The real problem isn't storing the data, it's accessing it. There is no way to address DNA, you can only "shotgun sequence" it. In doing so, you get random fragments of around 200 bases (400 bits). You can't get one such fragment, you get half a billion in one go, currently at a cost of around $5000. (Older, much more expensive technology, got up to 1000 bases... sometimes, and only 100 fragments per machine run.) So how are you going to access your archive? By sequencing the whole thing and (temporarily) storing it on a hard drive?

The manufacturers of modern sequencers (both Illumina and ABI) have been talking about this for at least 7 years (i.e. as long as they've been selling high throughput sequencers). They actually made a weaker claim: According to them, it makes no sense to keep a sequenced genome, because just sequencing it again would be cheaper than storing the data. In these 7 years, it hasn't happened. Instead, ABI's SOLiD technology all but vanished. Actually storing data in DNA is one step further, it's not going to happen for a long time.

(Source: My employer does a lot of sequencing. I talked to sales representatives of both companies, and I work on data sequenced using Illumina's machines. We store that data on spinning rust.)

I've often thought that if we ever decide to send nano spaceships filled with engineered DNA to populate other planets like spores we should include human knowledge in the DNA so when the spores turn into an advanced civilization they could read the DNA and learn about their progenitors.

> The researchers' biggest worry was that DNA synthesis and sequencing made mistakes as often as 1 in every 100 nucleotides. This would render large-scale data storage hopelessly unreliable — unless they could find a workable error-correction scheme. Could they encode bits into base pairs in a way that would allow them to detect and undo the mistakes? “Within the course of an evening,” says Goldman, “we knew that you could.”

how does this work? are the mistakes consistent enough that we can design encodings that rely upon them?

Even if you can make it work, DNA stability is poor.

I don't see why you wouldn't use a higher fidelity atomic storage solution.

Do we need to keep the DNA away from bacteria? Would it not be digested for nutrients or food? Or is that just propaganda from the salesman pushing memory carbon for my looongterm data storage needs?

DNA is also compressed in a very spectacular way. I wonder a similar compression can be applied to data.