Briefing Chat: Sweet! Elusive sugar molecules found in space

**Benjamin Thompson** (0:04)
Hi, listeners, Benjamin here. Welcome to the Friday Briefing Show, where we talk about a few stories we've read about in The Nature Briefing, which is of course Nature's daily email roundup of the latest science stories. And sitting opposite me this week is Nick Petrichow. Nick, how are you doing today?

**Nick Patrick Howe** (0:18)
I'm doing well, Ben. I'm looking forward to getting into it.

**Benjamin Thompson** (0:21)
Well, let's go then. Why don't I go first this week? And I've got a story that is based on a Nature astronomy paper that I read in Nature. And it's about a sweet discovery near the center of our galaxy. And it's all about sugar.

**Nick Patrick Howe** (0:37)
I am tasting the hint of a pun here with a sweet discovery and sugar. So what is this that they've found? Is this like sugar molecules somewhere or something like that?

**Benjamin Thompson** (0:46)
This is exactly right, Nick. So researchers, it turns out, have been looking for sugar in space for a very, very long time. Yeah, absolutely. And there's been hints that sugars on Earth that are essential for life originated in outer space. So ribose, this five carbon sugar, was previously found on some very old meteorite samples. But sugar itself has been hard to find actually in the sort of interstellar medium between stars.

**Nick Patrick Howe** (1:16)
I see, I see. And I guess this is a complicated molecule that would be difficult to just randomly come about. So interesting to find if it's out there.

**Benjamin Thompson** (1:24)
Yeah, and this is a sugar called arethulose. Now it's a natural sugar found in raspberries and used in fake tanning lotions. Now this is a four carbon molecule, right? So sugars, they have this kind of carbon backbone and this one has four carbons. Now a two carbon molecule was found back in 2000, this molecule called glycoaldehyde. Now some folk would say this is the simplest sugar molecule.
Other people would say it's not really a sugar. And so this is the discovery of a true sugar, in inverted commas, in interstellar space, swirling inside this cloud of gas and dust, as I say, near the centre of our galaxy.

**Nick Patrick Howe** (2:06)
It's quite surprising to imagine that there's sugar out there. Did they have any idea how it might have got there?

**Benjamin Thompson** (2:11)
Well, that's one of the open questions about this work, Nick. Potentially it was produced through chemical reactions on tiny interstellar dust grains. I don't know exactly how that happened is to be debated. But how it was found is interesting because it was this kind of combination of work between two groups of scientists. And what happened was a physical chemist in Spain shared some spectroscopic data about arithelos. So these are kind of the specific fingerprints of wavelengths that a molecule emits. Think about like a drawing of a comb, I suppose. Every molecule has its own individual comb. So it's been quite hard to get this kind of data for sugars until relatively recently. And so this data was shared with a group of astronomers. And to their surprise, when they looked at their data of space, they found that this arithelos fingerprint showed up in this molecular cloud near the center of the Milky Way. And they then used some other telescopes with deeper observations to see this thing more clearly.

**Nick Patrick Howe** (3:15)
And, you know, I'm guessing I'm veering into speculative territory here. But does this have any relationship with life and things like that? Because obviously these sorts of molecules are really important for all sorts of chemistry involved in life.

**Benjamin Thompson** (3:27)
It does get into speculative territory. But yes, this is kind of why scientists are interested in sugars more broadly. Now, these clouds are the birthplace of stars and planets. And the team say that if sugar exists in these clouds, it could be transferred to things like asteroids or comets as a star system forms. Now, Earth went through this period of very heavy bombardment of these asteroids and comets about four billion years ago. So it may be that sugar molecules were brought from somewhere else to the planet's surface. And potentially, arithylose could have provided feedstock for the first nucleic acids, very simple versions of the building blocks that then became the building blocks of DNA and RNA, if you see what I mean.

**Nick Patrick Howe** (4:17)
What do researchers want to do next to try and peer into this a bit further, I guess?

**Benjamin Thompson** (4:21)
Well, unlike the search for Spock, now we have the search for sugar. So these researchers are keen to try and find even larger sugars in interstellar space. Now one of the questions is why this one? They found a four-carbon sugar. People have found a two-carbon sugar in the past.