Stuart Atkinson has done it again and this he got in contact with Tom Pike, who (besides having an excellent musical taste...) leads a team from Imperial College which created the micromachined silicon substrates for Phoenix's microscope station. The substrate will hold soil samples for analysis by an optical microscope and atomic force microscope (AFM).
Here's the result of that interview:
Thanks for agreeing to answer some questions for us, I know you must be ridiculously busy as Landing Day approaches! On the Science and Technology Facilities Council’s website it says that you head up up the Phoenix team from Imperial College London, which has “provided micro-machined silicon substrates which provide a surface on which to hold the dust and soil samples for analysis in the microscope station attached to the Phoenix Lander.” Can you tell us some more about this instrument, the substrates you’ve provided for it, and what it will do?
Ths substrates form part of the microscopy station of Phoenix, an instrument that dates back to my time at the Jet Propulsion Laboratory where we first came up with the idea of sending a high-resolution microscope to Mars. As with much of the other hardware, the microscopy station was originaly intended for the cancelled 2001 Mars Lander, but we took it off the shelf and tweaked the hardware for Phoenix - the silicon substrates are one of those tweaks.
How does it feel to be a Brit involved in this high-profile US-led mission? Can you explain just how international a mission Phoenix actually is?
Planetary exploration has a very international feel to it – even when I was at JPL my colleagues came from all over the world. Phoenix itself has about a third of its scientists coming from outside the US.
There’s two of us from the UK, David Catling and myself, involved as Co-Investigators on this mission. We both became involved while working out in the States, but part of the reason we both returned was the increasing opportunities for space exploration emerging in Europe – I’m rushing back from Phoenix to take part in the first reviews of my hardware, this time its micromachined seismometers, for ExoMars.
Although HiRISE images of the landing ellipse in which Phoenix is planned to land show it is almost clear of boulders, are there still concerns that the ground might be uneven or even unstable beneath Phoenix after landing? Are there any concerns that the down-blast from the engines might damage or contaminate the landing site and make it less useful scientifically?
The ground might shift a little below us. In one of our operations simulations using a copy of Phoenix in Tucson we had to cope with this when it looked like the robot arm had dug in the wrong place for one of our samples – the sneaky simulation team had physically shifted the lander after the initial landing photos had been taken. It took a little while to figure out that our commanding was correct but our coordinate system had been twisted.
There’s been quite a bit of study as to how the landing itself will affect the site. Of course the very act of digging will get us into undisturbed soil, but one of the first microscope images we’re taking will be of any material thrown up onto a set of our exposed substrates during the landing.
We’ve all been poring over the HiRISE images, and there seems to be a consensus now that the landing site will look flat and fairly undramatic, some have even said “dull”. Surely it won’t be totally bland - what features MIGHT we see? Low hills? Mounds? Cracked ground? Frost patches?
The flipside of the thinking behind Phoenix, giving up mobility for capability, is the frustration if we see an interesting feature just out of reach. But for us the action is going to be unpeeling the surface layers of Mars. I’d be far more disappointed if we just dig up shovelfuls of uniform soil and fail to reach the ice, one of the prime scientific goals of this mission.
There is a good possibility, though, that we might land close enough to the edge of an ice-cracked polygons to be able to explore some of the very local surface variations.
Maybe you could set the scene for us, tell us what it’s like for someone involved in a mission to have to sit there, helpless, during the final few minutes of flight: where will you be during the landing itself? Will you be watching quietly at a desk, on your own? Watching monitors with other team members? Hiding in a toilet, unable to watch?
I’ll be at the Science Operations Center in Tucson, with both my colleagues and family (with a mission that has been so long in the making, there is some blurring between the two!). The University of Arizona converted a huge warehouse complex, previously a archaeological depositary, into a maze of operations rooms, labs and offices for the mission. The biggest hangar houses the mock-up of the Phoenix and for the landing they’ll be several hundred of us gathered there in front of a big screen.
An obvious and impatient-sounding question, I’m sorry, but one everyone is wanting to ask: how soon after the landing do you think all of us watching online will see the first picture from Phoenix? And what will it be of?
Engineering images will come first – not of great scientific interest but for those of us in that hangar we’ll be feeling like new parents when we see the first pictures. We’ll want to share these immediately!
Any idea how soon can we expect to be drooling over the first real colour panorama of the landing site?
We’re coming down in the Martian afternoon, and the engineers will be wanting to work out how Phoenix and the immediate neighbourhood looks first. I think we’ll have to wait until the next day until the full panorama comes down.
What are your own personal hopes – and fears – for the Phoenix mission? The “pluckly little Mars rovers” Spirit and Opportunity have – rightly – enjoyed incredible media coverage, and have really been taken to many people’s hearts. Do you think Phoenix will enjoy less media attention because it is a static lander?
The Rovers rather pushed in to the queue once the 2001 Lander was postponed, and then cancelled – and I think NASA were quite right to allow them to do so. With hindsight there was just not quite enough information to justify another static lander at the time. But there has been a huge amount of data gained from the three Mars orbiters since the rovers were launched, as well as from the rovers themselves, and this has been what has made a targeted lander mission like Phoenix once again the best choice.
My hope is that we’re able to reach ice, and that the microscopes will get an interesting mix of samples to look at. Beyond that I’m willing to work with whatever Mars chooses to reveal to us.
The MER teams are still working with their rovers several years after they were supposed to have “died”. We all know that isn’t a possibility for the Phoenix team, as lander will perish several months after landing as the conditions at its landing site deteriorate. How does that knowledge affect the scientists and engineers on the team? Does it make you all frustrated that you’ll be “against the clock” from the second you land? Or does it help you focus, and be determined to be as productive and efficient as possible?
Two of the instruments, the mass spectrometer and the wet chemistry laboratory, can only process four samples, so there is a clear end-point to the analysis however long the mission lasts. The microscope, though, can keep on looking. We have ten sets of substrates, but if we use them up we’ll just dump more material on top of the used substrates – not ideal but no worse than running out of fresh glass slides.
So for the first part of the mission we’ll be tightly choreographed so that every sample is given a thorough analysis by all the instruments of Phoenix. Towards the end, though, the microscope will take centre stage as we’ll be able to resample from any interesting locations we might have overlooked in the rush to get to the ice, as well as any new samples from fresh excavations.
NASA is taking great care to explain and make clear this is NOT a mission that is “Looking for life”, although surely Phoenix is playing a vital part in the continuing quest to find life on Mars. All the mission literature makes it plain that Phoenix will not be sending back images of wriggly martian microbes, or fossils, but is that 1000% impossible? In an interview for Nature Network London in Aug 2007 you were asked: So if you hit jackpot, and there are micro-organisms in the samples, would you be able to distinguish between living and fossilized remains? And you said: “If life really is active in the samples we’re looking at, we would look for motion upwards or sideways on the substrates (not just settling under Martian gravity) by taking multiple exposures. We can do effectively time-lapse photography with the optical microscope and AFM. But it might be rather difficult to distinguish between microfossils and dormant spores. We’d be looking to have confirmation from the mass spectrometer of TEGA that there is organic material in the samples.” Does that mean there’s actually a chance Phoenix’s microscope might send us back pictures of something… amazing?
Even if there ever was life on Mars the signature will take a great deal of work to recognise. Phoenix has some important tools to see how likely it might be that such a signature might even exist. But yes, we do have the capability of resolving down to the length scale of some microscopic organisms. Of course that’s no guarantee that we’ll see anything amongst the fine silt particles which actually set the resolution target of the microscope.
On the STFC website you said “Nobody has looked at Mars at this type of resolution before. It is very difficult to predict what we might find, but if you wanted to look for signs of the earliest forms of past or present life we will be the first to look closely enough.” Does that mean you think that even if it doesn’t image wriggling martian beasties, the microscope could actually image micro-fossils or some other type of evidence for past life on Mars?
Again, we have the possibility. Fossils are more likely than extant life – the best conditions for life there were several billion years ago. But even if the microfossils are there to be found, we may not be in the right place. On Earth the abundance of microfossils varies enormously - there is no guarantee of imaging them on a planet we know is teeming with life.
And finally, with just a few days (!!!) left to go until Landing Day, what’s the mood like in the Phoenix team? Is everyone quietly confident, now all the simulations and exercises have been completed, or is everyone a nervous wreck – like we are out here watching from the sidelines!
We’ve been so busy there really hasn’t been time to worry until now. On Friday we packed up the copy of the microscope station we have at Imperial to test out our operations scenarios – we’ll be using it in Tucson to support mission operations – so now we finally have a chance to feel anxious. I still have my day job, though – teaching undergraduates at Imperial. Perhaps the 150 exam scripts I have to mark before Friday will at least help keep the anxiety at bay.