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
Rocket boys
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.
Jay Smith/Discover
Rocket Reactions
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.
NASA-JPL/Caltech
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.
InterstellarMedium
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?
2/2 voyager.ap.jpg
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.