The new forums will be named Coin Return (based on the most recent vote)! You can check on the status and timeline of the transition to the new forums here.
The Guiding Principles and New Rules document is now in effect.
1 Week to Mars.
DruG
__BANNED USERS regular
__BANNED USERS regular
I found this today and thought I'd share:
Photonic thruster pulses into existence
I see this being adopted bloody fast, as the savings on satellites alone could be astronomical.
As a side note, there was another new development in laser technology last week that might also apply to mankind speeding its way to Mars.
Matter-antimatter molecules of positronium observed in the lab for the first time
So... who's up for a vacation on Mars?
Photonic thruster pulses into existence
PORTLAND, Ore. — Photonic thrusters have been imagined by engineers for about 35 years, but an experimental spacecraft propulsion system using a laser-based thruster will be described at the American Institute of Aeronautics and Astronautics's annual Space 2007 Conference (Sept. 18, Long Beach, Calif.). NASA funded the successful testing of the photonic laser propulsion (PLP) system earlier this year. This demonstration will be conducted by the Bae Institute (Tustin, Calif.) and its founder, Young Bae, a former SRI International, Brookhaven National Lab, and the Air Force Research Lab scientist.
Bae claims to have removed the last stumbling block to using photonic thrusters for spacecraft propulsion. The problem with other designs has been the minuscule thrust and difficulty in staying on target with the lasers. Bae claims to have solved these problems by integrating an optical cavity into a laser that traps the beamed photons, thereby amplifying their light pressure by 3000-times, while easing targeting with a centrally located laser in space.
Laser light emerges from both top and bottom of the photonic thruster, keeping it stationary as it pushes outward against spacecraft.
"Our approach to photonic laser propulsion is based on forming an active resonant optical cavity between two high-reflectance mirrors located separately in two space platforms," said Bae. "The breakthrough is in the fact that the laser gain medium in PLP is located within the optical cavity, in contrast to the previous failed attempts at passive resonant cavities, in which the laser gain medium was located outside the optical cavity."
Originally, PLP designers imagined using large ground-based lasers to generate enough intensity and to provide a backstop for pushing against, later moving to passive optical cavities located in space. Unfortunately, none of these designs was able to demonstrate enough thrust. In contrast, Bae's active optical cavity was demonstrated to supply milliNewtons (mN) of power using small, cheap lasers that can be operated from space so they don't have to suffer the distortion of cutting through the Earth's atmosphere. Rather than using the Earth as a backstop, the space-based laser platforms would send beams to push against spacecraft while keeping the central laser stationary with a balancing beam in the opposite direction, or with a conventional thruster attached to the laser platform.
For earth orbit use, Bae claims that satellites in space would no longer need a power supply for their own retro-rockets, but could use a centrally located laser platform to supply occational sychronized nudges from its laser beams to keep them in position. For deep-space missions, the feeble thrust from the pressure of light could build up over time. Since there is no fuel to run out when using photonic power--the spacecraft only requires mirrors to bounce the lasers off--once the laser is turned on, it can stay on for as long as necessary to continually accelerate spacecraft toward the theoretical limit of the speed of light.
Bae claims that the technique could be scaled up to accelerate a spacecraft to Mars in a week compared with the six months necessary using conventional rockets.
I see this being adopted bloody fast, as the savings on satellites alone could be astronomical.
Pun intended.
As a side note, there was another new development in laser technology last week that might also apply to mankind speeding its way to Mars.
Matter-antimatter molecules of positronium observed in the lab for the first time
The research paves the way for studying multi-positronium interactions – useful for generating coherent gamma radiation – and could one day help develop fusion power generation as well as directed energy weapons such as gamma-ray lasers.
So... who's up for a vacation on Mars?
DruG on
0
Posts
um
If we could get to Mars in a week though, that would be amazing. Science be damned.
More like, a new technology NASA will never have the funding to implement and utilize.
I don't think it means power. Newton is a measure of thrust.
So this is basically beamed laser propulsion but using a laser that's in space instead of on the ground. It took me reading at least twice to get it.
A week to Mars sounds cool but how do you brake when you get there? This would be good for an extrasolar probe or a flyby of Proxima Centauri or something.
Also, Photonic Thrusters go
Unless someone starts a rumor about an iranian mission to mars...
Mars closest approach is ~36,000,000 miles. That distance in a week is 214,285.7 mph. It would still take over 13,000 years to get to the nearest star. Damn it...forget my last post then. To the Jupiter system, its about 70 days.
Have to start somewhere.
corrrrect
The "one week" period is found by assuming that you accelerate at 1G for half the distance between Earth and Mars at its absolute minimum (which happens about every fifteen years) then decelerate at 1G for the other half.
How do you decelerate though? A laser in orbit around Mars? Or am I not understanding this concept...
The article's a pretty poor summary of the concept. They "Bae Institute" isn't seriously developing a there-and-back-again Mars craft, they're working on a single, very specialized type of component that could conceivably be put to use on such a thing. The rest, I think, is sensationalism leaking into scientific reporting - and bad scientific reporting, at that.
a laser pointing in the opposite direction (front) of the ship, I'd imagine
The same way they decelerate now?
Turn around and point the thrust the other way?
I mean I could be wrong but that seems like the simple way.
It's not a rocket.
From my understanding, the drive uses a system of mirrors to redirect the laser beam back and forth between the space-based launching platform and the spacecraft. Because the beam is coherent, it doesn't disperse and continues to push against the craft as it bounces back and forth between the mirrors. As a result, you'd have to put a rocket on Earth's space platform to stablize it against the momentum it's imparting and recieving. You'd also have to make it pretty massive, as it would have to house a nuclear power station just to be able to supply the necessary energy. Or you could just put it on the Moon, so as to avoid the atmosphere and mass issue altogether, while providing a more stable base for the power station and laser assembly.
So to decelerate at Mars, you'd have to be able to turn your ship around and start recieving momentum from another launch platform to provide the negative acceleration required to slow you down. While a first stage launcher could probably be put into Martian orbit with enough fuel and power to provide the negative acceleration for the first manned craft, you'd probably want to put it permanently on Phobos or Deimos for the return trip to create a proper transit system.
edit: or am I absolutely clueless?
I'm not sure, really.
It depends on how fast you're trying to get there. If you want to get there in a week, you need to be able to do some major slowing down.
That's not how space works.
Or more like NASA has this problem with using things that they didn't develop themselves. Or using things that they have developed themselves. They like to start projects, ignore all relevent existing material concerning said project, and then cancel the project after a few months because they've run out of funding.
You have been doing that a lot!
My husband works at JSC.
Excuse me. My husband and the people that I spend all of my time with actively work on and design existing and future programs at Johnson Space Center. I took my comments directly from the venting of my friends while we eat Chinese food on Friday night. While my husband maintains the solar panels on the International Space Station, my friend is in one of the many dozens of groups working on the design of new spacecraft and programs. I tend to believe what they say about the space program and what's happening over what the press releases.
When I talk about ignoring relevent material, I have been told about how the groups who are currently researching the CEV, which will be replacing the shuttle, have paid little or no attention to pre-existing programs such as Apollo and start from scratch. Also, I have been told tales of programs which have spent a great deal of time and money researching materials and ideas, and when another center picks up that program, they start all over again without looking at all of the previous research.
We're interested in examples backed up by hard facts.
Build a big laser on the Moon.
I'd say NASA's research into SCRAM jet engines hold hope as a way to achieve this, as they can achieve orbit velocities within atmosphere. Throw in a hybrid rocket engine for the final altitude burn so Earth's atmosphere isn't slowing you down and that should get you into a stable orbit without having to carry liquid oxygen and tanks. This would make it insanely cheap compared to the 10-story building they're launching into space now.
To achieve orbital velocity within atmosphere, you'd need to be moving over 3 times as fast as this was going when it melted, which means more advanced materials and cooling techniques need to be deployed. As the larger vessel would have an increased surface area to dissipate the heat, this should be possible to implement where it wasn't with the test engine. I've also heard of interesting work being done using microwaves to superheat the air infront of the ascending craft into a plasma, thereby reducing the friction-induced heat over the surface of the craft.
So yes... unless the right projects recieve the proper funding, I doubt this will ever happen. But since Google is offering $30,000,000 to the first company to land a private craft on the Moon, I'd say it's getting much closer to reality.
And just in case you didn't notice, for the final stage you'd be burning rubber and laughing gas all the way to space.