Throughout history, the sun, moon, and stars have been humanity’s companions. The next time you are outside, look up. The lights that shine down upon you now are the same that have guided sailors, mystified fortune tellers, and inspired populations. Those celestial bodies, both incomprehensible and oddly familiar, are embraced by our love and curiosity. Yet, for all of human history, the night sky’s immensity and distance has challenged our exploratory capabilities. At least for now. With the rise of technological and, subsequently, human capability, the future that lies ahead of us is dominated by space. In short, we live on the precipice of the space age. But, to examine where we are going, we must first uncover where we’ve been and understand where we are. 

How We Got Here.

Sight plays a pivotal role in the human experience. Whether it’s examining the deepest depths of our oceans or gazing towards the night sky, sight capably embodies our curiosity. Yet, with the night sky being so challenging to properly observe, humans have long imagined the celestial bodies that lay beyond Earth’s borders. That is until the development of the telescope.

While lenses had been around since the time of ancient Egypt, no one had turned their uses towards the night sky until the early 1600s (1). Enter the astonishing Galileo Galilei, a renowned astronomer whose immense contributions to astronomy would further humanity’s understanding of its place in the universe, whether or not it liked the new knowledge (2). Galileo’s development of the telescope enabled the observation of celestial bodies in a manner never done before. The subsequent telescope revolution and innovations enabled the onset of the sight humanity sorely needed to expand its understanding of the universe. Moreover, contributions from physicists and astronomers like Isaac Newton and Johannes Kepler ushered in a new study of the heavens, one dictated by math and scientific observation (1, 3).

These developments set the groundwork for physicists in the 20th century, perhaps most notably Albert Einstein. This broader understanding of physics and the universe culminated in the Apollo missions (4), which, to date, have been our most comprehensive and daring project of human exploration. In putting man on the moon, humanity has demonstrated a small extent of its capabilities. 

Where is Here?

In the years since the Apollo missions, humanity has, for the first time, sent space probes to beyond our solar system (5), rovers to the surface of another planet (6), and telescopes to gaze into the deepest depths of our universe (7). In the time since the Apollo missions, humanity has developed more capable technology, a deeper understanding of the universe, and, perhaps most of all, a cautious optimism towards the space programs of the future. Our current state in the age of space exploration is still in the womb. Presently, this time has been dominated by the International Space Station, Hubble Telescope, and Curiosity and Perseverance, the most recent Mars rovers. More recently, private enterprise has entered the fray for vying for space exploration. While long thought a possibility (8), companies like SpaceX, Boeing, VirginGalactic, and Blue Origin have all demonstrated remarkably capable vehicles for space exploration.

While the Apollo age is in its twilight, his sister, Artemis, is at its dawn. In the next few years, the moon mission Artemis will launch, fostering a new age of lunar and interplanetary exploration (9). Similarly, the James Webb Space Telescope has recently been deployed to study the universe, hoping to further shed light on our ancient celestial origins. Hopefully, this age will soon reach interplanetary travel, with the arrival of humans on Mars.

Where Are We Going?

While those may be some short term goals, the technologies that will characterize humanity’s expansionary period still exist only in the pages of science fiction novels. There are three of these technologies that I would like to briefly touch upon. 

Solar Sails:

Solar sails, which is, simply put, a sail using radiation as propulsion (much like a sail     on Earth uses wind), is perhaps our most easily “accessible” form of interstellar ravel  (10). These characteristics function on using differential in radiation pressure as a means of propulsion (11). In fact, the late renowned physicist Stephen Hawking was a notable backer of the technology (12). Hawking backed Breakthrough Starshot, an effort to reach a near star named Alpha Centauri through a system of lightweight space vesicles, lasers, and space sails (13). Solar sails represent a promising means of propulsion, so much so that NASA has begun missions to test out its viability (11).

Space Tethers:

Space tethers are, effectively, a large spinning rope in space. While no tethers have actually been built, this theoretical technology is physically possible, and NASA is exploring the possibility of sending a mission to test it out (14). Should this technology be developed, it would provide spacecraft with immense acceleration capabilities without carrying extra propulsion. A tether works by staying stationary around a point in space while the two ends of the rope spin around that axis, picking up spacecraft and other shipments along the way. This provides both acceleration and shortens the distance for spacecraft. In the book Seveneves, science fiction writer Neal Stephenson artfully constructs a form in which space tethers can be utilized, to improve access to low earth orbit (15). Regardless of the future applications of space tethers, it is likely to be a vital part of our future in space exploration. 

Mass Drivers:

Mass drivers (see figure 1) use electromagnetic fields to send objects into space (16). Interestingly, due to the acceleration forces passengers would feel, mass drivers are not feasible for passengers. That said, mass drivers serve an important role in bringing raw materials to space at a low cost. On large scale projects, like the terraformation of planets, mass drivers would be immensely beneficial. Much like space tethers, mass drivers have yet to be proven economically viable but remain physically possible (17). They will likely represent an extensive part of our capabilities as humanity develops into a space faring nation. 

Figure 1

While we have a long way to go, these technologies will become a key part of our future. The development of space technology should remain a priority of governments worldwide, as it would be a disservice to all humans, past, present and future, if we fail to expand our technological capabilities. So let’s reach for the stars. 

References

1. American Institute of Physics. The First Telescopes. https://history.aip.org/exhibits/cosmology/tools/tools-first-telescopes.htm 
2. Wolf, J. (2016, December 22). The truth about Galileo and his conflict with the Catholic Church. University of California, Los Angeles. https://newsroom.ucla.edu/releases/the-truth-about-galileo-and-his-conflict-with-the-catholic-church 
3. Commonwealth Scientific and Industrial Research Organization. Galileo & Newton. https://www.atnf.csiro.au/outreach/education/senior/cosmicengine/galileo_newton.html 
4. National Aeronautics and Space Administration. The Apollo Missions. https://www.nasa.gov/mission_pages/apollo/missions/index.html 
5. The Planetary Society. The Voyager missions. https://www.planetary.org/space-missions/voyager 
6. Erickson, K. (2022, March 8). The Mars Rovers. National Aeronautics and Space Administration Space Place. https://spaceplace.nasa.gov/mars-rovers/en/ 
7. James Webb Space Telescope: Goddard Space Flight Center. About: Webb vs Hubble Telescope. https://www.jwst.nasa.gov/content/about/comparisonWebbVsHubble.html 
8. Ryan, M. (1999). Business Scenarios for Space Development. National Space Society. https://space.nss.org/wp-content/uploads/Space-Manufacturing-conference-12-101-Business-Scenarios-For-Space-Development.pdf 
9. National Aeronautics Space Administration. (September 2020). Artemis Plan: NASA’s Lunar Exploration Program Overview. NASA. https://www.nasa.gov/sites/default/files/atoms/files/artemis_plan-20200921.pdf
10. The Planetary Society. What is Solar Sailing? The Planetary Society. https://www.planetary.org/articles/what-is-solar-sailing 
11. Johnson, L. Solar Sail Propulsion: Enabling New Destinations for Science Missions. Heliophysics Division’s Solar Terrestrial Probes Program. https://science.nasa.gov/technology/technology-highlights/solar-sail-propulsion-enabling-new-destinations-for-science-missions 
12. Malik, T. (2016, April 12). Stephen Hawking Helps Launch Project ‘Starshot’ for Interstellar Space Exploration. Space.com. https://www.space.com/32546-interstellar-spaceflight-stephen-hawking-project-starshot.html 
13. Breakthrough Prize. Starshot. Breakthrough Starshot. https://breakthroughinitiatives.org/initiative/3 
14. Marshall Space Flight Center. Space Tethers. National Aeronautics Space Administration. https://www.nasa.gov/centers/marshall/capabilities/space_tethers.html 
15. Stephenson, N. (2015). Seveneves. HarperCollins Publishers. 
16. O’Neill, G., H. Kolm (1980, November). High-acceleration mass drivers. Acta Astronautica, Volume 7, Issue 11, p. 1229-1238. 10.1016/0094-5765(80)90002-8
17. Kolm, H. (1980, September). L5 News: Mass Driver Update. National Space Society. https://space.nss.org/l5-news-mass-driver-update/