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Exploring Alien Worlds: Different Dimensions, Same Buzz

In an alternate universe, rather than researching extinct and frankly sometimes quite alien hominin species, I would be working in my other dream career: astronomy. More precisely, I would be on one of the teams currently pushing the bounds of our interplanetary exploration. Being on the Cassini mission would be pretty sweet, downloading endlessly beautiful and oddly abstract photographs of the vastness of Saturn and its rings, probing the haze of Titan (seeing reflections of methane lakes!), or the incredible geysers of Enceladus. But I have to admit there's a research field even more beguiling to me: the staggering fact of having robotic explorers actually on the surface of an alien world.  Hello, Mars.

Saturn and Titan, Cassini mission. NASA/JPL-Caltech/SSI
Enceladus' geysers, Cassini mission. NASA/JPL-Caltech/SSI

Cassini mission wins most awesome solar system photo: Saturn eclipse. NASA/JPL-Caltech/SSI

I've been a massive space geek since I was a kid, and probably the only reason I'm not an astronomer in this universe is that I thought I was rubbish at maths for ages, and stopped trying. I scraped my C-grade at GCSE, but perhaps if someone had pointed out the fundamental connection between studying maths and getting to work on a Mars rover, I might have knuckled down. Still, I'm a child of the space age, born the year of the first shuttle flight, so for me humans walking on the moon, and people floating around in space wasn't weird, just very cool. What I do think is remarkable however is the extent today to which anybody on earth with a spare five minutes and an internet connection can become part of the great era of robotic exploration we have embarked on in the past 30 years.

Although there were lunar rovers, landers on Venus and the Viking rovers between the 1960s to 1970s, we really started hurling hardware out into the solar system again from the mid 1990s. Many of these missions have gone to Mars, resulting in us now having an intimate understanding of this place as a world, from thousands of hi-resolution orbital photographs to scratching, drilling and sniffing its rocky surface.

Missions from the Jet Propulsion Laboratory since the 1950s. NASA/JPL
Mars is on my mind this week because we have now landed our most serious piece of kit yet on its surface, the Mars Science Laboratory, aka the Curiosity rover. I woke up early on Monday morning to watch the live broadcast of the final half hour before estimated landing. I wanted to be part of this next historic step in human space exploration, and I wasn't alone. I couldn't believe it as I saw the 'watching now' counter increasing by over 100 people per second, all logging on to see for themselves whether Curiosity would make it. At seven minutes to landing, there were 150,000 people online at the official NASA live feed; by the time the rover landed and the first images appeared ("It's a wheel!"), it was at 230,000.

The first thumbnail image received from Curiosity on Mars. People started shouting and crying when this appeared on the big screens inside the Entry, Descent and Landing flight centre, and probably all over the world too. NASA/JPL-Caltech

We're already receiving higher quality colour images of Gale Crater, the rover's new neighbourhood, including some views of the impressive topography in this region. There's already a tense feeling of wanting to get off and explore the slopes of the 6km high mountain at the centre of the crater, which reminds me of the only other really mountainous area we've experienced away from Earth: the Family mountains in the region visited during Apollo 17, the final moon mission.

Station Four, Apollo 17 with the Family mountains behind and Shorty crater to the right. NASA/JPL

So, what's this rhapsodising for a Martian dream doing on my Palaeolithic blog? In essence, I feel that the reason I'm drawn to both astronomy and archaeology is their similarity. Both fields of research are fundamentally about exploration of other worlds. Deep space astronomy is in fact sometimes directly likened to archaeology; "old light"- photons travelling across the cosmos- that make up astronomy's raw data must be collected, using intricate and inventive methods to ensure as as little as possible is missed. Then the analysis begins; but as with archaeology, there's no chance to re-run the same experiment, because what you're working with happened in the past. Astronomers have to become detectives, working with the scraps of evidence that find their way across unimaginable distances between a galactic jet or an interstellar gas cloud, to the dish or receiver of a telescope.

Archaeology is the same, we're essentially dealing with the detritus of human life, discarded in many cases thoughtlessly, with no expectation that it might be scrutinized hundreds of thousands of years later. Just like the scramble of telescopes swinging round en-masse to observe a supernova before it fades, archaeologists have one shot: we must plan excavations extremely carefully, apply the full battery of techniques available, sometimes under time pressure, before the site in question is destroyed and all that remains is an archive. To add to the challenge, the further back in time we go, as with astronomy (where you're also moving further away in space) the patchier and blurrier the record gets. What was a massive stellar explosion leaves faintly glowing trails of gas and dust; what was a blazing campfire leaves a fingerprint of charcoal and ash on the floor of a cave.

Cassiopeia-A, supernova remnant. NASA/JPL-Caltech
Neanderthal hearth at Abric Romani, Spain: another trace of a long vanished fiery event.

Most of the time, working with Neanderthals, we are dealing with accumulations of stone tools and production waste, animal bones (not all of which were necessarily butchered), and if you're in cave deposits, maybe some nice burned and ashy features identifiable as simple hearths. But there's also the tricky issue of taphonomy: what happens to objects between being dropped say 30,000 years ago, and being dug up in 2012 by an archaeologist's trowel. The archaeological record is not a static archive, it has history itself. Organics decay, chemicals transform, objects within deposits move, even whole sediment layers can become deformed over time.
There are several taphonomic equivalents within astronomy, the most obvious of which is red-shifting. During the eons since the universe was young, light emitted by early objects has not only travelled outwards from its source, but because everything is flying away from everything else (quick cosmology lesson here), the radiation- visible light or other wavelengths e.g. gamma- is also moving away from us. This creates the Doppler effect of 'stretched' light, just as your ears hear sound being stretched as a police siren passes you. The radiation from extremely distance objects appears to our peering telescopes as 'redder'- less energetic, longer wavelengths- than they really were. In 2011 the oldest object yet imaged was reported: stellar structure UDFj-39546284 is a staggering 13.2 billion light years away. Imaged in the Hubble Ultra Deep Field, this tiny glowing ember is most likely a compact dwarf galaxy of bright blue stars,shining less than 500 kyr after the big bang.

Current candidate for the most distant astronomical object observed: UDFj-39546284. NASA/ESA
Yet sometimes astronomers get lucky, in the same way as archaeologists get an extraordinarily well preserved site. For example, an odd effect of gravity means that where a very massive object warps the space around it, this can in the right circumstances act as a giant magnifying glass by bending light from distant objects behind it. This phenomenon, gravitational lensing, was predicted by Einstein's theory of General Relativity, but only recently have we seen its potential to allow us to 'time travel', showing us very distant and therefore old galaxies more clearly than we otherwise could.

Gravitational lensing: warped image of a spiral galaxy behind the massive Abell 370 cluster. NASA/ESA/Hubble SM4 ERO/ST-ECF
 There are many archaeological equivalents of these rare natural events and circumstances that allow us to see more clearly into the past. Most people have heard of Pompeii, where the volcanic eruption that buried the Roman city also preserved it in incredible detail, including the deeply affecting casts from inside concreted  hollows showing people cowering as they waited to die. There are some amazing Palaeolithic examples of exceptional preservation, where objects and features we might expect to have been destroyed over time can still be perceived. One of the most famous examples, but little known outside archaeological circles, is the site of Abric Romani. This is a large rockshelter in Spain with very deeply stratified occupational layers, rich in Neanderthal archaeology dating to over 50 kyr BP. One of the images above demonstrates that features such as ephemeral campfires are preserved here; in fact there are many hearths, spaced out within the rockshelter. But the really unique character of this site is the rapid (in a geological sense) deposition of thin layers of speleothem- like stalagmite- over the top of successive living floors, creating a multi-layered record of many different occupations.
 Interior of Abric Romani, showing speleothem layering in walls. V. Mourre Creative Commons BY-SA-3.0 licence

 This unusual process preserved in detail the spatial relationships between artefacts, bones and hearths; something which is very difficult to disentangle in most deep cave sites. But it also acted in a similar way to the ashy layers at Pompeii, covering organic artefacts, preserving them to some extent, and also creating negatives, or "pseudomorphs" of these objects. It's in effect a ghost-world of the things we know Neanderthals were doing with organic materials: collecting fuel for fires and carving wooden objects. Some enigmatic bowl-like wooden artefacts have been found at Abric Romani, and we know from distinctive micro-polishes on tools at many sites that they were frequently working wood. But recently the spectacular feature in the image below was found: a pseudomorph of a wooden handled object. On casting the negative feature in the speleothem it became clear that this was an entire tool made from wood, with an apparent cutting edge and a handle, like a wide spatula or knife. This is an incredible glimpse into the diversity of Neanderthal material culture that will for the most part (unless we really do invent a time machine) remain invisible to us.

The cast of a wooden Neanderthal tool from Abric Romani, next to the pseudomorph, showing preserved wooden fragments. Jordi Mestre / IPHES
I wouldn't say no to a chance to be on the Curiosity Rover team, investigating the pristine geological playground that is the surface of Mars, or to be a researcher working on one of the hundreds of astronomical research projects stretching our understanding right out to the edge of the visible cosmos. But I get the same buzz of mystery and wonder from exploring back in time, to the world of the Neanderthals. It's a world that is at times oddly alien, filled with strange alliances of plants without modern analogues, huge extinct creatures, and as yet no evidence of a representational art tradition. Yet it's often also intimately familiar: a humanly lived world of focused attention on precise gestures of tool making, the taste of a tender chunk of fatty meat, and watching light flickering on rocky walls as it grows dark.

Archaeology and astronomy are partners in the great human effort to understand where we came from, at all scales of our existence and history; from the heavy atoms born billions of years ago in the dying fires of a sun, to hunters stalking woolly rhino on the ice age plains of Europe, a mere 'blink of an eye' ago to the cosmos. I'm proud to be able to make some contribution to one end of that spectrum, and excited to be a part of the other end, watching along with millions of others as our newest adventurer crunches across the gravels of Gale Crater for the first time, forging a new chapter of discovery in the greatest story we can tell.

Read more:
The Official Abric Romani website

Julien Riel-Salvatore's blog has some great posts on the wooden finds from Abric Romani, and includes references for some of the publications of the site (although most are paywalled):
Large tree trunk, sleeping structure?
The wooden pseudomorph tool


Dr Space Junk said…
I love how you've woven archaeology and astronomy together here - and what an amazing site Abric Romani is!
Thanks so much Alice, that means a lot coming from a fellow astro geek!
Yes, Abric Romani is amazing, I'd love to visit it, don't think they've bottomed it yet either.

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