Breakthrough Starshot

 Edit: Sorry for the lack of recent posts! I have had a lot of work the last couple months, but am back now :)

So, Breakthrough Starshot. Chances are you have heard of it, but I will be explaining what it exactly is and how it works a little more in depth. Breakthrough Starshot is an initiative to reach the nearest neighboring star system Alpha Centauri using an alternative form of travel, solar sails. Before getting into what solar sails are, a little background on why they are being developed: using traditional thrusters and current rocket propulsion technologies, it would take tens of thousands of years to reach, given the distance from our home to Alpha Centauri is over 4 light years. The current timeline for this project estimates the first launch date at around 2035, since there are a multitude of engineering problems to overcome in order for this new form of space travel to be developed for use. 

Figure 1: Solar Sail Demonstrator - "Sunjammer"

Solar sails involve the use of high power lasers firing at extremely small and light solar sails, causing them to accelerate to up to 20% the speed of light (about 60 million meters per second!) within minutes. This would allow a craft driven by a solar sail to reach Alpha Centauri in just 5 years! These sails can also be used by sunlight, as the sun emits photons that exert a force on the sail, causing objects in space to accelerate ever so slightly away from the sun. This is because of Newton's third law of motion, that every object has an equal but opposite reaction. Over the course of trillions of photons either bombarding the spacecraft in the form of sunlight or a laser, it slowly accelerates to tremendous speeds.

However amazing this sounds, it does not come without its issues. First, there is no known way of stopping or controlling the motion of solar sails far beyond our own solar system, as the speed with which it is travelling is extremely fast. For now, the only plausible way to explore the star system of Alpha Centauri is to perform a fly-by, as the solar sail would only be able to stop if it crashed or got trapped in an incredibly strong gravitational field. Additionally, solar sails have to be extremely light in order to be able to feel the miniscule force exerted by photons, and so enhanced observational scientific material cannot be put on the sail, therefore not allowing for comprehensive scientific analysis if it passes by a star system like Alpha Centauri. As seen in Figure 1, the sail consists majorly of the actual sail with minimal scientific material placed in the center.

Solar sails have so much more to them than I described, if you want to learn more feel free to explore the below links :)

https://www.space.com/solar-sail.html

https://breakthroughinitiatives.org/initiative/3