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Antimatter solar sail

(old news 30 October 2002)

Hbar Technologies, LLC is an advanced technology company devoted to the development of commercial markets for antimatter, and the enhanced production and distribution of antimatter.

To get a spacecraft to the real edge of the Solar System and beyond in a reasonable amount of time, the company has turned to that most exotic of substances, antimatter.
In a study funded by the NASA Institute for Advanced Concepts (NIAC).
Steve Howe is laying the groundwork for a faster, better, cheaper antimatter drive.
Giant wire spheres may one day float near Earth, scooping up bits of antimatter for use as space fuel in solar sail spacecraft.

Antimatter forms naturally in the solar system when charged particles from space, called cosmic rays, slam into charged particles which stream from the Sun. If one were to collect this antimatter it could later be mixed with matter.
Antimatter would be collected using three concentric wire spheres. The outermost, spanning 16 kilometres, would be positively charged to repel protons from the solar wind and attract negatively charged anti-protons from space
These anti-protons would then slow down passing through the middle sphere and come to rest inside the smallest sphere, which would measure 100 metres in diameter. An electromagnetic field would trap the exotic particles there.

" Basically, what you want to do is generate a net, just like you're fishing " - Gerald Jackson, the project's principal investigator at Hbar Technologies in West Chicago, Illinois, US.

Howe's antimatter sail looks like yet another solar sail variant. The sail itself is considerably smaller than a several miles-wide solar sail. With a diameter of 5 meters, the antimatter sail is wonderfully compact.
The ship will provide its own "wind" in the form of puffs of antimatter released from the spacecraft. When these antiparticles encounter the sail thrust is generated in not just one, but two ways.

Antimatter particles share the same mass as their normal-matter counterparts but bear the opposite charge.

The tiny explosions will occur as the antimatter particles collide with the sail and more importantly, the antimatter's annihilation will react with a thin layer of uranium-235 coating the sail, creating a tiny amount of nuclear fission.

"We're using the base (fission) reaction, fundamentally. So we can keep our masses down." - Steve Howe.

The combination adds up to maximum bang for your buck in terms of mass. This means a smaller spacecraft can reach higher velocities more quickly.
Controlled reactions with the sail's normal matter could push the craft to Pluto with just 30 milligrams of antimatter.
While a little more - 17 grams - would take the craft to Alpha Centauri, the nearest star to the Sun.

And there is plenty of antimatter around to fuel those trips.

About 80 grams of the stuff in total may float between the orbits of Venus and Mars, while as much as 20 kilograms could be harvested within Saturn's far-out orbit.

However, any advanced design like this is not without its hurdles.
"The real hub is the storage. There's a lot of technology between here and there." - Steve Howe.

Since you can't store antimatter in a regular fuel tank, Howe has found two possible ways to capture antimatter created in the lab before it annihilates itself.

One method involves keeping magnetized antiprotons in a container of frozen hydrogen. The magnetic field and the deep cold would keep the particles from bouncing into the walls and destroying themselves.

The other method involves allowing positrons and antiprotons to clump together into antiatoms of antihydrogen. So that it would make them easier to store.

"(There's a device called an) Ioffe-Pritchard trap which supposedly should be able to build and hold the antihydrogen" - Steve Howe.

Either way, Howe expects the stored material would most likely take the form of tiny crystals, or "nanosnowflakes" of antihydrogen.

A Penning trap uses electric and magnetic fields to trap charged particles (ions). The two batteries at the two ends produce the electric field (red field lines). The magnetic field lines (green) travel from bottom to top. These field lines allow researchers to confine particles such as antimatter in the trap. imaging survey


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