Propulsion

The development of the Saturn-V rocket was key to the success of the Apollo pro­gram. The accomplishments of Werhner Von Braun and his team of German and American engineers are undeniable. The liquid rocket technology that began with the early efforts of Robert Goddard in the 1920s, the wartime development of the A-4 and V-2 missiles of World War 2 Germany under Von Braun’s leadership, the continuing development of ballistic missiles through the Cold War years of the 1950s and 1960s, led to the crowning achievement of the Saturn-V.

Current rocket propulsion technology does have its limitations. Using current rocket technology for Moon travel has been demonstrably practical. However, lon­ger trips into space beyond the Moon and within the Solar System demonstrates the limitations of current technology. Just to travel within the confines of the Solar System demands a staggering amount of fuel and rocket power for direct trips to adjacent planets. Deep space probes, such as Cassini, Galileo, and New Horizons, takes years of planning and reliance on planetary gravity assists to achieve the goals of the designed missions. Any manned mission to Mars and return to Earth becomes a multi-year effort, with considerable scientific, technological, logistical, and human health risks involved. Any attempt to travel to Mars with current rocket technology becomes an extraordinary expensive proposition.

Truth be known, a new propulsion technology is needed. If years of space travel can be cut to months, or even days, an attempt at Mars becomes more than a pipe dream. Unmanned probes, such as the Mars Orbiter, and the aforementioned Mars rovers are laying the groundwork, just as Ranger and Surveyor did for the Apollo program. Current propulsion technology works for remote probes, robotic landers, and rovers. But the exposure to the harsh realities of space renders a manned Mars mission a very risky business.

Like the chemical liquid fueled launch vehicles that NASA and the rest of the world relies on now, alternative space drive systems have been in slow development for over a century. Propulsion systems utilizing ion/plasma reaction engines have been proposed, with several designs undergoing some form of development.

The most promising of these alternative drive systems is the Variable Specific Impulse Magnetoplasma Rocket, or VASIMR. VASIMR uses radio waves to ionize and heat argon gas, and subjects the ionized argon to magnetic fields in order to accelerate the resulting plasma which provides thrust to a space vehicle. This plasma rocket technology was first introduced in 1977 by Franklin Chang Diaz, a Costa Rican scientist and astronaut.

A VASIMR driven spacecraft will allow for a mission to Mars with a travel period of just 39 days, almost 6 times faster than current rocket technology. The VASIMR driven spacecraft can develop speeds estimated at 35 miles a second, and will conceivably cover the distance between Earth and Mars in a more timely manner.

NASA rates new systems on a scale of one to ten based on its readiness to be deployed. The VASIMR system is currently rated by NASA as a six, which means that testing in space is the next step. NASA is testing a 200-kW VASIMR engine on the International Space Station in 2015. The engine is envisioned to provide periodic boosts to the ISS, which gradually drops in altitude due to atmospheric drag. ISS boosts are currently provided by spacecraft with conventional rocket thrusters, that consume about 7.5 tons of fuel per year. By cutting fuel use down to 0.3 ton per year, a huge cost saving can be realized in ISS operations. A success for VASIMR on the ISS will lead to a possible Mars application, with a nuclear reactor approximately equivalent to those carried aboard nuclear submarines. A reactor capable of generating 10-12 MW of power is required. Dr. Franklin Chang Diaz stated in a paper called The VASIMR Rocket which appeared in the November 2000 issue of Scientific American, that a 10-12 MW nuclear reactor is required for a 39 day journey from Earth to Mars. In addition, on September 29, 2009 Dr. Franklin Chang Diaz stated the following. “In fact, with the power close to what a nuclear submarine generates, you could use VASIMR to fly humans to Mars in 39 days.”

Leave a reply

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>