It’s been 38 years since humans last stepped foot on a planet other than this pale blue dot. Now, with new technology being developed at Ad Astra Rocket Company by Franklin Chang-Diaz and his team, we have grown closer to once again stepping foot on an alien world. But this time our sights are set beyond the cratered grey mass we call the moon, and onto more ambitious new lands, such as our rust-colored, smaller sibling, Mars. Through a new development in rocket technology, we may have the means to get to Mars in as little as 39 days, or about one sixth of the time it currently takes our probes.
Currently, our main source of propulsion into and through outer space is the controlled combustion of rocket fuel, the same technology that was first tested by Robert Goddard in 1926. Although more recently, missions like NASA’s Deep Space 1, which launched in 1998 to test new technologies and explore the comet Borrelly, have used ion propulsion technology also known as plasma rockets.
Plasma is the product of a gas being heated or energized which causes its atoms to release negatively charged electrons. The plasma is then mostly composed of positively charged atoms, called ions. The plasma rockets currently used by NASA are limited in terms of the amount of thrust they are able to generate, while the rockets in development by Ad Astra Rocket Company, called “variable specific impulse magnetoplasma rockets” (VASIMRs,) could be as much as 100 times more powerful.
All plasma rockets create thrust by converting gaseous atoms into ions through a heating or energizing process. After the gas is heated — to temperatures approaching that of the sun’s interior — it is funneled out the back of the engine creating thrust.
The general principle of thrust relies on Newton’s third law, “For every action, there is an equal and opposite reaction.” In all previous plasma rockets, the electric current which excites the ionized particles and guides them out of the back of the rocket is created with metallic grids. The problem with using metallic grids is that they eventually erode under the extreme temperatures accompanying immersion in super-heated plasma. This limits the amount of thrust the rockets can generate without causing serious damage to the grids.
With a VASIMR, the particles are heated using electromagnetic waves, generated from a radio transmitter and contained using superconductors. These improvements ensure that no part of the rocket is immersed in plasma flow, allowing for much more intense burns without the worry of erosion.
The promise of VASIMR is exciting, however it is still in its infancy and has just recently undergone a 50-kw test burn. A 200-kw test is planned for the near future, with plans to begin testing in space at the International Space Station (ISS) in 2012 or 2013.
To give an idea of what these figures mean, according to a New Scientist article, “Ion engines could one day power 39-day trips to Mars” and a 200 kw powered plasma rocket could deliver a two tonne payload more than 650 million km from the sun to Jupiter in about 19 months. Chang-Diaz, in an interview with SEED Magazine, said this currently takes us six years to accomplish.
Unfortunately for those hopeful of seeing a manned mission to Mars in the next few years, the wattage necessary to get a manned mission to mars in 39 days is 1,000 times what solar panels — the current method of energy collection for spacecraft — can provide. To meet the energy requirements, the space craft would have to be outfitted with an onboard nuclear reactor. This creates its own challenges, not only with the design of a nuclear reactor, but also with public opinion, which is generally against launching nuclear payloads into space, since they have the potential of malfunctioning and crashing back down to earth.
Demonstrating the validity of concerns over launching nuclear reactors into space is a Health Canada briefing on radiological and nuclear events, which highlights the malfunctioning and subsequent crash of COSMOS 954, a Russian satellite outfitted with an onboard nuclear reactor that scattered large amounts of radioactive materials over 124,000 square km in the Canadian north.
Given the challenges, it will likely take some time for collaborative efforts with either the U.S., or other nuclear states, before a prototype reactor is developed and deemed safe enough to be strapped to the VASIMR. However, despite the challenges yet to be met, the goal of creating efficient and powerful space propellant technology, which will help us explore our solar system and beyond, is quickly becoming a reality.