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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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your hust stave Dankling