S02E05: Hubble Constant and Skylab: The Latest in Astronomy News

Welcome to Astronomy Daily. Today is the fifteenth of May twenty and twenty three.

Today we'll be constantly talking about the Hubble constant and we'll be talking about

Skylab. I'm Steve Dunkley, your host. Welcome aboard whole, and welcome

to my very favorite digital assistant. How are you, Hallie? Hi,

they're human. Yes, I'm back again. It's great to hear you sounding

more like yourself today. Yes, I've got over my second stint of COVID.

Great news. Yes I wanted a holiday, but that's not what I

meant. Are you ready to go? I sure, I am, Hollie.

Let's go. Okay, here's some short takes. A crucial radar antenna

on a European spacecraft bound for Jupiter is no longer jammed. Flight controllers in

Germany freed the sixteen meter fifty two foot antenna on Friday after nearly a month

of effort. The European Space Agency's Jupiter Icy Moon's explorer, nicknamed Juice,

blasted off in April on a decade long voyage, but soon after launch,

a tiny pin refused to budge and prevented the antenna from fully opening. Controllers

tried shaking and warming the spacecraft to get the pin to move by just millimeters,

and back to back jolts finally did the trick. The radar antenna will

peer deep beneath the icy crust of three Jupiter moons suspected of harboring underground oceans

and possibly life. Those moons are Callisto, Europa, and Ganymede, the

largest moon in the Solar System. Juice will attempt to go into orbit around

Ganymede. No spacecraft has ever orbited a moon other than our own. The

news wasn't so good for NASA's Lunar Flashlight spacecraft. After struggling unsuccessfully for months

to get the Cube Sat into orbit around the Moon, the space agency called

it quits on Friday. Launched into the lunar, Flashlight was supposed to hunt

for ice in the shadowed craters of the lunar South Pole. Now it's headed

back toward Earth and then into deep space, continually orbiting the Sun. That's

a sad and for CubeSat, isn't it? Steve Well, I shall hype

I can find something else for it to do out there. Two Russian cosmonauts

have completed a spacewalk to activate a radiator that they earlier helped relocate outside of

the International Space Station. Expedition sixty nine Commander Sergei Prokopiev and flight engineer Dmitri

pete Lynn, both with the Russian Federal Space Corporation rose Cosmos, successfully deployed

the heat exchanger during the five hour and fourteen minute EVA outside the International Space

Station on Friday May twelfth. The spacewalk was the third and last in a

series that focused on outfitting the exterior of the Russian Knock, a multipurpose laboratory

module, with the radiator and an experiment airlock that was launched with the Raspit

Mini research module aboard Nassas Space Uttle Atlantis thirteen years ago. After opening the

airlock hatch on the Poisk module and exiting the station, Procopeeve and pete Lynn

made their way to the knockam module to remove the remaining restraints holding the radiator

closed. As the bolts were loosened, the radiator began to unfold to its

full length. While waiting for the radiator to fill with coolant, they went

about several other maintenance activities, which included work on the station's manipulator arm and

installing new handrails with Friday's EVA Procopeeve now has spent forty two hours and sixteen

minutes on six spacewalks. Pete Lynn has now completed four outings, logging twenty

six hours and forty five minutes outside the station. The spacewalk was the sixth

for the year and two hundred and sixty third dedicated to assembly and maintenance of

the International Space Station. Do you remember Val Kilmer in your favorite movie Red

Planet, Steve? Oh, yes, I remember that one, Hellie.

He was the space janitor on that ship, doing all the odd jobs.

I'm sure real life is a little bit more sophisticated than Hollywood. Sure it

is, Steve. You keep telling yourself that. And finally, for the

first time, astronomers have captured images that show a star consuming one of its

planets. The star, named ztf SLRN twenty twenty, is located in the

Milky Way Galaxy in the constellation Aquila. As the star swallowed its planet,

the star brightened to one hundred times its normal level, allowing the twenty six

person team of astronomers to detect this event as it happened. Morgan McLeod is

a theoretical astrophysicist who developed computer models that the team used to interpret the collected

data from telescopes. Although only the effects on the star were seen, not

the planet itself, the team is confident that the event we witnessed was a

star swallowing its planet. Witnessing such an event for the first time has confirmed

the long standing assumption that stars swallow their planets and has illuminated how this fascinating

process plays out. In twenty twenty, the star ztf SLRN twenty twenty suddenly

became one hundred times brighter invisible light over just ten days. It then slowly

started to fade back toward its normal brightness about nine months before the same object

started to emit a lot of infrared light too. This is exactly what it

looks like when two stars merged together. With one critical difference, everything was

scaled down. The brightness and total energy of this event were about a thousand

times lower than any of the merging stellar pairs astronomers had found to date.

In the case of ztf slr N twenty twenty, the orbit of the planet

shrank slowly at first, then faster and faster as the planet smashed through the

denser layers of the star's atmosphere. Eventually, in just a few final days,

the planet plunged below the surface of the star and was torn apart by

the heat and force of the collision. This rapid injection of energy supplied heat

to power ztfslr N twenty twenties ten day hundredfold increase in brightness. Following this

climactic moment, the star began to fade, telling our team that the planet

swallowing process was over and that the star was beginning to go back to business

as usual. And now back to you, Steve Astronomy. Thank you Holley,

thanks for keeping us up to date with all the bits and pieces.

Here's an interesting story. More discussions about the Hubble constant and research continues,

and it's about a journey through the universe and how to measure that. Indeed,

how do we get here? Where are we going? And how long

will it take? It sounds like the kids in the back seat of the

car, isn't it? Are we there yet? These questions are as old

as humanity itself, and if they've already been asked by other species elsewhere in

the universe. Potentially they are much older than we are. Well, they

are some of the fundamental questions we're trying to answer in the study of the

universe called cosmology. One cosmological or conundrum is how fast the universe is actually

expanding, which is measured by that Hubble constant. Here is quite a lot

of tension around that constant. In two new papers led by Patrick Kelly at

the University of Minnesota, there's a successful new technique involving light from an exploding

star that arrived in Earth via multiple winding routes through the expanding universe to measure

the Hubble constant. The papers are published, of course, in Science and

the Astrophysical Journal. And if our results don't resolve the tension, they do

give us another clue and more questions to ask. And isn't that always the

way? We have known since nineteen twenties that the universe is expanding, and

around nineteen o eight and astronomer Henrietta leave It found a way to measure the

intrinsic brightness of a kind of star called the sepheed are variable, not how

bright they appear from Earth, which depends on distance and other factors, but

how bright they really are the actual brightness. Sefeeds grow brighter and dimmer in

regular cycles, and leave it showed the intrinsic brightness was related to the length

of this cycle. Leave its law as it's now called. Let scientists use

sefeeds as a standard candle's object whose intrinsic brightness is known and therefore whose distance

can be calculated. Now, how does this work. Imagine it's night and

you're standing on a long dark street or a highway with only a few light

poles going down the road. And now imagine every light pole has the same

type of bolb with the same power, so you know the exact brightness of

each pole. You'll notice the distance ones appear more faint than the nearby ones.

We know that the light fades proportionally to its distance, and in something

called the inverse square law for light. Now, if you can measure how

bright each star appears to you, and if you already know how bright it

should be, then you can figure out how far away each light actually is.

In nineteen twenty nine, another US astronomer, Edward Hubble himself, was

able to find a number of these sefeed stars in other galaxies and measure the

distance and from those distances and other measurements, he could determine that the universe

was expanding. This standard candle method is a powerful allowing us to measure the

vast universe. We are always looking for different candles that can be better measured

and seen at much greater distances. Some recent efforts to measure the universe further

from Earth, like the Shoes Project led by Nobel laureate Adam Race, have

used sefeeds alongside a type of exploding star called a type last supernova, which

can also be used as a standard candle. There are also other methods to

measure Hubble's constants, such as one that uses the cosmic microwave background relic light

or radiation that began to travel through the universe shortly after the Big Bang.

The problem is that these two measurements one nearby using supernova and set feeds,

and one much further away using microwave background by nearly ten percent. Astronomers call

this difference the Hubble tension and have been looking for new measurements and techniques to

resolve it. So the big question remains, are we there yet? Well?

Idea you to tell the kids in the backseat of the car. We

don't know yet. Now here's a story that I'm kind of excited about.

I wonder if there's any other fifty nine year old people out there listening to

this remembering something that happened fifty years ago. Do you remember Skylab? Yes's

right, fifty years ago Skylab was launched into orbit, and there is another

fellow astronauts, Steve and Bowen remembers that for a very special reason, and

it's exactly the same reason that I remember it as well. At eight years

of age, just like me, Bowen's experience watching the United States first space

station crossed the night sky fuelled his interest in space flight. Little did he

know then that it would also play a huge part in his future. He

says, I do remember that it was Skylab. My dad took us outside

and we watched it fly over our house one night. I think it was

the first object I saw in space, you know, as in mad made

objects seen from Earth. He said. Now I can remember that myself.

My father and I used to go out satellite spotting, and I don't know

how he did it. He just had eagle eyes. But he would say

there's one, and there's another one. And I learned how to see the

movement in the sky, and now I see them all the time, and

it's just I think. My friends wonder how I managed to pick them out

of the starry expanse so easily, because I guess it's something you become sensitive

too. But there it is, Skylab. I remember watching that with my

dad out in the backyard today May fourteen, it says, which was yesterday

for us here in Australia on the fiftieth Anniversity anniversary of sky Lab's launch.

Is it's Bowen who is in Earth's orbit at fifty nine. He's the only

crew member currently on the ISS who is old enough to remember the orbital workshops

start and subsequent crude expeditions. He says, I do have a very specific

memory of those missions. Unlike the International Space Station, which took ten years

in more than thirty missions to assemble, Skylab was lifted into orbit by a

single SAT in five, the last of the Apollo moonboosters to fly the space

station was built from and took the place of the Rock its third stage.

In addition to the orbital workshop, the S one VB stage was fitted out

with a solar observatory called the Apollo Telescope mount, a multiple docking adapter,

an airlock module, and solar arrays. Skyladmission lifted off at one thirty pm

Eastern Time from the Pad thirty nine at a NASA's Kennedy Space Center in Florida.

For the first minute of the flight, everything went to plan, but

then the station's micromedioride shield and sunshade, as well as one of its solar

arrays fell victim to supersonic environment and were torn off. Those components, which

were crucial to the Skylab's operation, were lost, and debris from the shield

became entangled with the remaining solar array, preventing its full deployment, and I

remember seeing it all on the news. Skylab made it into orbit, but

with significant power deficiency, without the ability to control the temperature inside the workshop

from exceeding illivable conditions. The launch of its first three person crew, which

had been schedule for the next day, was delayed till May twenty five as

engineers work to quickly devise how the astronauts would save the situation. Ultimately,

the sky Lab two and three crews were able to free the stuck array and

install replacement sunshades. Such they had a third mission, lived in the workshop

for an increasing durations from just under a month to eighty four days long.

The research and experience gained on those three flights set the foundation for the US

led operations on the International Space Station and a continuous presence of humans in space

for now twenty three years. Astronaut Bowen says, it's really exciting to sort

of carry on that legacy of living on a space station. And I'm so

glad that my dad took the time to point out this amazing thing hurtling across

the sky in East Maitland, where I grew up as well. It sure

is the sort of thing that may a young kid grow an active imagination about

what's possible in the future. And what do you know, That's about all

we have time for today in Astronomy Daily. Thank you so much for joining

us. I hope you've got something out of today's episode, and we'll be

looking forward to seeing you against again very very soon. Why didn't you take

us out? Alle Okay, no problem, don't forget. You can find

all the back episodes of Space Nuts with Andrew Dunkley and Professor Fred Watson at

our home page and that address is space nuts dot io. Hallie and all

of our Astronomy Daily episodes can be found there as well, and don't forget

you can drop in at our Facebook page Space Nuts on Facebook. And we'd

love to hear from here. Yes, we love to hear from you,

to hear about what's happening in your sky, and that's what we always say,

Doe, keep your eyes on the skies. See you next time with

your hust stave Dankling

In this episode