This is a bit off topic for us, but it’s certainly worth talking about. In London’s Daily Express we read NASA works on laser propulsion spacecraft which could get to Mars in THREE days. Here are some excerpts, with bold font added by us:
In its latest video blog – NASA 360 – the space agency describes a spacecraft which is currently being developed and would rely on a technology known to experts as “photonic propulsion” which would allow spaceships to explore space at 30 per cent of the speed of light.
The video is no big deal. It’s only 2 minutes long. Wikipedia had an article on Photonic laser thruster. Let’s stay with the Daily Express:
The potential spacecraft, which NASA admits is still in its infancy, would be able to reach such pace as when the particles of light that it emits are reflected against an object, it would give the spacecraft speed and momentum, gradually getting faster and faster. NASA scientists Phil Lubin said: “There are recent advances that take this from science fiction to science reality. There is no known reason why we can not do this.”
Very nice, but it’s rather like shooting an arrow. Once it’s launched, you lose control. How does such a ship slow down and land at its destination? And unless there’s a laser setup on Mars, how does it return? The article continues:
However, for any aspiring astronauts hoping to be one of the first to explore space at speeds which have never been reached by humanity before, you’re probably out of luck. A spacecraft with the potential to reach such speeds would need be designed with weight in mind, which is why Lubin and co are proposing making the ship wafer thin meaning that humans would be too heavy, but would be perfect for robots.
But wait — that news is dated 24 February. Today there’s more! London’s Daily Mail has this headline: Forget three days, now physicist behind radical laser propulsion system explains how we could get to Mars in 30 MINUTES. It says, with our bold font:
A small probe could get to Mars in less time than it takes to watch ‘Interstellar’. That’s according to physicist, Phillip Lubin, who recently outlined how a probe could reach the red planet in just three days. Now, Lubin says that time could be reduced to just 30 minutes by using extremely powerful lasers to propel a wafer-thin unmanned spacecraft.
Good grief! It takes light from the Sun (traveling at the speed of light, obviously) 8 minutes to get to Earth. The distance from Earth to Mars varies as the planets move around the Sun, but still, 30 minutes is fast! At their closest, the distance between Earth and Mars is 56 million kilometers. If that can be done in 30 minutes, the ship would be traveling at 112 million km per hour. Light travels at 1,079,252,848.8 km per hour. The ship would be moving at about 10% of lightspeed. Okay, let’s read on.
The UC Santa Barbara physics professor first unveiled his ‘directed energy propulsion’ concept at a Nasa Innovative Advanced Concepts (NIAC) symposium last October. He’s now followed up his comments with a detailed 52-page paper in the Journal of the British Interplanetary Society.
We can’t find the paper at that journal, but the Daily Mail provides a link to a pdf file you can read online: A Roadmap to Interstellar Flight. We haven’t read it yet. Back to the Daily Mail:
He claims that by firing a laser at a spacecraft, it would have the ability to achieve frictionless acceleration in space. That would allow it to reach a more than a quarter speed of light in just minutes. … ‘[It would] reach Mars (1 AU) in 30 minutes, pass Voyager 1 in less than 3 days, pass 1,000 AU in 12 days and reach Alpha Centauri in about 15 years.’
Even the Daily Mail has noticed a couple of problems. They say:
There are some major flaws in Lubin’s plan, such as how such a fast-moving probe would slow down when it reached Mars. The difficulty of encountering space junk is a major problem. But according to Lubin, the accumulation of interplanetary dust won’t impact its speed.
But then the newspaper gets crazy: They mention time dilation:
The effect was shown in Christopher Nolan’s 2014 science film Interstellar, in which a group of astronauts fly into the center of a supernatural wormhole. As they move farther into the universe, the time they experience slows down. The same thing could happen to a crew if they were able to reach Mars in 30 minutes. While it would appear as if they only spent 30 minutes getting to the red planet, in reality decades would pass.
BWAHAHAHAHAHA! These are not difficult calculations. Relativistic effects don’t become significant until a ship is traveling faster than 50% of lightspeed. If a ship traveled at “only” a quarter of the speed of light, time dilation would be barely noticeable. Observers on Earth would see that the trip took 30 minutes, and it would seem like only 29.047 minutes to passengers on the ship. Not decades!
There’s more in both articles, but we’ve given you enough to mull over. If you have any thoughts, we’d like to hear them.
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