Watching A Spacewalk In Real Time

March 31, 2022 by Al Williams 6 Comments

If you go to, say, a football game, you probably don’t get to see as much of the game as close as you do when you stay home and watch on TV. But there’s something about being there that counts. That’s probably how [Sebastian Voltmer] feels. While we’ve all seen video of astronauts and cosmonauts spacewalking, [Sebastian] managed to take a snapshot of a pair of spacewalkers from his telescope.

Of course, this wasn’t your ordinary department store Christmas gift telescope. The instrument was a Celestron 11 inch EdgeHD Schmidt-Cassegrain telescope on a very expensive GM2000 HPS mount. An ASI290 planetary camera took the shot. You can see the gear and more about the photos in the video below.

Continue reading “Watching A Spacewalk In Real Time” →

NASA Continues Slow And Steady Pace Towards Moon

March 28, 2022 by Tom Nardi 61 Comments

It’s often said that the wheels of government turn slowly, and perhaps nowhere is this on better display than at NASA. While it seems like every week we hear about another commercial space launch or venture, projects helmed by the national space agency are often mired by budget cuts and indecisiveness from above. It takes a lot of political will to earmark tens or even hundreds of billions of dollars on a project that could take decades to complete, and not every occupant of the White House has been willing to stake their reputation on such bold ambitions.

In 2019, when Vice President Mike Pence told a cheering crowd at the U.S. Space & Rocket Center that the White House was officially tasking NASA with returning American astronauts to the surface of the Moon by 2024, everyone knew it was an ambitious timeline. But not one without precedent. The speech was a not-so-subtle allusion to President Kennedy’s famous 1962 declaration at Rice University that America would safely land a man on the Moon before the end of the decade, a challenge NASA was able to meet with fewer than six months to spare.

Unfortunately, a rousing speech will only get you so far. Without a significant boost to the agency’s budget, progress on the new Artemis lunar program was limited. To further complicate matters, less than a year after Pence took the stage in Huntsville, there was a new President in the White House. While there was initially some concern that the Biden administration would axe the Artemis program as part of a general “house cleaning”, it was allowed to continue under newly installed NASA Administrator Bill Nelson. The original 2024 deadline, at this point all but unattainable due to delays stemming from the COVID-19 pandemic, has quietly been abandoned.

So where are we now? Is NASA in 2022 any closer to returning humanity to the Moon than they were in 2020 or even 2010? While it might not seem like it from an outsider’s perspective, a close look at some of the recent Artemis program milestones and developments show that the agency is at least moving in the right direction.

Continue reading “NASA Continues Slow And Steady Pace Towards Moon” →

Satellite Snoopers Pick Up Surprising TV Broadcast

March 22, 2022 by Jenny List 25 Comments

While Internet based streaming services appear to be the future of television, there are still plenty of places where it comes into the home via a cable, satellite, or antenna connection. For most satellite transmissions this now means a digital multiplex carrying a host of channels from a geostationary satellite, for which a set-top box or other decoder is required. Imagine the surprise of satellite-watchers than when the Russian polar communications satellite Meridian 9 which has a highly elliptical orbit was seen transmitting old-style terrestrial analogue TV (ThreadReader Link). What on earth was happening?

How a Russian polar comms satellite picked up a TV station.

The TV signal in question comes from Turkmenistan, so were some homesick Turkmenistanis in an Antarctic base being treated to a taste of their country? The truth is far more interesting than that, because the signal in question comes from a terrestrial transmitter serving domestic TV viewers in Turkmenistan.

We’ve all heard of the idea that somehow every TV show ever transmitted is somewhere out there still traveling as radio waves across space, and while perhaps we can’t fly far enough out to check for 1960s Doctor Who episodes it’s true that the horizontal transmissions from a TV tower pass out into space as the earth curves away from them.

Thus Meridian 9 passed through the beam from the Turkmenistan transmitter which happened to be on a UHF frequency that matched one of its transponders, and the result was an unexpected bit of satellite TV. We’re indebted to the work of [@dereksgc] and [Scott Tilley] for bringing us this fascinating observation. We’ve featured [Scott]’s work before, most notably when he relocated a lost NASA craft.

In 2045: Alpha Centauri

March 15, 2022 by Al Williams 90 Comments

We’ve talked about project Breakthrough Starshot which aims to send a solar sail probe to Alpha Centauri within 20 years. A little basic math and knowing that Alpha Centauri is 4.3 light years away means you are going to need to travel over 20% of the speed of light to make the trip in that time. Some new papers have proposed ways to address a few of the engineering problems.

The basic idea is simple. A very small probe is attached to a very large sail. But calling it a solar sail is a bit of a misnomer. The motive power for the sail would be a powerful laser, which provides more reliable power to the tiny probe’s propulsion system. The problems? First, the thin sail could tear under constant pressure. The answer, according to one of the papers, is to shape the sail like a parachute so it can billow under pressure.

The other problem is not burning the sail up. Space is a hard environment to dump waste heat into since radiation is the only way to transfer it. Another paper suggests that nanoscale patterns on the sail will allow it to release waste heat into the interstellar environment.

Continue reading “In 2045: Alpha Centauri” →

Ion Thrusters: Not Just For TIE Fighters Anymore

March 3, 2022 by Lewin Day 42 Comments

Spacecraft rocket engines come in a variety of forms and use a variety of fuels, but most rely on chemical reactions to blast propellants out of a nozzle, with the reaction force driving the spacecraft in the opposite direction. These rockets offer high thrust, but they are relatively fuel inefficient and thus, if you want a large change in velocity, you need to carry a lot of heavy fuel. Getting that fuel into orbit is costly, too!

Ion thrusters, in their various forms, offer an alternative solution – miniscule thrust, but high fuel efficiency. This tiny push won’t get you off the ground on Earth. However, when applied over a great deal of time in the vacuum of space, it can lead to a huge change in velocity, or delta V.

This manner of operation means that an ion thruster and a small mass of fuel can theoretically create a much larger delta-V than chemical rockets, perfect for long-range space missions to Mars and other applications, too. Let’s take a look at how ion thrusters work, and some of their interesting applications in the world of spacecraft!

Continue reading “Ion Thrusters: Not Just For TIE Fighters Anymore” →

Astra’s Frugal Design Leads To Latest Unusual Failure

February 23, 2022 by Tom Nardi 36 Comments

We’ve all heard it said, and it bears repeating: getting to space is hard. But it actually gets even harder the smaller your booster is. That’s because the structure, engines, avionics, and useful payload of a rocket only make up a tiny portion of its liftoff mass, while the rest is dedicated to the propellant it must expend to reach orbital velocity. That’s why a Falcon 9 tipping the scales at 549,054 kilograms (1,207,920 pounds) can only loft a payload of 22,800 kg (50,265 lb) — roughly 4% of its takeoff weight.

As you might imagine, there’s a lower limit where there simply isn’t enough mass in the equation for the hardware necessary to build a fully functional rocket. But where is that limit? That’s precisely what aerospace newcomer Astra is trying to find out. Their Rocket 3 is among the smallest orbital boosters to ever fly, closer in size and mass to the German V2 of World War II than the towering vehicles being built by SpaceX or Blue Origin. Even the Rocket Lab Electron, itself an exceptionally svelte rocket, is considerably larger.

The reason they’re trying to build such a small rocket is of course very simple: smaller means cheaper. Assuming you’ve got a payload light and compact enough to fit on their launcher, Astra says they can put it into orbit for roughly $2.5 million USD; less than half the cost of a dedicated flight aboard Rocket Lab’s Electron, and competitive with SpaceX’s “rideshare” program. Such a low ticket price would have been unfathomable a decade ago, and promises to shake up an already highly competitive commercial launch market. But naturally, Astra has to get the thing flying reliably before we can celebrate this new spaceflight milestone.

Their latest mission ended in a total loss of the vehicle and payload when the upper stage tumbled out of control roughly three minutes after an otherwise perfect liftoff from Cape Canaveral Space Force Station in Florida. Such issues aren’t uncommon for a new orbital booster, and few rockets in history have entered regular service without a lost payload or two on the books. But this failure, broadcast live over the Internet, was something quite unusual: because of the unconventional design of Astra’s diminutive rocket, the upper stage appeared to get stuck inside the booster after the payload fairing failed to open fully.

Continue reading “Astra’s Frugal Design Leads To Latest Unusual Failure” →

How Big Is The Moon? Figure It Out Yourself

February 22, 2022 by Al Williams 4 Comments

We have to confess that we occasionally send friends a link to “let me Google that for you” when they ask us something that they could have easily found online. Naturally, if someone asked us how big the moon is, we’d ask Google or another search engine. But not [Prof Matt Strassler]. He’d tell you to figure it out yourself and he would then show you how to do it.

This isn’t a new question. People have been wondering about the moon since the dawn of human civilization. The ancient Greeks not only asked the question, but they worked out a pretty good answer. They knew approximately how big the Earth was and they knew the moon was far away because it is seen over a very wide area. They also knew the sun was even further away because the moon sometimes blocks the sun’s light in an eclipse. Using complex geometry and proto-trigonometry they were able to work out an approximate size of the moon. [Matt’s] method is similar but easier and relies on the moon occluding distant stars and planets.

Continue reading “How Big Is The Moon? Figure It Out Yourself” →