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In the history of space launches, which week has had the most space launches? It would be also nice to know the second and third place. I think its also interesting to ask about most busy month and day too but I am not sure if I should ask two separate questions or maybe should just rewrite the title question.

Related questions:

Most busy times in space launches by decade?

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  • 1
    $\begingroup$ We generally allow multiple closely related questions like these. $\endgroup$ Aug 1 '20 at 17:38
  • $\begingroup$ I think you are asking for the most launch vehicles that launched and that is what people answered. Other forms of busiest could include the most tones or payload shipped, the most mass that went up, the most number of payload craft/items delivered. I expect that many modern launches put a larger number of small payloads (statelites) into space, even if they only launch one a week. $\endgroup$
    – TafT
    Aug 3 '20 at 15:46
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+300
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The below data is based on the JSR Launch Vehicle Database, 2017 Dec 28 Edition. Specifically, it's based on a SQL schema I built from the JSR data. The data is trivial to install on an Oracle or Postgres database. And there are CSV files, so it should be relatively easy to load the data into other tools.

Once you have the data loaded into a database, it's easy to crank out these kind of numbers. But the interpretation is tricky. First, as Andrew mentioned in his answer, how exactly do you define a "day" or a "week"? Also, what exactly is a "space launch"? JSR has 10 launch categories and it's not always clear which ones you want to choose. (JSR has the categories orbital, military missile, test rocket, atmospheric rocket, suborbital rocket other than missile, deep space, high altitude sounding rocket, reentry test, launch from world other than Earth, and suborbital spaceplane with human crew. The names in my data set are slightly different for some of them because I guessed before all the codes were clarified in 2019.)

Busiest Day

35 days had three launches:

LAUNCH_DAY   LAUNCH_COUNT
----------   ------------
1962-04-26              3
1963-11-27              3
1967-02-08              3
1968-03-05              3
1969-10-24              3
1970-04-08              3
1970-12-12              3
1971-09-28              3
1972-06-30              3
1974-05-15              3
1975-02-06              3
1975-09-09              3
1976-07-08              3
1977-08-24              3
1977-10-28              3
1978-01-10              3
1983-05-26              3
1984-11-14              3
1985-08-08              3
1985-10-03              3
1987-09-16              3
1988-03-11              3
1989-02-10              3
1989-02-14              3
1990-02-28              3
1990-08-28              3
1993-03-25              3
1993-06-25              3
1994-11-29              3
1995-03-22              3
1996-04-24              3
2005-12-21              3
2010-06-15              3
2012-05-17              3
2017-06-23              3

Query:

select to_char(trunc(launch_date), 'YYYY-MM-DD') launch_day, count(*) launch_count
from launch
where launch_status = 'success'
    and launch_category in ('deep space', 'orbital')
group by trunc(launch_date)
order by launch_count desc, launch_day;

Busiest Week

Based on the ISO week, 1985-10-21 to 1985-10-27 was the busiest with 7 launches:

LAUNCH_DATE           FLIGHT_ID2
-----------           ----------
1985-10-22 07:00:00   Kosmos-1697
1985-10-22 20:24:07   Kosmos-1698
1985-10-23 00:42:07   Molniya-1
1985-10-25 15:45:00   Kosmos-1700
1985-10-21 05:04:00   FSW
1985-10-25 14:40:00   Kosmos-1699
1985-10-24 02:30:00   Meteor-3

Many weeks had 6 launches:

1962-04-23  1962-04-29
1968-04-15  1968-04-21
1968-08-05  1968-08-11
1970-04-06  1970-04-12
1971-04-19  1971-04-25
1971-11-29  1971-12-05
1971-12-13  1971-12-19
1973-10-29  1973-11-04
1977-09-19  1977-09-25
1978-06-26  1978-07-02
1979-06-04  1979-06-10
1981-05-18  1981-05-24
1981-08-03  1981-08-09
1983-06-27  1983-07-03
1984-06-25  1984-07-01
1987-12-21  1987-12-27
1988-09-05  1988-09-11
1993-06-21  1993-06-27
1994-08-22  1994-08-28
1994-10-31  1994-11-06
2015-03-23  2015-03-29

Query:

select
    to_char(trunc(launch_date, 'iw'), 'YYYY-MM-DD') week_start,
    to_char(trunc(launch_date, 'iw')+6, 'YYYY-MM-DD') week_end,
    count(*) over (partition by trunc(launch_date, 'iw')) launches_per_week,
    to_char(launch_date, 'YYYY-MM-DD HH24:MI:SS') launch_date,
    flight_id2
from launch
where launch_status = 'success'
    and launch_category in ('deep space', 'orbital')
order by launches_per_week desc, week_start;

Busiest Month

THE_MONTH   LAUNCH_COUNT
---------   ------------
1971-12               17
1983-04               17
1984-06               17
1975-09               16
1976-07               16
1977-09               16
1982-06               16
1984-08               16
1985-10               16
1965-12               15
...

Query:

select to_char(launch_date, 'YYYY-MM') the_month, count(*) launch_count
from launch
where launch_status = 'success'
    and launch_category in ('deep space', 'orbital')
group by to_char(launch_date, 'YYYY-MM')
order by launch_count desc, the_month;

Busiest Year

THE_YEAR   LAUNCH_COUNT
--------   ------------
    1984            128
    1983            127
    1976            126
    1975            125
    1967            124
    1977            123
    1978            123
    1981            123
    1968            121
    1985            120
...

Query:

select to_char(launch_date, 'YYYY') the_year, count(*) launch_count
from launch
where launch_status = 'success'
    and launch_category in ('deep space', 'orbital')
group by to_char(launch_date, 'YYYY')
order by launch_count desc, the_year;
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  • $\begingroup$ Wonderful answer! Consider having a look at Databases of “scrubbed” launch attempts? and a similar strategy might work for How do launches avoid leap seconds? Why? $\endgroup$
    – uhoh
    Aug 3 '20 at 7:28
  • 1
    $\begingroup$ @uhoh Thanks, I'll try to take a look at those questions tomorrow. $\endgroup$
    – Jon Heller
    Aug 3 '20 at 7:30
  • $\begingroup$ Both are great answers, it really hurts that I can only accept one one of them. Can I ask for the most busy years too? $\endgroup$
    – Joe Jobs
    Aug 3 '20 at 8:39
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    $\begingroup$ Nice! An actual database is much slicker than my approach, which was an unholy amalgam of bash processing and Google Sheets :-) $\endgroup$
    – Andrew
    Aug 3 '20 at 8:41
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    $\begingroup$ @JoeJobs That difference is because my list only counts successful launches, and the Wikipedia chart includes failures. $\endgroup$
    – Jon Heller
    Nov 11 '20 at 2:51
35
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I've done a very quick and dirty guess by pulling out all the dates of "things that look like orbital launches" from the JSR dataset, and looking for clusters of dates. I have omitted launch failures and suborbital launches, and converted everything into calendar days. It also omits everything before 1963 (which are recorded differently) but I think we can reasonably assume the record was not set that early. All dates are using UTC.

It suggests the seven day period with the most launches was March 2015, with a total of eight launches - two launches on 25 March, one on 26, two on 27, one on 28, one on 30, and one on 31. (Details)

There were periods with 7 launches in 7 days in October 1967, December 1970, December 1971, December 1975, December 1977, February 1979, September 1985, October 1985, March 1988, and August 1994.

Busiest day - there seem to be a few dozen days (defined as single days in UTC) with three launches each, but none with four. So a bit of a wash there. There is, however, one 24-hour period with four launches - two late on 5 September 1989, and two early on 6 September (details).

Busiest month - by calendar month, there seem to be five tying for 17 launches (December 1971, July 1967, June 1982, April 1983, June 1984). Within a 31-day period, the record is 20, covering 29 November 1971 to 21 December 1971 (plus a bonus three launch failures, so came close to being 23 - details)

This was a fun data-analysis exercise!

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    $\begingroup$ I'm surprised that the busy weeks and busy months are so spread throughout the decades. Nice work! $\endgroup$ Aug 1 '20 at 17:34
  • $\begingroup$ Well spread but bon existant after the end of Cold War it seems $\endgroup$
    – Joe Jobs
    Aug 2 '20 at 11:05
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    $\begingroup$ @JoeJobs thanks! And by all means add another question - I think I can't pull out US-specific launches from the data I have here, so I might need to try a different approach... $\endgroup$
    – Andrew
    Aug 2 '20 at 11:16
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    $\begingroup$ @JoeJobs turns out it was easier than I thought, so approach 2 tested and ready to answer the US-focused question whenever you are ready to post it :-) $\endgroup$
    – Andrew
    Aug 2 '20 at 12:03
  • 2
    $\begingroup$ How else could you define launches (world-wide) in one day, if not launches within a 24-hour period? I know your linked Wikipedia article uses UTC, but that is just an arbitrary convention. $\endgroup$
    – TonyK
    Aug 2 '20 at 12:29

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