Sun, Nov 15, 2009
Shown is a computer animation of the orbits of asteroids in the solar system. The plane of the planetary orbits is edge on rather than from above (or below). It quickly becomes clear that most asteroid orbit close to the plane of the planetary orbits. But a good number have highly inclined orbits compared to the orbits of the planets.
Mon, Nov 14, 2016
The recoil of a small caliber gun probably probably wouldn't give you much trouble in space and the propellant would work just fine, You're more likely to gain rotational momentum raising the gun to aim. But cooling of an automatic weapon, spontaneous welding and lubricant evaporation in a vacuum could be issues.
Mon, Jan 16, 2017
Xenon is the chemical of choice for ion engines even over comparable chemicals such as argon which is cheaper. Xenon has it happens produces twice the thrust per atom because it's much greater mass gives it more momentum and it is easier to ionize. But slightly more massive and even easier to ionize, cesium remains on engineers radar.
Fri, May 26, 2017
The Lunar Reconnaissance Orbitor operations team thinks the satellite was hit by a tiny meteor while photographing the lunar surface. An image suddenly became wavy before settling down again. Ananlyzing the data the team came up with an estimate of the meteors size. And another astronomer converted it to a sound.
Wed, May 31, 2017
Space X and the Space Shuttle made news about reusable spacecraft. But other spacecraft, rockets and satellites have flown in space more than once. The X-15, X-37B and SpaceShipOne space planes were designed for reuse. On other occasions it was just a matter of convenience. The old hardware happened to be available, in pretty good shape and, of course, cheap.
Wed, Jun 7, 2017
Scott provides a tour of his Saturn V models showing all the little weird protrusion and explaining what they do. Some are rocket motors to control the rocket during flight. Some are structural components that give strength to the rocket. And some our pipes and such that didn't fit well on the inside of the rocket.
Wed, Jun 28, 2017
Scott talks about a star, probably a brown dwarf, orbiting a giant star so closely that its orbit is within the giant star. Yes that is perfectly possible says Scott but like all stars these two will interact and evolve with some violence along they way. And it is just one of a few types of stars in this situation.
Fri, Jun 30, 2017
Ceres was first discovered by astronomers looking for a plant to fill a curious gap between mars and Jupiter. But it wasn't very big so astronomers kept looking and began finding the larger objects in the asteroid belt. Eventually astrophotography, sky surveys and space telescopes led to the multitudes that are know today including near Earth and Earth crossing asteroids that are of particular concern for the fate of humanity.
Sun, Sep 17, 2017
After a recent slip of his own Scott shares his ten favorite goofs in space exploration. Fortunately there were no injuries form these other than the dreams of many scientists and the pocketbooks of taxpayers. Still, most of these were software errors which makes you wonder about trusting your life to software.
Fri, Sep 29, 2017
Scott got his hands a couple astrolabes and explains how they work and notes a couple places where you can get one of you're own of for a gift. His are simple models with designs dating back to 200 BC. The technology uses trigonometric transformations which are a trifle difficult for we humans to do in our head.
Fri, Dec 29, 2017
Hydrogen bombs typically use a two stage design with a fission reaction used to initiate nuclear fission of hydrogen isotopes. Moving to fission permits much more powerful bombs because beyond a certain point it is not practical to assemble more fissionable uranium or plutonium into a bomb. A variety of fission bomb designs were attempted with some surprises along the way.
Sun, Apr 15, 2018
TESS, the new satellite that will follow up Keppler in the search for exoplanets, had a tight budget that required some unusual optimization. In particular its orbit is designed to minimize fuel requirements. So it used a lunar gravity assist to put it in an eccentric orbit of the earth to provide fast data transfer at perigee and avoid eclipses by the earth of its field of view. And it is 90 degrees out of phase with the moons's orbit to keep the orbit stable.
Wed, May 23, 2018
Near Jupiter is a retrograde asteroid in an unusual resonance orbit with the planet. Since retrograde asteroids are exceedingly rare astronomers want to know how it got there. So they ran a million simulations and found, first, it extremely lucky it wasn't thrown out of the solar system or into the Sun by Jupiter. And second, it may not have formed in the solar system.
Mon, May 28, 2018
Scott shares highlights from John Drury Clark's 1972 book "Ignition" about the development of rocket fuels. Scott's focus is on fuels that were somewhat ill advised. Hydrazine, nitric acid, fluorine, mercury, ozone are all on the list of chemical you don't want to be around in any quantity much less sitting on top of tons of it hoping to survive a trip to space.
Thu, Aug 9, 2018
NASA is finally going to take a close look, a really close look, at the sun with the Parker Solar Probe. Scott explains just how close it's going to get to the Sun, the surprisingly convoluted process of getting there and the extraordinarily efforts needed to protect it from the Sun's radiation.
Fri, Oct 19, 2018
If you want to do a quick flyby of another planet you can get there pretty quickly. But if you want to stop and go into orbit, or even land, you have to slow down once you get there. Turns out it's far more economical to take a more leisurely trip so you don't need so much fuel to slow down on arrival.
Mon, Oct 22, 2018
Scott uses Kerbal Space program space program and shows viewers how to modify the program for more realistic reentry scenarios. Of importance to the crew; in an aerodynamic reentry the spacecraft experiences lift which enables the it to remain in the thinner upper atmosphere longer and slow down more gradually. That means lower gees for the grateful crew.
Mon, Oct 29, 2018
A test pilots have a lot to do besides fly his aircraft. All the systems need to be tested and require the pilot's attention in flight. During a flight of the X-15 Neil Armstrong was apparently paying attention to one of these systems and didn't notice he was climbing back toward space and far from his landing site making for a very long glide home.
Thu, Dec 27, 2018
The competition for the first space plane was won by a missile designer and new comer to the X-plane program, North American, with its X-15 design. It beat out the Navy's historical designer Douglas which proposed a design using a light weight magnesium alloy containing radioactive thorium that would stay cooler during the aircraft's brief atmospheric reentry. Ironically, although the Douglas design better fit the specification it lost out because follow on projects would more severally test the heat resistance of air/spacecraft and X-15 would be a better precursor to them.
Wed, Jan 9, 2019
If you plan to hang with Scott on his Youtube channel you need to understand orbits. Here's his tutorial where he describes the types of orbits that are so useful that they have names. Scott demonstrates them with Universe Sandbox and explains how they work and what they're used for.
Tue, Mar 26, 2019
While in Florida Scott had occasion to witness the launch of a couple anti ballistic missiles at Vandenberg Air Force Base the video of which he of course shares. It also makes for a teachable moment to delve into the different types of anti ballistic missile systems and how the work.
Mon, Apr 22, 2019
Expander Cycle Rocket Engines use vaporized rocket fuel, typically hydrogen, to drive a turbine that pressurizes the fuel mixture as it enters the combustion chamber. These are some of the most efficient rockets ever built but they tend to be low on thrust. However, there are variation that provide higher thrust and, of course, Scott knows them all personally.
Mon, Apr 29, 2019
A dark matter experiment comprised of a huge vat of Xenon has detected an extremely rare two neutrino double electron capture process. Yes, Scott will explain what that means. But first you need a primer on nuclear decay processes so you're about to learn everything you ever wanted to know about alpha, beta and gamma decay.
Thu, Jun 20, 2019
Graveyard orbits generally apply to geostationary or Lagrange point orbits where space is limited. In other cases the satellite may be dangerous with, for example, a nuclear power supply. Most lower orbiting satellites are not an issue because they disintegrate on reentry - eventually. Obsolete geostationary satellites are supposed to be moved to a higher orbits and inclinations. Lagrange satellites are moved into an arbitrary solar orbit with there remaining fuel.
Wed, Jul 17, 2019
The Saturn V's F-1 Engine start sequence begins at T-9 and there is much to do in the nine seconds before liftoff. Fuel lines need to be purged and filled with fuel. Pumps need to be started. Fuel needs to be ignited. Thrust needs to build up. And every step needs to be timed to synchronize five engines.
Thu, Aug 1, 2019
Lightsail 2 is a tiny (4 kg), experimental, crowd-funded satellite with a large (40 sqm) solar sail that was developed by the Planetary Society. The Planetary Society reported that the sail successful used the momentum of the light from the sun to adjust the satellite's orbit around the Earth. Unfortunatly the large sail is also susceptible to atmospheric drag so it's average altitude is falling closer to the Earth.
Thu, Aug 22, 2019
If you you think nuclear war is a crazy-bad idea Scott shares ten alternative ideas that have been proposed over the years to use nuclear weapons for peaceful purposes. Some were tested and a couple even used. But the fact that you don't hear about these applications every day is a good indication that they were pretty much as crazy-bad as that war idea.
Fri, Aug 30, 2019
Amateur satellite trackers are clever and curious folk. From an apparent cellphone photograph of an a on screen image of an Iranian rocket launch site tweeted by the president they were able to determine the resolution capability of a US spy satellite, probably a KH-11. They even made a pretty good guess at which satellite is was, US-224. From there Scott was able to comment on how well optimized the satellite's resolution is to its mirror size.
Wed, Nov 13, 2019
Grab your television remote or computer pointer because Scott is going to give you control of your screen to scan the sky for satellites. They make for quite a swarm. Scott points out a few of special interest such as international space station and those in geosynchronous orbit. Then he displays some 15,000 pieces of space junk.
Mon, Nov 25, 2019
Cutoff from Soviet missile technology in 1960 China immediately started its own ballistic missile program and launched its dong feng 4 ICBM the following year. Soon there after China developed the Long March rocket based on the dong feng 4 for satellite launches. China continued developing its rocket program to the present day (2019) and now operates a series of rockets suitable for diverse missions.
Tue, Jan 7, 2020
Anyone whose's watched a NASA maned mission has seen the large map at the front of the control room. It obviously shows the position of the spacecraft over the earth. But there is much more such as areas of high radiation and what portion of the earth can be seen from the spacecraft.
Mon, Feb 17, 2020
NASA wants to build a Venus rover. Obviously it needs to work at the high temperatures and pressures on Venus. NASA has pretty solid ideas for a some of it but is looking for help with a mechanical steering computer and is offering cash for the best design. Scott also discusses some of the other challenges, like telemetry and power sources, and prospects for silicon carbide semiconductors.
Wed, Apr 29, 2020
The Lance missile was a tactical conventional/nuclear weapon that just happened to have two rocket engines one inside the other. The outer, more powerful engine served as a booster while the inner engine was like a second stage. Scott has photos of a cutaway engine. Now don't you want to know how it works?
Sun, May 10, 2020
In a detonation engine the combustion process occurs fast enough to exceed the speed of sound causing a shock wave. Theoretically such an engine would be simpler and more efficient than the deflagration engines used in aircraft. Pulse versions of detonation engines have been built. The challenge is to design a continuous rather than pulse version which is a challenge steeped in physics.
Thu, Jul 16, 2020
Over the decades of the Cold War the Untied States, and Russia, have built thousands of ICBMs that, thankfully, have never been used. Eventually they get old and even though they are still functional they are replaced by better rockets. That leaves a bunch of perfectly good, bought and paid for rocket that can be used to launch satellites. Currently the Minuteman Missiles are being converted to Minotaur rockets.
Wed, Aug 19, 2020
For its sixtieth anniversary Scott tells the story of the Corona spy satellite program and its successors. These satellites used film cameras to photograph the earth. The film was returned to Earth in a reentry vehicle which was captured, most of the time, during its decent by an airplane. The program evolved quickly and Scott has all the now declassified details.
Mon, Oct 12, 2020
Scott, spacesuit clad, challenges the claims about asteroid Psyche in the popular press and strives to set the record straight. Psyche is the subject of a NASA rendezvous with a planned launch of 2022. As psyche appears to be composed principally of iron and nickel it would be a good source of metals. The challenge is; how to get those metals.
Fri, Oct 23, 2020
OSIRIS REx is a sample return mission to asteroid Benu. Ironically it may have been a bit too successful. So much material was collected that the sample container lid stuck open and sample has been leaking out. It will be placed in a sealed reentry capsule assuming that doesn't get stuck by floating particles from the sample. The sample is due back in 2023 then we'll see what's left.
Mon, Nov 23, 2020
A big reason the Space Shuttle looks the way it does is a planned mission called Shuttle Reference Mission-3b. The plan was to capture and return a satellite from a polar orbit in less than 2 hours, a single orbit. It required a few rather difficult specification to the shuttle such as a large delta wing that then required a more robust heat shield. Plans for the mission were dropped before the shuttle flew probably because it was too ambitions but the changes lived on.
Fri, Jan 8, 2021
The Sierra Nevada Dream Chaser is poised be the first lifting body space plane to progress beyond the test phase with its launch in 2023. A a lifting body it makes orbital reentry easier due to the absence of wings. And as a plane it can land at a conventional airport in contrast to a space capsule.
Mon, Mar 29, 2021
Scott had the pleasure of consulting on the 2021 science fiction film "Stowaway". Here he answers some of the obvious questions skeptics have asked after seeing the trailer: How can the spaceship have artificial gravity? Why didn't the crew just fire their rockets and return to Earth? These simple questions lead to some interesting aspects of interplanetary space travel.
Wed, Apr 14, 2021
The United States has operated several generates of ships for tracking rocket launches and eventually spacecraft. With the Earth being mostly water, covering every meter of a trajectory or orbit with land based tracking stations is an impossibility. Scott knows all the tracking ships by name and shares their history, capabilities and pictures.
Sun, May 23, 2021
The asteroid Apophis made one of its close encounters with earth in April 2021. Asteroid watchers paid close attention because each close encounter alters the orbit of the asteroid by an amount that is hard to predict due to inaccuracies in velocity and distance measurements. Now that it is leaving Earth's vicinity, new measurements can refine the details of its new orbit. And we seem to be perfectly safe from Apophis until 2116.