On the dark side of the moon

Instead, it was a rocket carrying a spacecraft named Orion—the first of the Artemis missions, Artemis-I. It lifted off from Florida at precisely 1217 IST, soaring into the sky on pillars of orange fire that turned the night there nearly into day. In August and September, two previous attempts to launch Artemis-I were aborted at nearly the last minute because of unexpected leaks. That made this spectacular success all the more exhilarating to watch. The wait was definitely worth it.

Unmanned Orion is the initial thrust in mankind’s effort to return to the Moon. That is, taking humans there. Next month, it will be half a century since humans last set foot on our satellite, with the Apollo 17 mission. That passage of time alone makes the Artemis programme a very big deal. If Artemis-I is a success, the next mission will carry humans. First, to and around the Moon. After that, touching down so humans will roam again on the Moon.

In fact, Artemis is even more ambitious than that. This return to the Moon is an initial step in a complex, far-reaching effort to establish a viable long-term human presence on the Moon. Eventually, mankind will use that as a base to send humans elsewhere in space. Like Mars.

Big goals. For now, there are lesser, but still necessary and substantial, steps that Orion will take. Consider this. It will travel some 450,000 km from the Earth. At its farthest, it will be about 65,000 km beyond the “other” side of the Moon—which we Earth-bound humans never see. This is the deepest into space that any mission designed to ferry humans has ever penetrated.

From there, Orion will return to Earth. Whether it can do so safely is a major part of this test. Apart from whatever the long journey itself throws up, if anything, it has to re-enter the Earth’s atmosphere. It will be travelling at about 40,000 kmph when that happens. Friction with the atmosphere will slow it to about 500 kmph. That kind of friction produces extreme heat, so a heat shield protects Orion. It will have to withstand temperatures reaching nearly 3,000 degrees Celsius.

Once it does that, Orion will deploy a total of five parachutes. Those will slow its descent down to about 30 kmph. Then it will splash gently into the Pacific Ocean off the coast of southern California.

And if all that isn’t complex enough, there are the intricate manoeuvres that make this journey possible to begin with, for this is not like shooting a bullet at the Moon. Instead, the craft uses both celestial bodies’ gravities to “catapult” itself through space.

After take-off, Orion orbited the Earth, deployed arrays of solar panels to tap the Sun’s energy, and then initiated a “Trans Lunar Injection Burn”. Riding the momentum built up from the orbit, Orion fired its engines for 20 minutes, enough to escape Earth’s gravitational pull and set a course for the Moon. That’s the first catapult.

With the TLI Burn finished, Orion separated itself from the rocket mechanism (“stage”) that set it on this precise Moon-bound path. But that stage had more work to do. It deployed several “CubeSats”, tiny satellites weighing just 2 kg each. They will study the Moon or be set to other tasks; there are already close to 2,000 such miniature satellites in space.

But back with Orion, things get even more interesting as it nears the Moon. First, the Moon’s gravity captures the craft, drawing it into an orbit that takes it to within 100 km of the surface. Again, Orion will fire its engines as it swings around, catapulting itself into what’s called a “Distant Retrograde Orbit”. This is the path that will swing out 65,000 km beyond the Moon; “retrograde” because it is opposite to the Moon’s own rotation.

From there, Orion circles back, approaching the Moon again. Once more, it will swoop in and around, once more approaching within 100 or so km of the surface, once more seeking a catapult thrust. This time, the boost will let Orion set its sights on the Earth. At the right moment on that flyby, it will fire its engines and escape the Moon’s gravity.

A few days later, there’s that encounter with the Earth’s atmosphere.

None of this is new or surprising. After all, much the same kind of orbiting and catapulting manoeuvres fired India’s own Chandrayaan and Mangalyaan missions towards the Moon and Mars, respectively. But even so, that we humans can plan and execute a space mission with such precision is always enough to take my breath away, every time. That this is just a trial run for far more complex missions is … I don’t know what.

No, I don’t have the words to express the upwelling of awe that I feel. In a world riven by divisive politics and war, hatred and climate change, extreme poverty and extreme wealth, it is almost a miracle to know there are women and men who are showing us the promise and wonder of science, who are expanding our species’ reach, vision and imagination.

And maybe all of that is why I find new meaning in Pink Floyd’s classic, but otherwise ominous, words:

“And if the cloud bursts, thunder in your ear.

You shout, and no one seems to hear.

And if the band you’re in starts playing different tunes,

I’ll see you on the dark side of the Moon.”

I’ll see you, and maybe it’s not so dark.

Once a computer scientist, Dilip D’Souza now lives in Mumbai and writes for his dinners. His Twitter handle is @DeathEndsFun.