Project Bifrost: Rockets of the Future?

Project Bifrost is an ambitious study examining emerging
space technologies that could lay the foundation for future
interstellar flights and investigates the utility of fission for
future space missions.

Project Bifrost was initiated by Research Lead Tabitha Smith
(Strategic Officer of General Propulsion Science) and Brad Appel
(Program Manager of Nuclear Propulsion at General Propulsion
Science), working in collaboration with Icarus Interstellar Inc.
a nonprofit foundation dedicated to achieving interstellar flight
by the year 2100.

WIDE ANGLE: Project Icarus: Reaching for Interstellar

Chances are you own a smart phone or some kind of electronic
device with capabilities that would stun even an Apple engineer
from ten years ago. We’ve come to expect that technology advances
at a mind-boggling pace, but just how far has rocket technology
advanced in say, the past three decades?

Not much.

The rockets that sent men to the moon were powered by chemical
combustion, which in its most powerful form ignites hydrogen with
oxygen. The space shuttle main engine, essentially the state of
the art for rocket propulsion, uses the same chemicals.

No doubt, these rockets do their job well for what we ask of
them. Send astronauts to the International Space Station? No
problem. Send astronauts to the Moon? Sure. But, suppose we
wanted to dream a little bit bigger, and actually explore the
rest of the solar system and beyond. How far can these chemical
rockets send us?

Not very far. It turns out, through the quirky laws of
Newtonian mechanics, that the exhaust velocity of a rocket is one
of the most important parameters in determining how far it can
send a payload. Chemical rockets have fundamental energy limits
which give them a maximum exhaust velocity that is too low for
most piloted missions with destinations further than the moon.

(Keep in mind we’re talking about the huge spaceships that would
be required to transport people — chemical rockets can handle
the smaller robotic probes.)

PROJECT ICARUS: Which Exoplanet to Visit?

We live in an exciting time in which NASA’s Kepler Space
Telescope churns out discoveries of new exoplanets — whole other
worlds — on a daily basis. Just last month, scientists working
with Kepler
confirmed that they located a planet orbiting within the
‘habitable zone’ of its host star
— a special region where
an Earth-like planet could maintain liquid water on its surface.

You may be tempted to ask how long it would take for us to send a
spacecraft over to one of those exoplanets and take a closer
look. To answer that question, consider Voyager 1, one of
humanity’s fastest spacecraft, and certainly the farthest space
probe from Earth. If we were to suddenly re-aim Voyager 1 towards
one of these new solar systems, it would take over 70,000
to reach even the closest of stars.

While interstellar missions may seem like the stuff of science
fiction, the technology needed to enable them is currently an
active area of research, and novel propulsion systems typically
focus on highly energetic reactions as a means to liberate more
energy per unit mass of propellant.

Common areas of research include fission rockets, fusion rockets
and even antimatter rockets.
Project Icarus
, for example, is an international group of
volunteer scientists and engineers dedicated to working out the
challenges of interstellar voyages.

According to Richard Obousy, senior scientist for Icarus, “the
technology roadmap to antimatter, or even fusion rockets could
easily be decades in the making, but there is one technology that
we have available today that represents the critical first step
in the long road to the stars, namely fission.”

PROJECT ICARUS: What Would an Interstellar Mission Look

The fission rocket being referred to here is the Nuclear Thermal
Rocket, or NTR. An NTR uses nuclear fission as an energy source
instead of chemical combustion, and uses just hydrogen as a
propellant, allowing it to achieve a very high exhaust velocity
and high thrust. That’s the kind of mind-boggling technology
upgrade that means piloted missions to deep space, which are
beyond the pale for chemical rockets, suddenly become very

Beginning this month, Icarus Interstellar
, the managing company for Project Icarus, is teaming up
with General Propulsion Sciences, a small propulsion research
company based in Washington D.C., for a new effort to pursue the
development of NTRs and other fission-based space technologies.

The program, called Project Bifrost, recognizes fission as a
crucial stepping-stone technology towards the next generation of
space travel, and will take steps to advance the technological
maturity of NTRs. In the coming decades, sending humans to Mars
is considered by many to be the Holy Grail for space exploration,
a mission which NTRs are ideally suited for.

Brad Appel of General Propulsion Sciences frames the situation in
more familiar terms: “To look at it another way, imagine you are
planning a road trip from New York to Los Angeles and back.
Except, there are no gas stations along the way — you need to
pack all of the fuel along with you. Using a chemical rocket to
send humans to Mars would be like making the road trip in a
cement truck. You might barely make it, but it would be one
enormous, inefficient, and expensive voyage. Using an NTR,
however, would be more akin to taking a Prius. It’ll make it
there comfortably, and it can go a lot further too.”

PROJECT ICARUS: How to Navigate Interstellar Space

Priorities in NASA’s current space program emphasize developing
capabilities to take humans beyond Low Earth Orbit (LEO). And
while there are agreements in place between NASA and
private companies such as SpaceX
to deliver cargo and
potentially American astronauts to the International Space
Station, few outside of the U.S. Government are privately
exploring nuclear space technologies for their inevitable use in
the future of space exploration.

Private industry has the flexibility to pursue international
partnerships, as companies like Rocketdyne and Aerojet have done
in the past for propulsion subcontracting work with Russia.

Recently, Tabitha Smith, research lead for Project Bifrost and
chief strategic officer of General Propulsion Sciences was
invited to Moscow to become more familiarized with U.S.-Russian
business partnerships, and to collaborate with NTR and rocket
propulsion colleagues under the auspices of the newly created
Russian agency Rossotrudnichestvo — an initiative started by
President Medvedev to cultivate Silicon Valley-like
entrepreneurship and international projects in Russia.

International cooperation is seen as a vital part of future
large-scale space projects in the space community at large, as it
encourages transparency, expedites completion times, and splits

It’s worth noting that as with many technologies in space
exploration, the 1960’s were the golden age for NTRs. Between
1955 and 1973, the US Government spent $1.4 billion in an NTR
program called Rover/NERVA, anticipating it would be used after
Apollo was completed. Although it was ultimately canceled before
a flight could be achieved, the program was tremendously
successful in proving that NTRs work. The knowledge gained from
NERVA remains as a vital resource for future NTR development.

This spring, while we mark the 50th anniversary of John F.
Kennedy’s famous speech to Congress in which he challenged the
nation to go to the moon, perhaps it would be useful to reflect
upon what he said immediately after declaring that goal:
“Secondly, an additional 23 million dollars … will accelerate
the development of the Rover nuclear rocket. This gives promise
of some day providing a means for even more exciting and
ambitious exploration of space, perhaps beyond the moon, perhaps
to the very end of the solar system itself.”

© 2012 Discovery Channel

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