# Tag Info

46

why weren't they completely attracted by their gravitational field? How much a trajectory is changed, depends on 3 factors: the mass of the planet, the speed of the spacecraft, the distance between spacecraft and planet Voyager's speed and distance were chosen to make sure Voyager wouldn't enter orbit around the planet. Voyager's speed before approaching ...

21

To add to the answers @Hobbes & @Steve Linton posted, the mission designers indeed knew Jupiter's gravity field quite well from the orbits of Jupiter's moons. But before the Voyagers arrived they got additional measurements from the close flybys of two other spacecraft, Pioneers 10 and 11. @Steve Linton correctly describes the effect of the "sideways" ...

20

Whilst the main factors involved in transferring energy to space craft during a flyby are well known, I believe this is a reference to several observed anomalies that have occurred to various space probes, covering everything from the early Pioneer probes to the much more recent Rosetta probe. The researchers looked at five deep-space probes — Galileo to ...

18

JunoCam used different technologies than does the typical framing camera one buys at a store. A typical digital color camera uses a Bayer filter pattern, a row of alternating tiny blue and green filters, followed by a row of alternating tiny green and red filters, each filter covering a pixel, followed by a row of alternating tiny blue and green filters, and ...

18

Given the mass costs in terms of consumables and the risk and support costs of keeping humans in space for longer, it seems unlikely that the multiple Earth-Venus flybys used by a lot of robot probes to get out to Jupiter or in to Mercury will ever be a sensible choice for humans. A Jupiter flyby on the way to Saturn is probably a no-brainer apart from maybe ...

16

JAXA's Hayabusa came to within 44 meters of 25143 Itokawa, which, in an unfortunate sequence of events, lead to its lander MINERVA to miss the target: MINERVA was deployed on 12 November 2005. The lander release command was sent from Earth, but before the command could arrive, Hayabusa's altimeter measured its distance from Itokawa to be 44 m (144 ft) ...

16

In simple explanation, we won't able to know what's up with New Horizons right away. The probe will be busy collecting all the science data during the high-speed flyby. Closest approach will be at a distance of 3,500 kilometers at about 05:33 on 1 January UTC, and it’ll happen at a zippy 14.16 kilometers per second. [1] (empasis mine) As happened at ...

15

Let's try and understand how gravity works in space. This is kind of key idea to understanding lots of issues in space travel and astronomy. So imagine a space probe, or rock, which is heading in from deep space, aimed almost, but not quite towards a planet. We can break that motion into two parts -- the part towards the planet and the "sideways" part. The ...

14

Here is a paper which among other things includes the results of a trajectory search. They say Gravity assists of Earth, Venus, and Mars were included with a patched conics assumption. Jupiter was immediately discarded as it is out of phase during the desired time period. The trajectories proposed in that paper involve multiple Earth and Venus flybys. I ...

13

Here's how, using an approximate patched conic technique. The $\Delta V$ using instantaneous (e.g. chemical propulsion) maneuvers can be determined by repeated application of this equation that simply says that the total energy is the sum of the kinetic energy and the potential energy: $\mathcal{E}=\frac{v^2}{2}-\frac{\mu}{r}$ where $\mathcal{E}$ is the ...

13

The flyby distance will depend on how accurately they can measure 2014 MU69's orbit. This KBO was discovered only 3 years ago, and because it's so faint we only have a few observations to go on. For the Pluto encounter, the NH team went back to the Lowell observatory archives to measure the original plates made by Tombaugh when he discovered Pluto, in an ...

12

No, the Atlas 551 is not powerful enough to send Juno to Jupiter. From this article on NASA's website: The Juno spacecraft was launched from Kennedy Space Center in Florida on August 5, 2011. Juno’s launch vehicle was capable of giving the spacecraft only enough energy to reach the asteroid belt, at which point the sun’s gravity pulled it back ...

12

This last downlink transmission, ending ~24 hours before the flyby is a contingency plan. If New Horizons has a catastrophic collision as it passes through the Pluto system, we'll at least have some data. This downlink is called "Fail Safe D". NH Closest approach: July 14, 2015 11:49:57 UTC From Emily Lakdawalla's list, all times are Earth time (i.e. the ...

12

Yes, the Flyby Anomaly is still an unsolved problem. Studies have found several candidates for the cause of the anomaly. A recent study examined Juno's behavior on its Jupiter orbits, and found the anomaly there as well: “Our conclusion is that an anomalous acceleration is also acting upon the Juno spacecraft in the vicinity of the perijove (in this ...

11

It was displayed publicly yesterday! At a Karman lecture held by Mr. Blaine Baggett, Director, Office of Communication and Education, JPL. It might not be archived and available to download right now, but soon it will. And I'm sorry for being a spoiler, but it is in the last few minutes of his show. Even the crayons used to draw it are preserved. (I might ...

11

Yes, Jupiter can make a trajectory perpendicular to the ecliptic, which is exactly what it did for Ulysses, which observed the poles of the Sun: The function is just vector addition. It depends on the $V_\infty$ with respect to Jupiter and the flyby distance, from which you get a change in direction in the plane of the trajectory relative to Jupiter, which ...

10

During the maneuver? Certainly not. You don't mess with the spacecraft configuration around or anywhere near critical events unless it is absolutely necessary. Modern spacecraft are all designed to permit their flight software to be updated. A complete image of the new flight software is uploaded the spacecraft. The image's integrity is verified, and ...

10

Chinese Chang'e 2 flew 3.2 km from the asteroid 4179 Toutatis (size: 4.7×2.4×1.9 km) in 2012 after having ended its primary Lunar mission. Maybe a record for intentional flyby's? Here's a list of the 21 asteroids and comets and minor planets visited by spacecrafts, with closest approach altitude. One way to define it is in number of object radii, and then ...

9

What this is called primarily is called Attitude Determination, and is a part of the attitude control system in most spacecraft. Wikipedia has a great bit on that, which states: Two star cameras are used to measure the spacecraft attitude. They are mounted on the face of the spacecraft and provide attitude information while in spin-stabilized or 3-axis ...

9

Safe mode is a software state that is initiated by a detection of some inability of the system to do what it has been asked to do. There are many, many ways that can happen, such as insufficient power, inability to determine attitude, detection of a failed component, such as a reaction wheel, or a software fault or crash. In safe mode, only the minimum ...

8

Most satellites have some sort of a safe mode, a mode the satellite enters when it is having difficulties with certain things. The exact nature of the safe mode varies from satellite to satellite, but in general, it is a lower power state, thermally stable and power positive, turns off science instruments, and relies less on absolute pointing. I can say ...

8

This is purely a speculation, as I have not found any official sources to confirm it, but I think they want to be able to view Saturn's pole during the fly by. The trigonometry works out at least: If you want to get a close-up of the polar regions with a lower inclination, like 40, 50 or 60 degrees, the altitude required is larger than the gap between ...

7

I believe what's confusing you is that the NASA trajectory browser is applying your query parameters more literally than you're likely reading them. You see, your query has, among other parameter values, two values that would likely make it seem that your observations are indeed correct: Max duration: 20 years (Maximum acceptable total mission duration.) ...

7

In fact, the New Horizons team is now admitting that they missed the Pluto image, and likely Charon as well. Here's a few quotes from the Washington Post. If you look at the first big close-up photo of Pluto, you’ll notice the shadow line, the terminator. The spacecraft wasn’t supposed to aim right there And later on: The New Horizons team was aiming ...

7

We simply don't have the launcher system to accomplish that (see below). EDIT (hat tip to Mark Adler for an answer to a related question - although please have a look at his criticism of my answer here before judging for yourself and voting): That means a mission that can achieve Pluto orbit insertion (POI) after being launched from the Earth on a single ...

7

A gravity assist at Jupiter would have been used to decrease Solar Probe (Plus)'s orbital speed, lowering its perihelion as explained well in this answer. Credit: NASA/JHUAPL In fact, for such an extreme low perihelion, the Jupiter gravity assist is much more fuel-efficient than a direct transfer (note - Parker uses multiple Venus gravity assists to save ...

7

Update 2019-01-01: I've calculated detailed resolution and range values for the encounter's imaging schedule. The chart can be found in this answer (scroll down to Resolution during capture in meters per pixel). I was gathering data to do the math and came across this: New Horizons is planned to come within 3,500 km (2,200 mi) of 2014 MU69, three times ...

6

Keep in mind that until New Horizon gets there we don't know a great deal about the atmosphere of Pluto. There seem to be a number of theories (the article I'm using as a source doesn't match the paper linked in a comment) but our only way to observe the atmosphere so far has been during infrequent occultation events when Pluto moves between an observatory ...

6

The sad reality is that by splitting a probe into a few subprobes you decrease mass, thermal control, and energy budgets available for scientific payloads. mass: you still have to build the frame sturdy enough to withstand high g's at launch; command and data handling equipment is the same for a large and a small probe, etc. thermal control - heaters can ...

6

This image shows the trajectory of the Juno spacecraft. It can be seen that the closest approach takes place in the shroud of Earth's shadow, so most of the world is going to miss this. Source Two minutes before closest approach Juno will experience the only eclipse of its mission, passing into the umbra of Earth’s shadow for about 20 minutes. ...

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