Sunday, 8 December 2013

MAPSEC - a roadmap



In my July post 'Masers on Ice' I outlined a proposal to use overlapping maser beams to create a zone of melted ice into which a capsule could descend towards a subglacial lake and then return to the surface of the ice field via a similarly melted zone at the top of the device. As the zone of overlapping maser beams moved through the ice the melt-water would re-freeze, negating any problems caused by the pressurisation of lake-water due to the overburden of ice as well as eliminating contamination such as that caused by a drill hole. In this blog post I will outline a ‘road map’ to the realised project, although I promise not to use the phrase “going forward”.



1) The very first stage of the project would be for a laboratory to undertake an experiment in which masers operating on different frequencies projected beams into a block of ice, and where they overlapped, use constructive interference to generate the 2.45 GHz frequency commonly used by microwave ovens. An object placed on the surface of the block of ice could be made to descend into the ice and be navigated along a selected path. Theory about and observations of melting ice in microwave ovens predict that the process should be very slow because:

a)     The hydrogen bonds of ice are stronger than those of water and need more energy to heat up.

b)     Ice is less efficient at absorbing microwave energy.

c)     Only some of the harmonic waves produced by mixing beams of different wavelengths would be the water-heating 2.45 GHz frequency.

2) These manifestations of heating by radio frequency constructive interference in ice would not necessarily be a problem for this project if the otherwise wasted harmonic frequencies could be harvested and turned into heat or mechanical motion. Ideally this would be some form of coating on the outside of the capsule that heated in response to the non 2.45 GHz harmonic frequencies. Another approach could be to convert this radio energy into electrical current subsequently used to power conventional ohmic heaters on the skin of the capsule. This harvesting/heating process could create a layer of water between the skin of the capsule and the surrounding ice which would then interact with the 2.45 GHz frequency so as to produce further melting of adjacent ice. This region of water, although absorbing the 2.45 GHz energy, should remain transparent to the other harmonic frequencies harvested for power. The lattice of radio dipoles on the skin of the vehicle would be needed anyway to protect internal electronics from damage and radio frequency interference from the maser beams illuminating the skin of the capsule.

3. After experimenting with passive objects sinking into the ice, the above mentioned system of harvesting the harmonic frequencies would need to be evaluated.

a) At first the process of exploiting the electrical energy made available from the non 2.45 GHz frequencies would be used for heating the skin of the capsule. Later versions of the capsule could be constructed with contra-rotating upper and lower halves, powered by internal batteries or electrical current derived from the harvesting of radio energy. If the skin of the capsule were to be furnished with spiral ridges, with left and right handed threads on upper and lower halves, the contra rotating sections could propel the capsule through the ice. The upper and lower sections would need to be contra-rotating so as to work against each others torque. Reversing the direction of rotation would propel the capsule upwards.

b) Perhaps frictional heating caused by the kinetic energy of the rotating capsule could produce more melting than electrical heating? Rather than building bespoke swivelling robotic mounts to rotate and tilt the masers it might be possible to use modified mounts from the MAC 500 swiveling light, known for blurring the distinction between theatre lighting and disco lighting. Alternatively commercially available ‘go to’ telescopes currently marketed to amateur astronomers could be used. The controlling software would need to be replaced by a programme that enabled the masers to overlap their beams, although the MAC 500s can already do this. At a later stage controlling signals might be piggy-backed onto the maser beams to control movable steering fins on the non-rotating sections. The effects of creating the 2.45 GHz frequency from constructive interference from masers of different frequencies could be compared with the effects of creating the 2.45 GHz frequency from interference fringes in overlapping plane waves in beams of the same frequency. Tunable masers would be useful for this research.

4) At this stage it would become necessary to move out of the laboratory and start experimenting on glaciers or other areas of permanent ice. The transparency of ice to the selected maser frequencies would be of interest. Impurities in the ice could affect its transparency to maser beams. With the re-invention of masers by the National Physical Laboratory in 2012 the increased portability of the devices now means that it will be possible for scaled up versions to be transported to glaciers and ice-fields. Universities or research instructions within easy reach of such areas would be at an advantage. Ideally it would be possible to select a glacier close to a road. 

The personnel involved at this stage would be scientists interested in exploring glaciers and subglacial lakes, working in collaboration with electrical and mechanical engineers specialising in microwave masers, microwave radio conversion to power, remote device control, telemetry and pressure resistant submersible remotely operated vehicles. As the capsule was scaled up to become a relatively large device operating at some distance from the surface, the pointing accuracy of the maser beams would become more important. The expertise of engineers who build and operate radio telescopes might be needed. Initially, glaciologists might be content to deliver small probes on a one way journey to fluvial channels under the glacier.

5) If it proved possible to power and control a capsule within a glacier as well as melting areas of ice adjacent to it, some move towards using this technique to reach subglacial lakes would take place. Before committing to the construction of a by now technologically advanced and expensive device the final experimental step could be to combine a microwave beam fed into a metal drill string, in ice, with another beam directed from some distance away by a maser mounted on a tilting mechanism able to direct the beam to the drill tip. An estimation of the amount of ice melting could be made by measuring the resistance to downward pressure from the drill string or pumped fluids. This would also be an opportunity to experiment with fitting an outer sleeve to the drill tip to test different compounds designed to heat up in response to the various harmonic frequencies produced by constructive interference. Even after laboratory tests it would be time to test what actually occurred beneath hundreds of meters of ice.

6) The final all-up test of the system would take place above a subglacial lake. Perhaps the recently discovered lakes in Greenland would be the initial target, but the lakes in Antarctica would be the eventual goal. If these lakes have remained isolated from the outside environments for thousands of years they could be the closest thing in biology to exploring another planet. It is unlikely that the power requirements of such an exploration can be reliably calculated at present. However it can be expected that large amounts of electrical power would be needed for the scaled-up masers delivered to the Antarctic exploration mission. The 24 hours of daylight available in the Antarctic summer suggest that photo voltaic panels might be useful, especially if they formed the walls of buildings. As the Antarctic is a notoriously windy continent wind powered generators might be used. Delivering this equipment to an Antarctic site would be a challenge.

7) The long term exploration of Antarctica would generally benefit from the development of a long distance vertical and take of and landing (VTOL) aircraft. No military power has ever found the need to combine long range with VTOL capability. It would need the combined resources of an international consortium of scientific Antarctic exploring institutions to fund, design and build such a craft. The ability to fly directly from South America, Africa, Australia or New Zealand and land vertically at any site in Antarctica would benefit many projects. Perhaps it could take the form of a hot-air airship powered by turbines with their exhaust venting into an envelope. It would be capable of going forward with some speed as well as landing and taking off vertically. But that would be another project.

Did I say “going forward”?

Microwave Assisted Polar Subglacial Exploration Capsule.


MAPSEC returning.
 



















Original Post


Constructive interference Wikipedia






Ice in microwave ovens - the naked scientist