Itâ€™s true what they say. In space â€“ if youâ€™re out and about as opposed to in a spaceship â€“ no one can hear you scream. There may be sound waves but thereâ€™s nothing for them to shake, so nothing to hear. In the same way, around two months ago, when Nasa fulfilled the dream of one of its more visionary scientists by landing a spacecraft on an asteroid 200 million miles away and shoving a probe into its surface, it will have been almost completely inaudible.Â
The end of the probe looked like an air filter from a car. As the spacecraft touched down, the probe went about a foot into the asteroid (named Bennu after a mythical Egyptian bird). A blast of compressed nitrogen stirred up the dust and pebbles around it and some of them were sucked into a container the size of an instant coffee jar. Then the spacecraft backed away.
The whole encounter â€“ at the midpoint of a seven-year journey â€“ took about six seconds. If youâ€™d been there with a microphone or an ear right next to the probe you might have picked up a quick phut from the nitrogen. Otherwise, silence, like a thief in the night.Â
As a species weâ€™re getting good at this stuff. On 6 December, a Japanese space capsule 40 centimetres across dropped into the Earthâ€™s atmosphere at the end of another long journey to another asteroid, landing in the Australian outback. Five days before that, the Chinese landed a rover on the moon where it will get busy with a remote-controlled bucket and spade to bring back the first lunar regolith (rocks and soil) in 44 years.Â
And seven days before that, SpaceX, the American space upstart, conducted its 23rd launch of the year to put 60 small satellites in orbit, for a total of more than 800 in this particular communications system.Â
If you were visiting our solar system from elsewhere, pausing with a telescope somewhere between, say, Jupiter and Mars, you probably wouldnâ€™t be scribbling notes about Covid. If you were interested in Earth at all youâ€™d be scribbling about rockets, probes and satellites. In our close cosmic neighborhood, we donâ€™t look sick or fearful or locked down. We look busy. Weâ€™ve been â€“ quietly â€“ getting on with it.
This hush that hangs over space travel is not just a function of the great vacuum beyond our atmosphere. Itâ€™s also a function of computing. Itâ€™s often said thereâ€™s more computer power in a modern smartphone than there was in the entire Apollo 11 mission, and the corollary of that is that thereâ€™s more computer power in a modern rocket than we can possibly imagine.
Everythingâ€™s so automated that thereâ€™s not much left to chat about. For the first 40 seconds of that SpaceX flight, mission control barely said a word. Why bother? Everything was going flawlessly, and if something went wrong the algorithms would find the next-best scenario at the speed of light. So no role for people there either.
We should be clear that a lot still can go wrong. More than ever, in fact. The first stage booster of the Falcon 9 rocket used to put those satellites in orbit was being used a record seventh time. Getting a booster back from orbit in one piece to reuse it over and over again is a trick Nasa never even tried. It depends on thrust vectors, cold gas thrusters, reigniting engines, inertial and GPS navigation systems and titanium grid fins all working in perfect harmony to drop the booster with near perfect accuracy on a barge in the Atlantic in the middle of the night.Â
This isnâ€™t traditional rocketry. Itâ€™s rocketry fired up with AI, in which humans write the code and then let cooler heads take care of operations. The booming space sector is distinguishing itself with work thatâ€™s calm and purposeful and astonishingly sophisticated.
Which brings us back to Bennu. When planning missions to deep space you have to think ahead, and Nasaâ€™s visit to Bennu was conceived at the beginning of this century by Dr Michael Drake, a planetary scientist born in England who moved to Arizona in the 70s and never left.Â
Drakeâ€™s interest was, as he put it, in â€śthe origins and destiny of humanityâ€ť. He sought answers in asteroids for two reasons. The first was that theyâ€™re time capsules, apparently undisturbed since their formation in a catastrophic nebula collapse 4.5 billion years ago. The difference between carboniferous compounds on their surface and Earthâ€™s could reveal a lot about the emergence of life in the interim, says Erin Morton, who works at the Lunar and Planetary Laboratory in Tucson that Drake used to run. â€śOn Bennu theyâ€™re pristine,â€ť she says. â€śNo weathering by water, wind, atmosphere, people or bugs.â€ť The question, beyond that, is how theyâ€™re different and whether those that hit Earth in the past could have seeded life.
The second reason to pay attention to asteroids is that they could hit Earth again in the future and wipe us out (hence, destiny). So it would be useful to know how to nudge them off their course.Â
Drake chose an asteroid as wide as the Eiffel Tower is high that looked rich in carbon and could hit Earth within the next two centuries. At the time it was called 1999-RQ36. Once selected as the target of an $800 million Nasa expedition, it was renamed Bennu by a schoolboy from North Carolina.Â
Drake died soon afterwards, in 2011, but the mission he dreamed about has already yielded surprises. Bennu was expected to be solid and covered in sand, for example, but turns out to be full of voids and covered in boulders. Morton says that once Nasaâ€™s coffee jar of dust and pebbles makes it back to Earth â€śwe expect Bennu to surprise us againâ€ť. Cue screams, of one sort or another.