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Let's see ... when was the last time we had a rocket engine explode in flight?  When was the last time we had a jet engine explode in flight?  I agree with most of the people on this thread  --  waiting until technology is "mature" and all risk has been eliminated is a surefire way to justify never doing anything or going anywhere.  Murphy (of Murphy's law fame) is always hanging around.  The job of a good engineer is to manage the risks you know and try to have good work-arounds and  backups for the risks you don't know.

Be that as it may, I also agree with the people who say we are not quite ready for Mars yet.  I think we are at the equivalent of 16th century technology that was conquering the oceans.  (Satellites with their solar panels even remind me of sailing ships.)  We need to press forward as much as we can with the technology we have while we are also inventing/developing/implementing new technology to make our efforts faster, more economical, safer, etc.  It's time for the moon!   
Space Policy Discussion / Re: US Space Force - US to Militarise Space?
« Last post by RonM on 06/19/2018 02:21 PM »
USA 193 was "shot down" by a US Navy SM-3 missile. Like USAF and US Navy ICBMs, the Navy's SM-3 won't be part of a space force. Primary SM-3 use is antiaircraft.

Trump might want orbital ASAT, but he didn't say that. The Space Treaty bans weapons of mass destruction in space. That wouldn't include a KE ASAT. So, the USA could deploy orbital ASAT, but this is pure speculation.

Space Force sounds like a reorg for USAF Space Command to give it higher funding priority.
Rocket Lab / Rocket Lab NSF News Articles
« Last post by Chris Bergin on 06/19/2018 02:16 PM »
This is the home page link for Rocket Lab news articles that will automatically update as we add more articles:
Space Science Coverage / Re: JAXA Hayabusa-2 Discussion
« Last post by mcgyver on 06/19/2018 02:16 PM »

No, not really. 99.9% of drivers never even get remotely close to the actual performance levels of their cars round corners (anyone can drive fast in a straight line).

Please try to understand the difference between 75% and 99.9%. Your "99.9%" is actually about 75%.

Also, there are things like ice and water on the real roads in the real world.

75%? No way. Absolutely no way the 25% of drivers are capable of driving (safely) at the limits of whatever car they are driving.

Of course, quite a few exceed the limits, which is why they crash. But the number of people who drives safely AT the limits is few.

Ice/rain has nothing to do with it.

Anything which increases tire slip definitely matters, especially if you hit black ice which is virtually invisible. Possible several months a year in northern states or Canada.
Heating water from 273K to 373K needs only about 20% (419kJ/kg) of energy needed for vaporization - so basically only thing that matters is vaporization energy.

I see. The water actually cools a bit when some of the volume vaporizes because there is energy associated with the vaporization itself rather than just the temperature change. That explains some of the math I didn't understand. I'm sure someone told me this in high school.

Is there similar energy associated with the salt turning solid? Probably nowhere near as much if so.
Rocket Lab / Re: RocketLab Electron Smallsat Launcher
« Last post by Beittil on 06/19/2018 01:46 PM »
Hey, you know you have made it as a launch company when you get your own forum section on NSF right? :D
Commercial Space Flight General / Re: New Section for Rocket Lab
« Last post by ringsider on 06/19/2018 01:45 PM »
<tearful sobbing>

Our baby is all grown up....
ISS Section / Re: Expedition 56 Thread
« Last post by jacqmans on 06/19/2018 01:42 PM »

ISS Daily Summary Report – 6/15/2018

Post Extravehicular Activity (EVA) Activities: Following yesterday’s successful US EVA #51 Node 2 (N2) Forward External Wireless Communications (EWC), the crew began stowing the tools and cameras used during the EVA and conducted an Extravehicular Mobility Unit (EMU) water recharge.  The crew also participated in an EVA debrief with ground specialists.

Gravitational References for Sensitomotor Performance (GRASP): The crew configured the GRASP equipment for operations and performed three science operational runs in the seated position. GRASP is intended to provide insight into how the central nervous system integrates information from different sensory modalities, encoded in different reference frames, in order to coordinate movements of the hand with objects in the environment.  Performed on the ISS, in conjunction with a series of experiments performed on the ground, GRASP explores the interaction between all of the various sensory cues.

TangoLab-1: The crew moved the TangoLab-1 facility from EXPRESS Rack 4 in the JEM to EXPRESS Rack 7 in the US Lab and activated the payload to allow the ground to check telemetry. TangoLab-1 is a reconfigurable general research facility designed for microgravity research and development and pilot manufacturing on the ISS.

Nanoracks-Remove Debris Satellite (RemDeb): The crew inspected the satellite bolt holes for the RemDeb payload in support of the launch of the RemDeb planned for June 20th.  NanoRacks-Remove Debris demonstrates an approach to reducing the risks presented by space debris or “space junk”. Collisions in space may have serious consequences but research has shown that removing the largest debris significantly reduces the chance of collisions. NanoRacks-Remove Debris demonstrates using a 3D camera to map location and speed of debris and deploying a net to capture and de-orbit simulated debris up to 1m in size. Ground experts will analyze video of the demonstration runs.
ISS Section / Re: Expedition 56 Thread
« Last post by jacqmans on 06/19/2018 01:41 PM »

ISS Daily Summary Report – 6/14/2018

USOS Extravehicular Activity (EVA) #51: Today Ricky Arnold (EV-1) and Drew Feustel (EV-2) completed US EVA #51 Node 2 (N2) Forward External Wireless Communications (EWC) with a Phased Elapsed Time (PET) of 6h 49m. Today’s EVA tasks included:
•Routing EWC power and Ethernet cables between the US Lab and N2.
•Installing Worksite Interface (WIF) #16 and WIF #17 Booms and mating associated HD Camera and EWC connections.
•R&R Camera Port (CP)3 External High Definition Camera (EHDC) and Luminaire.
•Closing the Cloud Aerosol Transport System (CATS) Aperture Door.

The crew was also able to complete the Articulating Portable Foot Restraint (APFR) Relocate, Solar Array Blanket Boxes (SABB) Base Joint Tie Back, and Adjustable Grapple Bar (AGB) Relocate from External Stowage Platform (ESP)2 to Express Logistics Carrier (ELC)4 Get-Ahead tasks. Ground Controllers performed a Power Data Grapple Fixture (PDGF) Local Bus (LB) channel swap during the EVA to ensure that the data cables were install properly. They also completed functional checkouts of the new EWC HD Cameras and the CP3 EHDC and Luminaire.
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