NASA Uses Gravitational Wave Detector Prototype to Detect ‘Space Mosquito’ Splats

Artist impression of ESA LISA Pathfinder in interplanetary space (ESA)

Imagine speeding down the highway and plowing into an unfortunate swarm of mosquitoes. Now imagine that you had the ability to precisely measure the mass of each mosquito, the speed at which it was traveling and the direction it was going before it exploded over your windscreen.

Granted, the technology to accomplish that probably isn’t feasible in such an uncontrolled environment. Factors such as vibration from the car’s motor and tires on the road, plus wind and air turbulence will completely drown out any “splat” from a minuscule insect’s body, rendering any signal difficult to decipher from noise.

But move your hypothetical “car and mosquitoes” into space — as silly as that may sound — and things become a lot less noisy. And now NASA is measuring its own special kind of “mosquito splat” signal by using a rather unlikely space experiment.

The European LISA Pathfinder spacecraft is a proof of concept mission that’s currently in space, orbiting a region of gravitational stability between the Earth and the sun — called the L1 point located a million miles away. The spacecraft was launched there in late 2015 to carry out precision tests of instruments that will eventually be used in the space-based gravitational wave detector eLISA. Inside the payload is a miniaturized laser interferometer system that measures the distance between two test masses.

When launched in 2034, eLISA (which stands for Evolved Laser Interferometer Space Antenna) will see three spacecraft, orbiting the sun at the L1 point, firing ultra-precise lasers at one another as part of a space-based gravitational wave detector. Now we actually know gravitational waves exist — after the US-based Laser Interferometer Gravitational-wave Observatory (or LIGO) detected the space-time ripples created after the collisions of black holes — excitement is building that we might, one day, be able to measure other phenomena, such as the ultra-low frequency gravitational waves that were created during the Big Bang.

But the only way we can do this is to send stunningly precise interferometers into space, away from our vibration-filled atmosphere to stand a chance of detecting some of the faintest space-time rumbles in our cosmos that would otherwise be drowned out by a passing delivery truck or windy day. And LISA Pathfinder is currently out there, testing a tiny laser interferometer in a near-perfect gravitational free-fall, making the slightest of slight adjustments with its “ultra-precise micro-propulsion system.”

Although LISA Pathfinder is a test (albeit a history-making test of incredible engineering ingenuity), NASA thinks that it could actually be used as an observatory in its own right; not for hunting gravitational waves, but for detecting comet dust.

Like our mosquito-windscreen analogy, spacecraft get hit by tiny particles all the time, and LISA Pathfinder is no exception. These micrometeoroides come from eons of evaporating comets and colliding asteroids. Although measuring less than the size of a grain of sand, these tiny particles zip around interplanetary space at astonishing speeds — well over 22,000 miles per hour (that’s 22 times faster than a hyper-velocity rifle round) — and can damage spacecraft over time, slowly eroding unprotected hardware.

Therefore, it would be nice if we could create a map of regions in the solar system that contain lots of these particles so we can be better prepared to face the risk. Although models of solar system evolution help and we can estimate the distribution of these particles, they’ve only ever been measured near Earth, so it would be advantageous to find the “ground truth” and measure them directly from another, unexplored region of the solar system.

This is where LISA Pathfinder comes in.

As the spacecraft gets hit by these minuscule particles, although they are tiny, their high speed ensures they pack a measurable punch. As scientists want the test weights inside the spacecraft to be completely shielded from any external force — whether that’s radiation pressure from the sun or marauding micro-space rocks — the spacecraft has been engineered to be an ultra-precise container that carefully adjusts its orientation an exact amount to directly counter these external forces (hence the “ultra-precise micro-propulsion system”).

lisa-pathfinder
When LISA Pathfinder is struck by space dust, it compensates with its ultra-precise micro-thrusters (ESA/NASA)

This bit is pretty awesome: Whenever these tiny space particles hit the spacecraft, it compensates for the impact and that compensation is registered as a “blip” in the telemetry being beamed back to Earth. After careful analysis of the various data streams, researchers are learning a surprising amount of information about these micrometeoroides — such as their mass, speed, direction of travel and even their possible origin! — all for the ultimate goal of getting to know the tiny pieces of junk that whiz around space.

“Every time microscopic dust strikes LISA Pathfinder, its thrusters null out the small amount of momentum transferred to the spacecraft,” said Diego Janches, of NASA’s Goddard Space Flight Center in Greenbelt, Md. “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.”

So, it turns out that you can precisely measure a mosquito impact on your car’s windshield — so long as that “mosquito” is a particle of space dust and your “car” is a spacecraft a million miles from Earth.

NASA put together a great video, watch it:

Aside: So it turned out that I inadvertently tested the “car-mosquito” hypothesis when driving home from Las Vegas — though some of these were a lot bigger than mosquitoes…

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Shock and Awe: Curiosity Laser-Blasts First Mars Rock

The laser-zapped rock "Coronation" -- inset image was taken by the ChemCam instrument, featuring the small laser burn. Credit: NASA/JPL-Caltech
The laser-zapped rock “Coronation” — inset image was taken by the ChemCam instrument, featuring the small laser burn. Credit: NASA/JPL-Caltech

After Mars rover Curiosity’s thunderous landing on Aug. 5/6, any hypothetical Martian on the surface would have been forgiven for being a little confused.

Setting down on the flat plain called Aeolis Palus inside Gale Crater, the six-wheeled, one-ton, nuclear-powered rover would have looked more like an alien battle tank being dropped off by a rather ominous-looking “Flying Saucer” than a scientific mission. But after the famous “sky crane” maneuver that lowered the rover with the precision of a Harrier Jump Jet, the “alien” robot didn’t start rolling over the Martian landscape zapping Mars rocks with its laser. Instead, it just sat there. For days. Occasionally there’d be a bit of action — such as Curiosity’s cameras swiveling, mast raising and high-gain antenna tracking the sky — but apart from that, our hypothetical Martians would probably not have thought much of this lack-luster invasion by an airdropped tank.

But that all changed today. Curiosity blasted a rock with its laser, marking the beginning of Curiosity’s Mars domination! Shock and awe, Mars rover style.

Alas, this isn’t a military exercise, but it is significant. Today marks the first day that one of our interplanetary robotic emissaries have used a laser on another planet in the name of science. NASA mission operators gave the go-ahead to carry out a test-run of the Chemistry and Camera instrument, or ChemCam, targeting a small rock (called “Coronation”) with 30 pulses of its laser over a 10-second period. According to the JPL press release, each pulse delivered more than a million watts of power for about five one-billionths of a second.

The fist-sized Mars rock -- called "Coronation", previously designated "N165" -- has become the first casualty scientific target of Curiosity's ChemCam intrument. Credit: NASA/JPL-Caltech
The fist-sized Mars rock — called “Coronation”, previously designated “N165” — has become the first casualty of war scientific target of Curiosity’s ChemCam instrument. Credit: NASA/JPL-Caltech

“We got a great spectrum of Coronation — lots of signal,” said ChemCam Principal Investigator Roger Wiens of Los Alamos National Laboratory, N.M. “Our team is both thrilled and working hard, looking at the results. After eight years building the instrument, it’s payoff time!”

The laser works by vaporizing the surface layers of exposed rock. Under the intense heating by such focused energy, a tiny sample of material rapidly turns into plasma. The the flash of light generated by the small, rapidly dissipating cloud of plasma can then by analyzed from afar by the ChemCam’s spectrometer. The light reveals what kinds of elements are contained in the sample, aiding Curiosity’s studies of the Red Planet. And the best thing is that ChemCam appears to be working better than expected.

“It’s surprising that the data are even better than we ever had during tests on Earth, in signal-to-noise ratio,” said ChemCam Deputy Project Scientist Sylvestre Maurice of the Institut de Recherche en Astrophysique et Planetologie (IRAP) in Toulouse, France. “It’s so rich, we can expect great science from investigating what might be thousands of targets with ChemCam in the next two years.”

To find out more about this landmark day for Curiosity and Mars exploration, read the JPL press release: “Rover’s Laser Instrument Zaps First Martian Rock

Who Said Star Wars Was Dead? Introducing the Airborne Laser

A plane... with a frickin' laser attached to its head! Sorry, couldn't resist... The 747 plus ABL (USAF)
A plane... with a frickin' laser attached to its head! Sorry, couldn't resist... The 747 plus ABL (USAF)

The US Air Force and a number of military contractors have successfully test-fired the first aircraft-based military laser system called the “Airborne Laser” (or ABL). Airborne Laser? Looking at the laser-touting Boeing 747 above, you’d think the USAF would have come up with a more imaginative name… Like, “Project Lightning Strike“, “Winged Overlord” or “Delta Echo Alpha Tango Hotel (DEATH)“. There’s probably some military call-sign, but on reading about the ABL, I found myself a little bored of the concept until I saw the finished product…
Continue reading “Who Said Star Wars Was Dead? Introducing the Airborne Laser”