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In memory of Peter Fortescue.

12/7/2014

Peter Fortescue (centre) on the occasion of his retirement from lecturing on the Spacecraft Systems Course at ESA Estec in the Netherlands. L to R Maggie Hendricks (ESA), Adrian Tatnall (Southampton Uni), Richard Holdaway (RAL) and (a much younger) me (Southampton Uni).

It is with great sadness that I announce the death of Peter Fortescue, who passed away peacefully on Wednesday 3 December 2014.

Peter was a good friend and colleague who I shall miss greatly. He was also an editor and coauthor of a standard textbook on spacecraft engineering and design – ‘Spacecraft Systems Engineering’, published by Wiley currently in 4th Edition, which is being translated into Russian and Chinese –
see http://eu.wiley.com/WileyCDA/WileyTitle/productCd-EHEP002270.html
Global sales of the book since it was first published in 1991 have reached many tens of thousands of copies which makes it a ‘best seller’ for this category of book.

Peter was my ‘unofficial mentor’ when I joined the University of Southampton in 1987, and I am forever grateful for his help and kindness at that time in aiding my transition from the space industry to academia. He himself had made a similar transition from industry years earlier, and as an expert in control engineering he had fingers in many pies. But his main contribution, I believe, was that he established the now renowned Southampton courses in spacecraft systems engineering, along with John Stark, out of which grew the textbook mentioned above. Subsequently, the courses were established as part of ESA’s training programme and as a consequence many courses were presented to ESA staff over the years at a variety of ESA venues, including their technical HQ Estec in the Netherlands.

Thank you Peter for your kindness, and always giving generously of your time to advise and help. Your example was a great influence on my own development as a teacher of both students and industrial/agency engineers.

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First test flight of the Orion capsule

12/6/2014

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The Orion capsule, the Space Shuttle replacement.

The Orion capsule, the USA’s next generation of manned vehicles after the Space Shuttle, was lofted into orbit yesterday for its first brief test flight.

Clearly, when you look at the vehicle, it closely resembles the manned capsule of the Apollo era and this ‘next generation’ seems at first thought to be a retrograde step. However, Orion is about twice the size of the Apollo capsule and can accommodate 4 astronauts in reasonable comfort. Another advantage is of course that its design integrates the latest technology into the system. But its main benefit is safety – a lesson learned from the shuttle era. In the 30 years of Shuttle operation the US human spaceflight programme achieved a great many spectacular successes, but it also saw some tragic lows with loss of 2 crews in 1986 and 2003. The issue was the Shuttle’s complexity – although this allowed great flexibility in mission capability, it also made the vehicle dangerous. This was primarily because it had no genuine escape system for the crew.

Taking onboard these issues, the system designers of Orion have gone for relative simplicity in order to improve crew safety. The final launch vehicle for the Orion spacecraft – which is yet to be developed – will have a simple multi-stage configuration with an escape tower system to drag the manned capsule clear in the event of a catastrophic launch failure. Also the heat shield configuration of Orion is simpler than Shuttle, and protected from debris impact risk on launch, so reducing risk on re-entry into the atmosphere. So the philosophy is to launch people on a ‘simple’ and very reliable expendable launch vehicle, and launch the required hardware for the particular mission separately on a relatively less-reliable heavy lift launcher – the two component parts coming together and docking in orbit afterwards.

Coming back to yesterday’s test, the Orion vehicle was launched at 12.05 UT atop a (stand in) Delta 4 heavy lift expendable launch vehicle (see video).

The system then executed 2 orbits of the Earth prior to a re-entry and splashdown at 16.30 UT. The second orbit was elliptical with a high point of 5,800 km to increase the re-entry speed to around 30,ooo km per hour – the resulting 2,000 degrees Celsius providing a rigorous test of Orion’s thermal protection system. The principal objectives of yesterday’s events were to test the capsule’s heatshield and parachute systems, both of which performed successfully. A NASA summary of the Orion system in general, and yesterday’s test in particular is given in the second video.

Although yesterday’s test was encouraging – the US human spaceflight programme is up and running – nevertheless there is long way to go. The Orion system comprises two main components – the capsule which was tested yesterday and a service module which is yet to be built. The service module (again similar to its Apollo predecessor) is the necessary system required to provide essentially life support and propulsion for the Orion capsule. The European Space Agency (ESA) and Airbus recently signed a contract with NASA to build a service module based on ESA’s Automated Transfer Vehicle (ATV), and this is scheduled to be ready for an unmanned test flight in 2017/18. You may recall an earlier blog post about this (24 September 2014) ‘Chance encounter with a rocket man’ when I ‘bumped into’ a NASA engineer on a walking holiday in West Wales who was working on adapting the Space Shuttle orbital manoeuvring system engine for use on ESA's ATV?

The Orion capsule/service module configuration.

And then of course there is the requirement to develop a man-rated launcher for the Orion capsule/service module system. This is currently in the hands of US private industry, and a first unmanned test flight of this element is pencilled in for 2017/18. The first crewed launch of the whole system is not expected until around 2021, so don’t hold your breath! Given that the last flight of Shuttle was 2011, that’s a hiatus of 10 years in the US human spaceflight programme which is disappointing, in my opinion. The pace of events seems to be very slow, and with the vagaries of funding for such projects with changing political administrations in Washington DC, it does make you wonder whether the US will ever acquire sufficient momentum to take the next major steps in solar system exploration. I say this not as a critic of the US space effort, but as a supporter who wishes they’d just get on with it!

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What next for Philae?

12/2/2014

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Comet 67P captured by the Orbiter a few days after the Philae landing from a range of 42 km.

Now that the ‘dust has settled’ a little on the Philae landing on 12th November – what next for Philae?

Someone asked me recently why the lander was called Philae. Despite knowing all the ins and outs of the landing operations and onboard instruments, I had to admit that the answer to this question escaped me! Thank goodness for Google – in case you didn’t know, apparently Philae is an Egyptian island in the river Nile. An obelisk was discovered at the Temple of Isis on the island in 1815 by explorer and egyptologist William Bankes, and the hieroglyphs and Greek inscriptions on the Philae obelisk helped 19th Century scholars unlock the secrets of the Rosetta Stone and the language of ancient Egypt. However, I digress … getting back to the 21st Century Philae lander residing on the alien surface of a comet half a billion kilometres away.

While Philae made its descent to the comet’s, the orbiters narrow-angle camera tracked the ‘fridge-sized’ landing craft as it headed for its first touch-down. Below shows an amazing time-tagged mosaic of images of this event.

The Rosetta spacecraft's narrow-angle camera spots Philae on its descent to first touchdown.

A trace of Philae's power levels over time

After its two rebounds from the surface, Philae finally came to rest on third touchdown in a rather unfortunate shady spot, surrounded by boulders and/or cliffs. And to make things more interesting it settled in a ‘non-nominal attitude’ – that is, not sitting comfortably on its three spindly legs as intended. This aspect has unfortunately complicated the deployment of some of the post-landing experiments, with the consequence that not all the intended surface science was achieved. However, the scientists managing these experiments assured the waiting media that at least 80% to 90% of the science was achieved, and indeed a great deal of scientific data were received during the 60 hours or so before the lander’s power source was exhausted

The Philae power system comprises a primary (non-chargeable) battery system intended to give 60 hours of surface operations, a secondary (chargeable) battery system for extended surface operations and a primary power source in the form of body-mounted solar arrays to convert sunlight into electricity to charge the secondary batteries. However, due to the cold shaded place where Philae came to rest, there is insufficient sunlight to charge the batteries. The realisation of this situation after landing meant that the surface science teams had to work rapidly to devise a comprehensive plan to achieve as much as possible in the brief period before the primary battery expired – allowing some residual power, of course, to ensure that the results could be uplinked to the orbiting Rosetta spacecraft. Fortunately a great deal was achieved, and as the power levels dropped, Philae executed an automated process to put itself into hibernation. So the lander is not actually ‘dead’, and contrary to ‘popular opinion’ the lander mission may not be at an end. As the comet approaches closer to the Sun (closest approach between the orbits of Earth and Mars in August 2015), Philae’s temperature will rise, and solar intensity will increase by a factor of about 15. So there is a chance that we may hear from the surface of the comet again. Personally, I’m not sure how likely this is, but I probably wouldn’t bet on it – but it is possible.

In the meantime, the science teams have oodles of results to mull over in the coming weeks and years. Although some of these have been discussed in the media, many of them will require a great deal of work and further interpretation to provide a definitive view of the comet’s surface environment.

The results most highlighted by the media so far have been the claim that ‘carbon-based organic molecules’ have been detected independently by two onboard experiment packages. The COSAC instrument (COmetary SAmpling and Composition experiment) is designed to ‘sniff’ the comet’s thin atmosphere. If you’re into this stuff, COSAC is based upon a Gas Chromatograph/Mass Spectrometer (GCMS) system. The instrument’s principal investigators (PIs) could not definitively indentify exactly what molecules had been detected at the moment, and that they were ‘trying to interpret the results’. Another GCMS-based experiment called ‘Ptolemy’ later confirmed the COSAC finding, the PI commenting that “there is a rich signal there … there is clearly a lot of peaks (in the chromatograph’s trace). Sometimes a complicated compound can display a lot of peaks”. Ptolemy was programmed to ‘sniff’ the environment immediately after first touchdown, so presumably the observed surface impact cloud gave it plenty of raw material to work on.

Results concerning the nature of the surface were returned by an instrument called MUPUS (MUlti-PUrpose Sensors for surface and sub-surface science). This experiment deployed a hammer, which detected a dust layer about 10 to 20 cm deep overlying what is believed to be a hard surface of water ice. At the extremely low temperatures currently being endured by Philae, water ice is very hard – having characteristics similar to sandstone. Another key objective of MUPUS was to drill a sample of ‘soil’ and deliver this to COSAC’s oven for analysis – but unfortunately no such sample was delivered.

Reading all this back, I have to say the tone seems a little negative – but let me say that this is not intended. I think it’s amazing what has been achieved under very pressured and trying circumstances. And also it really is too early to understand the huge amount of information that Philae’s 60 hours of surface life has given us. It will take a while for it all to be assimilated, but I think there will some interesting and unexpected outcomes over the months to come. Congratulations to all on both the engineering and the science teams involved in the Philae landing mission!

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In memory of Peter Fortescue.

First test flight of the Orion capsule

What next for Philae?

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