Goddard’s Testing Facilities: where we build satellites then try to break them

a graphic showing the number of satellites currently in orbit

a graphic showing the number of satellites currently in orbit

On a clear night with limited light pollution (which rarely happens in New York), you might look up into the night sky and see space.  You might see a shooting star or check out the full moon. What you probably don't see (or realize you are seeing) are the 8,000 satellites currently in orbit around the Earth. However, not all of these are currently operational. In case you don't know, people use satellites to look into both deep space and to look back at earth.

A satellite experiences harsh environments in space and during launch. If a satellite were to break due to these environments, we would much rather it happen on Earth where we can fix it (even though it is absolutely terrifying to try to break the satellite you've been working on).  Before a satellite is launched, it undergoes a series of tests. I recently explored the NASA Goddard testing facility with a man on my team who has been at Goddard for nearly 50 years (WHOAAA).

Goddard's largest Thermal Vacuum Chamber

Goddard's largest Thermal Vacuum Chamber

In space, a satellite is going to be subjected to extreme heat and extreme cold in a vacuum (because there is no air in space). The vacuum makes keeping the satellite warm more difficult that it would be on earth. On earth we can use the air to heat things. But in space we use radiation from the sun and thermal blankets. Okay, that's a little science for you. I hope you are still with me. In order to test this environment, we put pieces of the satellite then the whole satellite into a thermal vacuum chamber. Someone watches the temperature rise and fall several times and prays it doesn't break. There are a variety of sizes but this one is the largest one at Goddard. This is only half of it. The other half goes a story and a half underground.

During launch, we get into several more hardships that could cause the satellite to break. If you have ever seen a rocket being launched, then you would know that the rocket is super loud and has a tremendous amount of acceleration in order to escape Earth's gravity. The vibrations from the launch can also cause damage to the satellite.

Flight dewar for XRS-1 on the vibration table

Flight dewar for XRS-1 on the vibration table

In order to deal with the massive amounts of acceleration and the vibrations of the launch, they place parts of the satellite and then the whole satellite on a shaker table which vibrates the object to simulate launch. While I toured the facility, the satellite GPM (Global Precipitation Measurement) had just finished a vibration test. There are different size tables for the different size parts.

The Acoustic Testing Chamber. The holes in the walls are the mouths of giant horns like in the bottom right of the photo

The Acoustic Testing Chamber. The holes in the walls are the mouths of giant horns like in the bottom right of the photo

In order to simulate the noise during launch, the satellite is placed in the Acoustic Testing Chamber. The satellite is subjected to 6 ft tall speakers (more like horns) that blast noise at the satellite for 2-minute intervals. It can get as loud as 150 decibels which is as loud as standing next to a jet engine during takeoff. They have to clear the building in order to run the tests. That's how loud it gets.

The shaker table simulates the acceleration due to launch. However, if there is a circumstance where the satellite will be subjected to a constant acceleration for a longer period of time, it will be also be tested using the centrifuge. The centrifuge is 120 feet long and can accelerate an object up to 30 Gs. GPM is a satellite that will require a centrifuge test.

Goddard's centrifuge

Goddard's centrifuge

Once the satellite can go through all of these tests successfully, it is ready for launch. We can then use its data to discover more things about outer space and our very own planet. I am currently using gamma-ray burst data from the satellite, Fermi. Without satellites, science would not be where it is today. We would not have the awesome pictures of our planet and outer space and I wouldn't have data to study this summer. With that being said, these tests are super important for the future of satellites and the future of earth and space science.

Carrie Holt

Author: Carrie Holt

Carrie is a senior physics major from South Carolina with a passion for astrophysics and music. You can most likely find her geeking out about physics and outer space, singing with Vocal Synergy or hanging out with her best friends.

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