Page 52 - Australian Defence Magazine October 2019

DEFENCE
PACIFIC
HYPERSONICS
“By the time you realize a hypersonic missile is coming your way, you’ve got less than 10 seconds to react.”
laterally through the atmosphere at over five times the speed of sound. How can this technology be overrated?
But that doesn’t mean no defensive sys- tem can exist.
“Any weapon potentially has counters,” Prof Davies said. “Hypersonic weapons won’t be 100 per cent effective.
“Is the effectiveness of hypersonics sub- stantially higher than previous weapons systems? Potentially yes, but there are still some technical problems in steering a hy- personic weapon towards a moving target.
“If something’s going really fast, it’s hard to turn. The laws of inertia don’t get turned off for hypersonic weapons. The rhetoric you see about highly manoeuvrable hyper- sonics – pick one or the other. You can’t have both. If you have a missile moving at Mach 9, it takes two and half seconds to move through 10 degrees, give or take. In that time, it travels 7.5 kilometres.”
According to Yelland, the question de- pends on the definition of manoeuvrability. “A fighter jet has a manoeuvrability up in the high single-G figures, possibly pull- ing up to 12 Gs. That’s regarded as highly manoeuvrable. You could easily pull 100
duce their vulnerability - but it is plausible. “The other thing that needs to be consid- ered is what guidance system the missile is using,” Yelland said. “If it’s also using some sort of radio frequency or infrared seeker
then you’ve got to counter that as well.” Some posit that direct energy weapons based on high-power laser beams might serve as an effective defensive system: but according to Yelland, hypersonics are de- signed to withstand the heat such systems
could bring to bear.
“Hypersonics are already designed to
withstand heat, so a laser directed energy weapon which relies on generating a lot of localised heat is probably not going to work,” Yelland said. “Of the directed energy weapons, RF-based ones are more likely to provide potential countermeasures, where you’re trying to upset the electronics.”
The key to defending against hypersonics may also lie earlier in their launch process, or what missile defence experts refer to as the ‘problem chain’. The first problem any missile needs to overcome is simply finding the target, meaning hypersonic missiles rely on data links that are vulnerable to cyber disruption. This concept has also been re-
ferred to as ‘left of launch’ in an integrated air missile defence (IAMD) sense; stopping the launch before it even happens.
“Anything that’s not line of sight is much harder to get an exact position on,” Prof Davies said. “Over-the-horizon radar will give a rough position but nowhere near good enough for position targeting.
“If you’re targeting a ship that’s a long way out at sea, you need line-of-sight or the ability to communicate to real-time satellite-based systems. All the data links there are vulnerabilities.”
The second problem both boost glide and scramjet hypersonic missiles must over- come is accelerating to speeds above Mach 5. This provides an opportunity to find and destroy hypersonic missiles while they’re still on the ground (or not far from it).
“There’s no doubt that if we had systems that could detect a launch and take out the missiles in the first phase of flight, that would be the way to do it,” Yelland said.
In short, whilst hypersonics are cer- tainly going to pose a significant challenge to warships and other large high-value targets, the threat may not be as drastic as some claim.
Test vehicle launch as part of hypersonics trial (HIFIRE-0) at Woomera in 2009.
Gs on a hypersonic missile,” Yelland said. “The difference is that the speed sig- nificantly increases the radius of turn. So while you’re pulling a lot of Gs, we might be talking about a half-kilometre radius turn with a fighter jet versus a 20-kilome-
tre radius turn with a hypersonic missile.”
Hypersonics are not invincible
This relative manoeuvrability problem means hypersonic missiles could be vul- nerable to technologies that disrupt their in-flight course corrections.
Research has shown that a 9.5-megawatt microwave source could damage guidance systems inside a hypersonic weapon 12.5 seconds before it hits, creating a half-degree angle change that would cause the missile to land 350 metres away from the target. This technology is not flawless - missiles could be designed as a Faraday cage to re-
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