MAIN ARTICLE: Space debris: why the US cannot go it alone.
"The US cannot afford to, nor should it attempt to, deal with space debris on its own." - Kirk Woellert
Poll Results: Low turnout for yesterday's poll as people start hitting the outdoors on the weekends.
Star Trek: In the News. Astronauts watch 'Star Trek' that's beamed up to International Space Station.
Yesterday's Comments: "Giant wad of aerogel?" - Simplify
Today's Poll: Should America go it alone cleaning up space junk or wait for an international commitment?
LEAVE THAT JUNK ALONE:
In response to a May 4, 2009 article, "Unilateral orbital cleanup", by Taylor Dinerman over at Jeff Foust's Space Review a new essay appeared today about space debris mitigation. It was a well written commentary by Kirk Woellert. The point he makes about the Dinerman article was that America should not go it alone, the problem is to big.
Space debris: why the US cannot go it alone by Kirk Woellert
"A recent article in The Space Review claims the US should deal with the issue of space debris unilaterally (see "Unilateral orbital cleanup", May 4, 2009). A complete analysis of individual space debris removal strategies is beyond the scope of this forum. For that matter, even the question of a passive or active strategy for dealing with space debris is a complex issue by itself. The purpose herein is to look at one active space debris strategy proposal and point out some technical and policy implications. The conclusion is the US cannot afford to, nor should it attempt to, deal with space debris on its own.
Technical
Considering the assertion in that article:
What is required is a new type of space maneuver vehicle, one that can rendezvous with, catch, and store a bit of debris, and then proceed to the next one. Such a vehicle would not need to move very fast: the process would be a leisurely one, and thus would allow for the use of a highly efficient space propulsion system such as a pulse plasma thruster or ion engine.
The proposal is for a dedicated spacecraft to maneuver and capture individual pieces of space debris. The proposed vehicle would rely on ultra-efficient propulsion such as ion or plasma arc-jet thrusters. On the surface the concept may appear sound. However, it’s worthwhile to delve into a bit of orbital mechanics.
First, there are thousands of space debris objects actively tracked and many thousands more that are not tracked. Although on a large scale there are clusters and gaps in the debris field, each of these objects are in unique orbits. Various types of orbital maneuvers would need to be continuously executed. These maneuvers will include changes in the vehicle altitude, period, right ascension, and inclination. A first order analysis of the mission profile would consider the most costly maneuver in terms of energy, a change in orbital inclination. Typically such analysis calculates the change in velocity or "deltaV" required to perform a maneuver. Although there are relative concentrations at select inclinations between roughly 60° and 100°, space debris takes on many inclination values spanning 0°–100°. Atmospheric drag dominates for circular orbits below about 200 kilometers. Hence any space debris orbiting at or below these altitudes will decay in a reasonable period of time."
--end quote--
LOOKING AT THE NUMBERS:
Kirk then goes into the orbital mechanics of a garbage collector probe utilizing ion thrusters, the most fuel efficient engines for space but very slow. He then asserts that basically every single piece of debris has it's own unique orbital path and that the delta V required to move to each item would make this process extremely slow going:
"Per the aforementioned analysis, a 1° change in inclination would require 9.7 days. This time does not include fine orbit maneuvers required to close to within a reasonable distance to the target debris. Another limiting factor to this concept is the mission profile does not allow for the advantage of continuous acceleration often cited for ion propulsion.
Continuing on with the analysis, NORAD tracks about 19,000 objects in orbit. Assume half of these objects, or 9,500, require an inclination plane change maneuver of at least 1° for the vehicle to achieve co-orbit with the target. This implies the time to capture these objects would be (9,500 x 9.7 days) = 254 years. Admittedly this analysis is simplistic but it gives some sense of the time scale involved."
--end quote--
Mr. Woellert then touches on U.S.space policy and how it is moving towards more international cooperation therefore America should get involved in that arena and bring the international space faring community on board.
He also mentions that the U.S. military should not be shouldered with this burden either as it has many kettles on the stove right now with two current wars.
He finally concludes with:
"Space debris concerns all spacefaring nations and should be addressed as an international issue utilizing a multilateral approach. International cooperation takes significant time to build consensus and on occasion has led to ineffectual results. Nevertheless, the US can best protect its interests in space not by unilateral action but by using its influence and leadership to establish an effective international response to mitigating—and perhaps one day eliminating—the hazard of space debris."
I guess we will just have to agree to disagree on what constitutes leadership. For myself leadership is about leading regardless if someone chooses to follow. People tend to want to follow a leader that leads by example not by committee.
America has to be seen as doing SOMETHING about a problem, that is what a leader does, they do not wait for committees and debate in the face of a problem.
Another point is, half of that space junk is ours, what does OUR garbage have to do with the international community, other then posing a risk to their satellites and spacecraft.
OUR GARBAGE OUR PROBLEM:
The first mistake America can make is leaving this problem for the government to personally handle. I have no problem with the federal government funding multiple commercial firms to do this. The more the better as it brings in competition and downward pressure on prices.
Pay by the piece, by the pound, by how difficult the orbit of the piece of junk is. By creating a commercial space debris recovery sector it would be in the international community's own economic self interest to set up their own firms to compete against ours putting more pressure on price.
Kirk states it would take 254 years for a collector to grab 9500 pieces of debris. Well it would only 25 years if there were 10 of them ran by multiple companies and you would have not have to grab everything right away but only the most troubling areas first.
The top image shows the aftermath of the chinese satellite shoot down. The debris that was created is in a very similiar path, so a few robotic collects following that stream could gather quite a bit without having to do major orbital shifts.
A PERSONAL NOTE:
Personally, I would rather see these as human crewed vessels, if something breaks they can fix it and they can monitor all kinds of sensors and climate change data while they wait for the next encounter.
We have to get away from the idea that everything that has to be done in space is going to be exciting filled with exploration and science. As we develop space there is going to be a lot of boring jobs (image United Galaxies Sanitation Patrol Cruiser)
that have to be done, just like on the ground and garbage collection is one of them.
POLL RESULTS:
Astronauts watch 'Star Trek' that's beamed up to International Space Station
"Beam me up, NASA.
Astronauts aboard the International Space Station watched the new Star Trek film Friday after NASA spent five hours re-formatting the blockbuster so it could be beamed up from Mission Control, 220 miles above the earth's surface.
The station's resident Trekkie, American spaceman Michael Barratt, requested the film because the original series inspired him to become an astronaut, NASA said.
Barratt, Russian cosmonaut Gennady Padalka, and Koichi Wakata from the Japan Aerospace Exploration Agency settled into the node of the spaceship after dinner, strapped their feet to the floor to keep them from floating and watched the specially adapted film on a computer
Movie nights on board the space station are a tradition."
--end quote--
YESTERDAY'S COMMENTS:
"I say fund them both. But what I really want is
a) some cheap, really cheap, method of putting a lot of technology up there in a very short time. Like Yesterday. Not people necessarily, but really heavy shit.
b) a giant orbiting magnet or vacuum cleaner (heh) that would clean up our man-made orbiting debris. Maybe giant rolls of old fashioned fly tape. but we certainly need something. it is REALLY getting messy out there." - agnostic
"F9 issues
- Elon
- 9 engines, that's just trouble in spades. If you READ the F9
ops manual it doesn't say anything about engine fault tolerance,
and most multi engine expendable can't handle an engine failure until
quite late in the mission.
- Elon
- the Merlin is underperforming.
- Elon
- Costs are going to double for the F9.
- Elon
- The burn rate at SpaceX is phenomenal.
- Elon
- The major customer for SpaceX is NASA.
Their Major customer used to
be DoD but they screwed DoD and DoD walked away. (See odd numbered
issues) One policy change and they are done for." - nathguy
"115 page Direct 2.0 pdf
On line announcement by Ross Tierney:
In response to the NASA Performance Analysis of October 2007 (which was kept secret for a year to prevent any counter-claims) The DIRECT Team is now prepared to release a formal Rebuttal to address NASA's negative claims.
In precisely the same way that the Constellation Program attempted to dismiss both the Atlas-V and the Delta-IV as replacements for the Ares-I, a very similar attempt to discredit the 1-vehicle, "2-launch" DIRECT proposal was also made at the same time, primarily intended to drive both public and political support away from any alternative but the 2-vehicle "1.5 launch" Ares architecture.
This Rebuttal stands as a step-by-step detailed description of the oversights and flaws in the Analysis of DIRECT 2.0 and reveals precisely how those errors led that study to its incorrect conclusions.
This Rebuttal is specific to the Performance Analysis of the DIRECT proposal as it stood in later part of 2007 and should not be confused with later versions of DIRECT, which continue to be a work in progress.
115 page pdf is here:
http://www.launchcomplexmodels.com/...
This refers to Direct 2.0 which is asserted to be superior to ESAS (Ares 1 & Ares V) however DIRECT 3.0 shall be rolled out at ISDC next week and that is asserted to be better than both ESAS and Direct 2.0." - Bill White
TODAY'S POLL:
Read other NASA and Space diaries on DKOS.
