How fast can we travel in space with current technology?
The current human speed record is shared equally by the trio of astronauts who flew Nasa's Apollo 10 mission. On their way back from a lap around the Moon in 1969, the astronauts' capsule hit a peak of 24,790mph (39,897km/h) relative to planet Earth.
These New Technologies Could Make Interstellar Travel Real
On October 31, 1936, six young tinkerers nicknamed the “Rocket Boys” nearly incinerated themselves in an effort to break free of Earth’s gravity. The group had huddled in a gully in the foothills of California’s San Gabriel Mountains to test a small alcohol-fueled jet engine. They wanted to prove that rocket engines could venture into space, at a time when such ideas were widely met with ridicule. That goal was disrupted when an oxygen line caught fire and thrashed around wildly, shooting flames.
For Brophy, inspiration came from Breakthrough Starshot, an extravagantly bold project announced in 2016 by the late Stephen Hawking and Russian billionaire Yuri Milner. The ultimate aim of the project is to build a mile-wide laser array that could blast a miniature spacecraft to 20 percent the speed of light, allowing it to reach the Alpha Centauri star system (our closest stellar neighbor) in just two decades.
Since his graduate student days in the late 1970s, Brophy has been developing a vastly more efficient type of rocketry known as ion propulsion. An ion engine uses electric power to shoot positively charged atoms (called ions) out of a thruster at high velocity. Each atom provides just a tiny kick, but collectively they can push the rocket to a much greater velocity than a conventional chemical rocket. Better yet, the power needed to run the ion engine can come from solar panels — no heavy onboard fuel tanks or generators required. By squeezing more speed out of less propellant, ion propulsion goes a long way toward taming the rocket equation.
TwoBrophy describes a lithium-ion-powered spacecraft with 300-foot wings of photovoltaic panels powering a full-size version of the engine he is developing at JPL. The laser would bathe the panels in light a hundred times as bright as sunshine, keeping the ion engine running from here to Pluto, about 4 billion miles away. The spacecraft could then coast along on its considerable velocity, racking up another 4 billion miles every year or two.
Alkalai wants answers, and he wants to see the results firsthand. He’s 60, so that sets an aggressive schedule — no time to wait for giant space lasers. Instead, he proposes a simpler, albeit still unproven, technology known as a solar thermal rocket. It would carry a large cache of cold liquid hydrogen, protected somehow from the heat of the sun, and execute a shocking dive to within about 1 million miles of the solar surface. At closest approach, the rocket would let the intense solar heat come pouring in, perhaps by jettisoning a shield. The sun’s energy would rapidly vaporize the hydrogen, sending it racing out of a rocket nozzle. The combined push from the escaping hydrogen, and the assist from the sun’s own gravity, would let the ship start its interstellar journey at speeds up to 60 miles per second, faster than any human object yet —and it only gets faster from there.
Solar Gravitational Lens
Solar thermal rockets and laser-ion engines, impressive as they may be, are still absurdly inadequate for crossing the tremendous gulf between our solar system and exoplanets — planets orbiting other stars. In the spirit of the Rocket Boys, Turyshev is not letting absurdity stop him. He is developing a cunning workaround: a virtual mission to another star.
“Ultimately, to see the life on an exoplanet, we will have to visit. But a gravity lens mission allows you to study potential targets many decades, if not centuries, earlier,” Turyshev says merrily.
A journey to the SGL would take us beyond Alkalai’s baby steps, well onto the path toward interstellar exploration. It’s another audacious goal, but at least the odds of catching fire are much lower this time around.
How far in space have we gone?
It has travelled more than 11 billion miles since it was launched nearly 36 years ago. And now Voyager 1 has boldly gone where no spacecraft has gone before – it has left the outer reaches of the Solar System. It is the furthest man-made object in space.