By Julie Cooper

Each month in “Slice of History” we feature a historical photo from the JPL Archives. See more historical photos and explore the JPL Archives at https://beacon.jpl.nasa.gov/.

Is it a JPL magic trick? — Photograph 328-161Ac

In 1960 through 1961, several different experiments were conducted at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., in search of a frictionless bearing for use in space applications, gyroscopes and other machinery. There were cryogenic, gas and electrostatic types of bearings, and the photo above shows a magnetic bearing. It was suspended by counterbalancing the force of gravity and an electromagnet. A servo feedback system continually corrected the current flow through the electromagnet to keep it stable.

This post was written for “Historical Photo of the Month,” a blog by Julie Cooper of JPL’s Library and Archives Group.

The founder of the Atmospheric Infrared Sounder Mission, Team Leader Dr. Moustafa T. Chahine

The founder of the Atmospheric Infrared Sounder Mission, Team Leader Dr. Moustafa T. Chahine, leaves behind a distinguished legacy of science, discovery, mentorship, and deep friendship. Beyond a career rich in accomplishment, Mous was a dear friend and colleague to so many over his 50-plus-year career at the Jet Propulsion Laboratory.

Please kindly leave your thoughts and acknowledgments below. These messages will be gathered up and presented to Mous’ family at a later date.

For more on Mous, visit:
› Mous Chahine Memorial Web Page
› Best Views on Climate: Chahine’s Vision Lives On Through AIRS

By Marc Rayman

NASA’s Dawn spacecraft is less than five months away from getting into orbit around its first target, the giant asteroid Vesta. Each month, Marc Rayman, Dawn’s chief engineer, shares an update on the mission’s progress.

Artist’s concept of NASA’s Dawn spacecraft at the large asteroid Vesta. The mission is less than five months away from getting into orbit around the large asteroid, its first target.

Dear Pleasant Dawnversions,

Deep in the asteroid belt, Dawn continues thrusting with its ion propulsion system. The spacecraft is making excellent progress in reshaping its orbit around the sun to match that of its destination, the unexplored world Vesta, with arrival now less than five months away.

We have considered before the extraordinary differences between Dawn’s method of entering orbit and that of planetary missions employing conventional propulsion. This explorer will creep up on Vesta, gradually spiraling closer and closer. Because the probe and its target already are following such similar routes around the sun, Dawn is now approaching Vesta relatively slowly compared to most solar system velocities. The benefit of the more than two years of gentle ion thrusting the spacecraft has completed so far is that now it is closing in at only 0.7 kilometers per second (1600 mph). Each day of powered flight causes that speed to decrease by about 7 meters per second (16 mph) as their orbital paths become still more similar. Of course, both are hurtling around the sun much faster, traveling at more than 21 kilometers per second (47,000 mph), but for Dawn to achieve orbit around Vesta, what matters is their relative velocity.

It may be tempting to think of that difference from other missions as somehow being a result of the destination being different, but that is not the case. The spiral course Dawn will take is a direct consequence of its method of propelling itself. If this spacecraft were entering orbit around any other planetary body, it would follow the same type of flight plan. This unfamiliar kind of trajectory ensues from the long periods of thrusting (enabled by the uniquely high fuel efficiency of the ion propulsion system) with an extremely gentle force.

Designing the spiral trajectories is a complex and sophisticated process. It is not sufficient simply to turn the thrust on and expect to arrive at the desired destination, any more than it is sufficient to press the accelerator pedal on your car and expect to reach your goal. You have to steer carefully (and if you don’t, please don’t drive near me), and so does Dawn. As the ship revolves around Vesta in the giant asteroid’s gravitational grip, it has to change the pointing of the xenon beam constantly to stay on precisely the desired winding route to the intended science orbits.

Dawn will scrutinize Vesta from three different orbits, known somewhat inconveniently as survey orbit, high altitude mapping orbit (HAMO), and low altitude mapping orbit (LAMO). Upon concluding its measurements in each phase, it will resume operating its ion propulsion system, using the mission control team’s instructions for pointing its thruster to fly along the planned spiral to the next orbit.

› Continue reading Dawn Spacecraft Creeping Up on Vesta

By Julie Cooper

Each month in “Slice of History” we’ll be featuring a historical photo from the JPL Archives. See more historical photos and explore the JPL Archives at https://beacon.jpl.nasa.gov/.

Transition Pipe — Photograph Number 327-287A

This test setup was part of an investigation in 1954 of the stability of laminar pipe flow with respect to disturbances of different frequencies and amplitudes. A disturbance generator was developed using vibrating aluminum reeds and instruments measured how a small amplitude disturbance in the air flow changed as it propagated down the 115–foot length of a 2” aluminum pipe. It appears to be located in the concrete channel that was used in the 1940s as a hydrodynamic tank with a rocket-propelled towing car (the “Hydrobomb”). At the end of the room you can see metal rungs that were used to climb down into the channel when the water was drained.

This post was written for “Historical Photo of the Month,” a blog by Julie Cooper of JPL’s Library and Archives Group.

By Amber Jenkins

I stumbled upon this video earlier today. It’s Isaac Asimov, famous science fiction writer and biochemist, talking about global warming — back in January 1989. If you change the coloring of the video, the facial hair style, and switch out Asimov for someone else, the video could pretty much have been made today.

Asimov was giving the keynote address at the first annual meeting of The Humanist Institute. “They wanted me to pick out the most important scientific event of 1988. And I really thought that the most important scientific event of 1988 will only be recognized sometime in the future when you get a little perspective.”

What he was talking about was the greenhouse effect, which, he goes on to explain, is “the story everyone started talking about [in 1988], just because there was a hot summer and a drought.” (Sound familiar, letting individual weather events drive talk of whether the Earth’s long-term climate is heating up or cooling down??)

The greenhouse effect explains how certain heat-trapping (a.k.a. “greenhouse”) gases in our atmosphere keep our planet warm, by trapping infrared rays that Earth would otherwise reflect back out into space. The natural greenhouse effect makes Earth habitable — without our atmosphere acting like an electric blanket, the surface of the earth would be about 30 degrees Celsius cooler than it is now.

The problem comes in when humans tinker with this natural state of affairs. Our burning of fossil fuels (coal, oil and gas) constantly pumps out carbon dioxide — a heat-trapping gas — into the atmosphere. Our cutting down of forests reduces the number of trees there are to soak up some of this extra carbon dioxide. All in all, our atmosphere and planet heats up, (by about 0.6 degrees Celsius since the Industrial Revolution) with the electric blanket getting gradually thicker around us.

“I have been talking about the greenhouse effect for 20 years at least,” says Asimov in the video. “And there are other people who have talked about it before I did. I didn’t invent it.” As we’ve stressed here recently, global warming, and the idea that humans can change the climate, is not new.

As one blogger notes, Asimov’s words are as relevant today as they were in 1989. “It’s almost like nothing has happened in all this time.” Except that Isaac Asimov has come and gone, and the climate change he spoke of is continuing.

Asimov’s full speech can be seen here.

This post was written for “My Big Fat Planet,” a blog hosted by Amber Jenkins on NASA’s Global Climate Change site.

By Ed Begley Jr.

A guest blog written for My Big Fat Planet by Ed Begley Jr.

I visit the NASA website and review the data. CO2: Up. Ocean and land temperature: Up. Sea level: Up. Polar ice: Down.

Oops.

But, as bizarre as this sounds … I find myself pulling for the climate change deniers. Wouldn’t it be swell if they were right? We could all just relax and ride around in huge cars, and life would be good again.

Like it was in 1970 when I showed up at the first Earth Day. Oh, wait. The smog kind of sucked back then. That might not be the best example.

But, what about the main reason the deniers give not to address climate change?: The cost.

As it turns out, a great example can be found back in smoggy Los Angeles in 1970. Many of us wanted to do something about the horrible choking smog of that era. But, we were told we couldn’t afford it.

“We’d love to do something too, Ed, but … the cost!” Fortunately, we didn’t listen to them. Fortunately we also weighed healthcare costs and lost productivity into the equation, and realized the cost of doing nothing was much greater.

And, now, even though we have millions more people in L.A., and four times the cars … we have far less smog. And, there were many jobs and tremendous wealth created by doing the things that addressed the problem.

Making catalytic converters, combined cycle gas turbines, spray paint booths, and a myriad of other clean technologies of that day - they all created new industries, and brought growth with them.

We have that same choice today. Do we want to accept the costs of doing nothing, and hope that the problem goes away?

So, please, do as I do, and direct everyone you know to reputable sources of climate data, such as NASA’s Global Climate Change website. At every talk I give, I make sure that everyone is aware that this information if available. The clock is ticking, and to ignore the science on this one is the worst bet we have ever placed.

Ed Begley Jr. is an Emmy-nominated actor who is active in the environmental community and turns up to Hollywood events on his bicycle. He currently lives near Los Angeles in a self-sufficient home powered by solar energy.