There are lots of things that are fast. Usain Bolt, arguably the world’s fastest man, can sprint at a top speed of 27.44 miles per hour. The quickest animal on earth is the cheetah of course, blistering in at over 60 mph. Humans are obsessed with speed; we have developed vehicles to help us traverse the earth quicker. Through great feats of engineering, cars have been developed that can break 300 mph and aircraft that can reach 4,473 mph. Travelling in space is much different. Apollo 11, the spacecraft that landed the first two people on the moon, had a top speed of 40,000 mph. That absolutely crushes all of the top speeds on earth. That is, except for the speed of light! If you had light and the Apollo 11 spacecraft race gave Apollo 11 a four hour head start, it would take light about 1 second to catch up.
Even though we have been able to engineer amazing spacecrafts to explore the universe, we are very limited by where we can actually go. The universe is big. However, over the years we have been able to go faster and faster, and some believe we may approach the speed of light someday.
Aerospace engineers have improved our rockets drastically since the Apollo 11 spacecraft launched in 1969. We are not even close to the speed of light yet, but we are improving. In 2006, NASA launched the New Horizons probe. The New Horizons mission planned to visit Pluto and the Kuiper belt. It escaped Earth at around 36,000 miles per hour. When you pair this with the velocity component of the planet’s orbital motion, the spacecraft was launched into our solar system with a speed of 100,000 miles per hour!
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The Sun is a jerk and had pulled New Horizons velocity down to 44,738 miles per hour by the time it reached Jupiter. This was a problem. The New Horizons mission was going to study Pluto. Pluto was getting close to its winter season. During the winter, Pluto’s atmosphere freezes and falls to the ground, making it difficult to study. The spacecraft was able to regain some speed, however, by using what is called a “gravity assist maneuver”. New Horizons was slingshotted out of Jupiter’s gravity 9,000 miles per hour faster than it entered.. It finally reached Pluto on July 14th, 2015. As it passed the dwarf planet, it was travelling about 31,317 miles per hour. Without the assistance of gravity, New Horizons wouldn’t have reached Pluto at the ideal time.
Gravity can speed up a spacecraft way faster than that however. On August 12th, NASA launched the Parker Solar Probe. This probe is going to become the fastest man-made object ever created. 6 years from now it will be traveling at 430,000 miles per hour. That shatters the previous record of 153,000 miles per hour, which was set by the Helios 2 Probe. The Parker Solar Probe is heading to the heart of our solar system to help us learn more about the sun. The Parker Probe will study “the sun’s atmosphere, the vast eruptions of energy and the charged particles that originate there”.
How is the probe going to travel so fast you ask? It is going to be assisted by gravity. The probe will be able to travel so fast because it will be accelerated by the overwhelming gravity of the sun. The earth is nearly 100 million miles away from the sun while the Parker probe will be within 4 million miles of the sun. The force of gravity exerted on the probe will be nearly 500 times the force the Earth experiences.
In order to get the probe where it needs to go, it will have to follow a complicated orbital path. The probe must go against Earth’s orbital speed so it can slow down enough to fall closer to the sun. The scientists at NASA have plotted a specific orbit that will have the probe pass Venus on every orbit and utilize the planet’s gravity to alter the trajectory of the probe towards the sun. This process will be repeated 7 times. There has never been a mission that has utilized so many gravity assists. Astronomer Jonathan McDowell puts the incredible speed and power of the probe into perspective, saying, “It has 20 million times more energy than a half-ton truck hitting you at 100 miles an hour.”
While using the sun to reach speeds of 400,000 miles per hour is amazing, it is still only .06% of the speed of light. Alpha Centauri, he closest star system to our solar system is 4.37 light years away. Scientists have discovered there is possible earth like planet orbiting it, Proxima B. There is likely water on the planet, and it would be a great destination for our first interstellar journey. If the New Horizons spacecraft embarked to reach Proxima B, it would take around 54,000 years. With our curennt techonology this would be possible. Scientists are currently working to design a spacecraft that they believe could get us to Proxima B in only 20 years. This project is named Breakthrough Starshot.
The Breakthrough Starshot project will launch a tiny laser-propelled space probe all 4.3 lightyears to visit Alpha Centauri. These micro-probes will be utilize light sails to help them reach one fifth of the speed of light. Also called solar sails, are “propelled by the pressure that solar radiation exerts on the sail due to the reflection and a small fraction is absorbed”. In other words, flat reflctive surface off of which photons can bounce and trander momentom. Photons have no mass, but still have momentum.
