It is always exciting to wake up to news that NASA has advanced their knowledge with a discovery of a new distant planet, particularly when they fall within what is known as the habitable zone. The implications are huge.

Of course, any excitement is often tempered by distance. As thrilling as it is to hear about the discovery of a new earthlike planet, when its located

**490 light-years away**you have to wonder what’s the point. Civilization isn’t going to see these worlds up close in any manner in the next millennium unless we discover ways to circumvent the current known laws of physics.
Yet leave it to

**Carl Sagan**to inject an ounce of optimism into the situation. Consider Mars. According to space.com, even using the fastest spacecraft to date, it would require 150+ days to reach Mars. But this is only using our current paradigm of space travel in which vessels are essentially given a boost and then travel at a constant velocity. If we could find a way to propel a probe with continuous acceleration we could conceivably have probes reach places like Alpha Centauri in a matter of years, not millenia.
Here is Sagan’s explanation from his masterpiece

*Pale Blue Dot*:Imagine we could accelerate continuously at 1 g — what we’re comfortable with on good old terra firma — to the midpoint of our voyage, and decelerate continuously at 1 g until we arrive at our destination. It would take a day to get to Mars, a week and a half to Pluto, a year to the Oort Cloud, and a few years to the nearest stars.”

This would require a new propulsion system that does not yet exist, but if you are including technology from the near future there is reason for optimism. Another important consideration is that the laws of physics do not prevent us from developing probes the size of pins with all the necessary capabilities. This would change things considerably in terms of required energy levels to sustain constant acceleration.

So even though these unimaginable distances may cool a lot of enthusiasm, there are reasons to be genuinely optimistic about what we will find out in the near future.

Every new discovery represents new possibilities.

*Supplemental Math*For those scratching their heads at this, the math supports Sagan’s quote.

Mars at its closest is 55 million kilometers from earth and at its farthest is at 225 million kilometers. This is according to: http://www.universetoday.com/14841/how-long-does-it-take-to-get-to-mars/

Because the planets are in orbit, its not a straight shot. The fastest we’ve gotten anything to Mars was the Curiosity Lander which required going about 72 million kilometers.

The average velocity of the Curiosity Lander which traveled at a constant was 20,000 km/hour. As a result, it took 150 days for it to arrive (an initial boost through a near frictionless environment). The math supporting this is very basic:

*Time = Distance / Rate*

Time = 72 million km / (20 km/hour x 24 hours/day)

Time = 150 days

So if we want to check Sagan’s math, we need to run this calculation accounting for 1g of acceleration. Since the trip is symmetrical (1g for halfway there and -1g the other half) we can solve for half the distance and then double our result.

Acceleration of Gravity = 9.8 m/s/s

*Time = sqrt ( 2 x Distance / Acceleration )*

Time = sqrt (2 x 36 million km x 1000 km/m / 9.8 m/s/s )

Time = 85,714 seconds =

**23.8 hours**

Thus is takes just under a day to reach halfway to Mars and the same for the second half making the total trip in under two days. Sagan said one day, but its clear his points stand on solid ground.

Pretty remarkable.