The real reason, which hopefully gives some engineering insight, is why not? It's a flyby mission whose primary data collection occupied only a couple of days. Like any spacecraft design they had to choose between high bandwidth (more power == larger RTG == more weight) or large storage (more memory modules == more weight). There is some tradeoff between the two that yields the optimal science return, and one would expect it would involve months of transmission: storing things locally to transmit low power requires way more resources than a high gain antenna used for 1 week only.
"and one would expect it would involve months of transmission: storing things locally to transmit low power requires way more resources than a high gain antenna used for 1 week only."
You're contradicting yourself there.
Memory today is cheap (even if we're talking about the radiation-hardened stuff, for "space mission" levels of cheap)
Getting data for a long time takes a lot of resources (basically usage of Deep Space Network infrastructure)
So, yeah, if they could they would download all the data more quickly, but you're right that the power budget wouldn't allow it (not sure how powerful it would have to be to get the data at, let's say 32kbps)
> Memory today is cheap (even if we're talking about the radiation-hardened stuff, for "space mission" levels of cheap)
New Horizons was launched in January 2006, but I suspect you know this and you're just being dramatic to make a point. :)
The problem with "cheap" as a metric whose context is solely monetary is that it's ignoring maaku's fundamental argument: More storage is more weight; more transmitter capability is more weight. So it's not just the cost of the storage you're looking at but also the cost to get that into space. Launches are not cheap, and you have to account for every bit of spacecraft weight which leads to design tradeoffs.
Sometimes you can have one or the other--not both.
Interestingly, the New Horizons program has its roots dating back to the 1990s, at least according to Wikipedia, with cancellations due to projected costs exceeding levels NASA was willing to fund. But this is par for the course when dealing with long-term, long-distance missions. Everyone has an argument about what to put on board, but there's neither budget nor space to accommodate them all (sadly).
Solid State Storage, even in 2006, wasn't that heavy (or costly - of course, for 'space mission' levels of cheap)
So, yeah, I'm not saying it is as small and light as the SD card on my phone that cost a dollar value having 2 digits and has double that space, but it's probably 'as good as it gets'
If we're talking about a mechanical data recorder I would agree
> not sure how powerful it would have to be to get the data at, let's say 32kbps
My back-on-the envelope calculation says the probe would have to emit with at least 6 times more power for that than it emits now (and I can be way off as I'm not taking into account all the competing noise at that distance). The RTG produces around 200 W for everything on the probe, and I estimate just the cost of the fuel for the current RTG alone in tens of millions. It's simply not worth optimizing for the fast burst when you expect the probe to be able to communicate for a few years more.
