عربي English Türkçe اردو فارسى
Logo
Latest News
Features

What are Solid-fuel Missiles, and Why is North Korea Developing Them?

Hwasong-18 intercontinental ballistic missile is launched from an undisclosed location in North Korea in this image released by North Korea's Korean Central News Agency on July 13, 2023. KCNA via REUTERS
Hwasong-18 intercontinental ballistic missile is launched from an undisclosed location in North Korea in this image released by North Korea's Korean Central News Agency on July 13, 2023. KCNA via REUTERS
TT
TT

What are Solid-fuel Missiles, and Why is North Korea Developing Them?

Hwasong-18 intercontinental ballistic missile is launched from an undisclosed location in North Korea in this image released by North Korea's Korean Central News Agency on July 13, 2023. KCNA via REUTERS
Hwasong-18 intercontinental ballistic missile is launched from an undisclosed location in North Korea in this image released by North Korea's Korean Central News Agency on July 13, 2023. KCNA via REUTERS

North Korea launched a suspected intermediate-range ballistic missile (IRBM) on Tuesday, in what South Korean officials said could be related to its development of a new solid-fuel hypersonic weapon.
The launch comes after North Korean leader Kim Jong Un oversaw a ground test of a solid-fuel engine for a new type of intermediate-range hypersonic missile to develop national defense capability, state media reported in March.
In January, North Korea test fired an IRBM that it said was equipped with a hypersonic maneuverable controlled warhead. State media did not immediately disclose details of Tuesday's launch.
Here are some characteristics of solid-fuel technology, and how it can help the nuclear-armed North improve its missile systems.
WHAT ARE SOME ADVANTAGES OF SOLID FUEL?
Solid-fuel missiles do not need to be fueled immediately ahead of launch, are often easier and safer to operate, and require less logistical support, making them harder to detect and more survivable than liquid-fuel weapons, reported Reuters.
"These capabilities are much more responsive in a time of crisis," said Ankit Panda, a senior fellow at the US-based Carnegie Endowment for International Peace.
WHAT IS SOLID-FUEL TECHNOLOGY?
Solid propellants are a mixture of fuel and oxidizer. Metallic powders such as aluminum often serve as the fuel, and ammonium perchlorate, which is the salt of perchloric acid and ammonia, is the most common oxidizer.
The fuel and oxidizer are bound together by a hard rubbery material and packed into a metal casing.
When solid propellant burns, oxygen from the ammonium perchlorate combines with aluminum to generate enormous amounts of energy and temperatures of more than 5,000 degrees Fahrenheit (2,760 degrees Celsius), creating thrust and lifting the missile from the launch pad.
WHO HAS THAT TECHNOLOGY?
Solid fuel dates back to fireworks developed by the Chinese centuries ago, but made dramatic progress in the mid-20th century, when the US developed more powerful propellants.
North Korea uses solid fuel in a range of small, shorter-range ballistic missiles, as well as in its new Hwasong-18 intercontinental ballistic missile (ICBM).
The Soviet Union fielded its first solid-fuel ICBM, the RT-2, in the early 1970s, followed by France's development of its S3, also known as SSBS, a medium-range ballistic missile.
China started testing solid-fuel ICBMs in the late 1990s.
South Korea has also said it has secured "efficient and advanced" solid-propellant ballistic missile technology, though in much smaller rockets so far.
SOLID VS LIQUID
Liquid propellants provide greater propulsive thrust and power, but require more complex technology and extra weight.
Solid fuel is dense and burns quite quickly, generating thrust over a short time. Solid fuel can remain in storage for an extended period without degrading or breaking down - a common issue with liquid fuel.
North Korea said the development of its solid-fuel ICBM, the Hwasong-18, would "radically promote" its nuclear counterattack capability.
After the first launch South Korea's defense ministry sought to downplay the testing, saying the North would need "extra time and effort" to master the technology.

Most Viewed

 
 
Features

New Mpox Strain Is Changing Fast; African Scientists Are ‘Working Blind’ to Respond 

Dr. Robert Musole, medical director of the Kavumu hospital (R) consults an infant suffering from a severe form of mpox at the Kavumu hospital, 30 km north of Bukavu in eastern Democratic Republic of Congo, August 24, 2024. (AFP)
Dr. Robert Musole, medical director of the Kavumu hospital (R) consults an infant suffering from a severe form of mpox at the Kavumu hospital, 30 km north of Bukavu in eastern Democratic Republic of Congo, August 24, 2024. (AFP)
TT
TT

New Mpox Strain Is Changing Fast; African Scientists Are ‘Working Blind’ to Respond 

Dr. Robert Musole, medical director of the Kavumu hospital (R) consults an infant suffering from a severe form of mpox at the Kavumu hospital, 30 km north of Bukavu in eastern Democratic Republic of Congo, August 24, 2024. (AFP)
Dr. Robert Musole, medical director of the Kavumu hospital (R) consults an infant suffering from a severe form of mpox at the Kavumu hospital, 30 km north of Bukavu in eastern Democratic Republic of Congo, August 24, 2024. (AFP)

Scientists studying the new mpox strain that has spread out of Democratic Republic of Congo say the virus is changing faster than expected, and often in areas where experts lack the funding and equipment to properly track it.

That means there are numerous unknowns about the virus itself, its severity and how it is transmitting, complicating the response, half a dozen scientists in Africa, Europe and the United States told Reuters.

Mpox, formerly known as monkeypox, has been a public health problem in parts of Africa since 1970, but received little global attention until it surged internationally in 2022, prompting the World Health Organization to declare a global health emergency. That declaration ended 10 months later.

A new strain of the virus, known as clade Ib, has the world's attention again after the WHO declared a new health emergency.

The strain is a mutated version of clade I, a form of mpox spread by contact with infected animals that has been endemic in Congo for decades. Mpox typically causes flu-like symptoms and pus-filled lesions and can kill.

Congo has had more than 18,000 suspected clade I and clade Ib mpox cases and 615 deaths this year, according to the WHO. There have also been 222 confirmed clade Ib cases in four African countries in the last month, plus a case each in Sweden and Thailand in people with a travel history in Africa.

"I worry that in Africa, we are working blindly," said Dr. Dimie Ogoina, an infectious diseases expert at Niger Delta University Hospital in Nigeria who chairs the WHO's mpox emergency committee. He first raised the alarm about potential sexual transmission of mpox in 2017, now an accepted route of spread for the virus.

"We don’t understand our outbreak very well, and if we don't understand our outbreak very well, we will have difficulty addressing the problem in terms of transmission dynamics, the severity of the disease, risk factors of the disease," Ogoina said. "And I worry about the fact that the virus seems to be mutating and producing new strains."

He said it took clade IIb in Nigeria five years or more to evolve enough for sustained spread among humans, sparking the 2022 global outbreak. Clade Ib has done the same thing in less than a year.

MUTATING 'MORE RAPIDLY'

Mpox is an orthopoxvirus, from the family that causes smallpox. Population-wide protection from a global smallpox vaccine campaign 50 years ago has waned, as the vaccinating stopped when the disease was eradicated.

Genetic sequencing of clade Ib infections, which the WHO estimates emerged mid-September 2023, show they carry a mutation known as APOBEC3, a signature of adaptation in humans.

The virus that causes mpox has typically been fairly stable and slow to mutate, but APOBEC-driven mutations can accelerate viral evolution, said Dr. Miguel Paredes, who is studying the evolution of mpox and other viruses at Fred Hutchison Cancer Center in Seattle.

"All the human-to-human cases of mpox have this APOBEC signature of mutations, which means that it's mutating a little bit more rapidly than we would expect," he said.

Paredes and other scientists said a response was complicated by several mpox outbreaks happening at once.

In the past, mpox was predominantly acquired through human contact with infected animals. That is still driving a rise in Congo in clade I cases – also known as clade Ia - likely due in part to deforestation and increased consumption of bushmeat, scientists said.

The mutated versions, clade Ib and IIb, can now essentially be considered a sexually transmitted disease, said Dr. Salim Abdool Karim, a South African epidemiologist and chair of the Africa CDC’s mpox advisory committee. Most of the mutated clade Ib cases are among adults, driven at first by an epidemic among female sex workers in South Kivu, Congo.

The virus also can spread through close contact with an infected person, which is likely how clusters of children have been infected with clade Ib, particularly in Burundi and in eastern Congo’s displacement camps, where crowded living conditions may be contributing.

Children, pregnant women and people with weakened immune systems or other illnesses may be at greater risk of serious mpox disease and death, say the WHO and mpox scientists.

Clade I has typically caused more severe disease, with fatality rates of 4%-11%, compared to around 1% for clade II. Ogoina said data from Congo suggests few have died of the new Ib version, but he feared some data is being mixed up.

More research is urgently needed, but three teams tracking mpox outbreaks in Africa say they cannot even access chemicals needed for diagnostic tests. Clade Ib can also be missed by some diagnostic tests.

Planning a response, including vaccination strategies, without this is difficult, the scientists said.

Karim said around half of cases in eastern Congo, where Ib is particularly prevalent, are only being diagnosed by doctors, with no laboratory confirmation.

Getting samples to labs is difficult because the healthcare system is already under pressure, he said. And around 750,000 people have been displaced amid fighting between the M23 rebel group and the government.

Many African laboratories cannot get the supplies they need, said Dr. Emmanuel Nakoune, an mpox expert at the Institut Pasteur in Bangui, Central African Republic, which also has clade Ia cases.

"This is not a luxury," he said, but necessary to track deadly outbreaks.