NIAC technologies of the future

August 10, 2011

I have listed in a previous some of the interesting projects funded by the NIAC in its phase-1 programme. I would like to detail some of these technologies and try to understand why they can be key elements in a revolution of the aerospace sector. In addition, I would like to put references on this topics as a ground for further analysis. In this review, I will be limited by the lack of accuracy of the different project’s titles; therefore, I will be forced to take some basic assumptions and any corrections of these assumptions will be welcome.  I will focus on this post mainly on propulsion:

Propulsion

One big unknown is the so-called “ambient plasma wave propulsion”, an original name proposed by J. Gilland from OAI. Looking at previous report (or even better, this one) from him, I think that this propulsion is based on the concept of helicon waves (but the title of the project is not precise enough to confirm it). The benefit of this method is to produce higher density plasmas than with the other types of plasma thrusters for a given level of power. This system can work as a rocket with the propellant on-board, or even clever, as an “air-breathing” engine using in-situ propellant, a kind of electrical ramjet. One advantage of this latter method is described in this document. One big pro is low altitude stationkeeping, using the ambient atmosphere as a propellant to make up the drag (I like the term  “thermosphere cruiser”). The same principle should be at stake in another NIAC project: “Atmospheric Breathing Electric Thruster for Planetary Exploration”.

Some more details can be found in this report: Propulsion Mechanism in a Helicon Plasma Thruster (N. Sinenian – MIT).

Concerning the project on Nuclear Propulsion through Direct Conversion of Fusion Energy, you will find a better description on Next Big Future and on the website of MSNW.  The principle is the creation of plasmoids, which are ring shaped plasmas with an internal reversed field (a bit like the Reversed Field Pinch used for fusion).

Aneutronic fusion propulsion belongs to the wide range of fusion concepts. Newspapers have recently focused on it because of the presentation of J. Chapman at the latest SOFE conference. The problem of “classical fusion” (for instance with tritium) is that a lot of energy is lost in fast 14MeV neutrons which are, in addition, dangerous for hardware and crew. Aneutronic reactions are less efficient but most of the energy produced can be harnessed. In the end, the energy budget could even present some gain.

Structures

There was a proposal called ‘Ultra-Light “Photonic Muscle” Space Structures’. But its author, Joe Ritter mentioned that the project was actually titled ‘Ultra-Lightweight Photonic Muscle Space Telescope’. This has to do with optics and not with structure. The idea is based on nanotechnology and the use of photoactive isomers which are layered in the primary mirror and actively controlled by lasers. Thus, the purpose is to replace the mechanical actuators of the active optics (like on the VLT) to get a more accurate control of the mirror surface. Please refer to his presentation for further details.

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Our satellite

August 10, 2011

I cannot resist to publish this picture of the moon featured on Universe Today.

The moon (Credits NASA)

 


NIAC Phase 1 selection

August 9, 2011

To celebrate its rebirth, NIAC, the NASA Institute for Advanced Concepts grant 100k$ to a list of selected projects. The principle of funding very preliminary ideas to assess their potential is very interesting.

I am trying out to get further details on each project to understand what they are all about. But I have already noticed some concepts which are of interest for me:

  • Enabling All-Access Mobility for Planetary Exploration Vehicles via Transformative Reconfiguration
  • The Potential for Ambient Plasma Wave Propulsion: I wonder whether it is something like this concept. Probably with a mix of this concept of helicon wave thruster.
  • Atmospheric Breathing Electric Thruster for Planetary Exploration
  • Entanglement-assisted Communication System for NASA’s Deep-Space Missions: Feasibility Test and Conceptual Design
  • SPS-ALPHA: The First Practical Solar Power Satellite via Arbitrarily Large PHased Array
  • High-temperature superconductors as electromagnetic deployment and support structures in spacecraft
  • Non-Radioisotope Power Systems For Sunless Solar System Exploration Missions
  • Ultra-Light “Photonic Muscle” Space Structures
  • Printable Spacecraft
  • In-Space Propulsion Engine Architecture based on Sublimation of Planetary Resources: from exploration robots to NEO mitigation
  • Metallic Hydrogen: A Game Changing Rocket Propellant
  • Nuclear Propulsion through Direct Conversion of Fusion Energy: the purpose here is to directly use the energy coming from the fusion reaction instead of converting it in electricity. That reduces the number of architectures but this choice is obvious in terms of mass budget.
  • Steering of Solar Sails Using Optical Lift Force
  • Aneutronic Fusion Spacecraft Architecture
  • Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study
  • Meeting the Grand Challenge of Protecting Astronaut’s Health: Electrostatic Active Space Radiation Shielding for Deep Space Missions
  • Radiation Protection and Architecture Utilizing High Temperature Superconducting Magnets
I have several comments on this list:
  • try to google these subjects: you will see that most of them are poorly document: it is a sign that they have received untill now little attention and deserve more funding to have a better idea of their potentials.
  • There are a lot of items which are oriented towards propulsion: this is indeed the major problem in advanced space engineering and it is acknowledge here.
  • There are also a good percentage of items dedicated to radiation shielding: NIAC shows clearly here that one main target is manned mission and even manned mission in deep space.
  • Curiously there is nothing on cooling systems: I however think there are a lot of things to do in this area; indeed no power system has a high efficiency; a large part of the power has to be evacuated from the spacecraft and passive thermal systems have a heavy mass cost. What about new solutions?
  • Solar Power Satellites are once again back on track! Without them an advanced program would probably not look like serious. I still wonder why they are listed: I think that there exist enough reports to explain the pros and cons and describe which key technologies are requires to enable their development. No further assessment is needed.
All in all, I am curious to see how this program will be managed and what the outputs will be. I just hope that the reports will not be thrown away once the conference in 2012 is done.

Efficient Mega-Engineering (part 2): birth of a project

August 8, 2011

A project can be seen as a compound of two ingredients: physics and engineering. It is a distinction that I dislike but which is all the same useful to understand how big project starts. In nuclear fusion, the physics tells which plasma configurations are the best to keep the particles confined and reach the ignition and engineering tells what kind of magnetic coils and of infrastructure is necessary to achieve this configuration. There is actually a balance to find between physics and engineering: the less  you understand the physics, the more you have to use heavy engineering to palliate this lack of knowledge.

Spheromak

We can take the example of toroidal magnetic confinement configurations for fusion research: one possible solution is the spheromak, where the plasma self-generates its own magnetic field, a kind of dynamo effect. It requires almost no external structure to keep confined; the problem is that it is in a permanent turbulent state which is hard to understand and to control; as a result, its confinement time is quite low (and the reduced amount of time and money accorded to this kind of projected prevented any significant progress on this type of facility). The solution chosen was to reduce the freedom of plasma by containing it inside a magnetic field. A lot of more engineering is involved and to limit its complexity, an axi-symmetric configuration was favoured; it was the birth of the tokamak. The problem is that this configuration is stable only if you induce a toroidal current inside the plasma, which has a deep impact on its physics (creation of instabilities). Therefore, another idea was to go a step further in engineering complexity with the stellarator and to give up the idea of axi-symmetry by twisting the magnetic field so that no more plasma current is necessary for the confinement. This short overview of the different types of fusion facilities show the difficulty to find the right balance between engineering and physics.

Tokamak

Aerospace is also a significant example: what prevents us from reaching Mars or even the other stars? The fact that it is impossible to find a balance between physics and engineering. Either you want to use a well-known physics based on chemical or electrical propulsion and, in this case, the cost of engineering necessary to solve the obvious shortcomings of these methods is too huge to be realistic. Or you want to use advanced physics (antimatter, warp drive or whatever exotic engines) and you areconfronted with the lack of knowledge.

Consequently, a project can start when the physics is sufficiently understood to be implemented in an engineering infrastructure with a limited level of complexity, i.e. which is tractable in terms of cost and of management (of interfaces).

Stellarator

Different scenarios can happen and trigger the start of a project: an unexpected discovery (for instance the H-mode confinement in tokamaks in 1982), the improvement of the technology (advances in superconductors), improvement of engineering tools (CAD, collaborative frameworks) and so on. In most cases, we have iterations over long times where both physics and engineering indicate the direction to follow in their respective fields of research.

One major difficulty in mega-projects is that the physics is multifaceted, involving many areas of interest with different conceptual tools; people in charge of preliminary designs need to have a large general culture both in physics and engineering and adequate tools to survey experiments and theoretical works with a possible impact on their projects.

The pre-design of a project is the first milestone in the connection of physics and engineering. We will see in a next post that it is the point where most of the difficulties met by a project in the later steps are rooted in.


Loneliness

August 7, 2011

Opportunity's shield on Mars - Credits JPL

I like this picture of Opportunity’s shield lost on the Martian desert. A nice piece of engineering, far, far away…


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