Author Topic: Captured Asteroid mission - Redefining EM-2 for the bold challenge  (Read 38268 times)

Offline Robert Thompson

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I went thinking about public outreach observations of ET-shaped asteroid transits, but the stable high orbits appear to be highly inclined.

Offline Hop_David

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I'm trying to gain a better understanding of the "stable lunar orbit" the Keck authors envision. [...] a semi-major axis of 24514 km

Further to this, I calculate the Hill Sphere of the Moon to have a radius of 61,464 km.[1] Wikipedia asserts it has a source for the claim that, "it appears that stable satellite orbits exist only inside 1/2 to 1/3 of the Hill radius." The more strict of those would put the limit at 20,488 km, and the Keck orbit would not quite qualify. But it comfortably meets the less strict (1/2) requirement, and they have clearly chosen cleverly an orbit that numerical simulation shows is stable for 20 years or more, which is certainly plenty of time for EM-2 to get there, even with "standard" NASA delays! ;)

Allowing an object at EML1 or 2 to fall to the moon will generally result in an orbit with a 60,000 km apolune and 4,000 km perilune. This lunar orbit with a 32,000 km semi-major axis is only a nudge away from either EML1 or EML2 (the apolune can pass near both since it's in a rotating frame)

In orbital sims the closest orbit I can get that lasts 20 years is a 38,000 km apololune and 4000 km perilune. I guess that's about a 21,000 km semi major axis.

Get the apolune much higher and the orbits seem short lived. If rock sails through EML1 at apolune, it will tend to fall into a 100,000 km x 300,000 earth orbit that is periodically perturbed by the moon.

If the rock sails through EML2 at apolune, it generally sails to a 1.8 million km apogee. SEL1 and 2 are 1.5 million kilometers from earth, so if the apogee is near either of these two, it can sail out of earth's sphere of influence altogether.

Not conclusive, but that's my experience.

Offline Chris Bergin

RELEASE 13-240

NASA Completes First Internal Review of Concepts for Asteroid Redirect Mission

NASA has completed the first step toward a mission to find and capture a near-Earth asteroid, redirect it to a stable lunar orbit and send humans to study it.

In preparation for fiscal year 2014, a mission formulation review on Tuesday brought together NASA leaders from across the country to examine internal studies proposing multiple concepts and alternatives for each phase of the asteroid mission. The review assessed technical and programmatic aspects of the mission.

"At this meeting, we engaged in the critically important work of examining initial concepts to meet the goal of asteroid retrieval and exploration," said NASA Associate Administrator Robert Lightfoot, who chaired the review at the agency's headquarters in Washington. "The agency's science, technology and human exploration teams are working together to better understand near Earth asteroids, including ones potentially hazardous to our planet; demonstrate new technologies; and to send humans farther from home than ever before. I was extremely proud of the teams and the progress they have made so far. I look forward to integrating the inputs as we develop the mission concept further." 

In addition to the internal reviews of concepts for the mission, managers also discussed the recently received more than 400 responses to a request for information in which industry, universities, and the public offered ideas for NASA’s asteroid initiative. The agency is evaluating those responses.

With the mission formulation review complete, agency officials now will begin integrating the most highly-rated concepts into an asteroid mission baseline concept to further develop in 2014.

The asteroid redirect mission is included in President Obama's fiscal year 2014 budget request for NASA, and leverages the agency's progress on its Space Launch System rocket, Orion spacecraft and cutting-edge technology development. The mission is one step in NASA's strategy to send humans to Mars in the 2030s.

Offline Khadgars

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Anyone catch this yet?  12 candidates already found, updated August 8th.

Offline JohnFornaro

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Good catch.  Threw an eyeball over it.

There are more than twelve qualifications governing the feasibility of the twelve candidates "already" identified.

But hey:  It's a start.  I suppose they'll need more money?
Sometimes I just flat out don't get it.

Offline rayleighscatter

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I was thinking about EM-2 today and that the mission commander would almost certainly have to be from among the current active astronauts. I noticed though that there's only 1 former shuttle commander still active (Scott Kelly) and I'd have to think he'd be at his permissible radiation limit after the year long ISS mission.

This would be the first manned flight of a new vehicle without an experienced commander since Mercury. That is unless they consider ISS commanders or future commercial crew flight commanders. I wonder if ISS command and launch vehicle command are considered that similar?