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91
Chinese Launchers / Re: Chinese launch schedule
« Last post by starbase on Today at 03:41 PM »
To clarify, this is the current situation at the original 3 Chinese launch sites:

Xichang

- TJS-3 on CZ-3C (rumored on December 25) - payload name and rocket was confirmed officially thanks to a CZ-3C certified for shipping to launch site press release by CALT, but nature of satellite still up in the air.

- The next launch there afterwards is apparently the last old generation BDS-2 replenishment navigation satellite still on the ground (BDS-2 G8? Or maybe -I8?), so January 2019 it is.

Taiyuan

- ZY-1-02D on CZ-4B - Nothing has been heard of it so far. spaceflightfans.cn current list this on December 29, but with a question mark.

Jiuquan

The situation is very confusing there with the possibility of a CZ-2D, a CZ-11 and a KZ-1A all possible to launch in the last 2 weeks of 2018!

- The one launch that is fairly certain is the CZ-2D (late December), reported to be carrying the first test satellite of CAST's Hongyan LEO comsat constellation. Several unspecified other satellites built by DFH Shenzhen (some say 9 total on this launch) are probably also on board. This launch may be the first time the YZ-3 upper stage is used.

- spaceflightfans.cn also lists KZ-1A s/n Y7 to launch on December 26 (delayed from November 25 as of September?), but so far the payload is unknown. So far CASIC has yet to announce any launches in the near future.

- Also listed is a CZ-11 launch in late December, originally attributed to launching the next batch of satellites for the Zhuhai-1 constellation - however the company stated a few days ago that their next launch is next year. 2 test satellites for the Lingque constellation, an EO microsat constellation from a Beijing based company, is listed instead as the payload on this flight by spaceflightfans.cn.

🤔

Thanks for the summary! I guess OneSpace OS-M1 test flight is off the list for this year then...
92
Is the 2nd stage de-orbit a requirement from the USAF, or is it a choice by SpaceX?  (Or something else?)

It's a requirement.
94
SpaceX General Section / Re: SpaceX New FCC Filings for Starlink
« Last post by deruch on Today at 03:33 PM »
If the satellites were ready to launch before final approval, there is nothing preventing SpaceX from putting them into the 550 km orbit, correct? Worst case is the satellites couldn't be turned on for commercial use until approval was secured. AIUI, the company would be free to do all the testing it would like, as long as it simply files a temporary bandwidth request, just like it did for Tintin and all other vehicles. Do I understand this correctly?

No.  They need bandwidth access for all communications with the satellites.  This includes any commanding or even satellite status signals.  I don't believe it would be an appropriate use of the FCC's Special Temporary Authority granting mechanism (or of their shorter-term licensing mechanism) to cover communications with the constellation regardless of whether it was in commercial operation or not.  Nor do I believe that the FCC would ever agree to grant/license bandwidth to such a constellation on those terms. 
95
Propellant filling of liquid strap-ons (L40) begins
https://twitter.com/isro/status/1075053868361277440
96
SpaceX General Section / Re: Elon and the moon
« Last post by RoboGoofers on Today at 03:29 PM »
1/100 c is ~3000 km/s, and requires 4.5e9 MJ (or ~1 Megaton of TNT)  for a 1000 kg probe.  in fact a nuclear bomb might be the best way to get the required potential energy to the track on the moon. much more mass efficient than building power plants and running cables.

the bomb energy isn't very focused, though, unless you use the special bombs designed for project Orion.

In fact, do away with the track as well and just build project Orion.
97
Hasn't it been a while since SpaceX has had a hold like this in the final 10-mins of countdown? 
98
With the press kit, we can now see the sequence of burns:

Launch into an LEO x 4000 km orbit (about 2 hour period).  Takes LEO + 830 m/s.

Wait one hour until apogee, then go 4000 x 20000 km (6.9 hour orbit) .  Takes 1960 m/s.  Release satellite.

Second stage coasts to apogee (3.45 more hours).   Then a retrograde burn at -480 m/s to a 100 x 20000 orbit (5.8 hour period).   Wait 2.9 hours and re-enter.

Total delta-V is about LEO+3270 m/s, as predicted.  Re-entry at launch + 6.5 hours, as stated.  Satellite needs about 970 m/s to circularize.
4000x35000 is a pretty standard second stage graveyard orbit for centaur, so if the deorbit burn is what pushed this expendable, it seems a bit wasteful...
Maybe this is a way of demonstrating and quantifying their extra performance.  It's minimum risk for the Air Force since they use the extra capacity after the spacecraft release, so all margins are available in case of contingency.  But if it works, maybe next time maybe the AF will allow them to use the margin for recovery instead of de-orbit (for a reduced price, most likely).
99
Did it get to warm or cold?

Out of family sensor, could also mean that the reading was not logical and thus false positive?

The phrase "out of family" just means "outside the known range of readings normally gotten from this type of sensor," because you're not going to get exactly the same reading from all sensors.

For example, if you set up ten sensors and put them in the bottom of the same LOX tank, you'll get 10 slightly different readings, but they should all be within an expected range. That's "family."
100
Did it get to warm or cold?

Out of family sensor, could also mean that the reading was not logical and thus false positive?

Wording was "thermally compensated limits", so that means the temperature reading was outside the specification of the used temp sensor. These sensors are built to compensate any errors (e.g. non-linear) changes in the readings for a specified temperature range. If the temp runs outside this window, the value is no longer accurate. Could be a faulty sensor or a temperature too high at the location. That's what SpaceX engineers now need to check. Worst case would be the need to replace the sensor.

I don't think we can say that based on the information currently available.  e.g. If this sensor is in a location which is supposed to be insulated from the cold temps and it suddenly showed as too cold, that could potentially indicate improperly applied insulation or potentially even a minor LOX leak, etc.  Also, the exact call from the LD was for temps "approaching thermally compensated limits."  So, it sounds like at the time of the hold, it might have still been reading within the allowed limits but clearly trending to a violation or possibly violating some rate of change limit (like not actually speeding but accelerating too hard).  All of which is pure hypothetical and just to say that we outsiders don't really know anything and therefore can't say what the worst case might be.
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