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Dr. Mike Griffin, Tuesday, 9-16-14 September 17, 2014

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Dr. Mike Griffin, Tuesday, 9-16-14

http://archived.thespaceshow.com/shows/2317-BWB-2014-09-16.mp3

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Guest:  Dr. Mike Griffin.  Topics: Human spaceflight policy, political choices, space technology, Mars, Moon, Asteroids and more.  Please direct all comments and questions regarding Space Show programs/guest(s) to the Space Show blog, https://thespaceshow.wordpress.com.  Comments and questions should be relevant to the specific Space Show program. Written Transcripts of Space Show programs are a violation of our copyright and are not permitted without prior written consent, even if for your own use. We do not permit the commercial use of Space Show programs or any part thereof, nor do we permit editing, YouTube clips, or clips placed on other private channels & websites. Space Show programs can be quoted, but the quote must be cited or referenced using the proper citation format. Contact The Space Show for further information. In addition, please remember that your Amazon purchases can help support The Space Show/OGLF. See http://www.onegiantleapfoundation.org/amazon.htm.  For those listening to archives using live365.com and rating the programs, please email me as to why you assign a specific rating to the show. This will help me bring better programming to the audience.

We welcomed back to the program Dr. Mike Griffin.  During the first segment of our 90 minute discussion, Mike talked about human spaceflight (HSF) and the commercial space market.  He said exploration would be a government project or at least with government in the lead, especially if the commercial market was not there.  He threw water on the argument that our space policy was budget driven.  Instead, he talked about it being based on choices we make. It was not and is not about the money.  His comments throughout or discussion on this topic supported his argument.  He even said the cost of space for the U.S. taxpayer was around 15 cents/day.  This discussion evolved to one on the importance of leadership which we agreed was in short supply today.  Included in this discussion was Mike’s vision for our space policy & program, plus he explained its importance and value to our nation both today and for the future.  He spoke to the issue of what society wants and the choices it makes that shape our future.  Space should be part of our national policy debate and hopefully such a debate would enable quality choices to be made that keep us on the leadership edge with all nations.   Mike was asked who he thought would be next on the Moon and he said China.  We also talked about the private sector taking us back to the Moon with HSF.  He said that the private sector could do this, capital was not an issue, but for the private sector to do it there needs to be a closing of the business case which he did not see at this time.  SLS John called in & asked about space advocacy diversity which he said seemed to be at war with NASA & whatever the program of record might be.  Mike had much to say about this, especially about inefficiencies in government organizations and projects.  He also said if the private venture or industry cannot make money, then it should be a federal project. Many times during our discussion he said that there are things that a society should do just because they are hard & they don’t have to look good on the balance sheet.  John also asked about the RD-180 engine, Mike offered us his conclusion as to why we should be a new version of the RD-180 so that we do not continue being dependent on Russia for space related hardware, etc.  Later, he was asked about cislunar space development which he said should be a public enterprise.  He cited many examples and models supporting the public development of this important space infrastructure.  SLS was discussed.  Mike very clearly articulated the case for SLS today and again repeated that SLS future missions are about choices, not the budget.  Don’t miss his comments.  As the segment ended, Randy emailed a question asking for the rational & silver bullet for HSF.  In my opinion, Mike gave an excellent response to this question so don’t miss it.

In the second segment, Mike got some questions about NASA doing more R&D and even forming a NACA-like division or program.  We talked about NASA R&D, the need for a NACA-like program and more.  Dave, our caller, commented on leadership, then Bill in Denver emailed in a question about using fuel depots and smaller launch vehicles rather than heavy lift vehicles like SLS.  Again, Mike had much to say about heavy lift, including that while possible to do smaller vehicle launches., the numbers don’t pan out for efficiency.  You need to listen to this full discussion which also addressed some bogus assumptions regarding inefficient heavy lift decision making.  Nuclear propulsion and Vasimr came up, , then we again focused on vision that takes on big challenges because we can!  More was said on lunar colonies evolving to longer BLEO missions plus cislunar commerce, especially cislunar cargo missions.  Another listener asked about being dependent on the Russians for HSF to the ISS and if shuttle was retired too early.  Mike talked about having wanted to fly shuttle at a minimum rate annually until a new vehicle was operational.  We talked about the role of the congress and White House as compared to the role of the NASA Administrator.  Later, we talked about the role of public support and individuals petitioning congress on space policy.  Listen to his story about the Hubble repair mission.  I even asked if poorly written and fantasy driven letters to informed staffers helped or hurt the cause.  Listen for Mike’s response. In summary, Mike said his wish was that people would share is view that there are important things for society to do but that don’t look good on a balance sheet.  In the end, he said he was optimistic that his positive views on space would prevail and that when policy makers realized that China was going to put people on the Moon and what that would mean for the US, it would not be allowed to happen.

Please post your comments/questions on TSS blog above.

Comments»

1. jimjxr - September 18, 2014

Well that’s disappointing, I wish Dr. Griffin would spend time discussing the technology and economics of reusability or commercial crew downselect instead, I have to say I disagree strongly with his view of space policy:
1. Yes, it IS all about the money. If you have to dress up this about choices, leaderships, then the reality is this: The American people has made the same choice for 45 years that 15 cents/day is the amount they’re willing to pay for the national space program, and for 45 years the elected officials from multiple presidents to multiple sessions of congress have also supported this level of spending, this is the fact.
2. So I don’t see how the budget for national space program can be increased, given these facts. And Dr. Griffin himself admits he doesn’t know how this can be changed, he’s hoping a new space race with China would do it, which sounds to me is no different from the la la land fantasy thinking Dr. Livingston has criticized repeated on this show. Sorry, a fantasy is still a fantasy even if it’s coming from a former NASA administrator.
3. Since there’s no foreseeable way to increase the space program budget, it is critical that the space program is designed to fit the budget, not the other way around. I think this should be common sense even without the space budget ceiling. Just because the general public deem a thing is important to do does not mean it automatically gets unlimited budget.
4. Government projects and programs do not get a free pass at inefficiency. While the tax payers support a military that protects them, this does NOT mean the military can be as inefficient as possible. Military projects that had huge cost overruns get canceled all the time, I don’t see why this can be different for projects in a national space program. No sane government project can run without a balance sheet, it needs to balance the cost to tax payers and the benefits obtained.
5. Since the overall budget is fixed, it’s important for NASA to choose which project to spend money on: Do they want a heavy lift rocket that they couldn’t afford to fly if the budget level stays the same, or do they spend the money on something like propellant depot or nuclear propulsion that can take us BLEO using existing LVs? I think the choice is obvious. Dr. Griffin admits he canceled NASA’s nuclear propulsion program due to Constellation, and we’re seeing this happening again with SLS eating up budgets for tech development, do we really want to repeat the history a 2nd time?
6. The discussion of the economics of heavy lift is clearly wrong. The key is the development and recurring cost (of maintaining the launch pad for example). If a commercial LV or EELV is used for the national space program, the development and recurring cost can be shared with commercial customers or DoD, this would not happen if NASA is the sole user of the heavy lift. This has nothing to do with assumption of efficiency, but everything to do with basic economics.
7. Private venture or industry does not have to make money, there’s this thing called non-profit organization. And there’re also those who run a private company not for profit but for realizing a dream, I think we all know whom I’m talking about. So while I recognize the importance of government leadership in a national space program, the private sectors’ willingness to spend money on non profit goals should not be underestimated.

Dwayne Day - September 18, 2014

You’re apparently really smart. Have you thought about running your own space agency?

jimjxr - September 18, 2014

You’re pretty smart too, how about you put some of that in actually discussing the issues instead of shooting off snarky remarks? And I’m pretty sure Dr. Livingston stated that personal attacks are against the rules here.

Matt - September 19, 2014

Good comments “jimjxr”, I agree with you. Another point: I am not a US citizen (so it is not about my tax money), but allow following question: Why does USA need three manned capsules at once? Is this not crazy?

2. Michael J. Listner - September 18, 2014

On reflection, I do disagree with Dr. Griffin when it comes to duplicating the RD-180. Dr. Griffin made the comment when referencing the RD-180 to the effect of why would we want to copy a 40-year-old design. The design of the RD-180 may be 40 years old, but the closed-loop design of the RD-180 and its predecessor the NK-33 is a robust design that Western rocket engine designers have yet to match. Old design yes, but the concept is still far ahead of the open-loop rocket designs favored by the West because they are less risky.

Matt - September 18, 2014

Yes, Mr. Listner that is correct! More advanced liquid Russian rocket technology keeps a open point for USA.

DDAY - October 2, 2014

Griffin did not explain what he meant, but he does indeed have a point. One of the shortcomings of the RD-180 is that it does not include engine health monitoring. Modern rocket engines have multiple sensors embedded inside them, allowing for monitoring of a lot more factors than simply input and output, and also allowing for fine tuning in flight, possibly even increasing safety (what if you could prevent a bad condition from happening instead of waiting for an explosion?). I have heard of that as one reason for replacing the RD-180, because it may be possible to improve the overall operation with a new engine.

3. Michael J. Listner - September 18, 2014

Excellent program! Dr. Griffin brings an experienced perspective to outer space activities.

4. The Space Show - September 17, 2014

Space Show Listeners:

After the discussion with Mike, I realized I forgot to ask him about rocket reusability. I sent Mike an email asking for his perspective on reusability and below is his reply which he has permitted me to post on this blog. Mike thanks to Mike for providing us with this comprehensive reply to my question about reusability.

David

“Regarding reusability, yes, I think it is an important advance if one wishes to do something that actually might be useful in reducing the cost of access to space. I further think that the place to start is with the first stage, as SpaceX is doing. That is the easier problem to solve, and has the further merit of being the most massive element and therefore, since aerospace hardware tends to cost in proportion to its weight, disproportionately expensive relative to its share of the total velocity to be gained in getting to orbit. Upper stages contribute more and are more sophisticated but, typically, have fewer engines and are much smaller. Aside from the avionics, which are becoming more trivial every day, the upper stage(s) yield less value relative to the effort to reuse them. Thus, you have a potential win-win by tackling the easier problem first.

Further, I think SpaceX’s approach to salvaging the first stage is a good one. The terminal velocity of an empty first stage will certainly be less than 100 m/sec — and that is a real upper bound. If we then say that the first stage must carry enough reserve propellant to remove 100 m/s of terminal velocity for a soft landing, then that means that you are carrying 4% of the empty mass of the first stage as landing propellant. Let’s make it 5% for design margin.

Now then, you need landing gear. A typical landing gear budget for an aircraft — which is what the first stage is at this point — is 4% of the mass to be sustained, which again in this case is the empty mass. So, then, our mass penalty is definitely less than 10% of the landed mass to reuse the stage using the rocket-assisted vertical landing approach.

If you were going to use parachutes instead, you would still need the landing gear and since the contact velocity will non-negligible, the landing gear mass will likely be more than with the rocket-assisted descent. So, what does the parachute weigh? A circular U.S. Army T-10 parachute can support a mass of 160 kg with a touchdown velocity of about 7 m/s with a parachute mass of 14 kg, or about 8.5% of landed mass. This mass ratio may improve as you scale up to a larger system, but will certainly not be less than the 5% mass penalty of the rocket-assisted landing system. Clearly the overall penalty of the parachute approach will be greater than that for the retrorocket approach, and so the SpaceX approach is to be preferred.

So, what is the penalty for employing such a system? For any given design the ultimate result of adding mass to the rocket is a reduction in payload mass. Payload mass is, obviously, a high-value item. If the penalty mass addition is to the final or injection stage, then the payload penalty is 1:1; i.e., 1 kg of added mass reduces payload mass by that same 1 kg.

For lower stages, the rocket staging equations are working in your favor. The amount by which this is true depends upon the specific rocket design in question, and can be from 5:1 to 10:1 or sometimes even more. If we assume an advantage of only 5:1, which is likely low for Falcon 9, then in the worst case there is a payload mass penalty of 2% owing to the incorporation of a landing system which adds 10% of mass to the first stage (which is again on the high side). Does this matter?

Now, most payloads do not actually max out the launch capability of their rocket. Some do, but I personally have never done so on any mission for which I was responsible, and I have seen only a few that did. Second, any launch provider keeps a few percent of total payload capability in reserve on their side of the interface, just to make sure that they are never in a close-but-not-quite situation w.r.t. orbital injection. I have no specific knowledge, of course, but on principle I am sure that SpaceX would choose to maintain such a reserve. In that case, the mass penalty can probably just come out of the reserve, which is entirely reasonable as knowledge of vehicle performance is refined and improved. Given that Falcon 9 as it exists today already launches with a certain amount of engine-out capability, and thus has considerably more margin than most launch vehicles, I strongly doubt that the theoretical 2% payload mass penalty for the first stage recovery system would ever be a problem.

So, net-net, the first stage recovery system is a good idea.”

Matt - September 17, 2014

Dear Dr. Griffin,

thanks a lot! However, you forgot the major propulsion phase (using 3 Merlin engines), which is necessary to turn the first stage velocity vector (1,8-2,3 km/s) at first stage cut-off vector in direction of a semi-ballistic return trajectory, because it is the final objective of SpaceX is to fly back the first stage to a place nearby the launch place. That phase requires much more delta-vee and therefore propellant as the final landing. I estimate about 1,8 km/s for vector turn. Even your 100 m/s for final landing is too small, because some hovering is involved.

Furthermore, the first stage needs also a more capable and massive attitude control system during descent. I see also potential limits of steering the first stage to a certain landing point, because it’s limited lateral acceleration and angle of attack capabilities. The first stage is not more as very thin-walled can, which is easily destroyed by falling into water even after approach or landing velocity was zero.

Elon Musk admitted himself that more as 30% payload are lost for a first stage return flight and about 15% for landing on a barge at sea, without large velocity vector turn maneuver.

5. Matt - September 17, 2014

Yes, we have a problem with good reasons for tax-payer supported manned space flight. This point comes always up.

I missed some controversy in the show, so it would be a great benefit to witness a direct conservation of Dr. Griffin and Dr. Bell.


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