Carnival of Space week 61 is up at Mangsbatpage
This site contributed the article on hypersonic technology of the Blackswift and other hypersonic programs
Centauri Dreams look at the NanoSail-D: Solar Sail Deployment Plan
Colony worlds look at solar steam to power martian cities
21st century waves looks at 10 reasons why China is good for space
Check out the Carnival for a lot more.
Showing posts with label solar sail. Show all posts
Showing posts with label solar sail. Show all posts
July 02, 2008
Carnival of Space Week 61
April 28, 2008
Vasimr 200KW almost flight ready in 2008 and the solar electric sail like a Dandelion seed
I will look at two near term space systems the Vasimr and the solar electric sail. Both could provide a significant increase in the performance of various space missions. Both have their advantages and would be welcome improvements in the capabilities of space systems. Vasimr can go up to higher power levels that are limited by the Vasimr system and the power system. The Solar electric sail uses no propellant while the Vasimr is ten times or more efficient than current chemical systems. Both could be in space flight tests in the next year or three.
The 200 kilowatt VX200 Vasimr system is almost ready for flight tests and the type of missions impacts it would have are discussed. The solar electric sail system which I reviewed last week is discussed again. Comparison is made to dandelion seeds and how the multiple parachute configuration could be used to combine the propulsion of several solar electric sails to move larger objects.
The 200 kilowatt Vasimr plasma engine is expected to reach NASA's technology readiness level 6 in 2008 An initial test firing of the full engine
prototype has been postponed until the 2nd quarter of 2008 in order to give Scientific Magnetics of Culham, UK. the needed time to complete its certification of the superconducting subsystem.
A 12 MW Vasimr system could send a ship to Mars in less than 120 days one way. A 200 MW Vasimr could go to Mars in 39 days.
1-2MW Vasimr lunar cargo vehicle could transfer up to 39% of the mass from low earth orbit to the moon.
The 6 page study of a Vasimr powered lunar cargo vehicle. Five of the 200 kilowatt Vasimr engines could make up a 1 MW plasma powered vehicle.
March 17, Alliant Techsystems (NYSE: ATK) [$4.1 billion company] and the Ad Astra Rocket Company of Houston, Texas signed and executed a Technology
Development Alliance to explore future in-space propulsion systems for lunar and planetary missions.
VASIMR versus the Solar electric Sail
A VASIMR system can get up to 300 kilometers/second and faster while the solar electric sail goes 100 kilometers/second. Both systems could be improved beyond those performance levels. The variable specific impulse magnetoplasma rocket (VASIMR) uses radio waves and magnetic fields to accelerate a propellant. Current VASIMR designs should be capable of producing specific impulses ranging from 10,000-300,000 m/s (1,000-30,000 seconds) - the low end of this range is comparable to some ion thruster designs. 
I was noticing how much like a dandelion seed the solar electric sail system would be. The solar electric sail would be blown by the solar wind.
I also believe that the solar electric sail could have multiple sails attached to one vehicle like a multiple parachute system.
Technology Readiness levels [6-9]
6. System/subsystem model or prototype demonstration in a relevant environment: Representative model or prototype system, which is well beyond the breadboard tested for TRL 5, is tested in a relevant environment. Represents a major step up in a technology's demonstrated readiness. Examples include testing a prototype in a high fidelity laboratory environment or in simulated operational environment.
7. System prototype demonstration in an operational environment Prototype near or at planned operational system. Examples include testing the prototype in a test bed aircraft.
8. Actual system completed and 'flight qualified' through test and demonstration.
9. Actual system 'flight proven' through successful mission operations.
They are expecting to get to a flight test in 2010.
April 16, 2008
Solar Wind Electric Sail Propulsion planning test mission
A simplified picture of the electric sail. An actual system would have 50 to 100 or more 20 kilometer wires. 100 kg spaceships could be accelerated to final speeds of 40-100 km/second. The electric sail is an extremely promising new propulsion technique which is nearly ready to be tested. If electron heating turns out to be successful performance may be increased even more. Costs for solar system missions will go down and new capabilities and performance will be possible.
The electric solar wind sail developed at the Finnish Meteorological Institute two years ago has moved rapidly from invention towards implementation. The main parts of the device are long metallic tethers and a solar-powered electron gun which keeps the tethers positively charged. The solar wind exerts a small but continuous thrust on the tethers and the spacecraft.
"We haven't encountered major problems in any of the technical fields thus far. This has already enabled us to start planning the first test mission,” says Dr. Pekka Janhunen. An important subgoal was reached when the Electronics Research Laboratory of the University of Helsinki managed to develop a method for constructing a multiline micrometeoroid-resistant tether out of very thin metal wires using ultrasonic welding. The newly developed technique allows the bonding together of thin metal wires in any geometry; thus, the method might also have spinoff applications outside the electric sail.
The electric sail could enable faster and cheaper solar system exploration. It might also enable economic utilisation of asteroid resources for, e.g. producing rocket fuel in orbit.
Deploying the wiresAn ideal (i.e. fully reflecting) solar sail receives a radiation pressure force of 9μN/m2 at 1AU distance from the Sun. Let us calculate how thin a solar sail should be, to reach the same specific acceleration as an electric sail wire plus electron gun subsystems. Using an 82 km/s final speed, one obtains that the solar sail should have an areal density of 1.1 g/m**2, which translates to 200 nm thickness if the material is aluminium and 50% of the mass is assumed to go to support structures. This is 5–10 times thinner than present technology.
The electric sail resembles the solar sail in that it provides small but inexhaustible thrust which is directed outward from the Sun, with a modest control of the thrust direction allowed (probably by a few tens of degrees). Some possible missions:
1. Missions going outward in the solar system and aiming for >50 km/s final speed, such as missions going out of the heliosphere and fast and cheap flyby missions of any target in the outer solar system. 2-4 years to Pluto instead of 10 years with chemical rockets and gravity slingshots.
2. By inclining the sail to some angle it can also be used to spiral inward in the solar system to study e.g. Mercury and Sun. Also a nonzero inclination with respect to the ecliptic plane is possible to achieve which may be beneficial for observing the Sun. Also the return trip back to Earth from the inner solar system is possible, as is cruising back and forth in the inner solar system and visiting multiple targets such as asteroids.
3. the electric sail could be used to implement a solar wind monitoring spacecraft which is placed permanently between Earth and Sun at somewhere else than the Lagrange point, thus providing a space weather service with more than one hour of warning time. Propulsion and data taking phases probably must be interleaved because ion measurements are not possible when the platform is charged to high positive voltage, although the plasma density and dynamic pressure of the solar wind can probably be sensed by an electron detector and accelerometer even when the electric sail voltage is turned on.
4. Once accelerated to a high outward speed an electric sailing spacecraft cannot by itself stop to orbit a remote target because the radial component of the thrust is always positive. For stopping under those circumstances one has to use aerocapture or some other traditional technique. Although the electric sail does not provide a marked speed benefit for such missions, being propellantless it might still provide cost saving; this remains to be studied. In interstellar space the plasma flow is rather slow. Thus the electric sail cannot be used for acceleration, but it can instead be used for braking the spacecraft.
5. It might also provide cheap transportation of raw materials such as water mined from asteroids and used for in-situ fuel making at high Earth orbit.
April 19, 2007
Centauri Dreams expands upon my Space bubble article
Centauri Dreams discusses how applying Devon Crowe space bubble ideas with nanotechnology could fully enable the ideas of Robert Forward for interstellar solar sails.
The prior article about Devon Crowe's space bubble concepts.
Prior article on the state of solar sails
Prior article on putting the brakes on laser mirror solar sails
Article on laser mirror solar sails for going to Mars
Article on laser mirror solar sails and photonic propulsion
Another way to deploy quite large solar sails is with magnetic inflation but the bubble system seems able to go larger.
April 16, 2007
Possibly the last NIAC studies are being released
The most interesting study released from the March 2007 meeting is Devon Crowe of PSI corporation for making large space structures from bubbles that are made rigid using metals or UV curing 
A single bubble can be 1 meter in earth gravity, 100 kilometer in low earth orbit or 1000 kilometers in deep space. Foams made of many bubbles could be far larger in size.
NOTE: the size of a 1000 kilometer bubble is nearly the size of Charon, the moon of Pluto. Charon is 1200 kilometers in diameter. Saturn's moon Tethys is 1050-1080 kilometers in diameter Ceres the largest object in the asteroid belt is 970 kilometers in diameter. A single tesselation foam (like in the picture) of 1000 kilometer bubbles would be about the size of Earth's moon. A Penrose tesselation like the one in the picture of 1000 kilometer bubbles would be in between the size of Neptune or Saturn. A Tesselation foam of 100 kilometer bubbles in earth orbit could form an object the size our existing moon or larger.
Metal can be evaporated to coat the inside of the bubble for reflective sails and telescopes.
The bubble system for making structures is compatible with the hypertelescope, New Worlds Imager and Maxim x-ray telescope and solar sails.
Large structures can make telescopes that are millions of times more powerful than the Hubble Space telescope and solar sails that are light weight and fast.
Extreme Expeditionary Architecture: Lightweight Lunar RVs that can be connected into a larger mobile base camp. Let 8 move around many miles and explore a lot of the moon. the two RV's could be deployed in one launch payload.
Two mobile rovers with inflated sections and built with composites can be 40% lighter and provide mobile base camps on the moon.
Hopefully NASA's Innovative Partnership program can pick up where the Nasa Institute for Advanced Concepts left off and continue this kind of innovative work.
Further reading on space propulsion and colonization on advancednano:
The prior article about Devon Crowe's space bubble concepts.
Prior article on the state of solar sails
Prior article on putting the brakes on laser mirror solar sails
Article on laser mirror solar sails for going to Mars
Article on laser mirror solar sails and photonic propulsion
Another way to deploy quite large solar sails is with magnetic inflation but the bubble system seems able to go larger.
Colonizing space going slower and closer
Colonizing space going lighter
Building new worlds become the greatest generation
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