[Updated] A potential use for satellites in Zuma-like 50-degree inclined orbits

SpaceX's launch of the Zuma satellite on 8 January was interesting, and not just because of the ongoing saga of whether it failed or not (see a previous post).  

The odd 50-degree orbital inclination is another element that made this launch interesting (see discussion in my pre-launch post here: sightings of the Falcon 9 Upper Stage over Sudan after launch later confirmed this orbital inclination).

New ideas started to form post-launch after the Falcon 9 sightings from Sudan made me realize that while it indeed was launched into a 50-degree inclined orbit, the orbital altitude (900-1000 km apogee) was higher than I initially expected, making a proposed link to USA 276 unlikely.

And then @Cosmic_Penguin posted this small message thread on Twitter, referencing this interesting publication. That struck a chord and reinforced an emerging idea about a potential role for satellites in such 50-degree inclined, ~1000 km altitude orbits.

As @Cosmic_Penguin notes, the publication specifically discusses ~50-60 degree inclined, ~1000 km altitude orbits. And it is all about Space-based Radar.

The report pitted several radar sat constellation configurations against each other, but all of them assumes the satellites being in a 1000 km high, 53 degrees inclination orbit. That's very close to the current search estimation of ZUMA's orbit by @Marco_Langbroek. 🤔 (2/2)

— Cosmic Penguin (@Cosmic_Penguin) 10 januari 2018

I had just been looking into the coverage of the Zuma orbit, and it lines up with content in that report.

The map below is a ground coverage map of Zuma, would it have been alive and well. One of the uses of a ~50 degree inclined ~1000 km altitude Space Based Radar satellite mentioned in the report, is for shipping surveillance.

Indeed, a satellite in a Zuma-like orbit would basically cover all Ocean surfaces, except for the high Arctic and Antarctic, which are not that interesting for the purpose discussed below (moreover, the Arctic is extensively covered by groundbased and airborne radar).

click map to enlarge

A (Radar) satellite in this kind of orbit therefore would be very useful to keep track of illicit shipping movements on the High Seas.

Think stuff like embargo-runners, e.g. embargo-breaking shipments of coal and oil to for example North Korea, illegal weapons exports from North Korea, oil exports from Syria, illicit weapons transports to the Middle East, and human trafficking as well as drugs shipments.

Ships engaged in such illegal activities sometimes turn off their transponder, making it harder to track their whereabouts once out of sight of landbased shipping radar (see also the story about one particular embargo-breaking ship here). The classified US NOSS duo ELINT satellites and similar Chinese Yaogan triplets are meant to track ships from passive radiosignal crosslocation, but when a ship displays strict radio silence, these systems will not detect them either. But Space-Based Radar will.

Embargoes have become an important geopolitical tool when outright war is deemed not an alternative. We currently see embargoes enforced with regard to for example Syria and North Korea. Means to enforce embargoes including detecting and stopping potential embargo violations therefore have become important. Human trafficking and drugs trafficking are growing geopolitical problems as well.

So was Zuma meant to be an (experimental, i.e. a technology demonstrator) version of such a Space Based Radar for Ocean shipping surveillance? It is an option.

What might argue against it is the extreme secrecy surrounding the launch. Very few details were made public about the Zuma payload, the Agency operating it was not disclosed, and the launch was announced very late.

For all of this, explanations can be sought, but that admittedly all is "special pleading". For example, maybe the secrecy is there because the mission involves cutting edge experimental Radar technology. Or the secrecy could simply be the result of the "secrecy cult" in some parts of the US Government going over the top. Or it could point to operation by an Agency that wants to keep this operation on the down low - e.g. the CIA. And I can think of a few more - much more outlandish, which is why I won't mention them here - potential reasons.

We have seen this kind of secrecy before with PAN (and its later sister ship CLIO), with Prowler, and more recently with USA 276. All of these were experimental satellites doing unusual things: PAN roved between, snug up to and eavesdropped on commercial geostationary satellite telephony satellites. Prowler was an experiment for covertly inspecting other geostationary satellites on-orbit. And USA 276 remains mysterious but a series of very close encounters to the International Space Station suggest it might be a technology demonstrator for observing rendez-vous manoeuvres in space.

Zuma (the more so now it might have failed) also strongly brings the infamous USA 193 satellite to mind, although there we do know that it was a satellite for the NRO, and likely an experimental radar satellite [edit: see added note 2 below].

Nevermind what Zuma really was meant to be, and who was to operate it: the message to take home is that High Seas shipping surveillance is a potential and viable role to keep in mind for any future satellite launched in a ~1000 km altitude, ~50 degree inclined orbit.


Added note 1: Cosmic Penguin pointed out to me that this was also earlier brought up in a forum post by Ed Kyle.

Added note 2, 12 January 2018:  This article suggests Zuma might be an electro-optical/SAR hybrid and a follow-on to the infamous USA 193:

"Second, the Northrop Grumman satellite may be a follow-on to another failed satellite US 193. [...] ...., a source with direct knowledge of the program told me it was a blend of radar and electro-optical and would not provide any more detail than that. A source with wide knowledge of classified space programs has told me that the Northrop Grumman-built Zuma may be the next iteration of this. Both were apparently experimental satellites, in that they were not part of a large constellation of similar satellites."

Such a spacecraft would be well suited for the purpose indicated in this blog post.

Also, Northrop-Grumman, the company that built Zuma, has actually worked on developing ideas for Space Based GMTI Radar, which again would suit well to the purpose I suggest in this blog post.


Acknowledgement: Hat Tip to @Cosmic_Penguin on Twitter for putting ideas into my brain.