Posted in | Temperature Sensors

Thermal Sensors to Help Characterize and Deflect/Destroy Comets Approaching Earth

Two teams of scientists from NASA are working install a highly compact, sensitive thermometer with the ability to characterize comets and also help in redirecting or probably destroying an asteroid on the course of a collision with Earth.

Comet Hartley 2 can be seen in detail in this image from NASA's EPOXI mission. It was taken as the spacecraft flew by from about 435 miles. The comet's nucleus, or main body, is about 1.2 miles long. Jets can be seen streaming out of the nucleus. A Goddard team would like to use a microbolometer to study these objects in greater detail. CREDIT: NASA.

In two technology-development efforts, scientists from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, are standardizing the application of a Goddard-devised infrared microbolometer camera (with a cross section that is only marginally greater than one quarter) to investigate near-primitive objects created during the origin of solar system 4.5 billion years earlier.

The Comet CAMera (or ComCAM) is a multi-spectral instrument developed partially by Shahid Aslam, a Goddard researcher. He worked in close partnership with the manufacturer of the device—the Canadian-based National Optics Institute—to develop the compact optics and integrated filters that help the device to be sensitive to chemical compounds such as carbon dioxide and water, which are of interest to comet researchers.

Thermal sensors, such as the ComCAM, evaluate heat or infrared radiation and are fundamentally highly sensitive thermometers. When an absorptive element is impacted upon by a radiation, the element gets heated up and undergoes a transformation in terms of the electrical resistance, which is proportional to as well as adopted to obtain the temperature. These evaluations offer a better understanding of the physical characteristics of the object under investigation. Researchers normally use these to investigate galaxies and very distant stars in the universe.

Microbolometers adopted to investigate the interstellar medium and galaxies in the submillimeter and far-infrared wavelength bands mandate super cooling, which is usually achieved by positioning the sensor inside a cryogenically cooled canister.

However, infrared microbolometers similar to the one partially designed by Aslam function with minimal cooling and do not need to be positioned inside a canister. Consequently, the cameras have smaller size and lightweight, but yet have the capability of sensing and recording infrared heat emitted from objects in the solar system.

Due to these features, at present, Tilak Hewagama, a researcher affiliated with the University of Maryland-College Park, and his colleagues—including Aslam, Catholic University’s Nicolas Gorius, and others from Goddard, the University of Maryland, Morehead State University, the Jet Propulsion Laboratory, and York University—want to fly ComCAM along with a conventional visible-light camera on a prospective CubeSat operation known as the Primitive Object Volatile Explorer, or, PrOVE.

Selected by NASA’s Planetary Science Deep Space SmallSat Studies, or PSDS3, program for further investigation, PrOVE is unlike other comet missions.

Using this conept, the small-sized craft will be positioned in a stable, deep-space orbit with the ability to gain access to a familiar periodic comet or a new one entering into the vicinity.

A CubeSat deployed from a parked orbit can produce high-quality science by traveling to any comet that passes through the accessible range, rather than a dedicated mission that cannot be prepared in time to investigate a new, pristine comet that comes into view.

Tilak Hewagama, a researcher affiliated with the University of Maryland-College Park

With the assistance from PSDS3, the researchers are determining perpetual parking orbits (or “waypoints”), transfer trajectories toward the waypoints, longevity of the spacecraft, intercept trajectories, and propulsion prerequisites to get closer to certain familiar comets and practical ranges for reaching new comets, and other such topics.

As it well known that PrOVE includes prevalent commercial-off-the-shelf components, such as a 6- or 12-unit CubeSat bus and the microbolometer camera, Hewagama is of the notion that the mission can be finished and launched as a secondary payload in comparatively short order.

Our study obviously will bear out important questions regarding PrOVE’s trajectory and orbit, among other technical questions, but this is a mission that could be deployed quickly. PrOVE represents an exceptional opportunity to advance the science of comets and other primitive bodies by studying them at close range. It would advance NASA science goals with data that only can be obtained with a spacecraft.”

Planetary Defense

Comet science is not the just the prospective beneficiary of a microbolometer camera such as PrOVE.

In yet other investigative attempt, Goddard scientists Josh Lyhoft and Melak Zebenay have been working to evaluate disparate sensor systems required to image and characterize an asteroid on the course of a collision with Earth. The sensors systems have the ability to provide a spacecraft with the guidance evaluations required to deflect or destruct the object.

Similar to Hewagama, Lyhoft is fascinated by the probabilities provided by a microbolometer sensing system. In order to precisely sense the location of the asteroid when it is approached by the spacecraft, “microbolometers can perform the task,” stated Lyzhoft. “We believe they’re sensitive enough for a terminal-intercept mission.”

From the time Lyhoft started his study, NASA declared that teams designing the agency’s first asteroid-deflection mission, that is, the Double Asteroid Redirection Test (or DART), will start preparatory designs. As part of this assignment, headed by researchers from the Johns Hopkins Applied Physics Laboratory, with assistance from Goddard and other organizations, DART will use a kinetic impactor to carry out an investigation that will assist in exhibiting the abilities that may be required in future to deflect an asteroid away from its course toward Earth. An investigation by using a small, asteroid that does not pose a threat—the smaller one among the two asteroids that form the Didymos system—is proposed for 2024.

NASA will almost certainly be flying other asteroid-intercept missions for science, planetary defense, or both, so, it’s very conceivable that Josh’s work will benefit future NASA asteroid missions, and that is certainly the intent of his work.

Brent Barbee, Scientist form Goddard

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