The Stars are Close

July 20th, 2014

While out taking a night walk, when looking up at the night sky a thought hit me: There are an awful lot of stars that are really close to us. When you look up at the night sky you can see a great many stars very clearly – about 50 of them are within 20 light-years from Earth and visible to us. 20 light-years sounds like a lot, but it’s not. You can see these stars clearly – many are like our sun, just a little farther away. These stars look to us like our sun would once you move to the edge of our solar system and look back towards its center.

If you were to travel to one of those 50 stars within 20 light-years from Earth, imagine that there is a space highway to get you there. Down the road as you drive through space you can keep your destination in view for the entire drive. These stars are close; they are right there. They beckon, letting us know exactly where to point our space-cars as we drive.

And when you get out to 250 light-years from Earth – there are 260,000 stars surrounding us. Since the Milky Way Galaxy is 100,000 light years across, these 260,000 stars are spread over just 1/200th of the diameter of the galaxy. It’s dense with stars where we live – there are 260,000 of them scattered nearby and around us in all directions.

About one third of the stars visible with the naked eye lie within 250 light-years, even though this is only a tiny part of our galaxy. An individual star must be close for us to be able to see it with our unaided eyes. Most of the bright dots you see in the night sky are clusters of many, many stars that look to us like an individual star. So when you can see a true individual star, you know it is close.

There are a whole lot of stars incredibly close considering the overall size of our Milky Way Galaxy. And when compared to the space around us covering the nearest 100 galaxies – those 260,000 stars around us are practically on top of us. These stars are close.

Once the first true starship is operational – there are going to be a whole lot of places to visit. It really will be like Star Trek. It will take a lot of time and effort to venture around our sub-galactic neighborhood to check out those 260,0000 stars. How many of them will have orbiting planets with life on them, whether plants or animals? How many of these planets will have intelligent beings living there? One day humans will find out, and the explorers in the first starships will see these other worlds up close.

A Dazzling Green Ring of Stuff Around the Equator in Space

July 10th, 2014

For as short of time as we have been in space, it’s amazing how much stuff we have managed to put up there. Commenter Mitchz95 found this cool 3D graphic of tracked orbital objects. Use your mouse roller to zoom in and out. And hold the left button down to rotate the view of Earth. Not much around the Earth’s poles – but check out that dazzling green ring around the equator.

I wonder which of those green dots you are using to read this website, if any.

Isaac Asimov’s Three Laws of Robotics

July 5th, 2014

A BTE commenter posted Isaac Asimov’s three laws of robotics on an earlier post that I wrote where I gave an estimated timeline for the development of humanoid robots. Asimov came up with these three laws all the way back in 1942. This was a guy thinking ahead of his time. The laws are:

1) A robot may not injure a human being or, through inaction, allow a human being to come to harm.

2) A robot must obey the orders given to it by human beings, except where such orders would conflict with the First Law.

3) A robot must protect its own existence as long as such protection does not conflict with the First or Second Laws.

When the humanoid robot technology revolution comes, these laws seem a reasonable starting point for bounding robot behavior. But of course things will get complicated. In law #1 it says that robots should not let humans “come to harm”. At first you think of physical injury – but this could be expanded to all sorts of things.

If a robot stole your wallet, did you come to harm? If a robot hurts your feelings, did you come to harm? What if your significant other starts spending more time with his or her robot friend because they find the robot more attractive and interesting than you. Did the robot harm you then?

In the end, robots will have to deal with the messy world of human ethics, a thing that we are all immersed in our whole lives.

Zubrin’s Hoax of a Debate

July 1st, 2014

Robert Zubrin says he wants a debate:

“Thursday, Mars Society President Dr. Robert Zubrin issued a challenge to a debate to Dr. Franklin Chang-Diaz, former astronaut and president and CEO of Ad Astra.”

Zubrin says he wants to debate Chang-Diaz, the inventor of the VASIMR electric propulsion engine, about whether electric propulsion makes sense for traveling to Mars. Zubrin, who came up with the Mars Direct idea, is stuck on the notion that using chemical rockets is the only way to go to Mars for our first trip there. But if you dig deeper you will see that this offer to debate might be more aptly called a hoax of a debate.

If I was Franklin Chang-Diaz I wouldn’t debate Zubrin. The first time Zubrin publicly criticized the idea of the VASIMR – to me he turned this into a rather personal attack on Chang-Diaz. In 2011 Zubrin gained press attention by claiming the VASIMR is a “hoax”. By calling it a hoax he implies that Chang-Diaz is being deceitful when saying that the VASIMR is a superior way to travel to Mars when compared to chemical rockets. However, with the right power system the VASIMR really can get you to and from Mars faster than chemical rockets.

In 2011 Zubrin did his best to make the VASIMR seem unimportant. He wrote:

“VASIMR, or the Variable Specific Impulse Magnetoplasma Rocket, is not new. Rather, it has been researched at considerable government expense by its inventor, Franklin Chang Diaz, for three decades. More importantly, it is neither revolutionary nor particularly promising. Rather, it is just another addition to the family of electric thrusters, which convert electric power to jet thrust, but are markedly inferior to the ones we already have.”

So along with saying Chang-Diaz is committing a hoax – Zubrin also says his baby is ugly! That is one heck of a way to win friends and debating partners. It is no wonder that Chang-Diaz has not publicly said much regarding Zubrin’s comments over the past 3 years. I think he understands that, in light of Zubrin’s disparaging attitude, that Zubrin is not acting worthy of engaging.

When Zubrin says that the VASIMR is “markedly inferior to the ones we already”, he is misleading. There are no megawatt-class electric propulsion engines anywhere near ready to go to space even as test prototypes. They are all only concepts and early prototypes here on Earth competing to become significant development projects one day. Chang-Diaz is the leader because he has an engine concept and a vision big enough to lead to the first megawatt-class production electric propulsion engine. Scroll down at this link to see a table of common power levels for existing ion thrusters and for electric engine prototypes being tested.

In 2011 Zubrin also added:

“But wait, there’s more. To achieve his much-repeated claim that VASIMR could enable a 39-day one-way transit to Mars, Chang Diaz posits a nuclear reactor system with a power of 200,000 kilowatts and a power-to-mass ratio of 1,000 watts per kilogram. In fact, the largest space nuclear reactor ever built, the Soviet Topaz, had a power of 10 kilowatts and a power-to-mass ratio of 10 watts per kilogram. There is thus no basis whatsoever for believing in the feasibility of Chang Diaz’s fantasy power system.”

The Topaz was a Soviet reactor last sent to space in 1988. That is a long time ago, and it is well known that the kg per kW of reactor system output electric power can be greatly reduced provided that this is given some priority for research. Zubrin very well knows this. It’s ironic that he accuses of Chang-Diaz of trying to pull a hoax, when Zurbin claims: “There is thus no basis whatsoever for believing in the feasibility of Chang Diaz’s fantasy power system.”

The Topaz was 32 kg per kW (kW of electric output power). But in recent research, for example in this 2011 NASA research paper, researchers believe that with new technology it’s reasonable to assume that 2 kg/kW is possible. And here is a paper that says: “These advanced reactors at the conceptual design level have potential for the generation of tens to hundreds of megawatts of power in space with specific mass of about 1 kg/kW.” Thus, 1 to 2 kg/KW nuclear power systems are feasible, it’s just a matter of time and investment money.

Let’s see what Chang-Diaz actually said in his paper about travel times to Mars and what is needed for kg/kW for the power system that would power the VASIMR:

“Using 12 MW of power and a total specific mass for the entire power and propulsion system of a challenging, but presently realizable 4 kg/kW, allows for a scenario with a crewed one-way mission time of approximately 3 months, and a round-trip mission time of approximately 10 months (including 1 month stay on Mars). Assuming advanced technologies that reduce the total specific mass to less than 2 kg/kW, trip times of less than 60 days will be possible with 200 MW of electrical power. One-way trips to Mars lasting less than 39 days are even conceivable using 200 MW of power if technological advances allow the specific mass to be reduced to near or below 1 kg/kW.”

This seems very up front and open regarding the potential of the VASIMR and what is needed for the power system. Chang-Diaz is hiding nothing and he’s giving a matter of fact description of what is possible “assuming advanced technologies” for the power system. There is no hoax in sight.