To Mars in 39 days
Last week in space - Nov. 29
This week's issue is a little rushed thanks to the Thanksgiving holiday. But, practice matters in both rockets and writing. So, let's roll.
Today's eye catching news - NASA has contracted with a company for continued development of a next generation engine.
The price tag? At least $9 million. I was intrigued by Chris Gebhardt's summary for AmericaSpace, so I dug in.
Named VASIMR (Variable Specific Impulse Magnetoplasma Rocket), the engine builds off of a tech that’s powered satellites and deep space probes for decades. (NASA ebook on the subject)
VASIMR is a variant of something called an ion engine. They’re used like the chemical rocket engines you’re familiar with, but that’s where the similarities end.
In a chemical rocket, you...well...mix some chemicals together. Specifically, you’re looking for materials that like to throw a bit of party. And you direct that party out the back of rocket. If party (explosion) doesn't tear your spacecraft apart, you get a boost.
Ion engines are different. The gas used in them is chosen for its stability. "Noble" gases, too high class for reacting with their peers among the periodic table, are regulars. Xenon is a top choice.
The xenon is bombarded with electrical energy to take it from a dull neutral gas into an ionized gas. The ions are essential. With the gas now charged, it will react to magnetic fields. Fields we can produce with just a little more power.
Our magnets fling the ionized gas out the back of our rocket, providing weak, but very efficient thrust.
Need more? NDG to the rescue.
Ad Astra, a company started by retired astronaut Dr. Franklin Chang Díaz, has spent the last decade working on a better way.
The Ad Astra engine uses a few tricks to take the ion engine concept and add some serious juice to it, without sacrificing efficiency. Just to give you a sense:
Instead of just an ionized gas, the VASIMR engine heats the gas up to levels you mostly find in the sun. You've heard of solid, liquid, gas. Above "gas" is a higher energy state. It's called "plasma" and mostly it's found in stars.
Plasma is hot. Too hot to manage with many normal materials. But, there's a solution. Our basic ion engine is already using magnetic fields to fling the gas out of the spacecraft. VASIMR takes this idea to the next level. Not only do the magnetic fields toss the material (now plasma, not gas) around, they're also used to control the flow and keep the engine safe.
If this all works, VASIMR could be THE option for interstellar travel. Why? NASA's contract tests a 200kW version of their engine.
Diaz has visions for a much bigger option. His hypothetical 200 MegaWatt design of the same engine packs a serious punch. He claims it could drop the time to get to Mars from 250+ days to 39.