NASA’s New Horizon Space Mission
At a young age, we are exposed to the idea of a distant world consisting of the sun, numerous planets, and other celestial bodies. This vast and complex system, known as the solar system, has fascinated humanity for centuries. Each planet offers unique characteristics and mysteries that are waiting to be uncovered. Through scientific research and exploration, we continue to deepen our understanding of the solar system and unlock the secrets of our celestial neighbours.
One planet that has brought significant attention to the world of astronomy is Pluto. Pluto was discovered in 1930 by astronomer Clyde Tombaugh, but because of its small size and distant location, it was a difficult planet to study. It wasn’t until the 1970s that astronomers were able to determine Pluto’s size and mass, and in the 1990s, the Hubble Space Telescope was able to image Pluto and its moons in more detail (MSFC, 2015). NASA’s space mission, New Horizons, was a mission that aimed to explore the dwarf planet Pluto and its moons while studying other objects in the Kuiper Belt. New Horizons was the first mission in NASA’s New Frontiers Program that tackled specific solar system exploration goals that were identified as top priorities by the planetary science community (Harbaugh, 2019). Before the New Horizons space mission, our knowledge of Pluto and its moons was limited. The mission was launched on January 19, 2006, and travelled through space for more than nine years, covering 4.9 billion kilometres, before it reached Pluto in July 2015, making it the first spacecraft to fly by Pluto (Stern, 2008). The New Horizons spacecraft was equipped with a suite of scientific instruments, including cameras, spectrometers, and particle detectors, which allow it to study Pluto’s surface, atmosphere, and composition (New Horizons : Spacecraft, n.d.). It also carried a cylindrical radioisotope thermoelectric generator providing the spacecraft with power (Fountain et al., 2008).
NASA’s objectives for the mission were the following: what is the atmosphere of Pluto and how does it behave? What does the surface of Pluto look like? Are their geological structures? And how do particles ejected from the sun interact with Pluto’s atmosphere (Stern, 2008)? This report aims to shed light on the New Horizons mission, outlining the methods and instruments used for launch, while presenting the outcomes and findings of the expedition.
Methods & Instruments
Spacecraft instruments have revolutionized our understanding of planets and have allowed for advances in technology and exploration. To answer the objectives listed above, NASA implemented the New Horizons mission with a variety of instruments and methods to explore the dwarf planet Pluto and its moons (Figure 1).
The first instrument was Ralph. This was a visible and infrared imager/spectrometer that provided colour, composition, and thermal maps. Its primary purpose was to map the surface geology and composition of Pluto and other Kuiper Belt Objects (KBO), while providing atmospheric data and surface temperature (Reuter et al., 2008). The second instrument, Alice, was an ultraviolet imaging spectrometer that analyzed the composition and structure of Pluto’s atmosphere and looked for atmospheres around the Charon and Kuiper Belt. Essentially, its goal was to determine the relative abundances of species in Pluto’s atmosphere (Stern et al., 2008). Next, the Radio Science Experiment, abbreviated to REX, measured atmospheric composition and temperature and acted as a passive radiometer (Tyler et al., 2008). Additionally, the Long-Range Reconnaissance Imager, also known as LORRI, was a telescopic camera which analyzed data at long distances and mapped Pluto’s far side while providing high-resolution geologic data (Cheng et al., 2008). More so, the Solar Wind Around Pluto, or SWAP, measured the atmospheric “escape rate” and focussed on Pluto’s interaction with the solar wind (McComas et al., 2008). Furthermore, the PEPSSI, or Pluto Energetic Particle Spectrometer Science Investigation, was an energetic particle spectrometer that measured the composition and density of plasma (ions) escaping from Pluto’s atmosphere (McNutt et al., 2008). Finally, the Student Dust Counter (SDC), as the name suggests, was built, and operated by students to measure the space dust that interacted with New Horizons during its expedition across the solar system (Horányi et al., 2008). It is also important to note that the instruments listed above not only targeted NASA’s interest but also acted as backups to other instruments in case one failed during the mission.
Once the data was collected from the aforementioned instruments and further analyzed, they proved to be invaluable in expanding our knowledge and understanding of the far reaches of our solar system.
Results
The New Horizons mission has provided a wealth of new information and insights into the dwarf planet Pluto, its moons, and the Kuiper Belt region. According to the science team at Johns Hopkins University that manages the mission for NASA, there are three key discoveries: mountain ranges on Pluto’s surface, four additional new moons, and the presence of flowing ice (Talbert, 2015).
Mountains
One of the most notable features discovered during the mission was a bright oval-shaped deposit informally known as Sputnik Planum or Sputnik Planitia in the Tombaugh Region (Schenk et al., 2015). Imagery detectors on board the spacecraft detected mountains that rise 2 to 3 kilometres above the surrounding terrain which implies the presence of water ice-based solid bedrock (Stern et al., 2015). Additionally, up-close images of Pluto show a bright heart-shaped feature where near its base, also considered the equatorial region, exists a mountain range with peaks reaching a height of 3,500 meters above the surface of the icy body (Figure 2) (Talbert, 2015). As mentioned, Pluto’s surface was not the only terrain being discovered. The view of Charon, Pluto’s largest moon, uncovered a relatively young and varied terrain. The abundance of cliffs and troughs that stretch about 1,000 kilometres suggests the widespread fracturing of Charon’s crust. The image also shows a canyon that is estimated to be 7 to 9 kilometres deep (Northon, 2015). Overall, the discovery of mountains on Pluto and Charon during the New Horizons mission provides an important insight into the geology and history of this distant dwarf planet, while raising intriguing questions about the ongoing processes that shape its surface.
Moons
Instruments on board the mission have also observed the smaller contributors of the Pluto system, which happens to include four additional moons: Nix, Hydra, Styx, and Kerberos. Although measurements for Styx and Kerberos have not yet been downlinked, panchromatic images from LORRI were taken of Nix and Hydra, uncovering their irregular shapes. For example, figure 3 is an image taken by LORRI and Ralph showing Nix’s triaxial ellipsoidal shape with dimensions of 54 by 41 by 36 kilometres (Stern et al., 2015). Furthermore, the latest image of Hydra revealed its non-spherical shape and size, estimated to be about 43 by 33 kilometres. Further observations indicate that both Nix and Hydra’s surface is coated with water ice, and spectroscopic data from Ralph exposed the abundance of methane ice (Figure 4) (Northon, 2015). However, it is important to note that this frozen surface on the moon differs from that of Pluto. These discoveries on Pluto’s moons during the mission have deepened our understanding of the outer solar system and provided us with important insights into the formation and evolution of Pluto’s system.
Flowing Ices
Images from LORRI have also shown signs of recent and unexpected geologic activity regarding the flow of ice (Figure 5). These images reveal details within the Sputnik Planum area which lies within the western half of the bright heart-shaped region, known as the Tombaugh Region. In this region, a sheet of ice appears to have flowed and may be continuing to flow, in a way that is similar to glaciers found on Earth. Additionally, the Ralph instruments indicate that the center of Sputnik Planum is rich in nitrogen, carbon monoxide, and methane ice. Newer ice deposits have been found in the dark, southernmost region near the equatorial region of the heart-shaped feature (Figure 6) (Gipson, 2015). The discovery of flowing ice on Pluto suggests that volatile ices may play a key role in shaping the surfaces of other icy worlds, such as those found in the Kuiper Belt beyond Neptune. In summary, the discovery of flowing ice on Pluto during the New Horizons mission has opened new avenues of research into the climate and potential for life in the outer solar system.
Discussion
The New Horizons’ encounter with the Pluto system revealed a wide variety of geological activity including surface features, the discovery of small satellites, and glaciological data. This mission has provided us with a wealth of new data and insights into the Pluto system, which has greatly expanded our understanding of this distant, icy world. Interpreting key findings will help us discuss their implications for our understanding of Pluto and the wider solar system.
One of the key findings is in reference to the smooth, featureless surface of Sputnik Planum which has provided important insights into the geology and geophysics of this distant world. Geological processes such as impact cratering and tectonic activity tend to create rough and uneven terrain. However, the absence of such features on the Sputnik Planum suggests that the surface has been recently reshaped by some other process, such as cryovolcanism or convection in the underlying ice (McKinnon et al., 2016). Additionally, imaging of Nix and Hydra showing their unusual shape suggests that the moon is not in hydrostatic equilibrium, meaning it has not settled into a stable, round shape under its own gravity. This contrasts with many of the larger moons in the solar system, including Charon, which is in hydrostatic equilibrium (Weaver et al., 2016). The irregular shape of Hydra also suggests that it is likely composed of a mixture of different materials, such as ice and rock, which do not settle into a stable shape due to their uneven distribution. This in turn suggests that the formation of Hydra was likely a violent and chaotic process, involving collisions and mergers of smaller bodies (Weaver et al., 2016). Finally, the flowing ices on Pluto are estimated to be a mixture of nitrogen, methane, and carbon monoxide, similar to the compounds that are thought to have played a role in the origin of life on Earth (Gipson, 2015). Studying them could provide important insights into the conditions necessary for life to arise.
To sum up, the data collected from the New Horizons mission has greatly expanded our understanding of Pluto and the wider solar system. The discovery of geological activity on Pluto has challenged our previous assumptions about the outer solar system, while the insights into the composition of Charon and other moons have shed new light on moon formation and the early history of the solar system.
Conclusion
Since its launch on January 19, 2006, NASA’s New Horizons mission has been a resounding success, exceeding all expectations by achieving ground-breaking scientific discoveries. After understanding the main objectives of the mission, the purposes of the spacecraft instruments, and interpreting data collected from those instruments, we can confidently say that the mission has shed new light on the geology, atmosphere, and composition of Pluto and its moons. It has also provided valuable insights into the Kuiper Belt, a region of space that was previously unexplored. New Horizons’ scientific findings have challenged existing theories about the formation and evolution of the outer solar system, and they will undoubtedly inspire further research and discovery in the years to come. Overall, the New Horizons mission has been an incredible achievement for NASA and the scientific community as a whole, with the exploration of the solar system being a testament to the wonders of the universe and a constant reminder of our place in it.
