Asteroid defence gets complicated when the asteroids get complicated

From Nature, we learn that one high-on-the-watchlist near-Earth object – asteroid (29075) 1950 DA -“is a loose blob of particles that clot together much as Moon dust collects on astronauts’ spacesuits”. Because it is spinning quickly, 1950 DA’s own gravity can’t be enough to hold it together, so cohesion is owing to van der Walls forces, the weak net attraction between molecules. The same may be true of other so-called “rubble pile” asteroids, if they are spinning fast enough.

And, says the study leader, planetary scientist Ben Rozitis of the University of Tennessee in Knoxville, that means we’d need to take great care in any intervention designed to prevent a collision with Earth. Specifically, he reckons, flying out there and blowing it up into pieces would be a bad idea, because we don’t (yet) understand the forces holding these lumps together and we may just end up turning one threat into many.

After last year’s meteor strike over Chelyabinsk in Russia, we are keenly aware of the danger from NEOs. One of the first priorities is to find them – the Chelyabinsk rock came literally out of the blue, ironically while scientists were watching the close pass of another, known, object. Thankfully, both NASA and the European Space Agency are dramatically ramping up search resources, and many serious scientists are working on plans for diverting NEOs from Earth-collision courses.

It’s worth looking back at my May 2013 flightglobal story for a guide to what’s being done to make sure we don’t go the way of the dinosaurs. And, for what it’s worth, if we survive the next decade or so without being blindsided by an undetected killer asteroid, I reckon we stand a good chance of keeping the worst of them at bay.

ATV era opens final chapter with ‘flawless’ space station docking

The International Space Station marked the end of an era on Tuesday, 12 August 2014 with a “flawless” arrival by the fifth and final resupply flight in ESA’s Automated Transfer Vehicle programme.

ATV-5 – named after Belgian priest and physicist Georges Lemaître, who formulated the Big Bang theory of the creation of the Universe – docked with the ISS at exactly 1330GMT, packed with 6,602kg (14,600lb) of fuel, water, gas and dry cargo. The spacecraft will remain docked to Russia’s Zvezda module of the ISS for six months, while it is unloaded and eventually packed with rubbish before being cut loose to burn up in the atmosphere during a destructive re-entry.

Meanwhile, from 14 August, ATV-5’s thrusters will perform a series of reboost manoeuvres to maintain the station’s altitude. Orbiting at only around 450km (280 miles), the ISS passes through enough residual atmosphere to slow it down slightly, so it would eventually fall out of orbit without boosts from visiting supply ships.

ATV-5 flying below ISS, August 2014 (credit NASA)

ATV-5 flying below ISS, August 2014 (credit NASA)

A more extensive report is available at flightglobal.com

UKSA’s bold vision is to be the most modern of space agencies

When Tim Peake dons his spacesuit and climbs aboard a Soyuz rocket in November 2015, it will not be just another expedition to the International Space Station – at least from the perspective of observers in the UK.

Peake – one of six astronaut trainees selected by the European Space Agency in 2009 – will be only the third British-born person to fly in space.

It has been more than a decade since a Brit last left Earth, and 25 years since a Union Jack made it to orbit. Peake’s predecessor, Michael Foale, was by any measure a star astronaut, with more than 373 days in space between 1992 and 2004 on three Space Shuttle missions and stays aboard both Russia’s Mir and the International space stations. But Foale, a UK-US dual citizen, flew for NASA with a stars-and-stripes patch on his shoulder. Britain’s spaceflight trailblazer, chemist Helen Sharman, made her trip to Mir in 1991.

So, it is hardly a surprise that Peake – a former Boeing/Westland AH1 Apache helicopter pilot and major in the British Army with a degree in flight dynamics – is poster child for the UK’s push to encourage young people to pursue the so-called STEM (science, technology, engineering and mathematics) subjects. Indeed, in 2009 Peake was appointed a UK ambassador for science and space-based careers.

Tim Peake (credit: UK Space Agency)

Tim Peake (credit: UK Space Agency)

The complete story is available at Flight International; register online for access to special features like this one

UK hopes regulatory light touch and commercial spirit will open path to space

The UK is laying the groundwork for a commercial space transport industry by opening a consultation on a site for a spaceport. And it is looking across the Atlantic for guidance on how to regulate the nascent business of ferrying passengers into space – with operations possible from 2018.

A memorandum of understanding signed at the Farnborough air show will see the UK Civil Aviation Authority and the UK Space Agency work with the US Federal Aviation Administration to ensure that operations are safe without keeping companies Earth-bound with excessive regulation.

Aviation minister Robert Goodwill – speaking in place of David Willetts, the science minister who lost his job in last week’s Cabinet reshuffle – said the UK goal was to command 10% of a global space business estimated to be worth some £400 billion ($680 billion) by 2030. Goodwill underscored the UK government’s appreciation of the fact that the spaceplane technology for so-called “space tourism” was “just over the horizon” and that it is expected to be adaptable to launch small satellites. Critically, he said, enabling more low-cost launches of small satellites – a UK industrial strength – was a key to that strategy.

The UK is looking to learn from best practice, which at this point means the FAA – the only safety authority yet to establish rules on so-called space tourism. As FAA associate administrator George Nield said at the show during the launch of the UK’s discussion paper on spaceplane operations, it needs to take a different approach to space tourism from aviation, by regulating operations rather than the equipment and treating the machines as experimental aircraft. “A certification regime would stifle commercial operators,” he says.

A more extensive report appeared in the 22 July edition of Flight International. Register for free online access.

Roadmap to Mars is paved with ambition, high hopes and money

For as long as there have been telescopes, there has been fascination with Mars and its tantalising similarities to Earth. Although it has been a very long time since anyone seriously believed in Martians or feared a HG Wells-style war of worlds, the orbiters and landers that have probed the Red Planet since the 1960s have left open the most fascinating question of all, is there – or if not was there ever – life on Mars?

As enticing as answering that question might be, however, it has been more than 40 years since the last Apollo mission to the relatively close Moon. NASA’s follow-up George W Bush-era Constellation programme was ultimately axed by the succeeding Obama administration – apparently because it was deemed unaffordable. Constellation had the goal of returning to the Moon by 2020.

So, it would seem reasonable to surmise that sending astronauts to Mars is not on the proverbial radar.

However, as NASA chief scientist Ellen Stofan recently explained to a full house at the Royal Aeronautical Society, there are reasons to believe that human explorers could resolve our questions about Mars the way robots never could – and there is indeed a plan to land on the Red Planet in 2035.

The complete article is available at Flight International; register online for access to special features like this one.

Steering a rover from orbit? Challenging but doable

When astronauts finally one day arrive at an alien world, they might want to send a robot advance party down to check out the surface before committing themselves to landing – but controlling a rover from space is far from straightforward, as the orbiting driver would only have intermittent line of sight contact with a ground vehicle.

So, the European Space Agency has been working on a “space internet” concept to store commands when signals are interrupted or the surface unit is lost, and then forward them once contact is re-established. And, on 7 August a trial run went better than expected, with ESA’s Alexander Gerst, orbiting Earth in the International Space Station, steering the agency’s Eurobot rover for 90 minutes around a test facility at its ESTEC technology centre in Noordwijk, the Netherlands.

This article originally appeared on flightglobal.com

Gaia reaches L2 orbit; stars in sight!

Two-and-a-half weeks after its launch, the European Space Agency‘s Gaia star-tracking spacecraft has reached its operational orbit, some 1.5 million km from Earth at the so-called Lagrange 2 point – one of five points where the gravity of the Sun and Earth balance, allowing for a stable orbit around the Sun.

For Gaia, this stability is critical. Once the spacecraft is shaken down, calibrated and commissioned, in about four months, its super-sensitive optics (including a billion-pixel digital camera, the biggest ever to fly in space) will begin scanning the skies to detail the positions of one billion of the Milky Way’s 100 billion stars. Each star will be spotted about 70 times during the five-year mission, so the resulting 3D catalogue will allow astronomers to see how our galaxy has shifted through time – including into the future.

Gaia is also expected to discover thousands of planets orbiting distant stars, as well has many asteroids and other objects inside our own solar system. To put this achievement in context, the catalogue that scientists rely on today – compiled by an earlier ESA stargazing mission – contains highly accurate measurements of only about 120,000 stars, and less-precise data on another 2.5 million.

But to achieve all this, Gaia needs to keep its instruments cold (at about -100°C) and it needs to control its position and rate of rotation very closely. At the L2 point, the Earth is always between Gaia and the Sun, minimising the amount of precious station-keeping fuel the spacecraft needs to expend to keep its 10m-diameter sunshield facing the Sun and its instruments on the deep space, cold, side.

Gaia lifts off from ESA's spaceport in Kourou, French Guiana (credit ESA)

Gaia lifts off from ESA’s spaceport in Kourou, French Guiana (credit ESA)

But the Lagrange points are actually more complicated than that – they are, ironically, unstable points. So, a spacecraft can’t “sit” at L2; rather it has to orbit around L2. In Gaia’s case, that orbit is a 263 000 x 707 000 x 370 000 km “ellipse” that it will round every 180 days. As Gaia spacecraft operations manager David Milligan puts it: “Entering orbit around L2 is a rather complex endeavour, achieved by firing Gaia’s thrusters in such a way as to push the spacecraft in the desired direction whilst keeping the Sun away from the delicate science instruments.” A small course correction will be made next week to complete the manoeuvre.

L2 is fortunately a large region and not really a point, so it can be used by multiple spacecraft. ESA’s Planck mission to measure the remnant radiation of the Big Bang operated there until its retirement in October 2013 to a more distant parking orbit, and the Hubble-successor James Webb space telescope will work from L2 following its launch in 2018.

Experience is a star with Gaia

People in the rocket launching business, no surprise, have seen lots of rocket launches. The same for people who make spacecraft, because they have to be on hand to make sure the payload is alright, which is the point of the whole expensive exercise. The rest of us had better treat a rocket launch like a special occasion.

I’m writing aboard a charter flight from Cayenne to Paris, returning home from Europe’s spaceport in French Guiana after viewing, as a guest of the European Space Agency, the launch of its latest science mission – Gaia, a €740 million project to map the Milky Way in unprecedented 3D accuracy.

Before I set off from London two days ago, friends or colleagues who learned where I was going invariably used the words “experience of a lifetime”. Having done it, I can only agree  – even as a journalist who’s had his share of experiences of a lifetime on other people’s money.

But for a few ticks of fate, this would actually have been my third trip to see a launch. But fate intervenes, so I wasn’t counting my experiences until I actually saw the Soyuz rocket leave the ground in its fire and fury. Weather or glitches happen, and it’s not unusual for a party like this one – mission stakeholders and press – to fly back home without seeing anything.

Vol, Gaia

Vol, Gaia

Such is the nature of this business, and that’s without considering the possibility of disaster. ESA, Astrium (which built Gaia) and Arianespace (which runs the launches in French Guiana) have an excellent reliability record, but every successful launch is a cause for celebration. As one of the men from Astrium could be heard calling out to Gaia as the brightest star in the early morning sky rose steadily above our heads, “Vol, mon petit – vol!”

My handheld photo here does the scene no justice, but I like to show the blossom effect of the rocket’s exhaust; more seasoned watchers said later that this excellent view – as dawn broke – of such a wonder made this the most perfect flight they’d seen.

By definition, I have to say I’m with them. But it’s hard to think how to improve on flight VS06, or Vol Soyuz no 6 (6 from Guiana, that is; since 1966 Soyuz rockets have flown more than 1,800 times). With lift-off at 0612 local time (0912 GMT), the sky was just getting light, so the rocket thrusting up on the pad lit it up like daytime and, once at altitude, the sun on the exhaust tail was magical; indeed, the backlit sky actually sparkled as debris settled when used stages were discarded.

That image, which could only be seen first-hand, is something I’ll remember vividly whenever I think about a mission to scan the sky and find a billion stars.

**

Another reason watching a rocket launch is such a rare treat is that, mostly, launch sites are remote places not easily visited. Cayenne is 10hrs’ flying time from Paris, so nobody just happens by and stops for a minute to watch a rocket scream away. Likewise the Russians’ main launch site, Baikonur cosmodrome in Kazakhstan. As for Plesetsk cosmodrome, that’s on a military base 800km north of Moscow and just outside the Arctic circle – useful for flying the modified ballistic missiles that nowadays lift many a satellite to polar orbit, but not exactly a tourism hot-spot.

The Chinese launch from remote places under strict military control; one colleague on this Cayenne trip who attended the recent International Astronautical Union conference in Beijing says he was surprised (or not, given China) to find that none of the Chinese journalists who follow spaceflight had seen a launch.

Kennedy Space Center at Cape Canaveral is probably the exception to the rule, at least for people in southern Florida. But tales are many of great expense and logistical hassle undertaken in vain to watch Space Shuttle launches that got delayed.

Security and safety also works against the launch fan. London, New York and Paris don’t have spaceports because it’s better if a failed launch drops pieces of burning rocket a little farther from populated areas.

And, it’s also best to launch as far south as possible, because the rotation of the Earth gives the rocket a big extra sling – on the order of an extra 460m/s speed in French Guiana – which translates into more payload to orbit. Baikonur is the most southerly point in the old Soviet Union, and remote. Canaveral likewise, though it’s only remote for launches to the East; they don’t launch to the North from there, so as not to fly over the Eastern seabord. When NASA or the US Air Force launch to a polar orbit, which is ideal for Earth observation satellites because the globe spins under them and hence they see every point on the surface periodically, launches are from Vandenberg air force base in California, to fly over the desert.

Hence the beauty of Europe’s facility in French Guiana, which is arguably the best place on the planet for launching rockets. At just 5° north of the Equator and on the shoulder of South America, launches to the North or East are over water and the payload benefit is huge – a Soyuz rocket launched there can orbit about 35% more mass than one flying from Baikonur.

Not only that, French Guiana is legally part of France, which makes life easy for Europeans visa-wise, and makes for good security.  And, it doesn’t have hurricanes – a problem for many Florida launches.

To which I would add that the food is good, the people friendly and the weather very pleasant; December conditions back in northern Europe have been particularly foul these last couple days, apparently.

By any measure, then, an experience of a lifetime!

Exoplanet search tools are getting sharper

  • A fifth of stars like our Sun may have planets like Earth orbiting in their habitable zones
  • The Gaia mission is set to narrow down the search for habitable planets
  • Scientists want to launch a dedicated mission to study “exoplanets”

Are we alone in the universe? Anybody looking for an answer to that age-old question has plenty to get excited about over the next couple months, because scientists are getting ready to use the most powerful new tool in astronomy to help them search for planets orbiting stars far from our Sun – and in January may get the go-ahead to build a spacecraft dedicated to studying distant worlds, including the handful known so far that are anything like Earth.

For centuries astronomers have thought that some other stars must have planets, but it wasn’t until the mid-1990s that the first so-called exoplanets were actually discovered. Since then, many experts have concluded that most stars have planets, and the total number of known planets outside our solar system has climbed to somewhere between 500 and 1,000. But just a few are known to be anywhere near Earth-sized. Most are hot-gas infernos, Jupiter-sized or bigger.

But with the European Space Agency’s 19 December launch of its five-year Gaia mission to map the Milky Way in unprecedented detail, the odds are going to shift, at least a little bit, in favour of the searchers.

One of the keenest searchers is University College London astrophysics professor Giovanna Tinetti. Professor Tinetti studies the atmospheres of so-called exoplanets – planets outside our solar system – and she is gearing up to analyse the deluge of star data that Gaia will stream home. With a 3D map of a billion stars and an expected 10,000 planet discoveries, she plans to find targets for the next generation of stargazing missions.

Titan

This 2012 image of Saturn’s moon Titan, taken by the Cassini orbiter, shows sunlight scattered by the moon’s atmosphere – the same technique can reveal details of an exoplanet’s atmosphere (credit NASA/ESA)

What Prof Tinetti and colleagues have found, detailed in the November issue of the Monthly Notices of the Royal Astronomical Society, is that Gaia data about exoplanet orbits is going to be at least 10 times more accurate than what is available even from the Hubble Space Telescope. And, as she told some 300 delegates to the annual Rutherford Appleton Laboratory space conference at Harwell last week, knowing where to look is crucial.

To study an exoplanets’ atmosphere, it is necessary to observe its parent star as the planet passes in front, or transits. Then, said Prof Tinetti, it is possible to record not only the change in the star’s brightness, but also the change in its light spectrum. Since different chemicals in the passing planet’s atmosphere absorb specific colours of light, the colours that are “missing” during transit tell us something about the composition of the planet’s atmosphere.

But as Prof Tinetti told the Harwell meeting more than once: “This is hard to do!”

The trick, she said, is going to be to look for large planets that orbit close to their stars, so that they transit frequently. Then, she added, if we look for planets that orbit close to stars that are cooler than our Sun, we have a chance of finding planets with atmospheres that, like Earth, are neither too-hot nor too-cold to be habitable.

The challenge of knowing where to look was highlighted in the 26 November issue of the Proceedings of the National Academy of Sciences in the USA, by University of California at Berkeley astronomer Erik Petigura, who studied data from NASA’s Kepler spacecraft, which is designed to find the tell-tale dimming of a star when an orbiting planet passes in front. Of 42,000 Sun-like stars, he found 603 planets – including just 10 that were roughly Earth-sized. But adjusting for Kepler’s “imperfect” detection capabilities Petigura concluded that maybe 22% of Sun-like stars – 8,400 of the stars he studied – could actually have Earth-sized planets orbiting in their habitable zones, and the nearest one could be 12 light years away.

More-precise observations will clearly help narrow the search. As he puts it: “Determining whether Earth-like planets are common or rare looms as a touchstone in the question of life in the universe.”

Prof Tinetti is hoping that her quest for deep understanding of exoplanets captures the imagination of ESA’s Science Programme Committee, which meets in Paris on 21 January to choose one of five mission proposals for development and launch in 2020-2022. She’ll be in Paris to champion her “EChO” project – if it gets the green light, this Exoplanet Characterisation Observatory will be the first mission dedicated to investigating the physics and chemistry of exoplanetary atmospheres.

That’s a long way from finding other life in the galaxy – but at least we should be able to focus on the most promising locations.

Space, Time and Money will be covering the Gaia launch from ESA’s spaceport in Kourou, French Guiana

Jupiter – the biggest particle accelerator in the Solar system

More from the Rutherford Appleton Space Conference – professor Michele Dougherty is presenting on the European Space Agency’s 2022-launch “JUICE” mission (Jupiter’s Icy Moons) to orbit Ganymede, studying its ice and (we think) liquid water layers, and its dynamo core-generated magnetic field, to explore characteristics of so-called habitable zones.

But one of the interesting side benefits of the mission will be access to Jupiter’s magnetosphere. The biggest object orbiting the Sun has a huge magnetic field and pulls the solar wind hard into its poles. That makes Jupiter the biggest particle accelerator in the solar system.

Meanwhile, physicists are telling  us that even the Large Hadron Collider at CERN in Geneva isn’t big enough. Maybe the next mission to Jupiter ought to be an orbiting particle laboratory?