Archive for the ‘Final frontier’ Category

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Strange sights

September 17, 2017

“Postcards from Saturn” is an NPR video about discoveries made by the Cassini probe.


And “How Not to Land an Orbital Rocket Booster” is a short tutorial from SpaceX.

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Happy Independence Day

July 4, 2016

NASA’s Juno Probe Just Made It Safely Into Jupiter’s Orbit

AT 11:54 PM Eastern tonight, NASA’s Jet Propulsion Laboratory in Pasadena, California erupted into cheers. No ooohs and aaaahs at fireworks displays here: The team of engineers had just received confirmation that their intrepid space probe, Juno, has successfully made its way into Jupiter’s orbit.

That maneuver, a 35-minute burn that began at 11:18 pm Eastern tonight, was the culmination of a five-year journey through space and many more years of work from the JPL team.

Juno has been whizzing toward Jupiter since it left Earth on August 5, 2011. And these 35 minutes have always been the 35 most perilous moments since launch. Juno had to turn on its engines precisely 2,609 miles away from Jupiter to get into position. If it didn’t slow down enough, the probe would go right past Jupiter, missing its target. At just the right speed, it would sync up with Jupiter’s gravity. […]

To make this even more of a nail-biter, signals from Jupiter take almost 49 minutes to reach Earth. That means by the time NASA got the signal that Juno had started slowing down, the probe had already slowed down enough to enter Jupiter’s orbit. If something went wrong, there’s no remote fix — and no way to know until after it’s all over. […]

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Make it so

May 3, 2015

Who needs reaction mass? And who understands the physics behind this?

I ran across a mention of testing an EM drive in vacuum a couple of weeks ago but didn’t pay it much attention because of where I found it. Then Paul sent a link to this article at a NASA site which makes me take it more seriously.

If you’re interested in space flight, RTWT. It could be a game-changer.

Evaluating NASA’s Futuristic EM Drive
April 29, 2015 by José Rodal, Ph.D, Jeremiah Mullikin and Noel Munson – subedited by Chris Gebhardt

A group at NASA’s Johnson Space Center has successfully tested an electromagnetic (EM) propulsion drive in a vacuum – a major breakthrough for a multi-year international effort comprising several competing research teams. Thrust measurements of the EM Drive defy classical physics’ expectations that such a closed (microwave) cavity should be unusable for space propulsion because of the law of conservation of momentum.

EM Drive:

Last summer, NASA Eagleworks – an advanced propulsion research group led by Dr. Harold “Sonny” White at the Johnson Space Center (JSC) – made waves throughout the scientific and technical communities when the group presented their test results on July 28-30, 2014, at the 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference in Cleveland, Ohio.

Those results related to experimental testing of an EM Drive – a concept that originated around 2001 when a small UK company, Satellite Propulsion Research Ltd (SPR), under Roger J. Shawyer, started a Research and Development (R&D) program.

The concept of an EM Drive as put forth by SPR was that electromagnetic microwave cavities might provide for the direct conversion of electrical energy to thrust without the need to expel any propellant.

This lack of expulsion of propellant from the drive was met with initial skepticism within the scientific community because this lack of propellant expulsion would leave nothing to balance the change in the spacecraft’s momentum if it were able to accelerate.

What amazes me (and apparently many others) is that you don’t need to haul along a bunch of reaction mass to throw away behind you in order to accelerate.

Heinlein wrote an article about interplanetary travel at constant acceleration. (He and many others have written novels based on that assumption, of course.) The travel times are remarkably shorter than building up an initial velocity and then coasting – which is how we do it now. The critical factor in using constant acceleration has always been carrying the reaction mass you needed to expel in order to get the acceleration.

Even a constant acceleration of 0.1G (0.98m/sec2) makes a huge difference in travel time.

And now – maybe – that’s not necessary after all? Wow. I don’t know if Larry Niven would classify this as an example of his reaction-less drive but I think it’s pretty close.

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