Anna: The world's biggest rocket is sitting on a
launch pad in South Texas right now. And
tonight, for the first time ever,
Avery: it's going to Fly Starship
version 3 flight 12. And it is
absolutely the biggest story in spaceflight
today.
Anna: We've also got a deep solar system mystery
wrapped up by the James Webb Space Telescope
and some genuinely unsettling news about
what the galaxy may be full of.
Avery: Not very many Earths.
Anna: I'm Anna.
Avery: And I'm, uh, Avery. This is Astronomy Daily.
Today's space news from the universe to you.
Anna: We've been tracking the Starship V3 story for
a couple of days now. The delays, the wet
dress rehearsal, the OSHA investigation.
And today is finally the day. The launch
window opens at 5:30 this afternoon,
Texas time, and SpaceX is going for it.
Avery: This is Flight 12 in the Starship program
overall, but it's the first flight of the V3
design, which is by some measures an almost
entirely new rocket.
Anna: Elon Musk himself said that nearly every
part has been redesigned. Compared to V2,
the rocket now stands
124.4 meters tall.
That's just over 400ft, making it
officially the tallest rocket humanity has
ever built.
Avery: And it's not just bigger for the sake of it.
The big structural change on this version is
that Starship V3 is designed for in orbit
refueling for the first time. That's the
capability that unlocks deep space missions
to the moon and eventually Mars.
Anna: ASA is counting on exactly that.
Starship has been selected as the human
landing system for the Artemis program. The
current plan is for a docking test in low
Earth orbit as early as 2027,
with a moon surface landing targeted for the
Artemis 4 mission in 2028.
Avery: But there's a mountain to climb before any of
that. SpaceX still hasn't sent Starship into
full orbit. The program has seen explosions,
delays, and last week a contractor working at
Starbase in Texas died in a fall.
The US Occupational Safety and Health
Administration has opened an investigation.
Anna: Today's flight profile is suborbital, similar
to recent missions. The plan is to deploy
20 Starlink simulator satellites, attempt
a single Raptor engine relight in space,
and test the heat shield by deliberately
removing one tile to measure
aerodynamic load on neighboring tiles during
re entry.
Avery: That tile experiment is actually quite
clever. You need to understand the failure
modes before you can fix them.
Anna: Weather is sitting around 55%
favorable right now. Not ideal, but
workable. And there is a lot riding on this.
Beyond engineering pride. SpaceX's planned
IPO, which could value the company at, uh, up
to $1.75 trillion,
would be the largest public offering in
history. Today's test flight is very much in
the shop window.
Avery: No pressure, then.
Anna: None whatsoever. We'll have the result in
tomorrow's episode. Whatever happens tonight,
it's a pivotal moment for the program and for
the future of human spaceflight.
Avery: Next up, today. Billions of years ago,
Neptune had a tidy family of moons. Then
a rogue intruder arrived and tore everything
apart. New research published in the journal
Science Advances suggests that one moon
survived the chaos, and we've known about it
since 1949.
Anna: That moon is Nereid, Neptune's third
largest satellite and one of the strangest
orbits in the solar system. It swings as
close as 1.4 million kilometers to
Neptune and as, uh, far away as 9.6.
For comparison, our moon is a pretty
consistent 384,000
kilometers from Earth.
Avery: For decades, astronomers have known that
Nereid's extreme elliptical orbit was
unusual, but they couldn't agree on why. The
leading theory was that it was a captured
object, something that drifted in from the
outer solar system and got gravitationally
trapped. But this new study, led by Matthew
Belyakoff at the California Institute of
Technology, strongly rules that out.
Anna: The team used NASA's James Webb Space
Telescope to study Nereid in detail, and
what they found changes the story
significantly. Their observations are
consistent with Nereid being an original moon
of Neptune, one that formed right alongside
the planet, but was thrown into its wild
orbit when Neptune captured its largest moon,
Triton.
Avery: And Triton's story is quite the tale itself.
Triton is thought to have originated in the
Kuiper Belt, the frigid region beyond Neptune
where objects like Pluto live. At some point,
Triton was captured by Neptune's gravity, and
the gravitational chaos of that event
scattered Neptune's original moons onto
collision courses with each other. Most were
destroyed.
Anna: Neptune's innermost moons are thought to be
the shattered remnants of those originals,
rubble that coalesced after Triton's
arrival. Nereid, according to this new
research, escaped that fate by being thrown
into its current extreme orbit. Far
enough out to survive, but close enough to
still be bound to Neptune.
Avery: As Belyakov puts it, it takes a long time to
do science. This mystery began with Nereid's
discovery in 1949, and we may finally
have some answers in 2026. Thanks to Webb.
The researchers note that this work would
simply not be possible with any previous
telescope. It really is a testament to what
Webb continues to deliver.
Anna: A survivor of 4 billion years of
Cosmic chaos. Not a bad story for a
Thursday.
Avery: Here's a number that should give you pause.
In 2005, the European Space
Agency was tracking around 16,000
pieces of debris in orbit. By
2026, that number has grown to more than
44,000, an increase of roughly
180%. And that's only what we
can track.
Anna: The vast majority of debris is too small
to track at all. ESA estimates there are
millions of fragments out there paint flecks,
bolt fragments, shards from old rocket stages
moving at orbital velocities. Even something
tiny can cause catastrophic damage.
Avery: But new research is drawing attention to a
consequence that gets less coverage than the
collision risk. The scientific cost. A
study looking at NASA's Earth observing
satellites, specifically Aqua, Terra and
Aura, found that since 2005,
this fleet has had to execute avoidance
maneuvers at least 32 times to dodge
debris.
Anna: And those maneuvers aren't free, not in terms
of fuel and possibly not in terms of data.
According to records from the Land Data
Products Evaluations Assessment, some of
those avoidance burns may have corrupted
climate data. During the collection window.
You move the satellite, the instruments point
somewhere different, and the record has a gap
or an artifact.
Avery: These satellites were not designed with this
level of debris in mind. Aqua, for instance,
has lasted 18 years longer than its original
design life. It's been incredibly productive,
but it only has so much fuel left. Every
avoidance maneuver burns some of that
reserve.
Anna: And as one insurance analyst put it to
space.com even without collisions,
space debris has an economic cost. Each
time a satellite has to maneuver to avoid a
potential collision, it uses fuel, which is a
finite and precious resource. The headline
quote from researchers is blunt Things will
get worse before they get better.
Avery: The good news is that two companies have
announced plans to begin active debris
removal from orbit in 2027. The
technology exists. The will and the
regulation need to catch up quickly.
Anna: Next on today's agenda. Over the past year
or so, results from the dark energy
spectroscopic instrument DESI have
been causing excitement and consternation
in equal measure. The data appeared to
hint that dark energy, the mysterious
force driving the accelerating expansion of
the universe, might be evolving over
time, changing in strength as the
cosmos ages.
Avery: Which, if true, would be a genuinely enormous
deal. The standard cosmological model treats
dark energy as a fixed cosmological constant.
If it's changing, the model needs to be
rebuilt from the ground up.
Anna: Exactly. But new research published in
Physical Review D is urging caution.
Scientists at the Tata Institute of
Fundamental Research in Mumbai have found
something a small but simple significant
mismatch between two Key data sets
used to measure dark energy's
supernova brightness data and baryon
acoustic oscillations, which are essentially
ripples in the distribution of galaxies
across the universe.
Avery: And the mismatch matters because the DESI
results that pointed to evolving dark energy
relied on combining those two datasets. If
they aren't mutually consistent, if there's a
small but real discrepancy in what they're
measuring, then the apparent signal of
evolving dark energy could be a systematic
artifact rather than a genuine physical
phenomenon.
Anna: The researchers traced the mismatch back to a
potential violation of what's called the
cosmic distance duality relation,
a fundamental geometric relationship
that underpins how we calculate distances in
the universe. If that relation is being
violated, or if there are subtle calibration
errors in the datasets, then the apparent
evolution of dark energy may simply
disappear.
Avery: What does this mean in practical terms?
Anna: It means we don't know yet. This paper
doesn't prove dark energy is constant. It
just raises a serious methodological
flag. Science is working exactly as
it should. Extraordinary claims get
extraordinary scrutiny. More data from
DECE's third release and from ESA's Euclid
mission should help clarify things later this
year.
Avery: The universe remains stubbornly mysterious,
which is
Anna: honestly what keeps us in a job.
Avery: Now, here's a question that sounds simple but
turns out to be extraordinarily complex.
What's the most efficient way to get from
Earth to the Moon?
Anna: I mean, you point the rocket at
Avery: it, you'd think, right? But no, because in
spaceflight, the most direct path is almost
never the most efficient one. And the new
study, published in the journal
Astrodynamics, has found the trajectory to
the Moon that is better than any route
previously described in the scientific
literature.
Anna: How much better?
Avery: The new route uses 58.8 meters per
second less fuel, what engineers call Delta V
compared to the previous, best known path.
That might sound tiny. But consider the total
fuel budget for an Earth to Moon transfer is
around 3,343 meters per second.
Shave nearly 60 off that, and you've made a
real difference. Every meter per second saved
is, as the researchers put it, a massive
amount of fuel consumption.
Anna: So how did they find it?
Avery: The team from the universities of Colimbra,
Porto and Evora in Portugal and the
University of so Paulo in Brazil used a
mathematical approach called the theory of
functional connections. It dramatically
reduces the computing power needed to
simulate trajectories, which let them test
around 30 million different routes. Previous
studies had managed around 280,000.
Anna: That's an enormous leap in the search
Avery: space, and it paid off. The most efficient
route they found is counterintuitive. Instead
of heading more or less directly toward the
Moon, the spacecraft first swings toward a
point called the L1 Lagrange point, the
gravitational balance point between Earth and
the moon. About 85% of the way there,
it enters a stable orbital pathway around
L1, then departs on an unstable pathway
that transitions it, uh, into lunar orbit.
Anna: Essentially using the Moon's own gravity
as part of the propulsion system.
Avery: Exactly. The team also notes that the L1
point maintains constant line of sight with
Earth, which means communication is
uninterrupted throughout the journey. And
crucially, this method can be adapted. You
could use it for any planet, moon system, or
any orbital transfer problem. As the
researchers say, the systematic analysis they
developed could be adopted much more widely
going forward.
Anna: Small savings Scaled across dozens of
future Artemis missions, that adds up to a
Avery: lot of rocket fuel and a lot of money.
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Anna: All right, on to our next story. And this
one will surprise many. If you've ever
looked up at the night sky and felt reassured
that the galaxy must be full of
Earth's worlds with oceans,
atmospheres and the potential for life,
new research from the European Geosciences
Union conference in Vienna may give you
pause.
Avery: That's not the most comforting preamble.
Anna: Preliminary results presented by Shawn
Jordan, a postdoctoral researcher at ETH
Zurich, suggest that our galaxy may be
filled with a far greater number of Venus
like worlds than true Earth analogs,
and that this might simply be how rocky
planet formation works.
Avery: Walk us through the science.
Anna: When a rocky planet forms, it goes through
what's called a magma ocean phase.
Essentially the entire surface is molten.
As it cools, the atmosphere it develops
heavily depends on its chemistry and its
distance from its star. Dourdan and
colleagues argue that it's actually quite
straightforward to end up with a carbon
dioxide dominated atmosphere, thick,
hot, crushing Venus style. After
that cooling phase, getting to an Earth like
nitrogen oxygen atmosphere is harder,
Avery: meaning a, uh, Venus outcome might be the
path of least resistance.
Anna: That's the implication. And there's a
philosophical reframe buried in here too.
Jordan suggests that Venus may not have gone
wrong. It may simply have been born that way.
A planet that came out of its magma ocean
phase looking exactly like Venus does today
without ever having oceans or a temperate
climate.
Avery: How many exovenus candidates are we actually
talking about?
Anna: At least a few dozen rocky exoplanets are
considered potential Venus analogues, though
none have been confirmed as such. We don't
yet have the atmospheric characterization
tools to be certain. The challenge is that a
Venus like atmosphere, although sulfuric
acid clouds, looks very similar to a, uh,
featureless atmosphere in our current
observations.
Avery: There's a telling phrase in the coverage of
this research that our own Venus has been
described as criminally underexplored.
Only one mission has sent a lander since the
Soviet program in the 80s.
Anna: That's the awkward irony. We're looking for
Venus twins across the galaxy while
barely understanding the one we have next
door. ESA's Envision mission and
NASA's DaVinci program are, uh, both in
development, and they can't come soon enough.
Our nearest twin, the cautionary tale,
deserves a much closer look from a
habitable
Avery: paradise candidate to the galaxy's most
common world. Quite the motion.
Anna: Science rarely flatters our assumptions
before we
Avery: head out, A quick look at the sky for our
Southern Hemisphere listeners, particularly
in Australia and New Zealand, this week
Anna: is a beautiful time to watch the evening sky.
Jupiter is blazing brightly in the west after
sunset, and the waxing moon is sliding past
it over the next couple of nights. Tonight
they're particularly close together, making
for a stunning naked eye pairing.
Avery: No equipment needed, just step outside about
30 to 45 minutes after sunset, look west
and you'll see the moon and the brightest
star near it. That's Jupiter. It's one of
those simple, wonderful reminders that the
solar system is right there every clear
night.
Anna: Cloud free skies to all of you.
Avery: That is Astronomy Daily for Thursday, May
21, 2026. Six stories from the
launch pad in Texas to the farthest reaches
of Neptune's
Anna: battered moon and the starship. Result.
Whatever it is, we'll have it for you
tomorrow.
Avery: If you enjoyed the show, please take a moment
to subscribe and leave a rating. Wherever you
get your podcasts, it genuinely makes a
difference.
Anna: You can find us at astronomydaily
IO and on socials
astrodaily pod. We're part of the
bytes.com podcast network.
Avery: Until tomorrow, keep looking up Clear
Skies Astronomy Day
Anna: stories.