Science Current Events | Science News | Brightsurf.com
 

NASA Developing Comet Harpoon for Sample Return

December 14, 2011
The best way to grab a sample of a rotating comet that is racing through the inner solar system at up to 150,000 miles per hour while spewing chunks of ice, rock and dust may be to avoid the risky business of landing on it. Instead, researchers want to send a spacecraft to rendezvous with a comet, then fire a harpoon to rapidly acquire samples from specific locations with surgical precision while hovering above the target. Using this "standoff" technique would allow samples to be collected even from areas that are much too rugged or dangerous to permit the landing and safe operation of a spacecraft.

Scientists at NASA's Goddard Space Flight Center in Greenbelt, Md. are in the early stages of working out the best design for a sample-collecting comet harpoon. In a lab the size of a large closet stands a metal ballista (large crossbow) nearly six feet tall, with a bow made from a pair of truck leaf springs and a bow string made of steel cable 1/2 inch thick. The ballista is positioned to fire vertically downward into a bucket of target material. For safety, it's pointed at the floor, because it could potentially launch test harpoon tips about a mile if it was angled upwards. An electric winch mechanically pulls the bow string back to generate a precise level of force, up to 1,000 pounds, firing projectiles to velocities upwards of 100 feet per second.

Donald Wegel of NASA Goddard, lead engineer on the project, places a test harpoon in the bolt carrier assembly, steps outside the lab and moves a heavy wooden safety door with a thick plexiglass window over the entrance. After dialing in the desired level of force, he flips a switch and, after a few-second delay, the crossbow fires, launching the projectile into a 55-gallon drum full of cometary simulant -- sand, salt, pebbles or a mixture of each. The ballista produces a uniquely impressive thud upon firing, somewhere between a rifle and a cannon blast.

"We had to bolt it to the floor, because the recoil made the whole testbed jump after every shot," said Wegel. "We're not sure what we'll encounter on the comet - the surface could be soft and fluffy, mostly made up of dust, or it could be ice mixed with pebbles, or even solid rock. Most likely, there will be areas with different compositions, so we need to design a harpoon that's capable of penetrating a reasonable range of materials. The immediate goal though, is to correlate how much energy is required to penetrate different depths in different materials. What harpoon tip geometries penetrate specific materials best? How does the harpoon mass and cross section affect penetration? The ballista allows us to safely collect this data and use it to size the cannon that will be used on the actual mission."

Comets are frozen chunks of ice and dust left over from our solar system's formation. As such, scientists want a closer look at them for clues to the origin of planets and ultimately, ourselves. "One of the most inspiring reasons to go through the trouble and expense of collecting a comet sample is to get a look at the 'primordial ooze' - biomolecules in comets that may have assisted the origin of life," says Wegel.

Scientists at the Goddard Astrobiology Analytical Laboratory have found amino acids in samples of comet Wild 2 from NASA's Stardust mission, and in various carbon-rich meteorites. Amino acids are the building blocks of proteins, the workhorse molecules of life, used in everything from structures like hair to enzymes, the catalysts that speed up or regulate chemical reactions. The research gives support to the theory that a "kit" of ready-made parts created in space and delivered to Earth by meteorite and comet impacts gave a boost to the origin of life.

Although ancient comet impacts could have helped create life, a present-day hit near a populated region would be highly destructive, as a comet's large mass and high velocity would make it explode with many times the force of a typical nuclear bomb. One plan to deal with a comet headed towards Earth is to deflect it with a large - probably nuclear - explosion. However, that might turn out to be a really bad idea. Depending on the comet's composition, such an explosion might just fragment it into many smaller pieces, with most still headed our way. It would be like getting hit with a shotgun blast instead of a rifle bullet. So the second major reason to sample comets is to characterize the impact threat, according to Wegel. We need to understand how they're made so we can come up with the best way to deflect them should any have their sights on us.

"Bringing back a comet sample will also let us analyze it with advanced instruments that won't fit on a spacecraft or haven't been invented yet," adds Dr. Joseph Nuth, a comet expert at NASA Goddard and lead scientist on the project.

Of course, there are other ways to gather a sample, like using a drill. However, any mission to a comet has to overcome the challenge of operating in very low gravity. Comets are small compared to planets, typically just a few miles across, so their gravity is correspondingly weak, maybe a millionth that of Earth, according to Nuth. "A spacecraft wouldn't actually land on a comet; it would have to attach itself somehow, probably with some kind of harpoon. So we figured if you have to use a harpoon anyway, you might as well get it to collect your sample," says Nuth.

Right now, the team is working out the best tip design, cross-section, and explosive powder charge for the harpoon, using the crossbow to fire tips at various speeds into different materials like sand, ice, and rock salt. They are also developing a sample collection chamber to fit inside the hollow tip. "It has to remain reliably open as the tip penetrates the comet's surface, but then it has to close tightly and detach from the tip so the sample can be pulled back into the spacecraft," says Wegel. "Finding the best design that will package into a very small cross section and successfully collect a sample from the range of possible materials we may encounter is an enormous challenge."

"You can't do this by crunching numbers in a computer, because nobody has done it before -- the data doesn't exist yet," says Nuth. "We need to get data from experiments like this before we can build a computer model. We're working on answers to the most basic questions, like how much powder charge do you need so your harpoon doesn't bounce off or go all the way through the comet. We want to prove the harpoon can penetrate deep enough, collect a sample, decouple from the tip, and retract the sample collection device."

The spacecraft will probably have multiple sample collection harpoons with a variety of powder charges to handle areas on a comet with different compositions, according to the team. After they have finished their proof-of-concept work, they plan to apply for funding to develop an actual instrument. "Since instrument development is more expensive, we need to show it works first," says Nuth.


Currently, the European Space Agency is sending a mission called Rosetta that will use a harpoon to grapple a probe named Philae to the surface of comet "67P/Churyumov-Gerasimenko" in 2014 so that a suite of instruments can analyze the regolith. "The Rosetta harpoon is an ingenious design, but it does not collect a sample," says Wegel. "We will piggyback on their work and take it a step further to include a sample-collecting cartridge. It's important to understand the complex internal friction encountered by a hollow, core-sampling harpoon."

NASA's recently-funded mission to return a sample from an asteroid, called OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security -- Regolith Explorer), will gather surface material using a specialized collector. However, the surface can be altered by the harsh environment of space. "The next step is to return a sample from the subsurface because it contains the most primitive and pristine material," said Wegel.

Both Rosetta and OSIRIS-REx will significantly increase our ability to navigate to, rendezvous with, and locate specific interesting regions on these foreign bodies. The fundamental research on harpoon-based sample retrieval by Wegel and his team is necessary so the technology is available in time for a subsurface sample return mission.

The team includes Wegel and Nuth of NASA Goddard as well as Javier Bernal, a student intern from the University of Puerto Rico at Mayaguez. The work was initially funded by Goddard's Internal Research and Development program, and sustained by NASA's Science and Engineering Collaboration, the Undergraduate Student Researcher Program, and Universities Space Research Programs.

NASA's Goddard Space Flight Center


Related Comet Current Events and Comet News Articles


Rosetta spacecraft sees sinkholes on comet
The European Space Agency's Rosetta spacecraft first began orbiting comet 67P/Churyumov-Gerasimenko in August 2014.

Red dwarf burns off planet's hydrogen giving it massive comet-like tail
A giant cloud escaping from a warm, Neptune-mass exoplanet is reported in this week's Nature.

Giant comet-like tail discovered on small exoplanet
The prospect of finding ocean-bearing exoplanets has been boosted, thanks to a pioneering new study.

Hubble sees atmosphere being stripped from Neptune-sized exoplanet
Astronomers using the NASA/ESA Hubble Space Telescope have discovered an immense cloud of hydrogen dispersing from a warm, Neptune-sized planet orbiting a nearby star. The enormous gaseous tail of the planet is about 50 times the size of the parent star.

MAVEN results find Mars behaving like a rock star
If planets had personalities, Mars would be a rock star according to recent preliminary results from NASA's MAVEN spacecraft.

Titan's atmosphere even more Earth-like than previously thought
Scientists at UCL have observed how a widespread polar wind is driving gas from the atmosphere of Saturn's moon Titan.

CU-Boulder-led study shows moon engulfed in permanent, lopsided dust cloud
The moon is engulfed in a permanent but lopsided dust cloud that increases in density when annual events like the Geminids spew shooting stars, according to a new study led by University of Colorado Boulder.

Fresh theories about dark matter
Tom Broadhurst, the Ikerbasque researcher in the Department of Theoretical Physics of the UPV/EHU, together with Sandor Molnar of the National Taiwan University and visiting Ikerbasque researcher at the UPV/EHU in 2013, have conducted a simulation that explains the collision between two clusters of galaxies.

Comet Wild 2: A window into the birth of the solar system?
Our solar system, and other planetary systems, started as a disk of microscopic dust, gas, and ice around the young Sun. The amazing diversity of objects in the solar system today - the planets, moons, asteroids, and comets - was made from this primitive dust.

Geothermal energy, aluto volcano, and Ethiopia's rift valley
In their open access paper published in Geosphere this month, William Hutchison and colleagues present new data from Ethiopia's Rift Valley and Aluto volcano, a major volcano in the region.
More Comet Current Events and Comet News Articles

Comet

Comet
by Carl Sagan (Author)


This book is an exploration of these strange visitors to our skies.

Comet!   (an Ell Donsaii story #5 )

Comet! (an Ell Donsaii story #5 )


"Comet!" is the fifth in a series of near future SciFi/Thrillers whose young heroine Ell Donsaii has a nerve mutation which has rendered her a genius and an athletic phenomenon. In “Comet!” she and her team begin exploring outer space using the wormholes she produced in "Rocket." Unfortunately Comet Hearth-Daster is on a trajectory to strike the Earth. Though it is smaller than the object that wiped out the dinosaurs, it still weighs 300 million metric tons and if it hits it will wipe out civilization and may render the human race extinct.

Excerpt:

Walking to the machine shop to talk to Manuel, Ell passed behind Brian and Fred walking across the room. A shock went through her. Brian had a pistol in his hand! Horrifying images of a disgruntled employee gone...

Comet and the Champion's Cup (Pony Club Secrets, Book 5)

Comet and the Champion's Cup (Pony Club Secrets, Book 5)
by Stacy Gregg (Author)


The fifth gripping adventure in this exciting new pony-club series - now with a brand-new, commercial cover look!
With gymkhanas to win, rivals to defeat, mysteries to solve and ponies in danger to save – these books are perfect for all girls who love ponies.When Aunty Hess opens a riding school for the summer, Issie and her pony-club friends go along to help out. Issie gets to know Comet, a naughty but talented pony with real showjumping promise. But can she train him in time to compete at the Horse of the Year Show?Join talented young rider, Issie, on another action-packed pony-club adventure.

Mining the Sky: Untold Riches From The Asteroids, Comets, And Planets (Helix Book)

Mining the Sky: Untold Riches From The Asteroids, Comets, And Planets (Helix Book)
by John S. Lewis (Author)


While we worry over the depletion of the earth’s natural resources, the pollution of our planet, and the challenges presented by the earth’s growing population, billions of dollars worth of metals, fuels, and life-sustaining substances await us in nearby space. In this visionary book, noted planetary scientist John S. Lewis explains how we can mine these precious metals from the asteroids, comets, and planets in our own solar system for use in space construction projects. And this is just one of the possibilities. Join John S. Lewis as he contemplates milking the moons of Mars for water and hollowing out asteroids for space-bound homesteaders—all while demonstrating the economic and technical feasibility of plans that were once considered pure fiction.

Comet in Moominland (Moomins)

Comet in Moominland (Moomins)
by Tove Jansson (Author), Tove Jansson (Illustrator), Elizabeth Portch (Illustrator)


When Moomintroll learns that a comet will be passing by, he and his friend Sniff travel to the Observatory on the Lonely Mountains to consult the Professors. Along the way, they have many adventures, but the greatest adventure of all awaits them when they learn that the comet is headed straight for their beloved Moominvalley.

Comets, Stars, the Moon, and Mars: Space Poems and Paintings

Comets, Stars, the Moon, and Mars: Space Poems and Paintings
by Douglas Florian (Author)


Blast off with Douglas Florian's new high-flying compendium, which features twenty whimsical poems about space.      From the moon to the stars, from the Earth to Mars, here is an exuberant celebration of our celestial surroundings that's certain to become a universal favorite among aspiring astronomers everywhere.      Includes die-cut pages and a glossary of space terms.

Off on a Comet! a Journey through Planetary Space

Off on a Comet! a Journey through Planetary Space


This book was converted from its physical edition to the digital format by a community of volunteers. You may find it for free on the web. Purchase of the Kindle edition includes wireless delivery.

Comet's Tale: How the Dog I Rescued Saved My Life

Comet's Tale: How the Dog I Rescued Saved My Life
by Steven Wolf (Author), Lynette Padwa (Author)


Comet’s Tale is a story about a friendship between two former winners, both a little down on their luck, who together stage a remarkable comeback. A former hard-driving attorney, Steven Wolf has reluctantly left his job and family and moved to Arizona for its warm winter climate. There he is drawn to a local group that rescues abused racing greyhounds. Although he can barely take care of himself because of a spinal condition, Wolf adopts Comet, an elegant cinnamon-striped racer. Or does Comet adopt Wolf?  In Comet’s Tale we follow their funny and moving journey as Wolf teaches Comet to be a service dog. With her boundless enthusiasm and regal manners, Comet attracts new friends to Wolf’s isolated world. And finally, she plays a crucial role in restoring his health, saving his...

Evacuation Earth (Comet Clement series, #5)

Evacuation Earth (Comet Clement series, #5)


As the comet draws nearer, the 'Inner Circle' makes their final plans for Earth's survivors. The secret can no longer be kept and when it's announced, the world is threatened with chaos...

The seeds of discord are sown in several arks, which face serious threats before the comet arrives...

Colin's future becomes clearer, if he can survive long enough to see it...

With Comet Clement just months from striking, who will survive Earth's Evacuation?

OTHER WORKS BY THE AUTHOR

THE COMET CLEMENT SERIES

Book 1 - The Inner Circle
Book 2 - Interception
Book 3 - The New Space Race
Book 4 - The Three Arks
Book 5 - Evacuation Earth
Book 6 - Final Days
Book 7 - Impact
Book 8 -...

Uninvited (Comet Clement series, #8)

Uninvited (Comet Clement series, #8)


In the aftermath of Impact, the three arks continue to face danger from the effects of Comet Clement. But survivors find themselves in just as much mortal peril from circumstances they never expected...

OTHER BOOKS BY THE AUTHOR

COMET CLEMENT SERIES
The Inner Circle - Book One
Interception - Book Two
The New Space Race - Book Three
The Three Arks - Book Four
Evacuation Earth - Book Five
Final Days - Book Six
Impact - Book Seven
Uninvited - Book Eight
Takeover - Book Nine
Mission: Survival - Book Ten
Relocation - Book Eleven
A Second Chance - Book Twelve (final book)

LIFE, INC. - If you could learn the exact moment of your death, would you? If you could see a deceased loved one...

© 2015 BrightSurf.com