Imagine, if you can, the first time human eyes see Earth as a  distant, pale blue dot. We’ve dreamed of deep space missions for  centuries, and during the Apollo era, space enthusiasts assumed we’d  surely be out there by now. Nevertheless, given the current state of  faltering economies and potential budget cuts for NASA and other space  agencies, sending humans beyond low Earth orbit might seem as impossible  and unreachable as ever, if not more.
But NASA has been given a presidential directive to land astronauts on an asteroid by 2025, a mission that some say represents the most ambitious and audacious plan yet for the space agency.
“The human mission to an asteroid is an extremely important national  goal,” Apollo astronaut Rusty Schweickart told Universe Today. “It will  focus both NASA’s and the nation’s attention on we humans extending our  capability beyond Earth/Moon space and into deep space. This is an  essential capability in order to ultimately get to Mars, and a  relatively short mission to a near-Earth asteroid is a logical first  step in establishing a deep space human capability.”
And, Schweickart added, the excitement factor of such a mission would  be off the charts. “Humans going into orbit around the Sun is pretty  exciting!” said Schweickart, who piloted the lunar module during the  Apollo 9 mission in 1969. “The Earth will be, for the first time to  human eyes, a small blue dot.”
But not everyone agrees that an asteroid is the best destination for  humans. Several of Schweickart’s Apollo compatriots, including Neil  Armstrong, Jim Lovell and Gene Cernan, favor returning to the Moon and  are concerned that President Obama’s directive is a “grounding of JFK’s  space legacy.”
Compounding the issue is that NASA has not yet decided on a launch  system capable of reaching deep space, much less started to build such a  rocket.
Can NASA really go to an asteroid?
NASA Administrator Charles Bolden has called a human mission to an asteroid “the hardest thing we can do.”
 Excited by the challenge, NASA chief technology officer Bobby Braun  said, “This is a risky, challenging mission. It’s the kind of mission  that engineers will eat up.”
 A human mission to an asteroid is a feat of technical prowess that  might equal or exceed what it took for the US to reach the Moon in the  1960’s. Remember scientists who thought the moon lander might disappear  into a “fluffy” lunar surface? 
That reflects our current understanding  of asteroids: we don’t know how different asteroids are put together  (rubble pile or solid surface?) and we certainly aren’t sure how to  orbit and land on one. 
“One of the things we need to work on is figuring out what you  actually do when you get to an asteroid,” said Josh Hopkins from  Lockheed Martin, who is the Principal Investigator for Advanced Human  Exploration Missions.
 Hopkins leads a team of engineers who develop  plans and concepts for a variety of future human exploration missions,  including visits to asteroids. He and his team proposed the so-called  “Plymouth Rock” mission to an asteroid (which we’ll discuss more in a  subsequent article), and have been working on the Orion Multi-purpose  Crew Vehicle (MPCV), which would be a key component of a human mission  to an asteroid.
 “How do you fly in formation with an asteroid that has a very weak  gravitational field, so that other perturbations such as slight pressure  from the Sun would affect your orbit,” Hopkins mused, in an interview  with Universe Today. “How do you interact with an asteroid, especially  if you don’t know exactly what its surface texture and composition is?  How do you design anchors or hand-holds or tools that can dig into the  surface?”
Hopkins said he and his team have been working on developing some  technologies that are fairly “agnostic” about the asteroid – things that  will work on a wide variety of asteroids, rather than being specific to  an iron type- or carbonaceous-type asteroid.
A weak gravity field means astronauts probably couldn’t walk on some  asteroids – they might just float away, so ideas include installing  handholds or using tethers, bungees, nets or jetpacks. In order for a  spaceship to stay in orbit, astronauts might have to “harpoon” the  asteroid and tether it to the ship.
Hopkins said many of those types of technologies are being developed  for and will be demonstrated on NASA’s OSIRIS-REx mission, the robotic  sample return mission that NASA recently just selected for launch in  2016. “That mission is very complimentary to a future human mission to  an asteroid,” Hopkins said.
Benefits
What benefits would a human asteroid mission provide?
 “It would add to our body of knowledge about these interesting, and  occasionally dangerous bodies,” said Schweickart, “and benefit our  interest in protecting the Earth from asteroid impacts. So the human  mission to a NEO is a very high priority in my personal list.”
Space shuttle astronaut Tom Jones says he thinks a mission to near  Earth objects is a vital part of a planned human expansion into deep  space. It would be an experiential stepping stone to Mars, and much  more.
 “Planning 6-month round trips to these ancient bodies will teach us a  great deal about the early history of the solar system, how we can  extract the water known to be present on certain asteroids, techniques  for deflecting a future impact from an asteroid, and applying this deep  space experience toward human Mars exploration,” Jones told Universe  Today.
“Because an asteroid mission will not require a large, expensive  lander, the cost might be comparable to a shorter, lunar mission, and  NEO expeditions will certainly show we have set our sights beyond the  Moon,” he said.
 But Jones – and others – are concerned the Obama administration is  not serious about such a mission and that the president’s rare mentions  of a 2025 mission to a nearby asteroid has not led to firm NASA program  plans, realistic milestones or funding.
“I think 2025 is so far and so nebulous that this administration  isn’t taking any responsibility for making it happen,” Jones said. “They  are just going to let that slide off the table until somebody else  takes over.”
 Jones said he wouldn’t be surprised if nothing concrete happens with a NASA deep space mission until there is an administration change.
“The right course is to be more aggressive and say we want people out  of Earth orbit in an Orion vehicle in 2020, so send them around the  Moon to test out the ship, get them to the LaGrange points by 2020 and  then you can start doing asteroid missions over the next few years,”  Jones said. “Waiting for 2025 is just a political infinity in terms of  making things happen.”
Jones said politics aside, it is certainly feasible to do all this by  2020. “That is nine years from now. My gosh, we are talking about  getting a vehicle getting out of Earth orbit. If we can’t do that in nine years, we probably don’t have any hope of doing that in longer terms.”
Can NASA do such a mission? Will it happen? If so, how? Which asteroid should humans visit?
 Over the next few days, we’ll take a closer look at the concepts and  hurdles for a human mission to an asteroid and attempt to answer some of  these questions.by "environment clean generations" 



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