* * * * * HALFWAY! * * * * *

There was no media blitz announcing it; no blaring trumpets, no flag-waving or cheering to celebrate it. But quietly, without any fuss or fanfare, sometime in the last day or so the Mars Exploration Rover “Opportunity“, now ‘2,355 days into its 90 day mission’ on the Red Planet, passed a major milestone on its epic trek to the huge Endeavour Crater.

A roll of its wheels took it halfway there.

‘Halfway’, that is, in terms of the driving distance between Victoria Crater – that beautiful, ancient, scalloped-edged, dune-filled bowl of an impact scar it spent a year exploring and studying and driving around – and the much larger, much older and potentially much more scientifically exciting crater “Endeavour”, which was named after the legendary ship of legendary explorer Captain Cook.

Oppy, as regular readers of this blog will know, is currently enjoying crossing a relatively flat area marked with patches of exposed bedrock criss-crossed by low, undulating dust dunes. It’s “good driving country” for the rover because it’s relatively flat, which is helping Oppy to clock up drives of 100m or so now, as her drivers, more and more confident in her abilities, and now using new and innovative driving techniques, steer her skilfully from one patch of bedrock to the next, like a frog crossing a river or pond by hopping from one lilly pad to another…

Oppy reached this “pavement” after spending month after seemingly-endless month slogging south and then east across a much less rover-friendly landscape of much more tightly-packed, much taller dunes that looked so much like the deep desert of Arrakis that no-one would have been too surprised to see a might sandworm erupting out of the ground in the distance…! Along the way she found many wind-carved meteorites, like this one…

… and studied intriguing blocks of ancient stone hurled into her path by impacts that shook this region of Barsoom millennia ago, like this one…

But all the while, ever since leaving the edge of Victoria Crater in fact, her eyes – and the eyes of the amazing science team behind her, and the eyes of rover fans around the world, too – have been on the horizon, focussed on what started out as a series of barely-there bumps but have grown over the weeks and months into a range of mountains that Ansell Adams would have loved to have painted.

Some of those mountains are the far rim of Endeavour Crater, great slopes of cratered rock that, as the picture below shows, are more than TWICE as far away from “Cape York” – the hillock section of the near rim which is expected to be Oppy’s landfall in a year or so’s time – as Oppy is from Cape York now!

So, obviously Oppy will never, never reach those stunning-looking faraway hills, but they are the features that are leading her onwards, onwards across the rippled dust sea of Meridiani. And although it (STILL!!!!! AAGGGHHH!!!!!) hasn’t got a name, the crater blasted out of those towering mountains on Endeavour’s far side is starting to resemble a giant, dark eye, watching over Oppy as she rolls steadily eastwards, towards what will in all probability be not just her final resting place but the most scientifically rewarding part of her whole mission, too…

Oppy’s latest drive was around 110m. Now, that might seem pretty modest, pathetic even, in our terms, and when I told someone at work how far Oppy had trundled on her last big driving daty they scoffed “100m? Is that all? That’s not very far, is it?! I could walk that in a few seconds!” Which is true, they could… probably… possibly… but they’re completely missing the point. Oppy is a rover, a robot, essentially a six-wheeled science cart that was dropped onto Mars by parachute and sent off to look for interesting stuff. It does that, brilliantly, but it is remotely controlled, from Earth, a world a hundred million miles away sometimes, so it can’t go haring off into the high martian desert shouting “Meep! Meep!!” like Roadrunner, it has to do travel oh-so-slowly because Mars likes nothing better than killing the machines Mankind sends to study it, and having tricked Spirit, Oppy’s “sister rover” into driving into and getting well and truly stuck in a camouflaged, dust-filled crater, the Red Planet would absolutely love to trap or kill Oppy too by having her drive recklessly into some pit or crack or fault that loomed up out of nowhere without warning. So, while 100m is, literally, a walk in the park for us, and can be covered by an Olympic sprinter in less than ten seconds, for Oppy, completing a 100m drive is like completing a marathon.

I was wondering about this recently, and decided to see for myself just how far 100m really is. Well, I mean, I know how far 100m is… it’s 100m… I meant how far 100m is in relation to my everyday world, or at least something familiar to me; I wanted to get a feel for just how quickly – or slowly – Oppy is driving across Meridiani. What familiar distance. or feature, could I compare a good 100m+ Meridiani drive to..?

Well, it turns out that the distance between the two towers of the Golden Gate Bridge is (Google-Earth-roughly) 1.3km…

That means it would take a dozen or so of Oppy’s 100m+ drives to cross it…

Hmm. Interesting! But still a bit abstract’; I wanted to get a feel for how long these loooong drives of Oppy’s are in relation to my day to day world. I needed a comparison closer to home.

…and it turns out that my very favourite part of my daily 1km walk to work route is 110m long – the same distance travelled by Oppy during her most recent long drive… 🙂

I made that walk this morning, at 7am. It’s one of the highlights of my day, to be honest, a genuine “calm before the storm” relaxing treat before I walk through the front door of the care home where I work and – well, you can fill in the blanks yourself. I love that 110m section of the walk because it runs beside the river Kent that flows through my town, and as I walk alongside it, watching the waters whirling and swirling, I often see a heron on the river, either standing on a stone, sentinel-still, or, if I’m lucky, flying upstream, its great wings wafting up and down, and up down, making it look like a pterodactyl as it powers its way up the river.

So, having worked that out, this morning’s walk to work was just a little bit more special, because, just for a short time, I “was” Oppy, wheels rolling, crossing another 100m or so off the journety to Endeavour. And as I went along the river, in the rain, under a leaden grey sky, walking under a canopy of lush, fat, green leaves that dripped water down my neck and onto my face as I passed under them, I was thinking about Oppy, out there on Mars, rolling across that vast, open, dune-rippled desert, getting slowly, slowly but ever closer to her goal…

It’s amazing to think that Oppy is now halfway to that goal. That’s a very emotive word, “halfway”. All journeys, long or short, epic or modest, have a “halfway point”. When it’s reached, a decision often has to be made – to turn around and go back again, or to push on, on, on, and strive even harder to reach the destination. But unlike mountain climbers, desert trekkers or deep sea divers, Oppy can’t turn back. Why would she? To go back and look at those (lovely!) meteorites again? To slog all the way north back to the jagged edge of Victoria Crater to take pictures of its slopes, bays and cliffs from just a slightly different view?

No. Oppy is heading east, and she will keep heading east from now on. Now, every turn of her wheel will bring her just a little bit closer to Cape York. Every precious centimetre she rolls across “The Pavement” will bring her a precious centimetre closer to the wonderfully flat terrain nicknamed “The Parking Lot”, which is so flat and dune-free that it will allow Oppy to fairly hare along towards Endeavour. And once on the “Lot”, every metre she rolls across that rocky ground will bring her a metre closer to the foothills of Cape York, where she might find clay-rich deposits, which would do nothing less than transform the whole MER mission…

But where is Oppy heading now? Well, she might be heading a little to the south, instead of due east, because there’s a very interesting looking group of craters down there that might be too tantalising a target for the rover team to ignore…

Here’s that “crater cluster” in more detail…

Now, groups of craters like that aren’t rare, they’re pretty common actually, and they are formed when either a) a single object breaks up above an impact site, like an exploding shell, each piece creating its own crater, or b) when a hail of objects hits the surface at the same time. Either way it’s a fascinating-looking place. Let’s see how big those craters are compared to Oppy… (I’ve superimposed Oppy on the next picture, at the correct scale. She’s the blurry dotty thingy on the end of the dark, winding trail that comes in from the left…)

I’d love to see Oppy trundle up to them to take some close-up images of those craters. Maybe there are some pieces of the meteorite(s) in the area too? Finding those would justify the detour, I’m sure…

But back to the present, and where Oppy is now. Here’s a 3D view of the scenery Oppy is surrounded by…

For backseat rover drivers like this blogger, reaching this “halfway point” is exciting enough. What must it be like for one of the people who actually drive the rovers in real life? Luckily, I know just the man – and the rover driver – to ask..!

Scott Maxwell is one of the amazing band of Barsoomian brothers and sisters who regularly guides Oppy across the dusty, dune-rippled surface of Mars. I have been lucky enough to met Scott a couple of times now, so I asked him, via Twitter, about the importance of Oppy’s latest achievement.

First I asked him how excited he felt now that Oppy had reached the halfway point of her epic, Lewis and Clark trek to Endeavour.

“Very excited, especially since the first half was likely the harder half. From here we should be able to floor the accelerator. Also, (it’s) a real testament to the team: we added 10km to a rover designed for 1km, which wasn’t new when we started. All while keeping her safe. Think of driving from NY to LA in an old car: when you got to Oklahoma and knew it was all desert driving now, & you could floor it … :-)”

Oppy has already travelled such a long way, and still has a long way to go. How confident is he that she will now reach the Endeavour rim?

“As for confidence, I’ve always felt we could make it. More than ever now.”

Readers of this blog know just how fascinated I am by the mountainous far rim we can now see on the horizon. How does he, as a rover driver, feel, seeing those features getting bigger and nearer?

“Those hills are magic. When we started, we couldn’t see them at all. They make our destination real. We’re gonna see them rise and tower. You thought the looming walls of Cape Verde (note: a feature inside Victoria Crater)  were something? Just wait ’til we reach those hills. You ain’t seen nothin’ yet, poet-dude.”

(“Poet Dude” is my ‘title’ on unmannedspaceflight.com, given to me after a certain Steve Squyres greeted me that way during my visit to JPL… 🙂 )

So, there you have it, straight from one of the rover team – this is an exciting time, and Opportunity is now well on her way to make landfall at Cape York. But don’t ask when, that’s an impossible question to answer. Her landfall date will depend on so many things – detours to study any too-good-to-drive-past outcrops, mini-craters or meteorites she spots; mechanical failures; The Unexpected – that it’s impossible to predict. Some people still insist on doing a back of the envelope maths calculation, dividing the distance remaining by the length of a typical drive, which gives a drive time of 93 days or so to Cape York, but that’s as impossible as it’s riduculous, she can’t be driven 100m every day for the next three months, she’d fall apart like a clown car! No, the answer to “When will Oppy get to Endeavour?” is very short and very simple:

She’ll get there when she gets there.

Until then, thanks to the openness of NASA, and the MER team’s policy of posting raw images from the rover on its websites almost as soon as they’re received back here on Earth, we can all enjoy this incredible adventure by virtually walking alongside Oppy as she crosses Meridiani. Just by clicking our mouse we can look around us and see the orange-red landscape of Mars stretching off into the far distance; we can kneel down beside Oppy and look at the patches of exposed ancient bedrock beneath her wheels; and we can lift our eyes to the horizon and marvel at the sight of a range of beautiful mountains, carved and shaped by countless aeons of alien wind and weather, rearing up before us, dominated by a great, dark Eye of Sauron crater that looks back into us every time we look at it, from a hundred million miles away…

Mars Exploration Rover Opportunity.

The Adventure Continues.

🙂