horstbort

8 ms·

1.
by horstbort 1y ago
You are never really floating freely, all gravitational wells extend to infinity. The curvature just becomes really small so the resulting acceleration is infinitesimally small too.
2.
by horstbort 1y ago
There is always microgravity, i.e. residual acceleration due to drag and thrusters, and especially vibrations. Worst offenders are actually the astronauts, especially when they work out on one of their exercise devices right next to your ex
3.
by horstbort 2y ago
Thankfully, the same measurement technique can be used to measure e.g. gravitational fields, and there are already devices available on the market which surpass classical gravimeters in accuracy and precision. There are also satellite missi
4.
by horstbort 2y ago
That's the gist of it, yes. The big advantage atom interferometers have over classical IMUs is that they do not need to be recalibrated every so often. They are thus often called "drift free". That still means that you need t
5.
by horstbort 2y ago
Related discussion a few weeks ago: https://news.ycombinator.com/item?id=40692333
6.
by horstbort 2y ago
You don't need any helium or nitrogen here, cooling happens only by laser cooling and evaporative cooling from magnetic or optical traps. The atoms are perfectly insulated in an ultra high vacuum. Electronics still take the bulk of the
7.
by horstbort 2y ago
There is no liquid nitrogen involved here. The instrument from the article is actually rather big, current generations of quantum IMUs are roughly half this size with lots of room for miniaturization. One big advantage of these atom interfe
8.
by horstbort 5y ago
Obligatory: https://git-man-page-generator.lokaltog.net/
9.
by horstbort 5y ago
Permanent magnets are typically a no-go, because these sensors employ matter-wave interferometry, i.e. interference between atoms. Those unfortunately do not only react to gravity, but also to magnet fields, so these need to be suppressed a
10.
by horstbort 8y ago
Author here. Yes, Doppler Cooling is the first step used in the experiment, in a Magneto Optical Trap [0]. It is followed by Polarization Gradient Cooling [1] to overcome the Doppler limit. Atoms are still way too "hot" after this
11.
by horstbort 9y ago
Correct, that's the main problem there. Demanding experiments are even carried out when the astronauts are sleeping, they also tend to vibrate ;-)
12.
by horstbort 9y ago
They're building something similar in Hannover: https://www.hitec.uni-hannover.de/einsteinelevator.html
13.
by horstbort 9y ago
Hey, that's my experiment! :-) So great to see that here on HN.
14.
by horstbort 9y ago
Hi, drop tower user here :-) Three drops per day is due to 20 min preparation, 90 min evacuation, 30 min to refill with dried air, 20 min recovery. The is indeed long, which was not anticipate when the tower was first built, this the lack o
15.
by horstbort 9y ago
Hi, long-time drop tower experimenter here :-) One very good reason to choose a drop tower over the vomit comet is microgravity quality, i.e. residual acceleration and vibrations. The drop tower provides roughly 10^{-6} g, which is a few o