the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 25 Sep 2024
Steering RECoverable Autonomous Sonde (RECAS) for accessing and studying subglacial lakes
Abstract. The study of subglacial lakes requires clean access and sampling technologies. One of the most promising alternatives is the newly developed hot-point RECoverable Autonomous Sonde (RECAS), which allows downward and upward ice drilling and subglacial water sampling while the subglacial lake remains isolated from the surface. The original sonde descends downward under the force of gravity, and the borehole trajectory cannot be controlled. However, in certain cases, the sonde would preferably be able to drill at specific angles and directions, enabling it to follow a desired trajectory (e.g., maintaining verticality within the desired range) or bypass obstacles in the ice (e.g., stones and other inclusions). The general principle for the steering RECAS is to adjust the voltage for the electric thermal head heaters, which provides an opportunity to control the heat distribution on the drill head surface, thereby altering borehole trajectory during drilling. In this paper, the general principles of steering RECAS are described, and experimental results on deviational ice drilling with a controllable electric thermal head are discussed.
- Preprint
(1844 KB) - Metadata XML
-
Supplement
(1688 KB) - BibTeX
- EndNote
Status: open (until 15 Dec 2024)
-
RC1: 'Comment on gi-2024-7', Anonymous Referee #1, 02 Nov 2024
reply
Reviewed is a thorough technical description and evaluation of an autonomous steerable thermal drilling sonde for Antarctic applications. The document is well organized, with supportive illustrations and thoughtfully written text. A detailed description of the instrumentation is provided, as well as a sound testing procedure with results. Overall this is a very well written document that can be published as is.
Citation: https://doi.org/10.5194/gi-2024-7-RC1 -
AC1: 'Reply on RC1', Mikhail Sysoev, 20 Nov 2024
reply
We sincerely thank the referee for positive feedback and recommendation for publication. Your encouraging comments are greatly appreciated.
Citation: https://doi.org/10.5194/gi-2024-7-AC1
-
AC1: 'Reply on RC1', Mikhail Sysoev, 20 Nov 2024
reply
-
RC2: 'Comment on gi-2024-7', Anonymous Referee #2, 13 Nov 2024
reply
The manuscript presents the design and preliminary test results of a steerable system of RECAS for accessing and studying subglacial lakes. The designed sonde prototype can be used for directional ice drilling with a controllable electric thermal head, which is meaningful to enabling melt probe to follow a desired trajectory or bypass obstacles in the ice. Generally, the manuscript is well-written and can be published after minor revision.
- The manuscript mainly discussed a steerable system developed for RECAS, which is not a real steering recoverable autonomous sonde (RECAS), so the title is suggested to be changed. For example, “A steerable system of RECoverable Autonomous Sonde (RECAS) for accessing and studying subglacial lakes” or “A prototype of steering RECoverable Autonomous Sonde (RECAS) for accessing and studying subglacial lakes: Design and test”.
- Line 11 and Line 23: “Thermal sonde”, “hot-point” and “thermal drill” have similar meaning, please use the same name throughout the manuscript.
- Line 56, 57 and 58: The melt probe IceMole can also perform directional drilling in ice, can you provide more information about the IceMole’s design in thermal head and its drilling performance. (References: Curvilinear melting – A preliminary experimental and numerical study; IceMole: a maneuverable probe for clean in situ analysis and sampling of subsurface ice and subglacial aquatic ecosystems)
- In the manuscript, there are many names of the thermal head, such as “melting head”, “thermal head”, “drill head”, “melting tip”, “thermal drill head”, “thermal drill bit”, please use the same name throughout the manuscript.
- Line 171 and 175: Is there any reference for the formula 5 and 6? How do you get the formulas?
- Line 184: If the radii of curvature ensuring RECAS passibility is 300-600 m, is it means that the RECAS is very difficult to bypass obstacles in the ice unless the RECAS start to deviate before a long distance to the obstacles? If yes, please clarify.
- Figure 10: What is the function of the limiter?
- Figure 11: It would be better if the photo can show the full thermal head, such as pressure chamber, thermal sensor and power connector etc.
- Line 288: “Dual axis inclinometer” or “two-axis inclinometer”? Please use the same name.
- Line 311: Polar Research Center laboratory of Jilin University?
- Line 334: How much is the 50% power and how much power is increased?
- Figure 15: It is better to have depth data in the figure.
- Line 342-344: After the four heater pairs on the opposite side were switched on, the inclination angle decreased to nearly zero and then gradually increased in opposite direction? If so, please clarify.
- Line 364-373: The two paragraphs should be part of the section of 5.3, which shows how you perform the four experiments. In section 5.2, only the preliminary test procedure and test results should be included.
- Line 369: Please present more information about “automatic alignment mode”? How do you control the power? How the power changed?
- Line 434: What kind of RECAS parameters?
- Line 444: The steering capability of melt probe can be used to maintaining verticality within the desired range or bypass obstacles in the ice. However, according to the research, it looks that a long melt probe is difficult to bypass obstacles in the ice because of its large radii of curvature. In RECAS situation, do you have other methods to bypass obstacles in the ice except for hinged joints?
Technical issue:
In the manuscript, the word “deviational” was used to describe non-vertical ice drilling process. However, Zagorodnov use the word “directional”. Please check the exact expression of this term.
(Zagorodnov V S, Kelley J J, Koci B R. Directional drilling. Memoirs of National Institute of Polar Research, 1994, Special issue 49:165-171.)
-
AC2: 'Reply on RC2', Mikhail Sysoev, 20 Nov 2024
reply
We sincerely thank the referee for detailed review and valuable feedback.
1.) The manuscript mainly discussed a steerable system developed for RECAS, which is not a real steering recoverable autonomous sonde (RECAS), so the title is suggested to be changed. For example, “A steerable system of RECoverable Autonomous Sonde (RECAS) for accessing and studying subglacial lakes” or “A prototype of steering RECoverable Autonomous Sonde (RECAS) for accessing and studying subglacial lakes: Design and test”.
Thank you for the suggestion. We have decided to revise the article title to the first option you proposed.2.) Line 11 and Line 23: “Thermal sonde”, “hot-point” and “thermal drill” have similar meaning, please use the same name throughout the manuscript.
"Thermal sonde" and "thermal drill" represent distinct concepts with specific meanings. The term "hot-point" has been replaced to " thermal drill" for consistency. Additionally, the keyword "thermal drill" has been added to improve searchability and relevance.3.) Line 56, 57 and 58: The melt probe IceMole can also perform directional drilling in ice, can you provide more information about the IceMole’s design in thermal head and its drilling performance. (References: Curvilinear melting – A preliminary experimental and numerical study; IceMole: a maneuverable probe for clean in situ analysis and sampling of subsurface ice and subglacial aquatic ecosystems)
The design and operational principles of the IceMole probe, including the directional drilling approach, differ significantly from those of the RECAS (shorter length of 2 m and less, square cross-section, combined thermomechanical drill head, maximum drilling depth ~25 m, and it can only operate in dry boreholes). Additionally, the mathematical model used for IceMole cannot be directly applied to our thermal drill head design, not only because of completely different geometrical parameters but also because it requires a specific approach to solving the equations by enumerating the parameters. This will require large computing power, which in our case has to be placed inside the sonde, which will reduce its reliability in the long term. To expand the background, we have included a reference to the IceMole project in our article for completeness.4.) In the manuscript, there are many names of the thermal head, such as “melting head”, “thermal head”, “drill head”, “melting tip”, “thermal drill head”, “thermal drill bit”, please use the same name throughout the manuscript.
All terms have been replaced with "thermal head" for text consistency.5.) Line 171 and 175: Is there any reference for the formula 5 and 6? How do you get the formulas?
Formula 5 is sourced from Zvarygin (2010). Formula 6 was derived following the methodology outlined in Shamshev et al. (1983) and has been presented in this manuscript in full (not simplified) form. In Shamshev et al. (1983), only the simplified form of the Formula 6 (Formula 7) is presented directly.6.) Line 184: If the radii of curvature ensuring RECAS passibility is 300-600 m, is it means that the RECAS is very difficult to bypass obstacles in the ice unless the RECAS start to deviate before a long distance to the obstacles? If yes, please clarify.
In general, yes. If an obstacle is encountered, bypassing it by deviating the borehole will require drilling upward for the necessary distance and then manually adjusting the borehole trajectory. Despite the relatively large radius of curvature required, we believe that this approach is feasible for bypassing small obstacles. (At depths of several kilometers in ice, it is unlikely we would need to bypass an obstacle like the size of a 2-3-m diameter stone.)7.) Figure 10: What is the function of the limiter?
The limiter is designed to restrict the position of the pressure chamber during installation within the housing.8.) Figure 11: It would be better if the photo can show the full thermal head, such as pressure chamber, thermal sensor and power connector etc.
The pressure chamber is shown separately in Figure 13. We agree that a photo of the assembled thermal drill head showing the thermal sensor and power connector could be helpful. However, we decided that the specific appearance of the standard factory thermal sensor and power connector look less important for understanding the structure of the thermal drill head, then photo of internal modified parts.9.) Line 288: “Dual axis inclinometer” or “two-axis inclinometer”? Please use the same name.
To avoid repetition and improve readability, the text has been adjusted to "inclinometer with two axes" instead of "two-axis inclinometer."10.) Line 311: Polar Research Center laboratory of Jilin University?
yes.11.) Line 334: How much is the 50% power and how much power is increased?
(Line 269) The total power is approximately 7.6 kW, so 50% corresponds to half of this amount. Specifying the exact value in kilowatts is unnecessary here, as total power may vary.
Regarding "how much power is increased" – thank you for identifying this inconsistency. The power was increased to 100%. The latter part of this sentence and the following sentence have been reordered, to improve understanding and readability. The corrected version of the text now reads:“Subsequently, the power was increased to the maximum, and half of the heaters on one side of the thermal head were switched off. Then, the ROP was increased to 1 m/h.”
12.) Figure 15: It is better to have depth data in the figure.
We opted to add the second X-axis with depth data.13.) Line 342-344: After the four heater pairs on the opposite side were switched on, the inclination angle decreased to nearly zero and then gradually increased in opposite direction? If so, please clarify.
No, after the four heater pairs on the opposite side were switched on, the four previously powered heater pairs were switched off. (line 344) You understood the essence correctly. To further clarify this, a corresponding comment has been added to the description of the section of Fig. 15.14.) Line 364-373: The two paragraphs should be part of the section of 5.3, which shows how you perform the four experiments. In section 5.2, only the preliminary test procedure and test results should be included.
We’d like to keep these paragraphs in section 5.2 because these are resulting conclusions of preliminary experiment.15.) Line 369: Please present more information about “automatic alignment mode”? How do you control the power?
To clarify the concept of “automatic alignment mode,” Section 2.1 has been expanded with additional details. The other procedures were explained in Sections 2.1 and 2.2.16.) Line 434: What kind of RECAS parameters?
The RECAS parameters include overall dimensions (length, diameter), weight, configuration of the thermal drill bit, number of heaters, diameter, and power consumption.
The parameters for the RECAS-200 and RECAS-500 are described in Table 1, line 81.
The parameters for the testing sonde prototype are provided in lines 261 and 268.17.) Line 444: The steering capability of melt probe can be used to maintaining verticality within the desired range or bypass obstacles in the ice. However, according to the research, it looks that a long melt probe is difficult to bypass obstacles in the ice because of its large radii of curvature. In RECAS situation, do you have other methods to bypass obstacles in the ice except for hinged joints?
Hinged joints will not directly assist in bypassing obstacles. Other methods for obstacle bypassing, aside from those described in response to point 6, are not currently being developed in this project.Citation: https://doi.org/10.5194/gi-2024-7-AC2
-
RC3: 'Comment on gi-2024-7', Anonymous Referee #3, 14 Nov 2024
reply
General comments
The MS dealt with difficulties presenting results and needs to be significantly revised. Several variables (PWM coefficients and a few others) must be defined and shown in modified figures (Figures 2 and 18). It will be easy for reviewers to understand the math if Figure 2 is in 3D format and all math symbols used in the following equations are shown there.
The description of the experiments does not include data on the power cable feeding rate and corrections for cable and sonde prototype angular changes.
I recommend excluding section 4.1.1. and fitting/fusing (?) experimental results to the RECAS concept. Authors optimistically demonstrate that the RECAS steering to bypass an obstacle is impractical. However, the MS experimental materials demonstrate the possibility of thermal electric probes steering to keep a straight vertical borehole trajectory. On the other hand, that task can be achieved by two methods of pendulum steering: bt cable feeding speed control and top "parachute" heater. These two could be a more straightforward solution. It could be helpful to compare the realization of these three methods of vertical stabilization of thermal-electric probes.
Based on the reviewer's comments, I hope the authors conduct more experiments and clarify a few hot-point probe steering control concepts. Below is the author's plan for future experiments that may allow a better presentation of the steering concept.
447 In future work, we plan to conduct experiments on a larger scale (e.g., with a borehole depth
448 of approximately 10 m) to refine the results in a deviation intensity range closer to that obtained
449 with a real RECAS.
Please consider submitting a new version of MS after the experiments in the cold well in a borehole at the entire length of the probe model positioned in the borehole.
The MS version may be titled "A new technique for thermal ice penetrating probes steering."
Significant comments and recommendations.
- At a 4-degree angle, the experiment requires deflection of the top of the sonde prototype for about 80 mm. It can be achieved in a borehole of about 300 mm in diameter(80+80+~140; 140 estimated housing OD). The authors did not specify the borehole diameter. In Fig 14, one can see that the experiment(s) was/were conducted with a partially hung top of the sonde prototype. The feeding rate of the cable is not presented, but data Figs 14-17 depends on it. Moreover, the demonstrated deflection angle correction can only be achieved with a low cable feeding rate. The presented data must be corrected for cable feeding speed and include angular changes of cable and the probe itself.
- The most confusing term used throughout the MS text is PWM coefficients. Example at line 371.
Several other undefined parameters are used in the MS, and they must be defined.
3) Conversion of Fig 2 to 3d format may allow a better understanding of the theory (more below).
4) Rewrite sections 2.2 and 2.3 based on Fig 2 in 3d format.
5) 2.3. RECAS positioning calculation example – Possibly, authors mean instant inclinometer reading – not an absolute RECAS position. ??? Please clarify. I believe the new Fig 2 in 3d format will help for a clear understanding of the math and meaning of unique terms.
6) 4.1.1. General testing stand design.
- a) I believe these materials have been published by authors before.
- b) In any case, I'm not sure if it deserves to be published. It is a trivia technique commonly used in lab and field applications in the last few decades of the previous century.
Specific comments.
14 "… the borehole trajectory cannot be controlled." The onboard tilt sensor allows control of the winch feeding rate, making pendulum steering possible. The same can be achieved with the "parachute" heater at the top of a probe. The question is, what option will be more reliable and power efficient?
- … to control the directional heat distribution on the drill head surface…
- Consider replacing drawbacks with limitations.
- Consider replacing possibilities with capabilities.
- Consider replacing parameter detection with a monitoring system
- Consider removing - similar to how a spider climbs on its silk line.
79-80. Confusing sentence. Are all heaters powered and not controlled? Consider removing - all heaters.
90-98. A bit confusing sentence due to excessive details. Maybe like that?
The sonde is steered using data from an inclinometer installed in the testing probe. The data from the inclinometer are transmitted to a personal onboard computer (PC), processed, and converted into pulse width modulation (PWM) coefficients, which determine the PWM duty cycle for a specified corresponding number of channels heater. In the subsequent tests using the RECAS-200 prototype, the PC will be replaced with a microcontroller mounted inside the sonde. The PMW coefficients are transmitted from the computer to a PWM generator (Sup. 2) inside the sonde prototype, where an individual PWM signal is generated for each channel. Each PWM signal is amplified using a power module (Sup. 3) and supplied to the corresponding heater inside the drill head. The PWM signal duty cycle limits the heater power.
Another option is to add a block diagram of signals passing through.
- Fig. 1. General schematic of the RECAS-500 with a 500-m-long cable inside (all dimensions are in mm)
Q – show inclinometer position. If the RICAS stem is flexible, then multiple inclinometers could be shown.
- Rotating collector. Likely, it is a slip ring.
- Fig 2. Please show all parameters used in eq.2 in this figure. Convert Fig 2 in 3d format.
- For the calculation example, random inclinometer values are taken as: X = 4.5; Y = −3.
134, 136, Please define and show in Fig 2 - the projection length of a heater.
164, 165, 169, ….the deviation intensity – ??? Time or space derivative of R, or angle ??
- zenith deviation intensity – what is it? Define the zenith deviation intensity.
189-256. I would remove this section. 1) you published it before; 2) These are well-developed devices. In use for many decades. What for to publish Sup 1…5? All materials are either well-known or commercially available. For instance, for DC-DC converters, see Vicor products.
308 Consider the following change. 5. Laboratory testing of self-steering sonde prototype
- Confusing statement. "ROP, which was controlled by the winch …" Then, the winch feeding rate (FR) will interfere with the heater stirring (HS). Please explain – is it gravity-driven penetration and HS, or is it a combination of HS and PS? More above in Significant comments and recommendations.
- 4. WOB, which changed with the ROP and was limited by the sonde prototype weight".
1) Statement in conflict with Fig 15 data.
- It can be so if the winch FR does not follow the sonde prototype ROP (corrected for changing the cable and the sonde itself angle).
Also, see below345-349.
MS does not present the "purl" steering with heaters. It is FR+HS steering. Please clarify.
- … affected by the controlled heat power INCERT azimuthal distribution on the drill head surface, which was controlled by limiting the heater power.
- limiting the heater power. > controlling
332 - Fig. 15. Recording of the preliminary experiment. Maybe – Parameters/data of the preliminary experiment.
345-349. It stated that the probe prototype (PP) was partly hanged, so the winch feeding rate affects the ROP. ???
Below Fig 15, I would add applied power and cable feeding rate (not linear, somewhat variable) graphs.
- Explain what are "the transients"?
356-357 up to 373. Hopefully, the revision of the MS section 2.2. and 2.3. allowed me to understand the meaning of this statement.
Consider replacing the "power consumption" with applied power.
- "alignment mode" - explain the term.
- … correction coefficient T … . T – is correction coefficient? How does it relate to PWM parameters?
- The ROP was kept constant at 1.5 m/h. How?
The WOB stabilised between 22 and 28 daN. How? Winch feeding rate? Then the sonde weight is partially hanged.
The applied power consumption was limited to 50% by setting yoff = 0.5.
Is the yoff the power coefficient? Then yoff is proportional or equal to the duty cycle. (?)
Why not call it the duty cycle?
Then what is T concerning the PWM?
The most confusing terms used throughout the MS text are PWM coefficients: T and yoff.
- It is worth noting that decreasing the PWM coefficient recalculation frequency…
Then, T is the PWM frequency. (?)
Do you control the duty cycle and frequency? The higher the frequency, the more sensitive the control is. Then, set the high PWM frequency why it has to be controlled. The big mass of a heater does not require high-frequency control.
"It is worth noting that decreasing the PWM coefficient recalculation frequency (i.e., slowing the response to inclination angle changes) can influence the borehole deviation intensity."
Please explain why PWM frequency needs to be controlled.
Instead of determining the optimum frequency for the specific device?
374-424. 5.3. Experimental results and analysis… Discussion of ….?
Possibly, the extended version of Figure 18 with R=infinity (strate borehole) and sections 1.0°-1.5° and 2.5°-4.0° allow for easy comprehension of the idea.
- How does the time scale in Fig 16 correspond to the time scale in Fig 15?
- .. "demonstrates that correction coefficient T …" Is it the same T as before or another one?
- Please define - the automatic alignment length.
431-432. The borehole deviation intensity during drilling can be corrected by controlling the correction coefficient T.
Is it the same T as above?
- … experimental drilling parameters, the borehole deviation radius intensity must be reduced.
437-442. Sequencing of RICAS could be a dangerous strategy for an expensive field program.
443 … Sonde passability at large borehole deviation intensity values can …
Citation: https://doi.org/10.5194/gi-2024-7-RC3
Supplement
Viewed
| HTML | XML | Total | Supplement | BibTeX | EndNote | |
|---|---|---|---|---|---|---|
| 161 | 24 | 71 | 256 | 10 | 2 | 3 |
- HTML: 161
- PDF: 24
- XML: 71
- Total: 256
- Supplement: 10
- BibTeX: 2
- EndNote: 3
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1