Recent comments in /f/space

-Prophet_01- t1_j6lliz1 wrote

Reply to comment by Worldofbirdman in NASA tested new propulsion tech that could unlock new deep space travel possibilities by Creepy_Toe2680

Heat exchange in vacuum largely works with a different principle and is much, much less efficient. Without other molecules to transfer heat to, we're left with black body radiation. Lower efficiency means bigger radiators. It's basically trying to cool down by giving off infrared light.

Something that could be done with a small coolant loop through a river or a glorified AC on earth, requires large sail-like structures in space (sails because it maximizes the surface to throw out that thermal radiation).

3

Sylph_uscm t1_j6llc2b wrote

Reply to comment by Rhaedas in ‘Extraordinary’ footage shows one of the closest known approaches of a near-Earth object — On 26 Jan. 2023, asteroid 2023 BU was about 2,200 miles above the surface of the Earth by marketrent

Funding the search effort is no different than funding technology to stop them, if that's the motivation behind the search (I don't believe that it is, I'm counterpointing people that believe that 'it's the life-or-death nature of impacts that make people search' here.)

Ergo, if we really want to survive impacts, we need to work on ways to stop them - our detection is already 10000x further than our ability to stop anything. It's more than good enough for our current abilities to stop anything.

2

Sylph_uscm t1_j6lkry9 wrote

Reply to comment by ttystikk in ‘Extraordinary’ footage shows one of the closest known approaches of a near-Earth object — On 26 Jan. 2023, asteroid 2023 BU was about 2,200 miles above the surface of the Earth by marketrent

Agreed, but last I checked, any detection is happening way to late to do anything with current technology.

My thoughts are that, if we were truly motivated by the 'life or death' nature of a potential impact as some here implied (I disagree with this reasoning) ; efforts would be going into means of stopping them (we have pretty much none), rather than detection.

1

BanditSixActual t1_j6ljqq9 wrote

Reply to comment by adamdoesmusic in What kind of items can I buy for my class that would be used on a Shuttle / ISS? by glastonbury13

Remember Tang? That nasty orange drink made popular by NASAs food experiments in microgravity. What's scary is how flammable that drink powder is when an aerosol, something easy to achieve in microgravity. We got some truly impressive fireballs throwing it in the air near a campfire.

2

glibgloby t1_j6ljg7g wrote

Reply to comment by FanOfPeace in 2 big pieces of space junk nearly collide in orbital 'bad neighborhood' by jeffsmith202

Kessler syndrome is wildly misinderstood. Probably thanks to the movie gravity. I suggest people read the actual wiki on the topic.

Yes, low to mid orbits could become difficult to hold. This would present itself as a small statistical likelihood per year for a satellite in these orbits to be struck.

Higher orbits would not be affected, nor would our ability to travel through these regions whatsoever. We would definitely still be able to travel into space just fine. But hanging out in lower orbits for long periods of time would be somewhat dangerous.

62

BanditSixActual t1_j6lj17e wrote

Reply to comment by -Raskyl in What kind of items can I buy for my class that would be used on a Shuttle / ISS? by glastonbury13

Everyone used pencils at the beginning of the space program. NASA ordered some mechanical pencils because there were fears over the flammability of wooden pencils after the Apollo 1 fire. They paid something like $130 per pencil in 1965 money, and there was public outcry. Fisher developed the space pen with their own money and offered it to NASA, who paid approximately $2.40 per pen by buying in bulk. The Russians ordered them too and paid the same price.

Both space programs have used them ever since, and one arguably saved the Apollo 11 mission when the astronauts used one to fix a broken arming switch, without which, they could not have returned to earth.

Fisher supposedly spent 1 million developing and patenting the space pen. When you think about how many pens have sold for $50 at various aerospace museums over the decades, it was a solid investment.

1

AWildDragon OP t1_j6lewvh wrote

Reply to Former NASA Astronauts to Receive Congressional Space Medal of Honor by AWildDragon

> Vice President Kamala Harris will award former NASA astronauts Douglas Hurley and Robert Behnken the Congressional Space Medal of Honor at 4:15 p.m. EST on Tuesday, Jan. 31. Hurley and Behnken will receive the award for bravery in NASA’s SpaceX Demonstration Mission-2 (Demo-2) to the International Space Station in 2020.

Always good to see these awards going to living astronauts.

19

coffeesippingbastard t1_j6ldvf2 wrote

Reply to NASA and DARPA to partner on nuclear thermal propulsion demonstration by returnofjuju

>The two agencies had been separately pursuing NTP projects. DARPA started DRACO with three Phase 1 awards in April 2021 to teams led by Blue Origin, General Atomics and Lockheed Martin to work on preliminary designs of reactors and spacecraft.

You hear nothing out of them and the social media consensus is that they're doing nothing but then you see their name pop up in stuff like this.

1

The_Solar_Oracle t1_j6lcoqk wrote

Reply to comment by GarunixReborn in NASA and DARPA to partner on nuclear thermal propulsion demonstration by returnofjuju

Ehhhhh . . . That's kind of misleading. While the risks of nuclear fuel dispersal is generally overblown (coal plants are hard to beat in this regard), there is not a zero risk of dispersal and there have been historic releases of fissile material.

In the 1970s, the Soviet Union's US-A radar imaging satellites (often known as RORSAT) depended on nuclear reactors to power them in lieu of RTGs and Solar panels. An unnamed launch failed to reach orbit in 1973 and resulted in the reactor entering the Pacific Ocean. Kosmos 954 and Kosmos 1402 had their cores reenter the atmosphere in 1978 and 1983 respectively, with the latter dispersing its debris over Canada. More recently, the Russia Federation's Mars 96 launch failure resulted in the reentry of its onboard plutonium-238.

The United States also had plutonium-238 enter the Earth's atmosphere during Apollo 13. As this material was originally intended to remain on the Moon to power surface instruments, it remained onboard since a landing attempt was aborted.

Only a small handful of launch providers can claim a 100% success rate, and nuclear reactors for man rated thermal rockets or electric rockets must inevitably much larger than any of those involved in the beforementioned incidents.

I also caution against people arguing that nuclear fission is the only way forward for space travel. There have been very encouraging developments in Solar electric propulsion in recent years, and nuclear power for spacecraft comes with engineering headaches that tend to be ignored more often than not. Nuclear reactors must have heavy shielding to protect the crew, and this shielding increases their already large minimum engine mass. Reactors generating electricity must also have significant mass dedicated to generating said electricity and then shedding the large amounts of waste heat produced as a result.

Moreover, nuclear reactors can only be reused so many times before they accumulate too many poisons and can no longer produce useful levels of energy. Once a reactor has also been used, they will also continue to generate radiation. This can make docking in particular very problematic, as economical shielding can only cover a certain 'cone' in front of the reactor and thus forcing other vehicles to enter via that safe zone once they've come within a certain distance of the nuclear-armed target.

6