Given that smaller asteroids routinely travel within roughly a lunar distance, would it make sense for an Orion flight to be dedicated to collecting samples(100+ kg)? It makes more sense than the asteroid redirect as that required unique hardware to be developed(the ARRM).
Just as a few examples:
asteroid: 2015 TB145
date: October 31, 2015
distance: 1.3 lunar distances
size: 600 meters
asteroid: 2018 CC
date: February 6, 2018
distance: .48 lunar distances
size: 15-30 meters
asteroid: 2018 CB
date: February 9, 2018 (i.e. yesterday)
distance: .16 lunar distance
size: 15-40 meters
2018 close approaches:
https://en.wikipedia.org/wiki/List_of_asteroid_close_approaches_to_Earth_in_2018This would fulfill goal #5 on the Augustine Commissions "Flexible Path" mission manifest.
https://www.nasa.gov/pdf/396093main_HSF_Cmte_FinalReport.pdfThe main issue seems to be finding an asteroid with a velocity relative earth within the EUS/Orion systems limits. The website below suggests this velocity can vary greatly (2 km/s to 20 km/s). Obviously, the high end of that range is out of the question.
https://cneos.jpl.nasa.gov/ca/
Sadly not likely, not because of the target but because of the trajectory and limits of the Orion itself. The Orion is limited to 3 weeks of life support at most. It's propulsive capability can't do better than high lunar orbit, hence why all the various orbits or Lagrange points have been frequently suggested because they are distant. And as for trajectory itself, while these asteroids are mainly the NEO variety any spacecraft still has to chase them down; just look to OSIRIS-REX and the JAXA asteroid missions; they require years to properly match their target and back in the ARM days of Orion even ideally a 6 month trip seemed a minimum to get to an asteroid.
This why they switched to asteriod retrieval concept.
You would need a propulsive unit and a habitat so extra development.
You would need a propulsive unit and a habitat so extra development.
Aren't those things going to be needed for almost anything? (Other than a space habitat not being needed for direct return to the moon).
Shouldn't NASA be spending the SLS money on those things? (Perhaps working with Bigelow on the space habitat)
I also understand that trying to identify a useful asteroid several years out (enough to plan a mission) would largely be based on luck right now.
You would need a propulsive unit and a habitat so extra development.
I suspect the habitat will fall out of NEXTstep-2
Sadly not likely, not because of the target but because of the trajectory and limits of the Orion itself. The Orion is limited to 3 weeks of life support at most. It's propulsive capability can't do better than high lunar orbit, hence why all the various orbits or Lagrange points have been frequently suggested because they are distant. And as for trajectory itself, while these asteroids are mainly the NEO variety any spacecraft still has to chase them down; just look to OSIRIS-REX and the JAXA asteroid missions; they require years to properly match their target and back in the ARM days of Orion even ideally a 6 month trip seemed a minimum to get to an asteroid.
I'm suggesting interception at closest approach. The 3 week time limit shouldn't be a problem given these are often closer than the moon and that takes ~3 days(and 3 days back). Stays would be limited to a day or 2. Nominally, you could limit it to 2 weeks with 1 week of margin. The endurance of EUS is a big unknown though as it would be needed for both interception of the trajectory and matching the trajectory at apogee(Orion would do station keeping and TEI). Ideally, you would find an asteroid just slightly beyond earth capture energy. Something a bit slower than the 2029 Apophis flyby at essentially geosynchronous altitude which is listed at 7.43 km/s(4.36 km/s faster than geosynchronous orbit). Other than the date being too far out and the speed being a few km/s too fast, that would be perfect.(not sure if it will pass earth over the poles/retrograde either which wouldn't be reachable from kennedy).
I wonder whether anybody at NASA has considered sending Orion/SLS to a
temporary moon, e.g., the recent 2016 HO
3.
Sadly not likely, not because of the target but because of the trajectory and limits of the Orion itself. The Orion is limited to 3 weeks of life support at most. It's propulsive capability can't do better than high lunar orbit, hence why all the various orbits or Lagrange points have been frequently suggested because they are distant. And as for trajectory itself, while these asteroids are mainly the NEO variety any spacecraft still has to chase them down; just look to OSIRIS-REX and the JAXA asteroid missions; they require years to properly match their target and back in the ARM days of Orion even ideally a 6 month trip seemed a minimum to get to an asteroid.
I'm suggesting interception at closest approach.
Still tricky at best, even if you manage to find something speeding just above Earth's capture speed. Nature doesn't exist for our convenience, so the asteroids you're looking for aren't garden variety otherwise the Earth would have dozens of small moons and Lagrange co-orbitals. More to the point, you're still talking about intercepting something flying as fast as a bullet, and interception is no easier to do than rendezvous.
I wonder whether anybody at NASA has considered sending Orion/SLS to a temporary moon, e.g., the recent 2016 HO3.
This is probably the closest thing to a convenient asteroid to visit. Still would need more effort than Orion alone can provide.
So, I exported
https://cneos.jpl.nasa.gov/ca/ to excel(limiting to 5 lunar distances and future results only) and added a few columns for conversions. Then calculated what the orbital velocity for a circular altitude at the nominal close approach altitude would be with √GM/a. Subtracting this value from the listed close approach velocity relative to earth gives the excess velocity relative to capture into a circular orbit. This should approximate how easy from a delta-v standpoint rendezvous should be.
You can see the resulting dataset sorted by "excess velocity" here:
https://docs.google.com/spreadsheets/d/1rO-IQ8egPLDYlz-lUVop9nxqjZsIAiu1Kq7a0SADUew/edit?usp=sharingIt seems that the top pick given these constraints is 2015 VO142 at 2.74 lunar distances and an excess velocity of 2.96 km/s in March 2026. You wouldn't need a hab to reach it and get back, but you would need a fairly powerful service module upgrade and/or lunar lander with 5 km/s+. Hardware could be common with a human lunar surface return. With NEAs being discovered at a rate of a few thousand a year, hopefully something better comes along