Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.

Hot answers tagged

36

Interplanetary communication is mainly dependent on signal strength (for transmission) and antenna size (for reception). The Pioneers use a 9-foot antenna and an 8-watt transmitter. The Voyagers use a 12-foot antenna and a 20-watt transmitter, allowing a substantially stronger signal to be received on Earth.


31

Voyagers are still active, and albeit they don't have the power required to run all the scientific equipment onboard and some of it stopped working by now, they still transmit telemetry data streams towards the Earth that is picked up by NASA JPL's 70-meter antenna at Goldstone, California, part of the Deep Space Network. Quoting from Wikipedia on Voyager ...


28

No, it's not feasible. The fundamental problems that prevent this are: The Pioneers do not have enough power to operate the transmitter, due to corrosion of the thermocouples The Voyagers and Pioneers, even at full power, use very low power transmissions The Pioneers would need to be able to receive and obey instructions to aim for a Voyager The craft are ...


27

In addition to a better transmitter, the Voyagers have better power reserves: their RTGs supplied 470 W at launch, while the Pioneer RTGs supplied 160 W at launch. So the Voyager RTGs will take much longer to decay to a point where they can't power the spacecraft. NASA seems to think RTG decay is the primary reason we can't receive Pioneer 10 any more: ...


25

Physical First and foremost, the physical reason is that objects accelerate as they approach massive bodies and decelerate as they recede: Parker Solar Probe achieves its peak orbital speed (almost 200 km/s eventually) at its closest approaches to the Sun - as it falls inwards towards the Sun on each orbit it speeds up then slows down again on the way back ...


25

Why the Pioneers didn't last as long: The Pioneers were a low-budget mission just to test if flying to the outer planets was feasible They used a smaller radio transmitter (8 W vs. 23 W) and antenna (2.7 vs 3.6 m diameter) so their signals are weaker The Pioneers used a smaller, earlier design Radioisotope thermoelectric generator as their power source (...


24

The initial plan was to visit all of the outer planets: The Planetary Grand Tour was to send several pairs of probes to fly by all the outer planets (and Pluto) along various trajectories, including Jupiter-Saturn-Pluto and Jupiter-Uranus-Neptune. Limited funding ended the Grand Tour program, but elements were incorporated into the Voyager Program, which ...


23

No, absolutely none. Even assuming Pioneer 11's transceiver still works, and there's no reason to believe that, that image you attach of distances between the three probes isn't showing it proportionally correct, since it's merely an approximate slice of euclidean space and is not axially aligned with anything to correctly appreciate distances involved. So ...


17

We currently cannot track Pioneer 10 or 11. Someone on the XKCD forum calculated how much radiation the Voyager probes emit besides their radio transmissions. The heat they give off is emitted as infrared light: We have a power source of 420 W at 1.78×1010 km, which gives a brightness of 1×10-19 Wm-2, or an apparent magnitude of 28. That is just ...


17

Yes, Pioneer 10 and 11 each carried a 0.000001 megapixel camera. The single pixel was scanned over the body by the constant spin of the spacecraft in one direction and a slew of the spacecraft in the other. Building up one image took a long time, over which the relative position of the spacecraft and the body changed quite a bit, distorting the image. ...


13

Voyager 1: separated from Centaur stage with velocity 18.3 km/s (relative to Earth, Dave Doody, Deep Space Craft: An Overview of Interplanetary Flight, 2010, page 120). Then 76.5N Injection Propulsion Unit of V1 did burn its solid fuel in 43 seconds giving additional 1,7 km/s (?), injecting the spacecraft into Hohmann transfer orbit. IPU was separated, and ...


13

I am infocat13 who wrote that unmannedspaceflight.com article, I base my opinion based on a personal communication with Dr. Stone, the PI of the Voyager project and many AIAA astrodynamics journal articles. Mr. Lasher, a JPL astrodynamics specialist, informed me of the Pioneer 11 missing its B plane Jupiter aimpoint before TCM-1, so that solid motor is ...


12

Pioneers Several factors lead to the loss of signal. Radiated power: Pioneer 10's broadcast power is particularly low. 8 W at ~2.2 GHz ① Very narrow beam; the antenna gain is +65dB, which means 1/(10^6.5) the broadcast surface area... which means a pretty narrow cone. (I don't know the math for the actual beam angle.) Input power decreases - the RTGs ...


11

I found this reference in a 2015 Reddit interview of the New Horizons team: Has the team had any success looking for Pioneer Anomaly type effects in New Horizon's position and trajectory data? Thanks for doing this AMA! Michael Vincent: We did look at that. It was attributed to the thermal radiation from the RTG pushing on the spacecraft ...


11

This is propulsion via infrared photons, which is similar to other photon propulsion methods. It's more common to hear about gamma (antimatter drives) and x-ray propulsion because we have mechanisms to drive higher power through it, whereas thermal photons are limited by the Stefan-Boltzmann law. To the question: How much heat would be necessary to ...


10

Pioneer 10 and 11 were built to gain experience in sending probes to the outer solar system. NASA had no experience at all of space outside Mars' orbit. The opportunity for a Grand Tour (one probe could cover all 4 of the outer planets) was recognized early enough to do some experiments. There wasn't much of a budget though, so the scientific payload was ...


8

No. And here's why: To establish radio communication between two points in space successfully, one has to achieve the Signal-to-Noise ratio (SNR) greater than some threshold which varies depending on the type of signal modulation and error correction used. This is done through several means: Pointing the antennas' radiation patterns) of the receiver and ...


8

"Current" positional data: Voyager 1 Spacecraft, ephemeris for Fri 7 February 2014, 02:13 UTC Right Ascension: 17h 11m 54s Declination: +12° 01’ 12” (J2000) [HMS|00:00:00|Dec] Distance from Sun: 18,968.76 Million Km Distance from Earth: 19,024.36 Million Km Magnitude: N.A. Constellation: Oph Voyager 2 Spacecraft, ephemeris for Fri 7 February ...


8

The Pioneer Anomaly gives a first-order answer. The Pioneer Anomaly was an acceleration of $(8.74±1.33)×10^{−10} m/s^2$. According to the paper in which the solution for the Anomaly was published, this acceleration was caused by about 50 W of heat output. So you get $10^{-11} m/s^2W$, or 100 GW for 1 $m/s^2$, for a spacecraft that weighs ~250 kg. So 40 MW ...


8

You have probably seen funnels like the above in shopping malls. Drop a coin in the funnel and it will move slowly at the edge and move faster as it nears the center. This is a good model of a gravity well. Stuff moves a lot faster in the inner solar system.


7

The list you linked to, shows that the instruments that are still active, are meant for the detection of solar wind and cosmic rays. The magnetometer could be useful, but a planet needs a liquid core to generate a magnetic field. It is unlikely that any KBO is warm enough to have a liquid core (or we'd be able to detect it using IR telescopes). What's left ...


7

Doppler and ranging are used routinely. They are both two-way, with the Doppler turning the frequency around and the ranging turning around a pseudo-noise signal. This is complicated, only for these spacecraft, due to the transmitting station on Earth rotating out of view (and in, and out again!) by the time the return signal hits Earth, being then received ...


6

Looking at the trajectories of the Pioneers, the wording "The Earth's motion has carried it out of the view of the spacecraft antenna" seems to be a poor choice of words. you can see that in the long term, Pioneer has to rotate to keep Earth in view. Once it's out of fuel, it can't do this maneuver any more. For Pioneer 11's last transmission, it's ...


6

It isn't known exactly, as we don't have a good way of tracking them. However, this question was brought up in the form unmannedspaceflight.com as @Hash mentioned, which mentions a Wikipedia article. Bottom line, we believe there are 11 artifacts that are leaving the Solar System that we launched: 5 probes (Pioneer 10, 11, Voyager 1, 2, New Horizons, and 4 ...


5

Here is a helpful image I received from Dr Lasher from one of his AIAA astrodynamics papers from the 1970's it reflects the Jupiter aim points for the Star 37E after separation from the Centaur upper stage for the pioneer spacecraft. The B plane of a planet is always changing do to spacecraft incoming speed and line of flight(geometry) and epoch(time) ...


3

Heat is radiated to space in form of infra-red radiation. Infra-red radiation is nothing else than long-wavelength light. And there is a theoretical concept for a spacecraft accelerated through a beam of light, called photon propulsion. The great thing about photon propulsion is that it requires no propellant, that means that when you have access to an ...


3

But they must have had an effect on the crafts' trajectories. Not really. The known unknowns included the masses of Saturn and Titan. To this day, the uncertainty in Saturn's gravitational parameter outweighs that of all of the moons of Saturn discovered since Voyager, and by many orders of magnitude. The uncertainty at the time of the Voyager mission was ...


3

It's been done before: in 2014, an amateur group established contact with ISEE-3, another old space probe (launched in 1978) on a heliocentric trajectory. The main obstacles: you need access to a large antenna. There are a few large dishes (25 m) operated by amateurs. The ISEE-3 effort was given time on the (even larger) Arecibo dish. you need to know ...


3

It's not impossible: The Pioneers have not been switched off (as evidenced by the later successful attempts to contact them). They're in constant sunlight so no thermal cycling which increases their life expectancy, and no batteries are necessary. There has been at least 1 other case where an old spacecraft was found to be alive after years of no contact (...


Only top voted, non community-wiki answers of a minimum length are eligible