SPACE - random thread about space stuff

Holman · Post by **Holman** » Tue Jun 23, 2015 9:25 am

stessier wrote:With New Horizons destined to meet Pluto on July 14, I've been doing some background reading and finally found someone who would be envious of Smoove's internet connection!

Communication with the spacecraft is via X band. The craft had a communication rate of 38 kbit/s at Jupiter; at Pluto's distance, a rate of approximately 1 kbit/s is expected. Besides the low bandwidth, Pluto's distance also causes a (one-way) latency of about 4.5 hours.

New Verizons.

wonderpug · Post by **wonderpug** » Tue Jun 23, 2015 9:27 am

Unagi wrote:How does the distance only cause a one-way latency? That makes about zero sense to me.

It causes 4.5 hour latency going one way. It also causes 4.5 hour latency going the other way.

stessier · Post by **stessier** » Tue Jun 23, 2015 9:29 am

Unagi wrote:How does the distance only cause a one-way latency? That makes about zero sense to me.

It's just 4.5 hours one way - 9 hours round trip. They quote it one way because it's not like you are doing a live chat with that type of latency. They will mostly just be listening as it beams back the data it gets.

Unagi · Post by **Unagi** » Tue Jun 23, 2015 9:31 am

Oh, OK - I get it.

Thanks.
For some reason, to my ear, it sounded like they were trying to say that there wasn't any latency in the other direction, or that the latency would be different.

stessier · Post by **stessier** » Tue Jun 23, 2015 9:33 am

If you can figure out how to do that, you can make a lot of money.

Unagi · Post by **Unagi** » Tue Jun 23, 2015 9:34 am

If I remove the (), I think it's how they say "The distance causes a one-way latency..." that I focused on...

Better:
Pluto's distance also causes a latency of about 4.5 hours (one-way).
or
Pluto's distance also causes a latency of about 4.5 hours (9 hours, round-trip).

AWS260 · Post by **AWS260** » Tue Jun 23, 2015 9:43 am

A great explanation from Emily Lakdawalla of what that tiny bandwidth means:

On Sunday, July 12, New Horizons will transmit the last of its optical navigation data. These images will have lower resolution than the images we have already received from Dawn at Ceres. Then, on Sunday and Monday, July 12 and 13, there will be a series of four "Fail Safe" downlinks. These are designed to return a minimum set of data from all instruments, just in case New Horizons does not survive the flyby. A last downlink ending overnight Monday July 13, called "E-Health 1," will include one last pre-closest approach photo of Pluto.

Then there is a nail-biting 24-hour period of waiting while New Horizons concentrates on flyby science and does not communicate with Earth, followed by the much-anticipated beep of the "Phone Home" downlink on Tuesday night, July 14. Following closest approach, on Wednesday and Thursday, July 15 and 16, there will be a series of "First Look" downlinks containing a sampling of key science data. Another batch of data will arrive in the "Early High Priority" downlinks over the subsequent weekend, July 17-20. Then there will be a hiatus of 8 weeks before New Horizons turns to systematically downlinking all its data. Almost all image data returned during the week around closest approach will be lossily compressed -- they will show JPEG compression artifacts. Only the optical navigation images are losslessly compressed.

The transmission of the High Priority data set will be complete on July 20, and then image transmission will pause. For nearly two months, until September 14, New Horizons will switch to near-real-time downlinking of data from instruments that generate low data volumes (like SWAP and PEPSSI) while it transmits just housekeeping information for all of the rest of the data. No new images will arrive on the ground during this time.

On September 14, New Horizons will begin downlinking a "browse" version of the entire Pluto data set, in which all images will be lossily compressed. It will take about 10 weeks to get that data set to the ground. There will be compression artifacts, but we'll see the entire data set. Then, around November 16, New Horizons will begin to downlink the entire science data set losslessly compressed. It will take a year to complete that process.

stessier · Post by **stessier** » Tue Jun 23, 2015 9:43 am

Indeed. I just noticed I didn't include the link.

It's from Wikipedia - you can make the change!

wonderpug · Post by **wonderpug** » Tue Jun 23, 2015 9:54 am

Unagi wrote:Oh, OK - I get it.
Thanks.
For some reason, to my ear, it sounded like they were trying to say that there wasn't any latency in the other direction, or that the latency would be different.

Don't worry, you're not crazy. : ) Their sentence was poorly worded.

Unagi · Post by **Unagi** » Tue Jun 23, 2015 9:59 am

stessier wrote:It's from Wikipedia - you can make the change!

Done !

The Meal · Post by **The Meal** » Tue Jun 23, 2015 10:31 am

stessier wrote:If you can figure out how to do that, you can make a lot of money.

Well actually... If there's a lot of pairity bits and redundancies in the signal from the probe, then that transmission may carry much less signal per unit time compared to the outgoing transmissions from Earth. Why? Because the probe is very limited in its battery capacity (and therefore transmission power) while terrestrial sources are not nearly so limited.

Five-million dollars, please.

stessier · Post by **stessier** » Tue Jun 23, 2015 10:36 am

The Meal wrote:
stessier wrote:If you can figure out how to do that, you can make a lot of money.
Well actually... If there's a lot of pairity bits and redundancies in the signal from the probe, then that transmission may carry much less signal per unit time compared to the outgoing transmissions from Earth. Why? Because the probe is very limited in its battery capacity (and therefore transmission power) while terrestrial sources are not nearly so limited.

Five-million dollars, please.

First I have no idea what I am talking about. Pretty much a given on the internet, but just wanted it out there.

How does that decrease latency? Isn't it the time from Point A to Point B? It's going at the speed of light (or there abouts) isn't it?

The Meal · Post by **The Meal** » Tue Jun 23, 2015 10:44 am

I'm talking out of my ass as well.

I think you're correct regarding latency. My statement would apply to transmission speeds.

Here's your five million bucks back.

wonderpug · Post by **wonderpug** » Tue Jun 23, 2015 10:59 am

You're not thinking fourth dimensionally!

Max Peck · Post by **Max Peck** » Tue Jun 23, 2015 11:02 am

The Meal wrote:I'm talking out of my ass as well.

I think you're correct regarding latency. My statement would apply to transmission speeds.

Here's your five million bucks back.

Well, FWIW, you can link the signal coding to latency since the processing time to decode the signal will increase the latency to some (probably negligible) degree. But not to the tune of a 5 megabuck prize...

The Meal · Post by **The Meal** » Tue Jun 23, 2015 11:33 am

Nice! 5¢ please.

Kraken · Post by **Kraken** » Sun Jun 28, 2015 12:05 pm

Ker-boom! goes the latest ISS resupply launch, this time by SpaceX. Third consecutive failure, but the first for the Falcon booster. No word yet on whether the astronauts are drawing straws. NASA usually issues a "no problem" statement after one of these missions fails...but after three in a row I imagine that some commodities must be getting a little tight.

Smoove_B · Post by **Smoove_B** » Tue Jun 30, 2015 11:24 am

The APOD for today is showing what appears to be a mountain on Ceres - possibly one of the bright spots previously viewed through as Dawn has been moving closer over the last few months...

El Guapo · Post by **El Guapo** » Tue Jun 30, 2015 11:32 am

Kraken wrote:Ker-boom! goes the latest ISS resupply launch, this time by SpaceX. Third consecutive failure, but the first for the Falcon booster. No word yet on whether the astronauts are drawing straws. NASA usually issues a "no problem" statement after one of these missions fails...but after three in a row I imagine that some commodities must be getting a little tight.

I saw a news piece this morning suggesting that, if the space station cannot be supplied sometime this summer, NASA would have to consider evacuating it. Which struck me as rather odd:

(1) Presumably NASA would need to send a shuttle up to bring the astronauts down, right? Wouldn't that shuttle just bring supplies? Or do the astronauts have a way to get down on their own?

(2) Isn't it kind of weird that we are dependent on a company to resupply an international space station? Though I guess it's better to have more options, I suppose.

Isgrimnur · Post by **Isgrimnur** » Tue Jun 30, 2015 11:36 am

The failure have been a team effort.

The failure is the third unsuccessful cargo mission over the past eight months. A Russian cargo ship did not complete its mission in April, and an Orbital Sciences Corp. capsule was destroyed in a launch accident in October.

And they have the means to return already there.

2012 wrote:The crew of the International Space Station (ISS) briefly took refuge in escape capsules as a piece of space junk hurtled by.
...
They were ordered by ground control to move into two Soyuz escape capsules in case the station was hit, but a Nasa spokesman said they were given the green light to return to the main station at 0238 GMT on Saturday.

LawBeefaroni · Post by **LawBeefaroni** » Tue Jun 30, 2015 1:01 pm

This is a bit old (and possibly posted in one of the random threads), but

Samantha Cristoforetti - Keeping Space Fun:

Max Peck · Post by **Max Peck** » Tue Jun 30, 2015 1:50 pm

El Guapo wrote:
Kraken wrote:Ker-boom! goes the latest ISS resupply launch, this time by SpaceX. Third consecutive failure, but the first for the Falcon booster. No word yet on whether the astronauts are drawing straws. NASA usually issues a "no problem" statement after one of these missions fails...but after three in a row I imagine that some commodities must be getting a little tight.
I saw a news piece this morning suggesting that, if the space station cannot be supplied sometime this summer, NASA would have to consider evacuating it. Which struck me as rather odd:

(1) Presumably NASA would need to send a shuttle up to bring the astronauts down, right? Wouldn't that shuttle just bring supplies? Or do the astronauts have a way to get down on their own?

(2) Isn't it kind of weird that we are dependent on a company to resupply an international space station? Though I guess it's better to have more options, I suppose.

The last I heard, the supplies on hand are sufficient to keep the 3-man crew going until October 2015. There are something like 4 resupply missions scheduled before then, although one of them was a Falcon 9 mission and would presumably be scrubbed if they don't sort out the most recent launch failure.

NASA doesn't have any way to launch/retrieve crew using their own equipment. So far as I know, they are completely reliant on the Russians for manned vehicles at the moment.

Max Peck · Post by **Max Peck** » Tue Jun 30, 2015 1:52 pm

LawBeefaroni wrote:This is a bit old (and possibly posted in one of the random threads), but

Samantha Cristoforetti - Keeping Space Fun:

I think I'm in love (again)...

Kraken · Post by **Kraken** » Tue Jun 30, 2015 7:07 pm

Max Peck wrote:
El Guapo wrote:
Kraken wrote:Ker-boom! goes the latest ISS resupply launch, this time by SpaceX. Third consecutive failure, but the first for the Falcon booster. No word yet on whether the astronauts are drawing straws. NASA usually issues a "no problem" statement after one of these missions fails...but after three in a row I imagine that some commodities must be getting a little tight.
I saw a news piece this morning suggesting that, if the space station cannot be supplied sometime this summer, NASA would have to consider evacuating it. Which struck me as rather odd:

(1) Presumably NASA would need to send a shuttle up to bring the astronauts down, right? Wouldn't that shuttle just bring supplies? Or do the astronauts have a way to get down on their own?

(2) Isn't it kind of weird that we are dependent on a company to resupply an international space station? Though I guess it's better to have more options, I suppose.
The last I heard, the supplies on hand are sufficient to keep the 3-man crew going until October 2015. There are something like 4 resupply missions scheduled before then, although one of them was a Falcon 9 mission and would presumably be scrubbed if they don't sort out the most recent launch failure.

NASA doesn't have any way to launch/retrieve crew using their own equipment. So far as I know, they are completely reliant on the Russians for manned vehicles at the moment.

The Falcon has 18 successful launches behind it, so this failure shouldn't be a huge setback for further cargo missions. Bigger question is whether it will affect their crewed launch timetable. SpaceX said that astronauts would have survived that explosion, btw.

Max Peck · Post by **Max Peck** » Tue Jun 30, 2015 7:32 pm

Kraken wrote:The Falcon has 18 successful launches behind it, so this failure shouldn't be a huge setback for further cargo missions. Bigger question is whether it will affect their crewed launch timetable. SpaceX said that astronauts would have survived that explosion, btw.

As I understand it there won't be any Falcon 9 launches until the cause of the failure is identified, which will hopefully not take too long.

Gwynne Shotwell, president, SpaceX wrote:Once we identify the issues we will submit that documentation to the FAA and it will be considered prior to the next flight. I don't have a timeline for that right now. It certainly isn't going to be a year - (more likely) a month or so.

Kraken · Post by **Kraken** » Mon Jul 06, 2015 1:41 am

Not good: NASA lost contact with New Horizons on July 4. When communications were restored the probe was in safe mode. They've got about a week to fix it before closest approach. It's turning into a nail-biter.

stessier · Post by **stessier** » Mon Jul 06, 2015 3:58 am

And back to working order.

No sweat.

stessier · Post by **stessier** » Mon Jul 06, 2015 11:35 am

In other good news, looks like the ISS was resupplied as well.

Lassr · Post by **Lassr** » Mon Jul 06, 2015 8:50 pm

Kraken wrote:Not good: NASA lost contact with New Horizons on July 4. When communications were restored the probe was in safe mode. They've got about a week to fix it before closest approach. It's turning into a nail-biter.

All is well

"The investigation into the anomaly that caused New Horizons to enter 'safe mode' on July 4 has concluded that no hardware or software fault occurred on the spacecraft," mission team members wrote in an update Sunday (July 5). "The underlying cause of the incident was a hard-to-detect timing flaw in the spacecraft command sequence that occurred during an operation to prepare for the close flyby. No similar operations are planned for the remainder of the Pluto encounter."

Kraken · Post by **Kraken** » Mon Jul 06, 2015 9:40 pm

I'm relieved that no lengthy trouble-shooting was required. With an 8.8-hour two-way communications delay, it would've unfolded in slow motion.

stessier · Post by **stessier** » Tue Jul 07, 2015 3:50 am

Lassr wrote:
Kraken wrote:Not good: NASA lost contact with New Horizons on July 4. When communications were restored the probe was in safe mode. They've got about a week to fix it before closest approach. It's turning into a nail-biter.
All is well

"The investigation into the anomaly that caused New Horizons to enter 'safe mode' on July 4 has concluded that no hardware or software fault occurred on the spacecraft," mission team members wrote in an update Sunday (July 5). "The underlying cause of the incident was a hard-to-detect timing flaw in the spacecraft command sequence that occurred during an operation to prepare for the close flyby. No similar operations are planned for the remainder of the Pluto encounter."

I guess I made my post from Pluto...that would explain your 16 hour delay in seeing it.

AWS260 · Post by **AWS260** » Sun Jul 12, 2015 10:41 am

A good article on the New Horizons speedbump.

Carpet_pissr · Post by **Carpet_pissr** » Sun Jul 12, 2015 11:18 am

Kraken wrote:"Stunning" NASA video of Soyuz docking at the ISS. A half hour of nothing happening very slowly won't be for everyone, but it does convey a strong you-are-there feeling from the Soyuz POV. I'd change "stunning" to "mesmerizing" and beautiful.

Nothing visual happens after target acquisition so spare yourself the last 8 minutes.

Fantastic. I would love to see an external shot as well, to see what it looks like from about 100' away.

Also, first thing that hit my brain when I saw the imagery was flashbacks to the movie 'Gravity'.

Isgrimnur · Post by **Isgrimnur** » Sun Jul 12, 2015 12:12 pm

Three billion miles from Earth and just two and a half million miles from Pluto, NASA’s New Horizons spacecraft has taken its best image of four dark spots that continue to captivate.

The spots appear on the side of Pluto that always faces its largest moon, Charon—the face that will be invisible to New Horizons when the spacecraft makes its close flyby the morning of July 14. New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado, describes this image as “the last, best look that anyone will have of Pluto’s far side for decades to come.”

The spots are connected to a dark belt that circles Pluto’s equatorial region. What continues to pique the interest of scientists is their similar size and even spacing. “It’s weird that they’re spaced so regularly,” says New Horizons program scientist Curt Niebur at NASA Headquarters in Washington. Jeff Moore of NASA’s Ames Research Center, Mountain View, California, is equally intrigued. “We can’t tell whether they’re plateaus or plains, or whether they’re brightness variations on a completely smooth surface.”

The large dark areas are now estimated to be 300 miles (480 kilometers) across, an area roughly the size of the state of Missouri. In comparison with earlier images, we now see that the dark areas are more complex than they initially appeared, while the boundaries between the dark and bright terrains are irregular and sharply defined.

Isgrimnur · Post by **Isgrimnur** » Tue Jul 14, 2015 8:11 am

AWS260 · Post by **AWS260** » Tue Jul 14, 2015 8:57 am

The Meal · Post by **The Meal** » Tue Jul 14, 2015 9:03 am

Indeed.

Isgrimnur · Post by **Isgrimnur** » Tue Jul 14, 2015 9:05 am

This picture is how Charon was discovered in 1978.

In 1994, this is the picture that Hubble took after corrective surgery:

Smoove_B · Post by **Smoove_B** » Tue Jul 14, 2015 9:24 am

Yeah, that picture they posted this morning is insanely awesome. Mind-boggling, almost.

cheeba · Post by **cheeba** » Tue Jul 14, 2015 9:29 am

Yeah it's beautiful. I expected it to be a big snowball before we started seeing good pictures from this mission.