|
|
| Fig. 1: Artist's depiction of space probe in flight with solar sail. (Source: Wikimedia Commons) |
In the eyes of many people, space is the final frontier. With so much of it unknown, interstellar exploration piques the curiosity of mankind with what might lie outside our solar system. From untapped resources to signs of life, successful interstellar travel could truly pay off in ways that we could only hope to imagine. Yet, the gap between us and reaping such cosmic rewards can be significantly widened or shrunk by how we supply energy to journey far enough beyond.
One method of vehicle propulsion is ion thrust technology. Ion thrusters utilize electrostatic energy that can output ten times the impulse achieved using typical hydrazine thrusters that powered the first shuttle missions.
It takes a shuttle with ion thrusters four days to go from 0-60 mph. [1] That time seems awfully slow but thankfully, that acceleration can continuously extend for long periods of time. Instead of slowly approaching its destination, the shuttle is continuously accelerating at the same rate. Therefore, after 8 days, the shuttle can go 120 mph; and after 12 days, the rocket is going 180 mph, and so on and so forth. This acceleration continues until they reach a peak of 112,000 mph. [1]
Solar sailing is a method of maneuvering spacecraft without any fuel. As shown in Fig. 1, by attaching giant reflective sheets (aka sails) to a payload/satellite, solar sails are able to harness solar photons emitted from the sun. When these light particles hit the sails, their momentum is transferred to the spacecraft creating a push which gradually accelerates the craft through space. [2] In short, the end result of the process is very similar to that of cloth sails and wind, hence their name. NASA has thrown support behind solar sails with research tests and planned missions such as Near Earth Asteroid (NEA) Scout.
Kilopower provides "a compact, low-cost, scalable fission power system for science and exploration." [3] The U-235 reactor uses well established nuclear fission to produce heat which is delivered by heat pipes to power generators. A Kilopower reactor could continuously produce 1-10 kilowatts of electrical power for 10 years or more. However, over the coming years, the reliability and safety of kilopower will still be tested.
After tackling the fueling problem, assessing the options and choosing the right source of power for the right mission is just as important. The need for reliable power has become essential but mankind's next steps do not have be fueled by earthly materials. There is still an intriguing possibility of finding a brand new source of energy on interstellar mission - to another planet, asteroid, comet, etc - that could power a spacecraft even further and faster.
© Fisayo Omilana. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] S. A. Gavit et al., "Interstellar Travel—Challenging Propulsion and Power Technologies for the Next 50 Years," AIP Conf. Proc. 552, 716 (2001).
[2] A. D. Guerman, G. V. Smirnov, and Ma. C. Pereira, "Comparison of Two Compound Solar Sail Schemes," AIP Conf. Proc. 1281, 485 (2010).
[3] M. Bartels, "What is Kilopower? NASA's Mini Nuclear Reactor That Could Power Life On Mars," Newsweek, 18 Jan 18.
