All posts by Duncan

MH370

Optimal Gliding Descent Scenarios for MH370

Optimal Gliding Descent Scenarios for MH370

Geoff Hyman, Barry Martin and Sid Bennett
14 July 2015
(Updated 15 July 2015)

 

Introduction

In this note we focus on the final descent of the flight of MH370 and explore the implications of an assumption that the last stage thereof was executed in the form of a glide rather than a spiral descent.

Glide scenarios are of interest because they may assist in the identification of an outer boundary of the search area. Whether MH370 descended in the proposed manner is not resolved here. On the other hand, lack of success in terms of finding the aircraft within the current priority area further raises the interest in plausible alternatives.

On best-available interpretations of the available satellite and flight simulator evidence, optimal glide scenarios represent extreme cases and would not be considered to be the most likely ones to have actually occurred. However, as long as glide scenarios, in some form, are a reasonable possibility, the implications for the search area merit further consideration.

This study was motivated by a proposal that, if under (human) pilot control, MH370 could have continued on an efficient gliding path after passing the 7th arc (00:19:29 UTC; all times herein are UTC). Previously [1] we explored an apparent anomaly in the BTO/BFO observations associated with the re-log-on event at 18:25 and SATCOM handshake transmissions shortly afterwards, concluding that an offset track might have been the cause. Such scenarios would have required human input after the time of final primary radar contact. Combining such considerations with the analysis reported in [2] provides a motivation for the scenarios examined here.

The present study considers a scenario involving events subsequent to 00:11, but there are only two satellite observation pairs available: at 00:11 and at 00:19:29. Inmarsat engineers [3] are confident that the corrected 00:19:29 BTO is usable. The assessment of alternative flight paths after 00:19:36 is problematic because no further BFO or BTO values were recorded. The current simulations are computed in 15 second time increments and are divided into two parts: the first is for the period with satellite observations, from shortly before 00:11 until 00:19:30; and, the second is an extrapolation of the position at 00:19:30 to the end of the flight.

The likelihood of MH370 having executed a simple glide descent, resulting in the aeroplane being ditched at considerable distance from the 7th arc,  is conditional upon rejecting the validity of the BFO at 00:19:29 as it is presently understood [3].  The BFO measurement is a part of the handshake during a re-log-on event with the Inmarsat ground station at Perth and we do not have sufficient comparative data to determine whether the BFO anomaly referred to by Inmarsat for the log-on sequence at 18:25 should be considered in this circumstance as well.  Further data from the ATSB relating to the log-on events would be welcome, including comparable data from similar flights. If the BFO measurement during the re-log-on (at 00:19:29 ) were to be determined to be valid, then the descent scenarios could be complex, and less efficient, with shorter ranges and/or reduced times aloft.

One consideration was the conflicting initial assessment of the location of the intersection of the flight path with the 7th arc. Subsequently, our group has reported a number of studies that strongly suggest that the location of that intersection is quite well established. This intersection may be some appreciable distance from the final location. However, with due recognition of the uncertainty of the descent trajectory, this still facilitates a more focused review of the future search area.

The current report also incorporates improvements to wind modelling, informed by [4]. It also includes refinements to deal with the brief period for which only one engine was operating.

 

Optimal Glide Scenarios

We consider two possible types of optimal glide scenario: maximum range and maximum endurance. The associated altitude profiles for speed and descent speeds are based in the relationships given in annex A below. These profiles are based on a drag model for the airframe alone which does not account for drag contributed by windmilling powerplants.

For the one engine inoperative (OEI) case the single engine thrust also needs to be incorporated. However this only applies to a brief period of the descent and is not reported here.

In Figure 1 we show a distribution of likely flight directions at the commencement of the glide stage. For the maximum range scenarios there are two modes (or peaks), while maximum endurance scenarios show a single peak.

Our previous studies indicated that the most likely flight azimuth, prior to the 6th arc, was 186 degrees True (i.e. six degrees to the west of due south). It appears that, after the second engine flame out, the aeroplane probably made a turn to the left through an angle of at least 20 degrees; alternatively our speed assumptions during the loss-of-power event might be too low. For both sets of glide scenarios the median azimuths are similar, the main differences being their implications for the distances flown beyond the 7th arc.

HMB_Fig_1a_HR

HMB_Fig_1b_HR

Figure 1: Initial direction for the Glide: a) Best Range; b) Best Endurance.

In Figure 2 we give a plan view of the simulated flight paths and the locus of sea level endpoints. The square labelled as IG nominal was reported in [5] as the intersection with the 7th arc, without consideration of a subsequent descent, and is included to assist orientation of this result with respect to previous studies.

HMB_Fig_2a_HR

HMB_Fig_2b_HR

Figure 2: Sample Flight Paths and Spread of Probable Endpoints.

In Figure 2 the maximum glide range may be considered as encompassing the region between the lines labelled Mode 1 and Mode 2. The maximum endurance path is shown as a single median line. As the distribution of angles in each case is fairly broad, based on Figure 1, a specific radial vector for the search is not suggested.

 

Summary of Model Inputs and Outputs

In all scenarios our modelled speeds begin to reduce one minute prior to the commencement of the descent. However, the speed reduction process after fuel exhaustion for the first engine does not have time to reach its optimal OEI speed before fuel exhaustion occurs in the second engine.

Our model inputs are listed in Table 1 below, along with the consequent outputs.

In reference [6] (specifically on page 26) the ATSB estimated a glide range of 120 NM for a descent from 35,000 feet. Our Table 2 below shows a comparison between the glide stages for our sample flight paths and the ATSB’s assumptions. The maximum range Mode 1 scenario covers a similar distance and has a similar gradient to the ATSB’s values.  The differences shown are within the errors of our modelling approximations.

The maximum range scenario for Mode 2 has a larger range and a flatter glide path due to the presence of a tailwind in our simulated flight path. The maximum endurance scenario covers a shorter distance, and but has a similar gradient to that of the ATSB report [6].

HMB_Table_1

 Table 1: Summary of Principal Inputs (I) and Outputs (O). 

 

HMB_Table_2

Table 2: Comparison of Glide Ratios with the ATSB’s Estimates [6]. 

 

Discussion

These scenarios excluded the BFO data at 00:19:29, which has been interpreted to be consistent with a rate of climb (RoC) of about
–4500 feet per minute (i.e. a rapid descent), whereas the RoC for the scenarios studied is about one quarter of this value, as is to be anticipated for a glide. As there are no further usable satellite data for later times, the possibility of a less efficiently flown scenario with a steep initial descent cannot be excluded. This would have the effect of decreasing the range that would be flown after fuel exhaustion (i.e. in the glide phase).

 

Conclusion

We have illustrated two glide range descent scenarios: maximum range and maximum endurance. The conclusions support the ATSB’s findings [6] that MH370 could have flown 120 nautical miles beyond the 7th arc. For pragmatic reasons the ATSB appears to have restricted its search area to a band located 40 nautical miles beyond the 7th arc and parallel to it. However a case is emerging that, if under the control of a pilot, the positions of impact could all lie further still from the 7th arc. Again, on best-available interpretations of the satellite and flight simulator evidence, optimal glide scenarios are not the most likely ones to have occurred, and only represent extreme possibilities. Appropriate risk analyses would be required prior to making proposals for future revisions to search area priorities.

 

Acknowledgments

The authors should like to acknowledge the contribution of Brian Anderson in providing assistance in checking the fuel exhaustion times. We should also like to acknowledge the contributions of Mike Exner, Victor Iannello, and other members of the Independent Group (IG) for their comments on an earlier draft. Any errors or omissions remain the responsibility of the authors.

 

References

[1] Bennett, S., Hyman, G. & Martin, B. (May 2015). MH370 Path Investigation Studies: The Implications of BFO and BTO  Data at 18:27 UTC. Independent Group; available from: https://www.duncansteel.com/archives/1699

[2] Anderson, B. & Exner, M. (March 2015). The Last 15 minutes of Flight of MH370. Independent Group; available from: https://www.duncansteel.com/archives/1461

[3] Ashton, C., Bruce, A. S., Colledge, G. & Dickinson, M. (2014). The Search for MH370. The Journal of Navigation, 68 (01), 1–22. Available from: http://dx.doi.org/10.1017/S037346331400068X

[4] (U.S.) National Centers for Environmental Prediction/National Weather Service/NOAA/Department of Commerce, NCEP FNL Operational Model Global Tropospheric Analyses (continuing from July 1999): Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory, Boulder, Colorado. (Updated daily.)

[5] Steel, D. (ed.) (September 2014). MH370 Search Area Recommendation. Independent Group; available from: https://www.duncansteel.com/archives/1023

[6] ATSB: MH370 – Definition of Underwater Search Areas.  External Aviation Investigation AE-2014-054 (26 June 2014; updated 18 August 2014); available from: ATSB: MH370 – Definition of Underwater Search Areas 

[7] Vinh, Nguyen X. (1993). Flight Mechanics of High-Performance Aircraft. Cambridge Aerospace Series. Cambridge: Cambridge University Press.

[8] Pereira, R. L. (2010). Validation of Software for the Calculation of Aerodynamic Coefficients. Degree project, Linkȍping University, Sweden; available from:
http://www.diva-portal.org/smash/get/diva2:329418/fulltext01.pdf 

[9] Jenkinson, L., Simpkin, P. & Rhodes, D. (2001). Civil Jet Aircraft Design. [Data sets] Butterworth-Heinemann; available from: http://booksite.elsevier.com/9780340741528/appendices/default.htm  (accessed 5th June 2015).

[10] Malaysian Ministry of Transport (2015). Safety Investigation for MH370: Factual Information, issued 08 March 2015; updated 15 April 2015; available from: http://mh370.mot.gov.my/

 

Annex A. True Airspeeds and Decent Rates for
Best Range and Endurance

The drag force is assumed to be given by an equation of the form:

HMB_eqn_A1

…where V is the true airspeed, and z is the altitude. The coefficients are given by:

HMB_eqn_A2

…where ρ(z) denotes the (ISA) density of air at altitude z and the remaining parameters are as in Table A.1 below.

HMB_Table_A1

Table A.1: Parameters Pertaining to the Drag Force

Drag coefficients K and C_d0, reported in [8] and reproduced here in Table A.1., are for the Boeing 777-300 model without operating powerplants, at Mach 0.84 and a Reynolds number of 8.7 × 10^5.

 

Maximum Range Descent

The airspeed which maximises range, in the absence of winds, is given by:

HMB_eqn_A3

In the absence of engines the steady-state rate of  descent, which maximises range, is [7]:

HMB_eqn_A4

…where W=mg is the aeroplane weight, and

HMB_eqn_A5

…is the minimum drag. The glide angle γmd for this maximum range steady descent is then given by:

HMB_eqn_A6

 

Maximum Endurance Descent

For maximum endurance (i.e. longest descent time) we can write the following relations (see reference [7]) so as to get the equivalent output parameters as in equations A4, A5 and A6 above:

HMB_eqn_A7

 

Astronomy & Space Science

Asteroid discovery efficiencies for the Korean Microlensing Telescope Network

Asteroid discovery efficiencies for the
Korean Microlensing Telescope Network

Duncan Steel
2015 May 19

Introduction
The Korean Microlensing Telescope Network (KMTNet) is planned to include three telescopes located in the Southern Hemisphere in a project aimed at the identification of Earth-mass planets orbiting other stars through gravitational lensing effects. The telescopes are to be located in Chile, South Africa and Australia.

The telescopes will have an aperture of 1.6 metres, and a field of view (FOV) covering about four square degrees which will be imaged using a 340 megapixel CCD camera. The intent is to obtain repeated images of four adjacent fields near the Galactic Bulge, with 24-hour coverage being possible in principle from these three observatory sites. The variation in light intensity received due to transient events may then indicate the presence of extrasolar planets, as described above.

The preceding two paragraphs comprise a brief (and inadequate) summary of the aims of KMTNet. The intent here, in this paper, is simply to indicate the possible effectiveness of the KMTNet telescopes for the discovery of near-Earth asteroids (NEAs). No specific data collection is envisioned; I am just exploring how often NEAs might be detected in KMTNet imagery routinely collected for the purposes of that project, should the imagery be processed to this end in a timely manner using suitable moving-object algorithms.

Gould and Yee have pointed out that microlensing surveys such as KMTNet will render a huge volume of useful data on main-belt asteroids. It is emphasized that here I am considering only NEA discoveries and not the far larger number of discoveries (and invaluable information on spin rates etc.) of main-belt asteroids that will be spawned by KMTNet and the like.

 

Current NEA search programs
Simply as background for the interested reader, I point out that ongoing NEA search programs are listed here. A notable new project due to commence at the end of this year is ATLAS. Note that ATLAS (that’s a different link) will make use of quite small telescopes (aperture near 50 cm) but will cover large areas of the sky.

 

Asteroid discovery efficiency metric
Twenty years ago I studied the feasible NEA discovery efficiencies for telescope systems at Siding Spring Observatory (SSO), and a few other systems, plus plausible NEA discovery efficiencies should suitable CCD cameras be installed on various systems at SSO. My analysis (the paper in question is available by clicking here; 1.85 MB PDF) was based on a method developed by Al Harris.

Subsequently (and consequently) the Uppsala Southern Schmidt Telescope at SSO was modernized and equipped with a CCD system, as part of the University of Arizona Catalina Sky Survey, and proved to be a highly-effective device for the discovery of NEAs and comets. Its limited aperture (0.6 metres), however, has meant that as the majority of large NEAs (1 km and above) have been found its utility has passed.

Larger aperture systems are now required, for the discovery of smaller NEAs (see this report from 2011, and for more up-to-date information see the various papers presented at the Planetary Defense conferences held in 2013 and 2015). Deliberate, dedicated searches are under way. However, there are also other astronomical surveys being conducted which will inadvertently turn up NEAs – astrophysicists have been known to term asteroids the “vermin of the skies” – and KMTNet is an example of one of the surveys.

All I have done here is to resurrect my software from two decades ago, and input the relevant parameters for the KMTNet systems. It is emphasized that I have not updated, say, the asteroid population model that I have used, as introduced by Harris; it would be useful if someone could perform such an update, and make use of the experiences obtained in the various NEA search programs over the past twenty years.

 

KMTNet systems parameters
I am indebted to Dr Michael Albrow for information regarding the KMTNet CCD cameras. The relevant parameters for the present analysis  are as follows:
   Detector system:  2 x 2 mosaic of 9k x 9k E2V 290-99 CCDs.
   Nominal FOV: 2 degrees x 2 degrees.
   Pixel angular width: 0.39 arcseconds.
(Note that 9,000 x 0.39 arcsecond pixels indicates a FOV 1.95
degrees wide; and this is the FOV I have used.)

The other input parameters to the NEA discovery efficiency software are as below:
   CCD quantum efficiency: 0.8 (assumed value).
   Minimum signal-to-noise ratio for asteroid detection: 6 (six).
   Exposure duration: 60 seconds.
   Exposures per hour: 24 (i.e. a duty cycle of 40 per cent).
Because there are four fields (each of four square degrees) being
repeatedly imaged, each of those fields is imaged six times per
hour.

Telescope effective aperture: 1.3 metres
(The actual telescope aperture is 1.6 metres, but the central
obstructions cut down the effective collector area. I have assumed
that about two-thirds of the aperture is free of obstruction:
[1.3/1.6]² ≅ 0.66.)

 

Results
Using the above input parameters I obtained results as shown in Figures 1-3 below. It is intended that these plots should be compared with Figures 2, (3 & 5) and (4 & 6) respectively in my previous paper.

CCDKMTFig1Figure 1: The limiting (asteroid) magnitude obtainable as a function of asteroidal angular speed between 0.25 and 128 degrees per day. 

 

CCDKMTFig2Figure 2: The logarithmic relative discovery rate as a function of asteroidal angular speed . 

 

CCDKMTFig3

Figure 3: The logarithmic relative discovery rate as a function of asteroid equivalent diameter. 

Discussion
If one compares the above plots with my previous results, there are few surprises in terms of the general form of the curves. The most pertinent results to compare with are those I derived for the GEODSS cameras, actually before they were brought into use for NEA detection. For these 1-metre aperture systems, assuming 30-second exposures, I found that the discovery efficiencies indicated are about eight to ten times higher than those found here for individual KMTNet telescopes, with relative discovery curves having shapes very similar to those in Figures 2 and 3 above.

Why are the KMTNet telescopes indicated to have lower NEA discovery efficiencies? There are several contributing considerations, as follows.

  • With 60-second exposures and 0.39-arcsecond pixels, only the slowest-moving NEAs will be pseudo-stationary (in the terminology of my earlier paper); those moving at one to eight degrees per day will produce short trails in the KMTNet images, while those travelling at angular speeds of 16 deg/day will result in long-trailed images, and there is no benefit in having trailed images, as such, in terms of moving object identification.
  • By repeatedly imaging the same fields, rather than covering new areas of the sky, the KMTNet observing routine will produce multiple detections of the same NEAs rather than a large number of discoveries; this has some advantages, in that the KMTNet system in effect will be doing its own ‘follow-up’ of NEA positions within each night (and over several nights for the NEAs moving at less than 2 deg/day), resulting in astrometric arcs lasting several days for most of its NEA discoveries, and this will be highly advantageous in view of the sparsity of asteroid follow-up astrometry in the Southern Hemisphere.
  • After the original NASA Spaceguard Goal (covering 1-km NEAs) was nominally achieved, the target sizes were dropped first to 140-metres, and now lower still. Consideration of Figure 3 indicates that the KMTNet systems will provide for peak discovery efficiencies in the 50 to 300 metre size range, and it will be these-sized NEAs that are moving quickly enough to replenish the FOV of the KMTNet cameras from night-to-night.
  • Systems like ATLAS will cover smaller sizes still, but not much; KMTNet will have substantial discovery efficiencies for NEAs in the 20- to 50-metre size range (smaller asteroids, such as the Chelyabinsk object, cause relatively little damage on impact) and, since KMTNet will be operated with self-consistent observing routines and directed at only a small region of the sky, it might be anticipated that the analysis of results from KMTNet will be of especial interest in terms of developing improved understandings of the population and orbital distribution of small NEAs and therefore their impact frequency on Earth.

Acknowledgement: I thank Dr Michael Albrow for discussions and correspondence regarding KMTNet.

 

Astronomy & Space Science, Orbital Debris

New Zealand and the Fifth Domain of Warfare: Space

New Zealand and the
Fifth Domain of Warfare: Space

Duncan Steel
2015 May 14

A submission to the public consultation for the
New Zealand Defence White Paper 2015 

A PDF version of this submission (523 kB) is available from here.

 

Summary
Geography, in terms of the supposed remoteness of New Zealand, is often cited as a reason why this country does not need a strong Defence Force. However, as I indicate in this brief submission, it is in fact geography that must surely lead to NZ playing a major role as humankind’s activities in outer space grow to include warfare, as already happens to be the fact.

The core geographical reason is this. The majority of satellites orbit the Earth in the prograde direction, from west to east. The nations that presently have orbital or sub-orbital (i.e. ICBM) launch capabilities, or are expected to do so soon, and which might be anticipated to be possible adversaries of NZ and its allies, are essentially all in Asia; for example, China, North Korea, Russia, Pakistan, Iran. Prograde orbits mean eastward launches. Simple physics dictates that rockets launched eastwards from Asia will turn southwards, cross the equator, and on first pass will cross the southern Pacific. In fact, if one draws a line from NZ’s sub-Antarctic islands to the northernmost part of the Realm of New Zealand (i.e. the north of the Cook Islands, and Tokelau) then it is almost inevitable that satellites launched by Asian nations will cross that line on first pass, this being the time (about 30 minutes post-launch) that NZ’s allies in North America and Europe would need to have such objects detected and tracked if they are to be informed in advance of the approach of potentially-hostile spacecraft.

I give simple examples in the map below. I have shown orbital tracks (at altitude 500 km) for two launches each from the Chinese launch site at Jiuquan, and the Indian site at Sriharikota. For each launch site I have shown one satellite launched due east, which then has an orbital inclination (tilt to the equator) equal to the latitude of the site: 41 degrees for Jiuquan (path in red) and 14 degrees for Sriharikota (path in orange). I have also shown a more highly-inclined satellite launched from each site: inclination 52 degrees (in yellow) from Jiuquan, and 55 degrees (in green) from Sriharikota. I have additionally drawn three rings (actually circles of radius near 3,000 km, but distorted in this 2D mapping) to indicate potential coverage of suitable radar systems located at Invercargill, Auckland and Avarua (Cook Islands): these would, between them, be capable of tracking all four satellites.

NZR_cone_map_06

Also shown in this diagram are Kwajalein (Marshall Islands), where the US DoD is to build its new Space Fence radar mark II (cost US$2 billion and growing); and Hawaii, where the USAF maintains an optical tracking facility on Maui. Such US assets would not be able to track the two of these satellites that travel furthest south.

Finally I note that the US and Australia have recently entered into a Space Situational Awareness (SSA) agreement involving various assets being installed and operated in Australia, but tracking of such satellites by these assets will not be feasible on first-pass. It is only NZ-sited sensors that could guarantee coverage of potentially hostile rockets and satellites crossing the southern Pacific.


Introduction
During the 20th century a third domain of warfare (Air) was added to the two ancient domains, Land and Sea. As we entered the 21st century a fourth domain was recognized and added: Cyberwarfare.

It should be obvious, however, that a fifth domain has already entered the fray, whether we like it or not. This domain is outer space. Modern armed forces depend to a large extent on satellite-borne communications for various aspects of their C4ISR. The race to the Moon in the 1960s was clearly not about science and exploration alone, and now a new space race is beginning. A quest for military domination of outer space seems unavoidable.

That this 21st century space race involves more than simply national prestige is obvious. As Sun Tsu wrote more than two millennia ago, “All armies prefer high ground to low, and sunny places to dark.” Space is the ultimate high (and indeed sunny) ground. In modern times (2007) the Chinese have already executed a hostile action in space, an anti-satellite demonstration that has left the densely-populated altitudes between 800 and 900 km – an especially important height bracket due to its utility for sun-synchronous orbits – badly polluted with debris from the meteorological satellite that they destroyed using a ground-launched missile.

The tracking of such debris, and all orbiting objects, is conducted by the US DoD through a variety of optical and radar sensors, and the information database is maintained by the Joint Space Operation Center (JSpOC). Sensors include various optical systems such as the GEODSS cameras spread around the globe, and also the former Space Fence radar array that had transmitter and receiver sites located in various US states. Canada has also been a close, long-term collaborator with the US in NORAD (the predecessor to USSPACECOM and now USSTRATCOM) due to the perceived likelihood of ICBM attacks on the US being routed over Canadian territory, in the context of the Cold War.

Affairs in space and national defence have now moved on, and other potential aggressors occupy the attention of the US Government, and its allies. The US is currently building a new Space Fence radar, in Kwajalein (Marshall Islands). The choice of that remote location, rather than within the US itself, is not accidental: there is a need on the part of the US to detect and track orbiting or at least space-transiting objects coming from the west and crossing the Pacific towards the US mainland. Similarly the US wishes to locate early-warning radars in Romania and Poland because ICBMs launched by Iran (for instance) would travel over eastern Europe before passing over the Arctic en route to the USA via geodesic paths.

Since the beginning of the Space Age almost 60 years ago two of the Five Eyes nations, the UK and Canada, have worked closely with the US in military space projects, in particular Space Situational Awareness (SSA). Over the past five years Australia and the US have concluded agreements on SSA in the annual AUSMIN meetings. Specific actions now underway include: (a) The shifting of the prototype Space Surveillance Telescope (SST, the largest camera ever built, at a cost of around $200 million) to the northwest cape of Australia (i.e. Learmonth); (b) The installation of a C-Band radar near Darwin for the detection and tracking of satellites and debris in orbit; and (c) Planning for an additional Space Fence radar to be located in Western Australia.

This means that NZ is the only one of the Five Eyes nations not directly involved to any significant extent in space tracking activities. However, as I show below, the geographical location of New Zealand and its Realm – east of Asia and south of Kwajalein and Hawaii – results in a realisation that this is a vital range of locations for the operation of suitable sensors, tracking orbiting objects in general and satellites on first pass post-launch in particular.

 

Optical Sensors
I will write comparatively little here about NZ as a likely location for optical sensors for tracking objects in geocentric orbit; that is, narrow-field telescopes and wide-field cameras. What I will note is that Mount John Observatory at Lake Tekapo is the southernmost year-round professional astronomical observatory in the world, having just passed its 50th anniversary.

Despite the well-known vagaries of cloud cover in the Southern Alps, and indeed NZ as a whole, Mount John would be an excellent candidate location for suitable telescope systems similar to those the USAF maintains and operates at the AMOS (Air Force Maui Optical and Supercomputing observatory) site on Maui. In terms of the needs of modern astronomy, Mount John is not a competitive site; but neither is anywhere in Australia (and yet the SST is to be installed at one of the poorest ‘astronomical’ sites in that country), and in any case we are not talking about abstract astronomy here. The tracking of Earth-orbiting objects is a different game. What Mount John has in its favour is its latitude, and longitude.

The history of the USNO operating a small telescope at Black Birch (near Blenheim) is well-known.

Finally under the heading of ‘optical sensors’ I note that the Australian DoD has been supporting for some years the use of LIDAR (laser radar) systems for the tracking of orbiting objects, through the activities of the Canberra-based company Electro-Optic Systems.

 

Space Radars
My main intent in this submission is to illustrate how and where suitable radars might be located such that NZ might independently make a major contribution to the Five Eyes SSA capabilities. I am not suggesting that the US (or anyone else) be invited to locate sensors of any type, or conduct SSA operations of any form, within New Zealand. What I outline here is a space situational awareness capability that NZ should be able to design, construct and operate on its own, with a range of likely benefits to the nation that I will discuss in a later section of this submission.

In the map included in my summary section above I showed orbital tracks (at altitude 500 km) for two launches each from the Chinese launch site at Jiuquan, and the Indian site at Sriharikota. For each launch site I employed one satellite launched due east, which then has an orbital inclination (tilt to the equator) equal to the latitude of the site: 41 degrees for Jiuquan (path in red) and 14 degrees for Sriharikota (path in orange). I also showed a more highly-inclined satellite launched from each site: inclination 52 degrees (in yellow) from Jiuquan, and 55 degrees (in green) from Sriharikota. These were not chosen randomly: it happens that such inclinations lead to ground tracks which, as the spacecraft ascends to attain orbit and drops its upper stages, do not pass over the territory of other nations: look carefully at those yellow and green tracks.

Additionally I drew three rings (actually circles of radius near 3,000 km, but distorted in these 2D maps) to indicate potential coverage of space radars located at Invercargill, Auckland and Avarua (Cook Islands): these would be capable, between them, of tracking all four satellites. The positions shown for the satellites in that first map are all about 30 minutes post-launch, on their first pass over the Pacific.

Also shown in these diagrams are Kwajalein (Marshall Islands), where the US DoD is to build its new Space Fence radar mark II; and Hawaii, where the USAF maintains a major optical tracking facility on Maui (AMOS). Such US assets would not be able to detect and track all of these putative satellite launches on first pass.

In the map below I have stepped forward 60 minutes. The tracks show how two of these spacecraft/rockets, if they had a hostile intent, might have attacked the east coast of the US, or Europe.

NZR_cone_map_07

Stepping forward another 40 minutes (i.e. a little more than two hours post-launch) the satellites have passed again through the putative radar coverage available from Invercargill, Auckland and Avarua, as shown in the map that follows. One (the green track) is heading fairly centrally for the US and yet has not been within the range of the US Space Fence on Kwajalein, nor AMOS. It should be apparent from this that there is a need for suitable radar coverage in the southern Pacific, not just the north.

NZR_cone_map_08

It would be appropriate here to indicate the type of radar system that is being mooted. The first thing to make clear is that the radar systems involved here are entirely different from the Australian OTHR JORN system, which operates on completely different principles, uses much lower frequencies (MF/HF), and has entirely different intended targets (slow-moving ships and aircraft).

The original Space Fence, spread across the Continental USA, operated in the top end of the VHF band, at frequencies near 217 MHz, corresponding to a wavelength near 1.4 metres. Due to the scattering properties of small objects, this was relatively insensitive to the weak echoes from objects much smaller than that, whereas most space debris fragments are of 10 cm sizes and smaller. Consequently the new Space Fence will be operated in the S-band (circa 3 GHz; decimetre wavelengths). This is quite a different technology to the previous Space Fence, and hugely expensive.

From the perspective of NZ’s possible role, it is the early identification of intact (therefore large) satellites that is important, and so a VHF radar operating between 200-300 MHz would seem appropriate. The detection and tracking of smaller debris items, as the US will be accomplishing from Kwajalein, is a different task that speaks to spacecraft safety. Of concern to NZ should be potentially-hostile or dangerous satellites passing above the nation, and its realm, and posing a threat to its allies.

In the three-dimensional graphic that follows I show the form of the radar coverage that could be delivered by radars located as in the preceding maps. Each radar I have modelled as having an upward-directed broad cone of coverage, which I have cut off at altitude 2,000 km simply because that is the conventional height limit of satellites classified as being low-Earth orbiting (LEO). The opening angle of each cone is 150 degrees (i.e. each radar delivers coverage for all elevations more than 15 degrees above the local horizon). This produces a ‘base’ to the cone (i.e. at the ‘space’ end) that is about 3,000 kilometres in radius (6,000 km wide).

NZR_cone_01

In the graphic below I have shown the four model satellite paths described earlier, as they emerge from the coverage from these three radar sites. The satellites with inclination 14 degrees and 41 degrees would have been detectable only from Avarua; those with inclinations 52 and 55 degrees would have been detectable from both Auckland and Invercargill. In all cases the satellites remain within the coverage of at least one radar for a minute or two, enabling orbit determination on this first pass, and therefore prediction of their paths over the next few hours.

NZR_cone_03

The three radar locations as modelled above would be adequate to cover satellite passes over the whole Realm of New Zealand. However, additional coverage/additional sensors are always a good idea. In the graphic below I show the coverage for five model radars (the two added being located in Niue and Tokelau), but in a different way. Now I have shown the radar coverage limits as circular ‘fences’, the bases of the fences being each located 1,500 km from its radar site, and extending over an altitude range from 200 km (no satellites stay for long below that height, due to atmospheric drag) to 2,000 km (the top of the LEO altitudes). With suitable radar equipment any satellite passing through any one of those fences would be detected, and tracking would continue during the two or three minutes the satellite was within that fence, enabling orbit determination and hand-over to other sensors in a Five Eyes network.

NZR_cyl_03

 

Arguments in favour of such a Defence capability
There are numerous arguments that could be put forward which would support the concept of developing a Defence capability for New Zealand along the lines of that proposed above. The following list is by no means expected to be complete.

1. National Security
The week before this text was being written there was a large out-of-control Russian spacecraft passing over New Zealand twice a day at an altitude below 200 km (i.e. closer than the lateral extent of NZ’s EEZ). Towards the end of its orbital lifetime it dipped down to 100 km. It eventually re-entered over the eastern Pacific on May 8th, but if that uncontrollable event had been delayed by four hours then it would have occurred as the spacecraft was crossing the South Island from NW to SE; another six hours later and it would have been passing over the length of NZ from SW to NE.

It seems that no-one in New Zealand (apart from myself) had any definitive knowledge or understanding of what was going on, with the local media simply copying what they were told by overseas sources. I see no evidence of the NZ Government having any capability to assess such threats. New Zealand has no space data sharing agreement with the US, unlike Australia (plus Japan, South Korea, Canada, France, Italy, the UK, and ESA), so that quick access to vital information (generally through Defence rather than civilian channels) cannot be obtained.

This is a startling situation, inappropriate for any developed nation. The Space Age is more than half a century old. Space is a burgeoning sphere of military activity. New Zealand is at most 45 minutes from any launch site on Earth. Thousands of orbiting objects pass over NZ every day at distances less than that between Auckland and Christchurch. This is the reality of the modern world. The requirements of National Security demand that NZ has at least some awareness of what is going on in our skies.

2. Contribution to Global Security
Consider New Zealand’s position in terms of its contribution to global security in the context of various multi-national agreements (e.g. ANZUS; Five Eyes [US, Canada, UK, Australia, NZ]; Five Powers [UK, Singapore, Malaysia, Australia, NZ]). As recent experience indicates (cf. sending of advisors and security forces to Iraq) there is widespread domestic disapproval with regard to New Zealand sending its armed forces to serve in conflicts in faraway places. This limits the contributions that the nation can make, and yet we would rely upon other larger, better-equipped nations for our own defence if there ever were a threat to NZ territory and interests.

What contribution might NZ be able to make that does not involve marked domestic opposition? The answer lies with benign activities where a special case can be made for New Zealand’s involvement. As I have indicated above, NZ’s geographical location provides such a special case; and monitoring of space surely represents a benign activity in itself. The US radar system used to patrol the high frontier is called the Space Fence; as the saying goes, good fences make good neighbours.

3. NZDF and radar
The needs of the New Zealand Defence Force with respect to radar systems is obvious. The project mooted here will lead to much upskilling, and potentially the domestic development of other types of radar system with military applications. This is what has occurred in Australia as the result of the JORN OTHR project.

4. Involvement of the Realm of NZ nations
The same geographical arguments as those raised above also apply to the Realm of New Zealand nations: the Cook Islands, Niue, and Tokelau. Although I have in diagrams above placed monostatic radar systems in each of these nations, note that bi-static or multi-static systems are feasible, even desirable, as was the case in the original US Space Fence. That is, there might be a transmitter in Avarua but receiver sites in Niue and Tokelau.

Such a network of radar systems, including sites in NZ itself, lends itself to many benefits, including international collaboration on both the military and civilian fronts, economic stimulus, upskilling of local populations (e.g. local staff being sent to NZ to obtain university education and training), and so on.

5. Involvement of the friendly neighbouring nations
Precisely the same arguments as made above for the involvement of the Realm of NZ nations can be made here for other friendly neighbours, for example Tonga, Samoa, and Fiji.

6. Inspiration and motivation for NZ students to study STEM subjects
The US is still benefiting from the Apollo space program of the 1960s, which inspired and motivated many students to enter the STEM fields (Science, Technology, Engineering, Mathematics). This echoes on in US industry. Perhaps a similar program here, on a much smaller scale, could have a similar effect.

It is well known that there is a shortage of students entering New Zealand universities to study the STEM subjects, starving local industry of the technical talents that are needed, whereas there is a huge surplus of students taking courses for which there is no direct career path. How to motivate students to study the ‘hard’ sciences and numerate subjects has been a long-term problem for many Western countries, whereas in Asian nations the industries and militaries are well-supplied with suitable graduates, providing major economic and technical advantages.

In New Zealand there have been few career paths for STEM graduates, and many of them depart overseas, never to return. This project would assist in reversing that trend, with widespread benefits.

7. Stimulus for NZ industry and universities
The project as envisaged would provide a major stimulus for NZ industry. If the radar systems in question were to be sourced and built locally, there would be a substantial requirement for R&D both on the hardware and the software (e.g. signal processing) fronts. That such projects do result in boosts for local industry is evidenced by the Australian experience over recent decades, where the needs of radio astronomy have led to technological advances largely accomplished by the CSIRO Division of Radiophysics which have had substantial commercial outcomes (e.g. better airport approach radars); similarly the JORN OTHR radar developed through the ISR Division at DSTO has led to many commercial applications.

8. Overlap into other scientific and commercial fields
Whilst the stimulus envisioned under the preceding heading was limited to radar systems, it should also be anticipated that the technological developments and weight of experience gained will lead to other benefits in separate fields. Clearly, building and operating space radars of the type envisioned would lead directly to capabilities in similar activities (e.g. satellite ground station design, construction and operation) but also a wide range of other fields such as signal processing, short- and long-range communications, plus others yet to be identified.

9. History of NZ research in radar
New Zealand has a proud and prominent history of research in radar which can be tapped. The writer is a PhD graduate of the atmospheric radar research program at the University of Canterbury, which has been in operation since the mid-1950s. Other universities and research institutions also have well-established research programs that are directly relevant, in engineering, physics, and mathematics.

10. High-profile status of space-related activity
No-one could doubt that space activities are high-profile, and generally meet with public approval. This again points to the potential of this overall capability project. NZ is too small to be involved in space in a big way, but there are niches that it can fill, to advantage. This is one of them.

11. Space-based internet
Australia is currently spending several billions of dollars on a fibre-based national broadband system. New Zealand already leads the way in terms of broadband connectivity, although there are many NZ residents not yet able to connect.

The reality is that within five or six years everyone worldwide should have broadband through satellite-based WiFi. The following graphic shows my visualisation of a satellite constellation as originally proposed by Google in 2014.

Strawman_WiFi_Constellation_950km

That constellation consists of only 180 satellites; SpaceX is proposing to build and launch a constellation of over 4,000 satellites to provide WiFi broadband globally. (For further information and links, see my post here.)

Such connectivity must revolutionize communications in the same way as the internet itself and smartphones have in recent years. Very soon the connected population of the world will double, as more than three billion people in developing countries get broadband access. Once that connectivity is achieved, the world will be a different place in many ways. It would seem incongruous were this to occur and New Zealand not even have a domestic capability to monitor what is flying through our skies.

 

Conclusion
Any and all space-linked activity such as that outlined in this submission must help New Zealand to position and prepare itself for the world’s space-linked future. Current estimates of the annual turnover of the global space industry put the figure at close to $1 trillion [sic], once one realises that the GPS systems that guide cars, jet aircraft, and trampers in the NZ bush, are all based on a satellite constellation thousands of kilometres above our heads; and that constellation is operated by the US military.

Space is the Fifth Domain of Warfare. That is inevitable, and it’s already begun. The militaries of the world largely depend on space segments for communications, for ISR, for weather forecasts, and so on. Whilst the militarisation of space is largely forbidden by UN agreements, the reality is that aggressive acts have already occurred in space; ICBMs would transit space during flight; and attacks on the ground by orbiting assets, and satellite-against-satellite attacks, may well be inevitable.

As I have shown above, New Zealand’s geographical location happens to place it under the flight path of newly-launched spacecraft from Asian nations, which will be a major concern for NZ’s allies, especially as these countries boost their space activities. The fact of this is apparent from the new arrangements between the US and Australia for space-related collaboration from a military rather than civilian perspective. North Korea and Iran have both put satellites into orbit, which is proof-positive of their long-range missile capability. Other potentially-hostile nations will surely follow.

My submission, in essence, says simply that New Zealand should recognize this fact of the next several decades, and take appropriate steps to develop a domestic Space Situational Awareness capability which would contribute in a vital way to the major facilities now being brought on-line by this nation’s core allies.