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 Off to Decipher a Comet's Secrets
"Hello World." Upon hearing that brief message, scientists at the European Space Agency (ESA) and followers around the world sent up a collective cheer. Rosetta - the ESA spacecraft currently on a 10-year mission to orbit and land on a comet - awoke in January after a three-year hibernation, and was ready to get to work.

NASA's Swift Satellite Tallies Water Production of Mars-bound Comet
In late May, NASA's Swift satellite imaged comet Siding Spring, which will brush astonishingly close to Mars later this year. These optical and ultraviolet observations are the first to reveal how rapidly the comet is producing water and allow astronomers to better estimate its size.

Comet theory false; doesn't explain cold snap at the end of the Ice Age, Clovis changes or mass animal extinction
Most supposed impact indicators at 29 sites are too old or too young to be remnants of an ancient comet that proponents claim sparked climate change at the end of the Ice Age, killed America's earliest people and caused a mass animal extinction.

Impact glass stores biodata for millions of years
Bits of plant life encapsulated in molten glass by asteroid and comet impacts millions of years ago give geologists information about climate and life forms on the ancient Earth.

Vitamin B3 Might Have Been Made in Space, Delivered to Earth by Meteorites
Ancient Earth might have had an extraterrestrial supply of vitamin B3 delivered by carbon-rich meteorites, according to a new analysis by NASA-funded researchers.

Meteorites Yield Clues to Red Planet's Early Atmosphere
Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks.

Study Tests Theory that Life Originated at Deep Sea Vents
One of the greatest mysteries facing humans is how life originated on Earth. Scientists have determined approximately when life began (roughly 3.8 billion years ago), but there is still intense debate about exactly how life began.

A satellite view of volcanoes finds the link between ground deformation and eruption
ESA's Sentinel satellite, due for launch on April 3rd, should allow scientists to test this link in greater detail and eventually develop a forecast system for all volcanoes, including those that are remote and inaccessible.

NASA's Hubble Space Telescope Spots Mars-Bound Comet Sprout Multiple Jets
NASA released Thursday an image of a comet that, on Oct. 19, will pass within 84,000 miles of Mars -- less than half the distance between Earth and our moon.

Crashing Comets Explain Surprise Gas Clump Around Young Star
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in northern Chile have today announced the discovery of an unexpected clump of carbon monoxide gas in the dusty disc around the star Beta Pictoris.
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'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...

Comet! (an Ell Donsaii story #5 )

Comet! (an Ell Donsaii story #5 )
by Laurence E Dahners (Author)


"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 wild and shooting people...

The Three Arks (Comet Clement series, #4)

The Three Arks (Comet Clement series, #4)


With a new president in office - and an apprehensive new ally in the Inner Circle - the men planning for the end of the world face new struggles. Will the space station be finished in time? How will they get passengers on board the space station without giving away the secret of Comet Clement?

Tyler Ainsworth faces his own troubles with his seacraft. He needs more money to complete his boat but doesn't want to go to the Inner Circle for fear of losing even more control. How will he raise the funds? Can he maintain control of his seacraft's ownership? Will his high-class passengers lose their patience while waiting for the end of the world?

The underground facility deep in the Ural Mountains seems to face the least amount of problems and some of the space...

Relocation (Comet Clement series, #11)

Relocation (Comet Clement series, #11)


In the penultimate book of the Comet Clement series, all three arks face the impending decisions to return to a new Earth.

Aboard the underwater seacraft, Tyler Ainsworth plots to take back control and rid his craft of unwanted passengers once and for all...

In space, President Marshall is urged to push forward with one final deceit to better the odds of more space station passengers surviving a return to the Earth below...

Underground, the Russians are ready to return to the surface while Americans at the facility prepare for a lengthy journey back to their home country. But one young couple decides to make their own plans to stay together while their families try to pull them apart...

Relocation is Book 11 of the Comet Clement series...

The Night of the Comet: A Novel

The Night of the Comet: A Novel
by George Bishop (Author)


A KIRKUS REVIEWS "BEST BOOKS OF 2013"
 
NEW YORK POST "REQUIRED READING"
 
PEOPLE MAGAZINE STARRED REVIEW
 
From the acclaimed author of Letter to My Daughter comes an engrossing coming-of-age tale that deftly conveys the hopes and heartaches of adolescence, and the unfulfilled dreams that divide a family, played out against the backdrop of a small southern town in 1973.
 
For his fourteenth birthday, Alan Broussard, Jr., receives a telescope from his father, a science teacher at the local high school who's anxiously awaiting what he promises will be the astronomical event of the century: the coming of Comet Kohoutek. For Alan Broussard, Sr.--frustrated in his job, remote from his family--the comet is a connection to his past and a bridge to his son,...

The Inner Circle (Comet Clement series, #1)

The Inner Circle (Comet Clement series, #1)


1908... Siberia... A tiny comet rips through Earth's atmosphere and explodes above the Tunguska region of Siberia, instantly engulfing thousands of square acres of the mostly desolate region. The explosion is heard for hundreds of miles, the light of the comet seen halfway across the globe. Had the comet hit a few hours earlier in a more populated area, millions would have been killed...

A century later, another comet - this one hundreds of times bigger and more powerful - encounters a black hole in deep space and is pushed onto a new, deadly course leading straight to Earth...

A small group of humans - including the President of the United States, a former astronaut and a middle school science teacher - discovers the existence of this potentially deadly comet...

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 -...

Final Days (Comet Clement series, #6)

Final Days (Comet Clement series, #6)


With only days remaining until Comet Clement reaches Earth, final preparations are made for the three arks. Even as the world waits to see if the last-ditch Domino Deflection attempt will work, pandemonium still erupts...

Peter Mansfield is tasked with gathering the last group of people to leave the planet, the 'specials' who have ties to the space station that they don't yet know about. Mansfield has faced many difficult decisions over the years but will he survive long enough to make it to the station?

All three arks face serious danger and not every member of the Inner Circle will survive through the final days as Comet Clement approaches Earth for the moment of impact....

OTHER WORKS BY THE AUTHOR

COMET CLEMENT SERIES
BOOK ONE...

Interception & The New Space Race (Comet Clement series, #2 & #3) (The Comet Clement series)

Interception & The New Space Race (Comet Clement series, #2 & #3) (The Comet Clement series)


**BOOKS 2 AND 3 TOGETHER FOR ONE LOW PRICE**

Book 2 - Interception
The Inner Circle's plans to deflect the comet are in place but Neil Peterson's long journey to intercept Clement faces serious tests...
The president is embattled in a bitter re-election attempt and knows that losing could lead to the comet secret being exposed to the world...
NASSA's plans to build the biggest space station for 'scientific purposes' are put into effect...
Earl Ackerman's paranoia leads him to making rash decisions about the secret that's slowly destroying the little sanity he has left...
The secret can't stay hidden forever...

Book 3 - The New Space Race
Plans continue to move forward on the space station, which draws the ire of the country,...

© 2014 BrightSurf.com