Posts Tagged space
Spacecraft DART scores a direct hit on asteroid Dimorphos
Posted by mark in science, Uncategorized on September 27, 2022
It was amazing to see today the videos from NASA showing a direct hit by their spacecraft DART (an acronym for “Double Asteroid Redirection Test”) on the asteroid Dimorphos.
Here are some amazing statistics on this astounding feat of physics:
- DART traveled 56,000 miles to accomplish its $330 million suicidal mission against the 560-foot diameter Dimorphos.
- DART came in at 1,260 pounds to impact the 11-billion-pound Dimorphos, similar in scale to a house-fly smashing into an NFL running back. This seems harmless if not for the fact that the fly is going 15,000 miles per hour!
- NASA’s boffins predict that the impact will shift the orbit of Dimorphos around its bigger sibling Didymos by 1%–reducing it by 7 minutes from the current rate of about 12 hours per revolution.
The big question is: Could we really deflect an asteroid heading for Earth? Given the success of DART, I am now a lot more optimistic that, by the time a planet-threatening object comes our way, a defense system will be in place.
“We do not currently know of any object of “moderate” size which has a chance of impact in the next 100 years. …Please keep in mind that anything smaller than about 30 meters in size will have an airburst and is unlikely to reach ground (excluding metallic NEAs). Our atmosphere is very efficient at protecting us from small impacts.”
– Asteroid scientist Marina Brozovic
NASA shoots the Moon
I got up a bit earlier than usual to set up my 8-inch reflector telescope for a view of the 6:31 AM CDT collision of NASA’s Lunar Crater Observation and Sensing Satellite (LCROSS). The weather was ideal – clear skies with no wind. Never mind that we had our first frost – Minnesotans like me don’t mind temperatures at the freezing point (knowing full well that soon this will be considered balmy!). However, despite a spectacular view of the Moon’s South Pole, I saw no evidence of the “man in the moon” getting ‘goosed.’ To placate the alarmists who thought the Moon might be destroyed, NASA likened their crash to an eyelash hitting a jetliner. From what I could see myself and the video by NASA, that is an apt analogy, assuming the eyelash came off a gnat.
So LCROSS proved to be a lot less dramatic than us skywatchers hoped for. However, if the follow-up satellite sensed water blown up by its self-destructive predecessor, the mission will be a big success. This will take a while to decipher as noted by Wired magazine’s GeekDad blogger Brian McLaughlin. If you are geeky like me, you will keep an eye out for the final outcome of this shoot-for-the-moon experiment.
PS. All this is mindful of the book by Jules Verne From the Earth to Moon posted with illustrations from an 1886 edition by NASA in their Space Educators Handbook
(“One small click for all mankind.”). It’s fantastic!
Close encounters with improbable events (‘Goofers’) and implausible beliefs (Martians)
On my flight home yesterday from vacation in Arizona and New Mexico, a lady from Santa Fe asked about my screen saver showing photographic evidence from NASA that water flows freely on the surface of Mars. She told me that this is just a cover up by the US Government of Martians living under the surface of their planet. “The truth will come out soon,” this New Mexican said, “They cannot suppress the bloggers who know that aliens really do exist.”
Photo by H. P. Anderson
I suspect this woman scoffed at NASA’s high resolution photos taken in July of the Face on Mars showing it to be only a geological mesa — not an artificial monument by extraterrestials. The diehard believers in Martians, represented by a caller to the Art Bell “Coast to Coast” radio show, say that NASA dropped a nuclear bomb this structure to de-face it!
My trip last week featured a few other improbabilities. Its purpose was to see the Minnesota Gopher football team play in the Insight Bowl at Arizona State University’s stadium in the Phoenix area. Us Minnesotans cheered wildly as our team went up by 31 points past the halfway point of the game. Sadly, the ‘Goofers’ blew their seemingly insurmountable lead and let the Red Raiders of Texas Tech win in overtime. This reportedly was the biggest comeback in a Division 1A bowl. Cursory research on the history of bowl games shows them going back over a century with accelerating frequency in recent years — perhaps a few thousand games in all. I suppose I should feel lucky to see this unlikely event, but what really pleases me is that the coach got fired immediately afterwards.
The other unusual event experienced by me and my traveling companions was a record 16 inch snowfall in Albuquerque where I’d booked our flights to save on airfare. Fortunately the weather cleared just in time for takeoff. En route to the airport we stopped at Meteor Crater where NASA astronauts train for extraterrestial missions. Some people, like my fellow traveler from Santa Fe, believe that this was where the NASA perpetrated the hoax of man traveling to the moon. After seeing the Minnesota team implode at the Insight Bowl and then on my trip home almost getting stuck in over a foot of snow in supposedly sunny New Mexico, I am ready to believe that just about anything can happen. Come on NASA — quit covering up: Bring on those eight-fingered aliens! By the way, how are they at handling oblate spheroids?
Mercury — a transitory mote in the eye of the sun
On Wednesday residents of my hemisphere saw (?) the planet Mercury transit the sun. This happens only about every decade. One really couldn’t see Mercury because it is so small relative to the sun, which burns far too brightly for the naked eye to withstand. I watched the transit live from an astronomer’s view (Kitt Peak, Arizona*) via the webcast by San Francisco’s Exploratorium. The funny thing is that a speck in their Meade 16 inch reflector’s optics showed up more prominently than Mercury itself. For a perspective on how small this planet appears from earth (only 1/200th the diameter of the sun) see this photograph from VisualUniverse.org. Nevertheless, when Mercury first hit the edge of the sun, the astronomer directing the webcast said the he and his colleague were doing a little “happy dance”! 🙂 By virtue of owning an 8-inch Meade reflector, I am a very amateurish astronomer myself. Seeing Mercury was a rare treat worth savoring. Here’s something really rare that’s reported at Wikipedia: On July 5, 6757 residents in Eastern Siberia can watch the simultaneous occurrence of a solar eclipse and a transit of Mercury. If you want to see this, I advise you go there now, drink a barrel of vodka, set your atomic-powered alarm clock 4751 years ahead and, finally, bury yourself in the snow. Good luck and mind the mastodons!
*Located by red star on map showing zones of visibility. For great views of the telescopes, background narration and the transit itself, click the RealVideo link to the saved webcast.
Longer-term perspective on global warming (and other catastrophes)
On March 16th I blogged about the sharp upturn in global temperatures that some liken to the blade of a hockey stick. The blog provides a link to a graph reproduced by the BBC which goes back 1000 years. Aside from questions about how data are fitted, simple changes to scales and other attributes of the graphs themselves can paint very different perspectives on seemingly straightforward scientific questions such as whether we ought to be worried about global warming. Andy Sleeper shows this in part 7 of his white paper titled HOW TO LIE WITH STATISTICAL GRAPHICS. The color-coded graph generated by the U.S. National Oceanographic and Atmospheric Administration is very alarming. However, it only provides 122 years of history and the y-axis scale is restricted to about 2 degrees C. A few figures later in Sleeper’s paper one sees another graph based on 400,000 years of temperatures estimated from core samples of Antarctic ice. It reveals cyclic temperature swings of 12 degrees C! In this context, should a less than 1 degree increase in global temperature be considered abnormal, that is, due to a special cause such as man-made carbon dioxide?
PS. Here’s something to really worry about. The November issue of Sky and Telescope features a heads-up on “The Most Dangerous Asteroid Ever Found” — a 1000-foot pile of rock called Apophis. It will just miss the Earth on April 13, 2029. If Apophis hits a narrow zone — called the keyhole, it will be dragged enough by our gravity to put it on a course that collides with Earth seven years later. One can only hope that NASA’s proposed gravity tractor will pull the asteroid off target and save the planet.