How destructive are Russia's nuclear weapons and could it use them in the Ukraine war? DART: What you need to know about NASA's mission to smash a spacecraft into an asteroid

EuronewsSept 23, 2022Read original

Over the past six months, Russia has repeatedly waved the threat of using nuclear force to have the upper hand in its war in Ukraine.

This week, President Vladimir Putin announced a

of reservists and issued another thinly-veiled threat of Moscow’s readiness to use nuclear weapons in the conflict.

His televised address came days after the Ukrainian army pulled off a surprise counteroffensive to recapture territory around its second-largest city, Kharkiv, in the east.

"I want to remind you that our country also has various means of destruction... and when the territorial integrity of our country is threatened, to protect Russia and our people, we will certainly use all the means at our disposal," Putin said.

"It’s not a bluff," he added.

The comments sparked

in the West, with US president Joe Biden accusing Russia of making "reckless" and "irresponsible" threats.

"A nuclear war cannot be won and must never be fought," Biden told the United Nations General Assembly, repeating a Cold War pledge from both countries to abide by the 1968 Treaty on the Non-Proliferation of Nuclear Weapons.

So, what nuclear weapons does Russia have at its disposal, and how destructive could they be?

Nuclear weapons have never been used in a war since 1945, when the two atomic bombs dropped by the United States on Hiroshima and Nagasaki devastated the Japanese cities and instantly killed tens of thousands of people.

"That's a 76-year tradition of non-use of nuclear weapons. And that is the single most important feature of the nuclear age, and we really want to keep it that way," Nina Tannenwald, senior lecturer in international relations at Brown University in the US, told Euronews Next.

The horror of the bombings shocked the world into the age of nuclear deterrence, where global powers raced to develop such weapons, all the while knowing that their use would be catastrophic for humanity - and thus refraining from wielding them against one another.

Nowadays, Russia has the world’s largest nuclear arsenal with around 6,257 nuclear warheads, while the United States admits to having 5,550, according to a

.

Of these, the so-called "strategic" weapons - those with the largest yield - are deployed on submarines, bombers and intercontinental ballistic missiles.

"Strategic nuclear weapons are the big city busters," said Tannenwald, who authored a book on nuclear deterrence.

"These are unbelievably destructive weapons. If we got into a nuclear war with strategic weapons, that would be essentially the end of civilisation in both countries".

But some 2,000 of Russia’s nuclear warheads are short-range, so-called “tactical” nuclear weapons kept in storage facilities throughout the country.

These are much smaller nuclear weapons, designed to be used on the battlefield against troop formations, tanks, or military installations and bunkers.

These can be launched on the same short-range missiles Russia is currently using to bombard Ukraine, such as its Iskander-M ballistic missile, which has a range of about 500 km.

Tactical weapons were developed during the Cold War with the aim to "enhance" nuclear deterrence, said Tannenwald.

"Because the concern was, well if all you have is these really big city-busting weapons, people are going to be too afraid to use those, they're just too destructive. And therefore, the deterrent threat at some point is less credible," she said.

"The argument was: If you have these smaller, less destructive nuclear weapons, the threat to use them would be more credible because they're less damaging and therefore deterrence would be stronger".

The risk today, however, is that "they do appear to be more usable and therefore it makes it more likely that leaders could reach for them in a crisis".

Pavel Podvig, an expert on Russian nuclear forces and senior researcher at the United Nations Institute for Disarmament Research (UNIDIR), says there are very few scenarios in the battlefield where the immense power yielded by nuclear weapons might actually have a tactical purpose - for example, to destroy hardened underground structures or bunkers.

He argues that the main goal of tactical nuclear weapons remains a strategic one: to terrorise the enemy and gain the upper hand in a conflict.

"This whole notion of mini-nukes or limited strikes is just a way of finding a mission for those weapons and somehow justify their existence," Podvig told Euronews Next.

"Their main mission is not attacking military targets. The main mission of these weapons is to demonstrate your willingness and readiness to attack and kill a lot, a lot of civilians".

Most nuclear weapons nowadays are variable-yield, or "dial-a-yield," meaning their amount of explosive energy can be dialled up or down depending on the military situation and objectives.

For example, the latest version of the B61 nuclear bomb developed by the US

. In comparison, the Hiroshima bomb packed a force of about 15 kilotons.

"We're talking about still incredibly destructive weapons," Tannenwald said.

"And they are nuclear weapons, so they would produce a mushroom cloud, a fireball. They would set fire to everything in sight. They would release massive amounts of radiation. So nobody should think that these are somehow actually more usable weapons".

In the first-of-its-kind, save-the-world experiment, NASA is about to clobber a small, harmless asteroid millions of kilometres away.

A spacecraft named DART (Double Asteroid Redirection Test) will zero in on the asteroid on Monday, intent on slamming it head-on at 22,500 km/h.

The impact should be just enough to nudge the asteroid into a slightly tighter orbit around its companion space rock – demonstrating that if a killer asteroid ever heads our way, we’d stand a fighting chance of diverting it.

“This is stuff of science-fiction books and really corny episodes of “StarTrek” from when I was a kid, and now it's real,” NASA program scientist Tom Statler said on Thursday.

Cameras and telescopes will watch the crash, but it will take days or even weeks to find out if it actually changed the orbit.

The $325 million (€333 million) planetary defense test began with DART's launch last year.

The asteroid with the bull’s-eye on it is Dimorphos, about 9.6 million kilometres from Earth. It is actually the puny sidekick of a 780-metre asteroid named Didymos, Greek for twin.

Discovered in 1996, Didymos is spinning so fast that scientists believe it flung off material that eventually formed a moonlet. Dimorphos – roughly 160 metres across – orbits its parent body at a distance of less than 1.2 kilometres.

“This really is about asteroid deflection, not disruption," said Nancy Chabot, a planetary scientist and mission team leader at Johns Hopkins University's Applied Physics Laboratory, which is managing the effort.

"This isn’t going to blow up the asteroid. It isn’t going to put it into lots of pieces.”

Rather, the impact will dig out a crater tens of metres in size and hurl about 1 million kg of rocks and dirt into space.

NASA insists there’s zero chance either asteroid will threaten Earth – now or in the future. That’s why the pair was picked.

The Johns Hopkins lab took a minimalist approach in developing DART given that it’s essentially a battering ram and faces sure destruction.

It has a single instrument: a camera used for navigating, targeting and chronicling the final action.

Believed to be essentially a rubble pile, Dimorphos will emerge as a point of light an hour before impact, looming larger and larger in the camera images beamed back to Earth.

Sometimes we describe it as running a golf cart into a Great Pyramid

Nancy Chabot

DART mission team leader

Managers are confident DART won’t smash into the larger Didymos by mistake. The spacecraft’s navigation is designed to distinguish between the two asteroids and, in the final 50 minutes, target the smaller one.

The size of a small vending machine at 570 kg, the spacecraft will slam into roughly 5 billion kg of asteroid.

“Sometimes we describe it as running a golf cart into a Great Pyramid,” said Chabot.

Unless DART misses its target – NASA puts the odds of that happening at less than 10 per cent – it will be the end of the road for the spacecraft.

If it goes screaming past both space rocks, it will encounter them again in a couple of years for Take 2.

Little Dimorphos completes a lap around big Didymos every 11 hours and 55 minutes. The impact by DART should shave about 10 minutes off that.

Although the strike itself should be immediately apparent, it could take a few weeks or more to verify the moonlet’s tweaked orbit. Cameras on DART and a mini tagalong satellite will capture the collision up close.

Telescopes on all seven continents, along with the Hubble and Webb space telescopes and NASA’s asteroid-hunting Lucy spacecraft, may see a bright flash as DART smacks Dimorphos and sends streams of rock and dirt cascading into space.

This is why we test. We want to do it now rather than when there’s an actual need

Andrea Riley

NASA program executive

The observatories will track the pair of asteroids as they circle the sun, to see if DART altered Dimorphos’ orbit.

In 2024, a European spacecraft named Hera will retrace DART’s journey to measure the impact results.

Although the intended nudge should change the moonlet’s position only slightly, that will add up to a major shift over time, according to Chabot.

"So if you were going to do this for planetary defense, you would do it five, 10, 15, 20 years in advance in order for this technique to work,” she said.

Even if DART misses, the experiment still will provide valuable insight, said NASA program executive Andrea Riley.

“This is why we test. We want to do it now rather than when there’s an actual need,” she said.

Planet Earth is on an asteroid-chasing roll. NASA has close to 450 g of rubble collected from asteroid Bennu headed to Earth. The stash should arrive next September.

Japan was the first to retrieve asteroid samples, accomplishing the feat twice. China hopes to follow suit with a mission launching in 2025.

NASA’s Lucy spacecraft, meanwhile, is headed to asteroids near Jupiter, after launching last year.

Another spacecraft, Near-Earth Asteroid Scout, is loaded into NASA’s new moon rocket awaiting liftoff; it will use a solar sail to fly past a space rock that’s less than 18 metres next year.

In the next few years, NASA also plans to launch a census-taking telescope to identify hard-to-find asteroids that could pose risks.

One asteroid mission is grounded while an independent review board weighs its future. NASA’s Psyche spacecraft should have launched this year to a metal-rich asteroid between Mars and Jupiter, but the team couldn’t test the flight software in time.

Hollywood has churned out dozens of killer-space-rock movies over the decades, including 1998′s “Armageddon” which brought Bruce Willis to Cape Canaveral for filming, and last year's “Don’t Look Up” with Leonardo DiCaprio leading an all-star cast.

The good news is that the coast seems clear for the next century, with no known threats.

What’s worrisome, though, are the unknown threats. Fewer than half of the 140-metre objects have been confirmed, with millions of smaller but still-dangerous objects zooming around.

“These threats are real, and what makes this time special, is we can do something about it,” Zurbuchen said.

Not by blowing up an asteroid as Willis’ character did — that would be a last, last-minute resort — or by begging government leaders to take action as DiCaprio’s character did in vain. If time allows, the best tactic could be to nudge the menacing asteroid out of our way, like DART.