NASA's Psyche spacecraft beams back a 'Hello' from 10 million miles away NASA has fired up its Deep Space Optical Communications (DSOC) aboard the agency's Psyche spacecraft and received test data from nearly 10 million miles (16 million kilometers) away. At first glance, the achievement isn't all that much. Sure, that's approximately 40 times farther than the Moon is from the Earth, but other …
Please, this standardisation on US units is insane when it comes to science which sticks with SI and derived units for a reason. 10^9 m should either be expressed as km or using astronomical units (light seconds, minutes etc.) when distances get really, well, astronomical.
But let this rant not detract from what really is a fantastic achievement!
The original article states both units. Even more weird: Throughout United States of America it seems to be a law for more than a decade to state both units everywhere? So the transition to metric is on the way and will probably finished in 150 years since it is not forced to abandon the imperial system, like they could in monarchy or dictatorship countries. 150 years as "will take two generations".
> Throughout United States of America it seems to be a law for more than a decade to state both units everywhere?
Never heard of that one. Yes, both-systems is routine on beer/soda and some other packaged goods, but to some degree this is to recognize our various cultures (there are a LOT of good Hispanic buyers in Texas and California).
That doesn't work that way. Unless it is mandatory companies won't invest money in "recognize various cultures". So guess what? *I* am right.
Actually sad that *I* have to go on USA wikipedia to pull the facts here whereas those, who are obviously from the United States of America and should know better than me, voting me down for know enough about their own proud home country, even refusing to check this tiny bit.
Wikipedia, Metrication in the United States, https://en.wikipedia.org/wiki/Metrication_in_the_United_States
1975, Metric Conversion Act of 1975, https://usma.org/laws-and-bills/metric-conversion-act-of-1975
What is going on here? I am from Germany, and even I knew "law for more than a decade", where as nearly five decades seem to be the truth. But the comments on this little part tells me "will take 250 years".
Normally I hate to be this type of commentard, but there is a limit of wrong BS to accept. And no, I won't expand that abbreviation.
Oh, and don't forget to downvote be for "being offensive directly" without "talking around the bush" or "soften the blow". We Germans are direct, and it is our way to be polite because wasting someones time by "beating around the bush" is seen as offensive here.
I'll bite. Couldn't care less whether you're "right" or not, have a downvote for being obnoxious.
Note for future reference: it's possible to be direct without being a dick. And don't blame it on your culture; I work with Dutch and Israeli clients, both are WAY more direct than Germans yet generally manage to communicate without causing offence.
"Metric Conversion Act of 1975, https://usma.org/laws-and-bills/metric-conversion-act-of-1975"
Here in Canada it was two years earlier for the law that was passed to do it, that was actually enforced and mandated to be used everywhere. It did not take long for it to be done as people had no choice in the matter but to use it. And as always the parasite corporations took it as the cue to thieve our money on the size transitions, always rounding down for smaller size same or higher price, same as they have continued to do up until this day. Plus ca change, plus ce la même chose.
Thank you for not understanding the second link. It is not written literally that both units must be there, however to meet "(2) to require that each Federal agency, by a date certain and to the extent economically feasible by the end of the fiscal year 1992, use the metric system of measurement in its procurements, grants, and other business-related activities" they must put it on there else they will have no federal business at all. And since even "controlling whether the amount of content matched the description on the box" is a federal activity no one will risk this. The whole "metric conversion act" implies metric usage all over the place everywhere for any federal purposes.
If you want to stay in business you don't fight such federal definitions, you use the least resistant / most common consensus between what federal demands and what the people are used to: You use both measurements to drive away none. This not only applies to food, it applies to kitchen appliances, fuel, speedometer in cars and so on. Counterexample: For US speed signs it was not adopted since the con still outweights the pros, as the law itself states by using the phrase "economically feasible" and other wordings of bad side effects of confusion of such a change. This might change in a few decades though, so the speed signs might get replaced around 2050 as earliest, i.e. when "a complete generation from birth to death has gone since the act was instated".
"like they could in monarchy or dictatorship countries."
You seem to be very parochial. Have you ever been outside the USA? Something you may not be aware of, but the US is one of only two countries IN THE WORLD to have not gone metric yet.
150 years as "will take two generations".
A generation in human terms is normally regarded as about 20-30 years, ie the time it takes a person to grow up and propagate the next generation and is very imprecise as a measure, worse even than converting metric to imperial :-)
> Have you ever been outside the USA? ....US is one of only two countries....
I've never been INSIDE United Stated of America. How do you come to that conclusion? And of course I know that Burma is the other one. I am from Europe, pretty much the central country now (previously know as the split EU Non-EU country).
As for generations I refer to "complete from birth to death" cycles, so I may have been a bit ambiguous by your standards. There are things that only change when the old people are gone. See the change of alcohol consumption culture in the last few years in EU.
Also you might note that the article in El Reg, or indeed the press release, is not say what speeds were actually achieved. Just woolly words about being faster:
“DSOC was designed to demonstrate 10 to 100 times the data-return capacity of state-of-the-art radio systems used in space today”
What makes of radio systems? At what distances? FFS just tell us what speeds?
Looks like you're a good customer for this T shirt.
I rather like the Oz directness - also, I agree :).
I acknowledge that the transition is a pain, though - we thought going from individual currencies to Euros was bad*..
* Which hasn't really changed anything, now we have UK Pounds, Euros and Swiss Francs..
Yes Voyager can be received too, but at the distance of Voyager anyone on any of our inner planets (yes, including Jupiter) can receive the signal. Jupiter because its orbit is below the 2° limit another article at Nasa mentioned as precision limit for the voyager antenna to receive a signal. Saturn is is beyond that limit, at least half of the time.
Doing the same with laser is another dimension of precision, I suspect they need to more precise then "just earth", rather "which region of earth". I would love to know what size the beam has one it arrives here, but that details is not even in the original article. Maybe just a few hundred km, or less than 100 km? maybe less than 10? Each size difference makes a huge difference on the precision to aim, on top of the "moving objects" problem the original article mentioned.
@Reg: Nice article!
You can deliberately diverge the beam to make pointing less critical, but that of course negates the link advantage of using light (wavelength in the um range) instead of radio (in the cm range) for any low rate missions.
And no, at that distance it is not "high rate" by near-Earth standards. For near-Earth use laser comms promises a lot higher data rate than radio as you can have many, many, GHz of modulation bandwidth that is simply not available in most of the usable radio spectrum, here the advantage is the sharp focus of the laser in delivering enough power where (hopefully) you are listening and not elsewhere.
A perfect diffraction limited system (ignoring laser beam coherence and beam waist stuff) the angle it spreads out by only depends on the size of the transmitting telescope and the wavelength.
So call it 1um infrared wavelength and a 1m telescope (7llinguini = about the biggest you could reasonably put on a space probe and point accurately)
That gives you an angle of 1 in 1million, so a 1km wide spot at 1M km (or should that be 1Gm ?) or 16km at 10M mi
Make the telescope a compact 1 Linguni ( 14cm ) and you have a beam 6-7km wide per million km
Of course that's the best case, you can always make it wider by buying a cheaper mirror or being a bit more cack-handed during assembly. Interestingly the atmosphere has a much smaller affect looking down than looking up at stars. Since you only get the wibbly-wobbly atmospheric turbulence when the light is almost at its destination it doesn't have time to bend out of the way much.
Scientists: We found the least noisy IR frequency, modulated it with the least noisy intermediate frequency, then modulated that again with the least noisy bandwidth for signal encoding.
Aliens: Yes, it's free of noise because it's reserved for distress calls. Please stop sending JP2 images and telemetry.
As far as I can see, Larry Niven and Jerry Pournelle used this mechanism in the seventies in The Mote in God's Eye (and invented the mobile phone as computer at the same time!)
So one of these both for NASA and Niven (sadly too late for Pournelle) --->
Wave length (1.55µm) times beam width is about telescope diameter times separation (1.6E9m)
Psyche telescope diameter = .22m: width = 11km
Earth transmitter diameter = 1m: width = 2.5km
Earth receiver diameter = 5m: width = 500m
As Psyche is moving a few km per second the Earth telescopes must be pointing in slightly different directions. Psyche receive is probably a little off center but Earth can carry a much more powerful laser.
I'm still waiting for NASA to use their X-ray modulator for space communication. GHz modulated X-rays FTW!
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