Mission improbable

The United States space programme has plans for asteroids and Mars, but are these missions too hard, even for Nasa?

SPACE AGENCY Nasa is looking for a rock. It has to be out there somewhere – a small asteroid circling the Sun and passing close to Earth. It cannot be too big or too small. Something up to 30 metres across would work. It cannot be spinning too rapidly, or tumbling knees over elbows. It can’t be a speed demon. And it should not be a heap of loose material, like a rubble pile.

The rock, if it can be found, would be the target for what the National Aeronautics and Space Administration calls the Asteroid Redirect Mission. Almost out of nowhere it has emerged as a central element of Nasa’s human spaceflight strategy for the next decade. Rarely has the agency proposed an idea so controversial among politicians, so fraught with technical and scientific uncertainties, and so hard to explain to ordinary people.

The mission, which could cost upward of US$2 billion (NZ$2.55b), would use a robotic spacecraft to snag the small rock and haul it into a stable orbit around the Moon. Then, according to Nasa’s plan, astronauts would blast off in a new space capsule atop a new jumbo rocket, fly toward the Moon, go into lunar orbit, and rendezvous with the robotic spacecraft and the captured rock. They would put on space-walking suits, clamber out of the capsule and examine the rock in its bag, taking samples. This would ideally happen, Nasa has said, in 2021.

‘‘That’s our plan,’’ Nasa’s top official for space technology, Michael Gazarik, said. ‘‘We have to merge it with reality.’’

Plans, goals, dreams, and technological realities are difficult to sort through these days at Nasa. Apart from the asteroid mission, the human spaceflight programme has few attainable destinations in the near term. Astronauts in 2021 may simply orbit the Moon and come home, a significant feat, but one the agency first achieved in December 1968. Or they could fly to a gravitationally stable point in space beyond the Moon, a potential base for future activities.

Nasa has what might be called middle-age problems.

Founded 55 years ago, America’s civilian space agency had its greatest glory in its youth, with the Moon shots, and it retains much engineering talent and lofty aspirations. But even as the agency talks of expanding civilisation throughout the solar system, it has been forced to recognise its limitations.

Flat budgets have become declining budgets. The joke among agency officials is that, when it comes to budgets, flat is the new up.

Nasa lacks the money and the technology to do what it has long dreamt of doing, which is to send astronauts to Mars and bring them safely back to Earth. It has resorted to fallback plans.

Thus was born this improbable Asteroid Redirect Mission.

The human spaceflight programme has long been searching for a mission beyond low Earth orbit (Leo). That is where Nasa has been sending astronauts since the 1970s, and where the underappreciated international space station circles the planet, currently occupied by two Americans, three Russians and an Italian.

The asteroid mission not only goes beyond Leo, it scratches many other itches at the agency. Nasa has marketed this as planetary defence – a way to get the upper hand on asteroids that could potentially smash into Earth. The agency also said this could boost the commercial mining of asteroids, thus expanding humanity’s economic zone. And the robotic part of the proposal involves new propulsion technology that Nasa thinks could be crucial for an eventual human mission to Mars.

There are also political factors. United States President Barack Obama vowed in 2010 to send humans to an asteroid. Nasa officials have said this mission meets that goal. Most important, the ensnared asteroid would provide a destination beyond Leo for new, expensive hardware that Nasa is already building – a new big rocket and the Orion crew capsule. The mission could deflect accusations that the government is building rocket ships to nowhere.

‘‘It is really an elegant bringing together of our exciting human spaceflight plan, scientific interest, being able to protect our planet, and utilising the technology we had invested in and were already investing in,’’ Nasa’s deputy administrator, Lori Garver, said.

But the mission is viewed sceptically by many in the space community. At a gathering of engineers and scientists at the National Academy of Sciences last month, veteran engineer Gentry Lee expressed doubt that the complicated elements of the mission could come together by 2021 and said the many uncertainties would boost costs.

Al Harris, a retired Nasa planetary scientist who specialises in asteroids, said: ‘‘It’s basically wishful thinking in a lot of ways – that there’s a suitable target, that you can find it in time, that you can actually catch it if you go there and bring it back.’’

Mark Sykes, a planetary scientist who chairs a Nasa advisory group on asteroids, said: ‘‘Of course, there’s always luck. But how much money do you want to spend on a chance discovery that might have a very low probability?’’

If the target rock is not scoped out well in advance, it could even turn out, on close inspection, to be something other than a small asteroid – say, a spent Russian rocket casing that is footloose around the Sun.

Nasa officials understand this and have recently been floating a different scenario, a plan B. Instead of the robotic spacecraft trying to nab a small and potentially unruly rock, the spacecraft could travel to a much larger, already-discovered asteroid and break off a chunk to bring back to lunar orbit, where astronauts would visit it.

That would eliminate a lot of unknowns. In space missions, unknowns ratchet up costs and create delays. But under this plan, the target might be an underwhelming boulder the size of, say, a washing machine. Presumably, that is not what Obama meant in 2010 when he vowed to send humans to an asteroid.

NASA is in a tricky position, trying to improvise a coherent strategy for human spaceflight even as political winds have shifted dramatically. If Nasa is lurching along these days, that is in part because the agency has been

‘Some believe that we should attempt a return to the Moon first . . . but I just have to say pretty bluntly here: We’ve been there before.’

US President Barack Obama

jerked around. It has been in difficult transitions before. Doug Cooke, who spent 37 years at the agency before retiring in 2011, remembers the post-Apollo 1970s: ‘‘It was scary. You realise that you’re not really flying. And it’s a vulnerable time.’’

With the shuttle retired, Nasa can no longer launch American astronauts on American rockets, but rather must buy seats at US$71m a pop on Russian spaceships.

Nasa wants to see American astronauts ride to orbit on commercial spacecraft by 2017, though tight budgets could make that schedule slip by a year or more. Three companies, Boeing, SpaceX and Sierra Nevada, are competing for the ‘‘commercial crew’’contract.

Nasa’s turmoil dates from the morning of February 1, 2003, when the space shuttle Columbia disintegrated over Texas, killing the seven astronauts on board. The grieving space community decided to rethink the enterprise of human spaceflight, from the architecture of rockets to the fundamental purpose of launching people off the planet. Many people inside and outside of Nasa wanted to get back to exploration, which would mean sending humans beyond low Earth orbit for the first time since the early 1970s.

President GeorgeWBush proposed a plan to return astronauts to the Moon by 2020. The new Nasa programme, Constellation, included plans for two rockets, a crew capsule called Orion and a lunar lander.

But at Nasa there’s a saying: ‘‘Budget is mission-critical.’’

Constellation’s funding fell short of what top Nasa officials expected. The programme fell behind schedule. A new rocket, Ares I, had some delays and technical problems.

Obama won the presidency and, before long, Bush’s Constellation programme was gone. Obama’s pick to run his Nasa transition team, Lori Garver, never liked the back-to-the-Moon strategy. ‘‘If your goal is Mars, that is certainly a detour,’’ she said recently.

Obama appointed General Charles Bolden Jr, a four-time shuttle astronaut, to the administrator position, with Garver as his deputy. The president also tapped retired aerospace executive Norman Augustine to lead an advisory review of the Nasa human spaceflight programme.

The Augustine committee skewered Constellation, saying that without more money it would not get astronauts back to the Moon until the late 2020s, and even then there would not be any money for a lander, much less a Moon base.

In killing Constellation, Obama adopted what the Augustine Committee dubbed the ‘‘flexible path’’ strategy. The concept is arguably a sign of institutional maturity: Nasa would focus less on destinations and more on creating new technologies. The idea was to advance spaceflight capabilities, with the long-term goal of sending people to Mars. Commercial companies could take over the routine taxi rides to orbit, and Nasa would tackle harder missions. But there is a problem with the harder stuff: Often it is just too hard.

Just about everyone in the space community wants to go to Mars. Rovers are great, but they are sluggish, and scientists fantasise about a human geologist being able to decide where to dig into the Martian soil for clues about the planet’s history and possible signs of life.

Many people feel strongly that societies that do not explore the frontier will invariably go into decline. The fourth rock from the Sun haunts the imagination of people from the third rock. Mars has as much land area as the Earth. Someone like Elon Musk, the visionary founder of SpaceX, is not necessarily going to wait for a Nasa mission; he talks of establishing a Mars colony, and says he wants to die there – just not while attempting to land.

A private venture called Inspiration Mars hopes to send two astronauts on a fly-by mission of Mars in 2018.

However, Nasa is not an entrepreneurial outfit. Its plans have to pass layers of technical, political and budgetary review. A fundamental presumption of Nasa missions is that the astronauts will come back alive.

A journey to Mars would take about two years and expose astronauts to extremely high levels of radiation. The Martian atmosphere is a nightmare, just thick enough to cause problems but too thin to be of much use in braking a speeding spacecraft. Last year Nasa landed a one-tonne rover on Mars, but to put humans there, engineers think they would need to land a 40-tonne payload, including a habitat, fuel and food. To scale up by a factor of 40 is not as simple as, for example, making a parachute 40 times as big. Physics and aerodynamics do not work that way.

More achievable is a human mission to orbit Mars. Astronauts could essentially telecommute to work, operating rovers and other instruments from orbit. Indeed, a Mars orbit in the 2030s is an official Nasa goal, direct from Obama. On April 15, 2010, in a speech at the Kennedy Space Centre, the president said that by 2025, Nasa will begin missions to ‘‘deep space’’, starting by ‘‘sending astronauts to an asteroid for the first time in history’’. Then would come a Mars orbital mission in the mid-2030s, he said.

‘‘And a landing on Mars will follow,’’ he said, without giving a date. ‘‘I understand that some believe that we should attempt a return to the surface of the Moon first, as previously planned. But I just have to say pretty bluntly here: We’ve been there before.’’

MONTHS after Obama’s speech, senators from states with Nasa centres and contractors took steps to salvage major chunks of the Constellation programme. Congress directed Nasa to continue building a heavy-lift rocket that could take payloads beyond low Earth orbit. Orion would also go forward.

The new rocket is called the Space Launch System, although the less reverential name for it in the space community is the Senate Launch System.

It is being designed in Alabama and built in Louisiana, and will be tested in Mississippi before being launched in Florida and supervised by Mission Control in Texas. It has many supporters.

What the jumbo rocket and the Orion capsule cannot do, without a lot of costly hardware, is fly to a distant asteroid orbiting the Sun.

It is natural to envision spaceflight as a journey from point A to point B. But it’s a lot more complicated than that, because points A and B are both moving, and at different speeds. Thus engineers rarely talk about distance, and instead talk about trajectories, orbital dynamics and ‘‘delta V’’ – the change in velocity.

Just about any mission to an asteroid, even a ‘‘near-Earth’’ asteroid (one in an orbit that comes close to Earth, as opposed to the asteroids beyond the orbit of Mars, in the Asteroid Belt), would take hundreds of days. But the new Orion capsule can support astronauts for only about three weeks.

Nasa, therefore, needed a fallback to the Obama-style asteroid mission. Hence the Asteroid Redirect Mission.

Humans have never moved an object out of its natural orbit. Two years ago, engineers and scientists at the Keck Institute for Space Studies in Pasadena, California, proposed doing just that with a small asteroid, citing potential scientific interest. The idea caught on in the corridors at Nasa.

‘‘It’s not as crazy as it seemed at the beginning,’’ said Charles Elachi, the longtime director of Nasa’s famed Jet Propulsion Laboratory, run in Pasadena by Caltech. Elachi’s people honed the mission and declared it feasible. These are engineers who know what they are doing: Elachi’s office is sprinkled with models of craft that landed on Mars, circled Jupiter and Saturn, probed distant moons and zoomed to the edge of interstellar space.

What the laboratory does not have is a firm target for the asteroid mission. These objects are small, and appear fleetingly in telescopes, leaving behind minimal information about their size and composition. Without knowing the albedo – the shininess – of the object, it’s impossible to know how big it is when that streak of light appears in the telescope.

Nasa has an advisory committee of scientists who specialise in small objects in the solar system and, after a meeting last month, the group produced a blistering draft report saying that Nasa needed to do a lot more homework. For example, the report said: ‘‘Such small objects may be rapidly rotating rubble piles, which could be hazardous to spacecraft during interactions with the target object.’’

So where does this leave the asteroid mission, and Nasa? Back in a familiar place, with a plan that does not seem rock-solid.