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Spitzer’s Journey till Exoplanet Spying: Engineering Modifications made it Possible

NASA's Spitzer Space Telescope has a trail of achievements that was probably not visualized at its inception. It evolved, improved and has a story to narrate, where its engineers have worked towards a sole aim of studying exoplanets. They’ve worked hard to refurbish it into a premier observatory.

Spitzer Space Telescope is supervised by NASA's Jet Propulsion Laboratory in Pasadena, Calif. And the data obtained is housed at the Infrared Science Archive at the Infrared Processing and Analysis Center at Caltech.
While its 10th anniversary is approaching, there are a multitude of points to pore through.

Its journey to the final destination of exoplanet spying is replete with engineering endeavors. Its extraordinary design has touched the present turf only after three important improvements- the modified heater cycling, repurposed Peak-Up camera and the in-depth characterization of individual pixels in the camera.

In 1996, the telescope’s design was prepared even before the discovery of transiting exoplanets.

Spitzer had an adequate amount of coolant till the time it was completely exhausted after more than five-and-a-half years. However, its engineers had a built-in backup plan. One set of infrared cameras was fixed at super-operational temperature of 407 degrees Fahrenheit with the aid of passive cooling system. Since then, the infrared cameras have worked efficiently to perpetuate with its mission.

Engineers had tossed their grey matter to find a solution to the problem of coolant. In order to keep it consistently cool, it was painted black on the side that was away from the sun. This move helped in radiating good amount of heat into space. On the other side, facing the sun, there was a shiny coating that reflected a large amount of heat from the big star and the solar panels.

It was a maiden endeavor of this kind, the concept of which was followed for other missions as well.

Another intelligent improvement was reducing the wobbling movement of the shaky telescope. The telescope was stable but the camera was encountering some problems. Problems such as periodic brightening and dimming of light from a star turned out to be a big thorn in the course of the study. First thing that the engineers did was to look at the root of the problem.

After delving into the problem, they found that the wobbling was cyclic in nature. The cycle was found to coincide with that of the heater which switched on to keep the battery kicking at a specific temperature. This shook the star trackers and telescope, and eventually the telescope was seen to wobble.

Finally the engineers found in October 2011 that the heater did not require to be cycled every hour. This helped in reducing the shake by 50%.
The engineers couldn’t keep their anxiety to a halt when they repurposed Spitzer’s Pointing Control Reference Sensor “Peak-Up” Camera. The main purpose was to negate the wobble completely. The camera was used in the original cryo mission where it collected infrared light into the spectrometer and also perform regular calibrations of Spitzer’s star-trackers.

The telescope naturally trembled but it was really important to fix it. The engineers fixed Peak-Up to the infrared camera observations that enabled the astronomers to keep stars exactly on the center of a camera pixel. Through the journey, they also found a ‘sweet spot’ which gives them the most firm observations.

According to one of the engineers, "Because of these engineering modifications, Spitzer has been transformed into an exoplanet-studying telescope. We expect plenty of great exoplanetary science to come from Spitzer in the future."