Spaceflight Insider

NASA scientists contemplate using LISA Pathfinder as ‘comet crumb’ detector

LISA Pathfinder in space

An artist’s impression of LISA Pathfinder in space. Image Credit: ESA/ATG medialab

Launched on Dec. 3, 2015, from the European Spaceport in French Guiana, the European Space Agency’s Laser Interferometer Space Antenna (LISA) Pathfinder mission is turning out to reveal far more than the elusive gravitational waves it was designed to detect.

The spacecraft was engineered to shield two 1.8-inch (46-millimeter) gold-platinum cubes from all internal and external forces. This shielding is in combination with its approximately 310,686-mile by 497,097-mile (500,000-kilometer by 800,000-kilometer) Lissajous orbit around the Sun-Earth Lagrange Point 1 (SEL1) – an area where the gravity of Earth cancels out some of the Sun’s to allow an object to remain in that spot – provided the greatest hope of achieving its goal.

The Laser Interferometer Gravitational-wave Observatory (LIGO), which detected the first known gravitational waves in 2015 and which were reported in 2016, utilizes two large-scale offset laser interferometers in Livingston, Louisiana, and Hanford, Washington, to detect these waves that were first predicted by Albert Einstein in 1916.

LISA Pathfinder: Technology Package Core Assembly and Inertial Sensors

The LISA Technology Package. (Click to enlarge) Image Credit: ESA/ATG medialab

The LISA Pathfinder, however, utilizes the distance and movement of the two gold-platinum cubes to detect gravitational waves. In order to do this, the spacecraft has an ultra-precise micro-propulsion system to maintain an exact position at SEL1.

Generally, when one thinks of space, one thinks of it as being empty; however, in actuality, it isn’t really a perfect void. In order to accurately detect gravitational waves, LISA Pathfinder needs to be able to compensate for the influence of space, including the effect of tiny micro-particles, sunlight (photons), and interplanetary dust – some of which measure less than 10 micrometers in size.

Even at such minuscule sizes, impacts and interactions still have an effect on the spacecraft that must be counteracted in order to maintain the precision necessary for the mission’s success. LISA Pathfinder’s construction was such that its drag-free micro-propulsion system overcomes minute impacts and the influence of the nearly massless photons from the Sun on the spacecraft.

The engineering of LISA Pathfinder has been incredibly successful at accomplishing this goal. Because of this success, scientists at NASA’s Goddard Spaceflight Center in Greenbelt, Maryland, have been able to use LISA Pathfinder’s position correction data to make serendipitous scientific discoveries that could have far-reaching impacts on the understanding of the Solar System and the objects in it.

“We’ve shown we have a novel technique and that it works,” said Ira Thorpe, who leads the team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The next step is to carefully apply this technique to our whole data set and interpret the results.”

The ability to monitor and track dust particles at this crucial quiet zone at SEL1 can provide innumerable insights. Experts are using the micro-propulsion data to trace the direction and velocity of impacts.

“Every time microscopic dust strikes LISA Pathfinder, its thrusters null out the small amount of momentum transferred to the spacecraft,” said Goddard co-investigator Diego Janches. “We can turn that around and use the thruster firings to learn more about the impacting particles. One team’s noise becomes another team’s data.”

This data is allowing scientists to track the movement of everything from the remnants of comets, which had previously passed by that point in space, to asteroids shedding their bulk post impact or gravitational interference, to what remains of the initial stellar soup that created the planets and other bodies in the Solar System.

“This is a very nice collaboration,” said Paul McNamara, the LISA Pathfinder project scientist at ESA’s Directorate of Science in Noordwijk, the Netherlands. “This is data we use for doing our science measurements, and as an offshoot of that, Ira and his team can tell us about microparticles hitting the spacecraft.”

Although LISA Pathfinder doesn’t have specific detectors to reveal the exact composition of what it is being impacted by, there’s still a wealth of information that can be gleaned from the data. This information includes the direction, density, and velocity of the impacts, all of which give researchers a unique view into the history of the Solar System.

Video Courtesy of NASA Goddard



A native of the Greater Los Angeles area, Ocean McIntyre's writing is focused primarily on science (STEM and STEAM) education and public outreach. McIntyre is a NASA/JPL Solar System Ambassador as well as holding memberships with The Planetary Society, Los Angeles Astronomical Society, and is a founding member of McIntyre is currently studying astrophysics and planetary science with additional interests in astrobiology, cosmology and directed energy propulsion technology. With SpaceFlight Insider seeking to expand the amount of science articles it produces, McIntyre was a welcomed addition to our growing team.

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