While scientists pore over the latest pictures from Mars, a team of UK engineers is preparing to probe a cosmic body much closer to home. Jon Excell reports.
As the 700mph missiles slammed satisfyingly into their targets, the scientists and engineers assembled at Qinetiq’s Pendine test facility in South Wales last month congratulated each other on a job well done.
To a casual observer, it was business as usual: the range is regularly used to put military projectiles through their paces. But the attendance list, dominated by the cream of the UK’s space and planetary scientists, revealed this project had much less destructive aims.
Last month’s tests represented the first steps in Moon Lightweight Interior and Telecoms Experiment (MoonLITE), an ambitious UK plan to create a geophysical sensor network on the moon by firing a series of projectiles into its surface.
The aim is to launch four heavily instrumented penetrators from an orbiter at previously unexplored areas of the lunar surface: the two poles and the lunar far side. Hitting the moon at speeds of up to 300m/s, they will become embedded up to 3m beneath the lunar soil, or regolith, where they will use a purpose-built suite of scientific instruments to probe the rock and measure seismic activity.
The moon is like a piece of planetary blotting paper that’s been sitting there for 4.5 billion years soaking up the history of the solar system
Dr David Parker, BNSC
It will be the first time any in-situ lunar science has been carried out since the final Russian lander mission in 1976, and the first time any in-situ science has been carried out on the lunar far side and at the polar regions.
The project team, headed by UCL’s Mullard Space Science Laboratory, includes Surrey Satellites(SSTL), which is developing the orbiter; Imperial College, responsible for the primary scientific instruments; and Qinetiq, which has built the prototype penetrators. Other partners include Birkbeck College, the Open University and, intriguingly, NASA, which recently signed a memorandum of understanding to work with the UK on future lunar missions and appears keen to use MoonLITE’s findings to help plan a lunar base.
If the project attracts the estimated £100m funding required to get it off the ground, it could be launched as soon as 2013, propelling the UK to the forefront of what is being heralded as a new era of lunar exploration. ‘There is a genuine renaissance in lunar science,’ said Dr Ian Crawford, MoonLITE’s scientific lead and Birkbeck planetary scientist. ‘Partly it’s for political reasons, driven by the US intention to send people back to the moon. But scientifically there’s a realisation that Apollo was 40 years ago and while it taught us a lot, the Apollo data hasn’t answered all the scientific questions we’ve got about the moon.’
In terms of pure science, those involved in MoonLITE believe a lunar-wide network of sensors could help answer some fundamental questions about the origins of the solar system. While signs of the earth’s early history have largely been eroded, the ancient surface of the moon has been preserved. Dr David Parker, director of space science at the British National Space Centre (BNSC), likens it to ‘a piece of planetary blotting paper that’s been sitting there for 4.5 billion years, soaking up the history of the solar system’.
The task of developing the tools to read this open book now falls to the MoonLITE engineers. The UK’s expertise in scientific instrumentation and robotic space systems is well established and UK devices are regularly flown on some of the biggest space missions. This summer, a UK-developed compact imaging X-ray spectrometer will be a key part of the payload for Chandryaan-1, India’s first mission to the moon. But what is particularly exciting about MoonLITE is that, apart from the launch vehicle, every element of the system will be designed and developed in the UK.
The first link in the chain is the orbiter that will be used to launch the penetrators. According to SSTL engineer Andy Phipps, this is probably the easiest part of the mission to develop. ‘We’ve built quite a few low-earth-orbit spacecraft and a medium-earth-orbit spacecraft and it’s not much of an extension of our capabilities to go to the moon,’ he said.
The biggest challenge for SSTL is keeping the cost down. ‘These kinds of mission can easily be done, but you don’t want to spend billions of pounds,’ said Phipps. ‘The NASA budget is in the region of $17bn (£9bn) a year, and we could easily do it with that sort of money. The question is “can you do it on a farthing?” ‘
Once in lunar orbit, the tricky business of launching the penetrators gets under way. Dr Rob Gowen, MoonLITE co-ordinator and MSSL scientist, said: ‘The penetrators will be released from the orbiter by a spring system, spun up and oriented with an attitude control system, and the thrusters will then fire to slow them down for the speed of impact.’
Once embedded in the lunar regolith, the penetrator’s scientific payloads, hopefully undamaged by the impact of their collision, will spring into action.
The primary scientific instrument is a micro-seismometer, which has been developed by engineers at Imperial College London for monitoring the quakes that ripple across the lunar surface.
Although the Apollo missions shed some light on this phenomenon, the widely distributed nature of the MoonLITE penetrators should provide a more detailed picture of the moon’s seismic environment. ‘The Apollo programme landed a number of instruments and deployed a network of seismometers,’ said Crawford, ‘but that network essentially forms an equatorial triangle slap bang in the middle of the near side of the moon. That means that the seismic data returned really is only relevant to what is underlying the near side.’
The moon experience shallow quakes measuring 5 on the Richter scale – these are sufficiently strong that if you were building a moon base you’d want to know about it
Dr Rob Gowan, MoonLite coordinator
As well as helping to establish the existence or nature of a lunar core, the data acquired by MoonLITE has more immediate practical implications. ‘This data could have a bearing on the design and location of future lunar bases and telescope installations,’ said Gowen. ‘The moon experiences shallow quakes measuring 5 on the Richter scale — these are sufficiently strong that if you were an engineer building a moon base, you would want to know about it.’ The US, which is said to be keen to build a base close to the lunar South Pole, will be keen to acquire this data.
The penetrators will also carry instruments for measuring the chemical composition of the soil into which they are embedded. Chief among these will be a mass spectrometer, developed by the Open University, which could be used to test the theory that the deeply shaded craters at the lunar poles contain water ice.
‘Orbital missions have already indicated the presence of enhanced hydrogen,’ said Gowen, ‘but if we can detect water ice directly in the shaded craters, that has implications for life elsewhere and also for astrobiological material that might have arrived from comets that could have helped seed life on earth.’ Ice could also be used by future lunar bases as a source of hydrogen and oxygen, he added.
Theories about the existence of a lunar core will be further tested by a series of temperature sensors that will measure heat flow from the moon. ‘If you can detect the heat flow coming from the centre of the moon, it can tell you about the materials along the way and the radiogenic sources inside the moon — the deep internal structure of the moon,’ said Gowen.
To transmit its findings back to the lunar orbiter, the penetrator will also require some form of antenna. Although the porous characteristics of the lunar regolith mean transmission from beneath the surface is unlikely to be a problem, Gowen said the group is investigating developing a trailing antenna. This could be deployed in the event of a penetrator landing in a crater containing volatile compounds, which could attenuate the signals.
The other component of the system is the penetrator — a 600mm long, 120mm diameter aluminium alloy projectile designed to protect its sensitive payload from a 700mph collision with the moon and an impact deceleration of 3,000G to 5,000G.
During last month’s trials to test the survivability of this package, Qinetiq’s rocket-powered test sled was used to fire the penetrators into a simulated lunar surface at close to the speed of sound. Although the full test results have not yet been released, the signs are that the penetrator and instruments have survived, and that MoonLITE is well on track.
Despite the enthusiasm surrounding MoonLITE, some UK space scientists believe it would be a mistake for Britain to put all its energies into visiting its nearest neighbour. Astrium, the UK’s biggest space company, claims the moon’s chief importance lies in its potential as a stepping stone to exploration elsewhere in the solar system, in particular Mars — currently in the news courtesy of NASA’s Phoenix lander.
Astrium is developing the rover for ESA’s ExoMars Martian Lander mission, and is also thinking ahead to the Mars Sample Return Mission, a joint ESA/NASA mission proposed for 2020 that hopes to bring a sample of Martian rock back to earth.
‘Any lunar mission should be seen in the context of exploring Mars,’ said Dr Ralph Cordey, Astrium’s head of space science and exploration. ‘Going to Mars and bringing back a sample is probably the most important thing we can do over the next one to two decades.’
These priorities are illustrated by the fate of Astrium’s MoonTwins study on the feasibility of developing a pair of lunar landers, which would also rehearse rendezvous manoeuvres in lunar orbit. Although the project is now unlikely to go ahead, Cordey said the ability to get robotic craft to rendezvous could be the preferred means of retrieving a sample from Mars. ‘We think you would take a spacecraft to Mars, land it on the surface, collect a sample and fire it into orbit, where another spacecraft would rendezvous with a little canister weighing 5kg and measuring 10cm to 15cm across.’
MoonLITE’s Gowen agrees the moon is important in terms of further exploration and is already looking at applications of penetrator technology elsewhere in the solar system. ‘They can be used on any other airless world in the solar system,’ he said. ‘And after the moon, we’ll try to get involved in missions to Europa [Jupiter’s moon] and Titan and Enceladus [Saturn’s moons].’
Crawford said the moon was the perfect testing ground for the technology that would be required to put men on Mars. ‘In the context of human exploration, because the moon is only a few days away and Mars is eight months away, testing all this stuff on the moon before committing people to Mars is absolutely essential.’
BNSC’s David Parker suggested the moon may present more severe engineering challenges than the red planet. ‘It’s a horrible environment for engineering because of the dust, which is very fine and very gritty. The lunar environment is very challenging from an engineering point of view.’
Crawford said putting men back on the moon would enable even more detailed lunar science to be carried out. ‘To really understand lunar geology, we need people back on the moon — so much more can be done with people in-situ.’
While its emphasis on unmanned probes and robotic systems means that the UK space industry is unlikely to spearhead any future manned missions to the moon, Crawford believes that as a result of its involvement in MoonLITE, it will have plenty to experience when the next manned exploration begins. ‘MoonLITE is important because it is building up a community of scientists and engineers in the UK with an interest and knowledge in the moon. Later on, when people are returning to the moon, the UK will have a base of lunar expertise built up.’