Posted on 11/20/2021 1:07:44 AM PST by blueplum
For a few years now, ion propulsion technology's sci-fi mechanics have raised the standard for flying spacecraft, replacing fiery rocket tails as the new in-thing. Ion propulsion can be about 10 times faster than normal fuel and can continuously run for prolonged periods of time, gaining a wicked amount of speed along the way.
One drawback, however, is it's typically employed with xenon thrusters. JAXA's Hayabusa2 mission used the classic xenon as a fuel. Xenon, a heavy noble gas, is exceptionally rare on Earth, pricey and difficult to maintain. That's why French aerospace company ThrustMe is pursuing a plan for better ion propulsion tech. They suggest using iodine instead of xenon....
(Excerpt) Read more at cnet.com ...
Extra speed is good.
What happens when they want to slow down?
Does it take the same amount of time and distance to reach orbital speed?
Slowing down - not quite as good.
The thrust is small. These are used after the satellite is in orbit, to maintain orbit and “attitude,” which is the direction they point.
IIRC, the atoms are ionized then accellerated through a magnetic field. Total mass of xenon on a satellite is maybe 50 - 150 pounds.
Slowing down, reversing, etc. is done by firing in the opposite direction.
Re: Slowing down, reversing, etc. is done by firing in the opposite direction.
I know.
My point - does it take 50% of the fuel and 50% of the travel time to slow down enough to go into orbit around something?
The ion drives are used for navigation, not for getting into orbit in the first place.
There is study into using ion propulsion for interplanetary and similar long distance. You are partly correct, the amount of energy used to accellerate is the same as the energy to decel (in open space), so if the mission used 50% to speed up, then 50% to slow down. Or 20-20, 31-31, or whatever "equal" amount.
Getting into orbit around an object is a little more complicated, but the "same amount" approximation is good enough.
Just to add my 2 cents.
There are 2 ways to measure a rocket’s effectiveness: thrust and specific impulse. The first is essentially the total power output, while the latter equates basically to fuel efficiency. You usually get one at the expense of the other. Ion thruster deliver good specific impulse, but low thrust.
For launch you need high thrust to combat earth’s gravity, so chemical rockets are still a must at this point. Once in orbit, however, specific impulse is more important because gravity is no longer slowing you down and robbing your fuel efficiency. Even if the engine thrust is tiny, none of it is wasted. It’s here that ion thrusters are most useful, because with high specific impulse you can get more total speed per pound of fuel.
There are still times when high thrust is needed, however. That is when engine burns at specific orbital nodes are required, such as orbital injections, if you want a close orbit of Mars instead of a fly by, for example.
That’s about the limit of my rocket sciencery.
Really? No one’s going to comment on the name of the company, “ThrustMe?” This thread had potential, but it was wasted on serious talk about the actual topic. /s
Currently, it takes a spacecraft about 6 months to travel from Earth to mars because the spacecraft is “coasting” much of that distance. Using even the very modest thrust provided by an ion drive to continue to accelerate could reduce that travel time from months to weeks.
https://www.bbc.com/news/science-environment-48912458
Good post and an interesting article. I am a bit concerned this was launched on a Chinese rocket.
Also, I do not want to put in a Google search for “ThrustMe.”
They just use the air brakes to slow down. Now we’ll just call them space brakes.
Space X STARLINK satellite internet service uses Krypton ion thrusters for station keeping and to deorbit the satellites
Krypton is rare, but not quite as Xenon
That’s why you turn over halfway there and slow down.
“We brake for nobody!”
Lots of interplanetary and perhaps interstellar stuff is going to get done using ion upper stages. Manley's a Demagogic Party fan, apparently, but ignore his snarks.
Next Week NASA plans to launch its Double Asteroid Redirect Test Mission on a Falcon 9 rocket out of Vandenberg Space Force Base. The DART mission is a technology demonstrator which will test the operation of various new technologies in spaceflight, and ultimately crash the spacecraft into a small asteroid to demonstrate the ability to change the orbit of an object using a kinetic impactor.NASA's DART Mission Will Move Mountains In Space | November 18, 2021 | Scott Manley
That’s what she said?
All I needed to know about engineering and science I got through Looney Tunes. Bugs Bunny, Elmer Fudd, Daffy, Sylvester, Marvin the Martian, Taz, Tweety, etc...
I’ve seen Bugs use air brakes to stop a plane from crashing.
In reading the article, when I came to “ThrustMe” I went back and checked whether this was a Babylon Bee caper. I guess it isn’t, but I’m still hesitant to believe any of it.
Xenon Thrusters = Joe & Hunter
Always comforting to know that someone is vigilant and on guard...😁
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