiss)

The Space Shuttle Columbia delivered Chandra to a low Earth orbit. Then, the Inertial Upper Stage rocket boosted Chandra up to a higher altitude where a built-in propulsion system took Chandra to its final orbit. This elliptical orbit takes the spacecraft to an altitude of 133,000 km (82,646 mi) — more than a third of the distance to the moon — before returning to its closest approach to the Earth of 16,000 kilometers (9,942 mi). It takes approximately 64 hours and 18 minutes to complete an orbit.

The Chandra spacecraft spends approximately 85% of its orbit above the Van Allen belts, charged particles that surround the Earth. This makes uninterrupted observations of as long as 55 hours possible, making the overall percentage of useful observing time much greater than the low Earth orbit of a few hundred kilometers used by most satellites.

Satellite Tracking Tutorial

Follow along with this tutorial to see for yourself what Chandra's orbit path looks like.

In a browser window, bring up: and click on the navigation button "Solar System Interactive"

Allow some time for the tool and its database to load. After it loads, you should be viewing the Sun with numerous circles around it. Near the Sun, you'll see a label for "Earth". Follow these steps:

  1. Click on "Earth", then click again on "(click to zoom)". You will zoom towards the Earth. The Earth data will take a few seconds to load and then you will have a view of our blue planet.
  2. Earth view, image of screen
    Figure 1


  3. Zoom out from the Earth until you see several satellites around our planet. You should see "Chandra" as one of them. If you don't see Chandra, you may need to zoom out farther (see figure 2: circle & arrow).
  4. View of Chandra orbit, image of screen
    Figure 2


  5. Move your mouse over "Chandra" click to highlight a spot on Chandra's orbit. Notice the size and shape of Chandra's orbit. Compare Chandra's orbit with some of the other satellites shown, such as "SDO", "GEOTAILL" and "Polar". Click on "Chandra" and then click on "Chandra" again to focus in on the spacecraft (see figure 3).
  6. View of Chandra spacecraft, image of screen
    Figure 3


  7. You can click and drag your mouse to move Chandra around and see what's nearby. Try also the following:

    1. Zoom out from the Earth until you see "Chandra" again. Keep zooming out a bit more until you see "Moon." Click "Moon" and click again to zoom in and focus on the Moon (see figure 4). Chandra orbits more than a third of the distance to this body! Click and drag the Moon around until you see "Chandra" again. Click on "Chandra" and then Click on "Chandra" a second time to focus in on the spacecraft again.
    2. Earth's Moon view, image of screen
      Figure 4


    3. In the left side panel, click on "COMPARE SIZE". The comparison mode splits the screen, showing Chandra on the left and various objects on the right to scale. On the right side, click through the objects to compare their sizes with Chandra.
    4. Image of Chandra compared to the size of a school bus
      Figure 5


    5. Click on any other satellite to see it's name and orbit. (You can always get back to Chandra by repeating steps "1" and "2").

    6. Next, zoom back until the Earth takes up most of your window. You will see low-altitude satellites which include missions such as Hubble ("HST"), the Space Station ("ISS"), WISE, and many others.

    7. Still having fun? You can try visiting our Sun or some of the planets in our Solar System. Or you could try additional tutorials on accelerated time, camera angles, and more at You can even see which spacecraft NASA's Deep Space Network is talking to in real time at
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