Sub-orbital spaceflight
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Name | Year | Flights | Location |
---|---|---|---|
Mercury-Redstone 3 Mercury-Redstone 4 |
1961 | 2 | Cape Canaveral |
X-15 Flight 90 X-15 Flight 91 |
1963 | 2 | Edwards AFB
|
Soyuz 18a |
1975 | 1 | Baikonur Cosmodrome |
SpaceShipOne Flight 15P SpaceShipOne Flight 16P SpaceShipOne Flight 17P |
2004 | 3 | Mojave Air and Space Port |
Blue Origin NS-16[1] Blue Origin NS-18 Blue Origin NS-19 |
2021 | 3 | Corn Ranch |
Blue Origin NS-20 Blue Origin NS-21 |
2022 | 3 |
Name | Year | Flights | Location |
---|---|---|---|
X-15 Flight 62 | 1962 | 1 | Edwards AFB
|
X-15 Flight 77 X-15 Flight 87 |
1963 | 2 | |
X-15 Flight 138 X-15 Flight 143 X-15 Flight 150 X-15 Flight 153 |
1965 | 4 | |
X-15 Flight 174 | 1966 | 1 | |
X-15 Flight 190 X-15 Flight 191 |
1967 | 2 | |
X-15 Flight 197 | 1968 | 1 | |
Soyuz MS-10 | 2018 | 1 | Baikonur Cosmodrome |
VSS Unity VP-03 | 2018 | 1 | Mojave Air and Space Port |
VSS Unity VF-01 | 2019 | 1 | |
VSS Unity Unity21
VSS Unity Unity22 |
2021 | 2 | Spaceport America |
VSS Unity Unity25 Galactic 01 Galactic 02 Galactic 03 Galactic 04 Galactic 05 |
2023 | 6 | Spaceport America |
Galactic 06 | 2024 | 1 | Spaceport America |
A sub-orbital spaceflight is a
For example, the path of an object launched from Earth that reaches the Kármán line (about 83 km [52 mi] – 100 km [62 mi][2] above sea level), and then falls back to Earth, is considered a sub-orbital spaceflight. Some sub-orbital flights have been undertaken to test spacecraft and launch vehicles later intended for orbital spaceflight. Other vehicles are specifically designed only for sub-orbital flight; examples include crewed vehicles, such as the X-15 and SpaceShipTwo, and uncrewed ones, such as ICBMs and sounding rockets.
Flights which attain sufficient velocity to go into
A flight that does not reach space is still sometimes called sub-orbital, but cannot officially be classified as a "sub-orbital spaceflight". Usually a rocket is used, but some experimental sub-orbital spaceflights have also been achieved via the use of space guns.[3]
Altitude requirement
By definition, a sub-orbital spaceflight reaches an
Orbit
During
where is the standard gravitational parameter.
Almost always a < R, corresponding to a lower than the minimum for a full orbit, which is
Thus the net extra specific energy needed compared to just raising the spacecraft into space is between 0 and .
Speed, range, and altitude
To minimize the required
If one's goal is simply to "reach space", for example in competing for the
Compare this with orbital spaceflights: a low Earth orbit (LEO), with an altitude of about 300 km, needs a speed around 7.7 km/s, requiring a delta-v of about 9.2 km/s. (If there were no atmospheric drag the theoretical minimum delta-v would be 8.1 km/s to put a craft into a 300-kilometer high orbit starting from a stationary point like the South Pole. The theoretical minimum can be up to 0.46 km/s less if launching eastward from near the equator.)
For sub-orbital spaceflights covering a horizontal distance the maximum speed and required delta-v are in between those of a vertical flight and a LEO. The maximum speed at the lower ends of the trajectory are now composed of a horizontal and a vertical component. The higher the horizontal
For larger ranges, due to the elliptic orbit the maximum altitude can be much more than for a LEO. On a 10,000-kilometer intercontinental flight, such as that of an intercontinental ballistic missile or possible future
The minimum delta-v and the corresponding maximum altitude for a given range can be calculated, d, assuming a spherical Earth of circumference 40000 km and neglecting the Earth's rotation and atmosphere. Let θ be half the angle that the projectile is to go around the Earth, so in degrees it is 45°×d/10000 km. The minimum-delta-v trajectory corresponds to an ellipse with one focus at the centre of the Earth and the other at the point halfway between the launch point and the destination point (somewhere inside the Earth). (This is the orbit that minimizes the semi-major axis, which is equal to the sum of the distances from a point on the orbit to the two foci. Minimizing the semi-major axis minimizes the specific orbital energy and thus the delta-v, which is the speed of launch.) Geometrical arguments lead then to the following (with R being the radius of the Earth, about 6370 km):
The altitude of apogee is maximized (at about 1320 km) for a trajectory going one quarter of the way around the Earth (10000 km). Longer ranges will have lower apogees in the minimal-delta-v solution.
(where g is the acceleration of gravity at the Earth's surface). The Δv increases with range, leveling off at 7.9 km/s as the range approaches 20000 km (halfway around the world). The minimum-delta-v trajectory for going halfway around the world corresponds to a circular orbit just above the surface (of course in reality it would have to be above the atmosphere). See lower for the time of flight.
An
The initial direction of a minimum-delta-v trajectory points halfway between straight up and straight toward the destination point (which is below the horizon). Again, this is the case if the Earth's rotation is ignored. It is not exactly true for a rotating planet unless the launch takes place at a pole.[7]
Flight duration
In a vertical flight of not too high altitudes, the time of the free-fall is both for the upward and for the downward part the maximum speed divided by the acceleration of gravity, so with a maximum speed of 1 km/s together 3 minutes and 20 seconds. The duration of the flight phases before and after the free-fall can vary.
For an intercontinental flight the
Sub-orbital flights can last from just seconds to days.
To calculate the time of flight for a minimum-delta-v trajectory, according to
Using
This gives about 32 minutes for going a quarter of the way around the Earth, and 42 minutes for going halfway around. For short distances, this expression is
From the form involving arccosine, the derivative of the time of flight with respect to d (or θ) goes to zero as d approaches 20000 km (halfway around the world). The derivative of Δv also goes to zero here. So if d = 19000 km, the length of the minimum-delta-v trajectory will be about 19500 km, but it will take only a few seconds less time than the trajectory for d = 20000 km (for which the trajectory is 20000 km long).
Flight profiles
While there are a great many possible sub-orbital flight profiles, it is expected that some will be more common than others.
Ballistic missiles
The first sub-orbital vehicles which reached space were
Tourist flights
Sub-orbital tourist flights will initially focus on attaining the altitude required to qualify as reaching space. The flight path will be either vertical or very steep, with the spacecraft landing back at its take-off site.
The spacecraft will shut off its engines well before reaching maximum altitude, and then coast up to its highest point. During a few minutes, from the point when the engines are shut off to the point where the atmosphere begins to slow down the downward acceleration, the passengers will experience weightlessness.
Megaroc had been planned for sub-orbital spaceflight by the British Interplanetary Society in the 1940s.[9][10]
In the autumn of 1945, the group M. Tikhonravov K. and N. G. Chernysheva at NII-4 rocket artillery Academy of Sciences technology on its own initiative the first stratospheric rocket project was developed by VR-190 for vertical flight two pilots to an altitude of 200 km based on captured German ballistic rocket V-2.[11]
In 2004, a number of companies worked on vehicles in this class as entrants to the Ansari X Prize competition. The
In 2005,
Scientific experiments
A major use of sub-orbital vehicles today is as
Sub-orbital transportation
Research, such as that done for the
However, the size of rocket, relative to the payload, necessary to achieve this, is similar to an ICBM. ICBMs have delta-v's somewhat less than orbital; and therefore would be somewhat cheaper than the costs for reaching orbit, but the difference is not large.[15]
Due to the high cost of spaceflight, suborbital flights are likely to be initially limited to high value, very high urgency cargo deliveries such as courier flights, military fast-response operations or space tourism.[opinion]
The
SpaceX is potentially considering using their Starship as a sub-orbital point-to-point transportation system.[17]
Notable uncrewed sub-orbital spaceflights
- The first sub-orbital space flight was on 20 June 1944, when MW 18014, a V-2 test rocket, launched from Peenemünde in Germany and reached 176 kilometres altitude.[18]
- White Sands Proving Grounds. On 24 February 1949 the upper stage reached an altitude of 248 miles (399 km) and a speed of 7,553 feet per second (2,302 m/s; Mach 6.8).[19]
- Albert II, a male rhesus macaque, became the first mammal in space on 14 June 1949 in a sub-orbital flight from Holloman Air Force Base in New Mexico to an altitude of 83 miles (134 km) aboard a U.S. V-2 sounding rocket.
- USSR – Energia, 15 May 1987, a Polyus payload which failed to reach orbit; this was the most massive object launched into sub-orbital spaceflight to date.
Crewed sub-orbital spaceflights
Above 100 km (62.14 mi) in altitude.
Date (GMT) | Mission | Crew | Country | Remarks | |
---|---|---|---|---|---|
1 | 1961-05-05 | Mercury-Redstone 3 | Alan Shepard | United States | First crewed sub-orbital spaceflight, first American in space |
2 | 1961-07-21 | Mercury-Redstone 4 | Virgil Grissom
|
United States | Second crewed sub-orbital spaceflight, second American in space |
3 | 1963-07-19 | X-15 Flight 90 | Joseph A. Walker | United States | First winged craft in space |
4 | 1963-08-22 | X-15 Flight 91 | Joseph A. Walker | United States | First person and spacecraft to make two flights into space |
5 | 1975-04-05 | Soyuz 18a
|
Oleg Makarov
|
Soviet Union | Failed orbital launch. Aborted after malfunction during stage separation |
6 | 2004-06-21 | SpaceShipOne flight 15P | Mike Melvill | United States | First commercial spaceflight |
7 | 2004-09-29 | SpaceShipOne flight 16P | Mike Melvill | United States | First of two flights to win Ansari X-Prize
|
8 | 2004-10-04 | SpaceShipOne flight 17P | Brian Binnie | United States | Second X-Prize flight, clinching award |
9 | 2021-07-20 | Blue Origin NS-16 | Jeff Bezos Mark Bezos Wally Funk Oliver Daemen |
United States | First crewed Blue Origin flight |
10 | 2021-10-13 | Blue Origin NS-18 | United States | Second crewed Blue Origin flight | |
11 | 2021-12-11 | Blue Origin NS-19 | Laura Shepard Churchley Michael Strahan Dylan Taylor Evan Dick Lane Bess Cameron Bess |
United States | Third crewed Blue Origin flight |
12 | 2022-03-31 | Blue Origin NS-20 | Marty Allen Sharon Hagle Marc Hagle Jim Kitchen George Nield Gary Lai |
United States | Fourth crewed Blue Origin flight |
13 | 2022-06-04 | Blue Origin NS-21 | Evan Dick Jaison Robinson
Victor Vescovo |
United States | Fifth crewed Blue Origin flight |
14 | 2022-08-04 | Blue Origin NS-22 | Clint Kelly III Sara Sabry Steve Young |
United States | Sixth crewed Blue Origin flight |
Future of crewed sub-orbital spaceflight
See also
- Canadian Arrow
- CORONA
- DH-1 (rocket)
- Interorbital Systems
- Land of the Giants
- List of rocket launch sites
- Lunar Lander Challenge
- McDonnell Douglas DC-X
- Office of Commercial Space Transportation
- Project Morpheus NASA program to continue developing ALHAT and Q landers
- Quad (rocket)
- Reusable Vehicle Testing program by JAXA
- Rocketplane XP
- Spaceport
- SpaceX reusable launch system development program
- Supersonic transport
- XCOR Lynx
References
- ^ Foust, Jeff (20 July 2021). "Blue Origin launches Bezos on first crewed New Shepard flight". SpaceNews. Retrieved 20 Jul 2021.
- ^ https://scholar.smu.edu/cgi/viewcontent.cgi?article=1126&context=jalc
- ^ "Martlet". Archived from the original on 2010-09-26.
- ^ "100 km Altitude Boundary for Astronautics". Fédération Aéronautique Internationale. Archived from the original on 2011-08-09. Retrieved 2017-09-14.
- ^ Whelan, Mary (5 June 2013). "X-15 Space Pioneers Now Honored as Astronauts". nasa.gov. Archived from the original on 11 June 2017. Retrieved 4 May 2018.
- ^ "85. U.S. Statement, Definition and Delimitation of Outer Space And The Character And Utilization Of The Geostationary Orbit, Legal Subcommittee of the United Nations Committee on the Peaceful Uses of Outer Space at its 40th Session in Vienna from April". state.gov. Retrieved 4 May 2018.
- S2CID 225017449.
- ^ Germany's V-2 Rocket, Kennedy, Gregory P.
- ^ Hollingham, Richard. "How a Nazi rocket could have put a Briton in space". bbc.com. Archived from the original on 14 November 2016. Retrieved 4 May 2018.
- ^ "Megaroc". www.bis-space.com. Archived from the original on 30 October 2016. Retrieved 4 May 2018.
- ISBN 9783709106488.
- ^ "Scaled Composites: Projects - Test Logs for SpaceShipTwo". Archived from the original on 2013-08-16. Retrieved 2013-08-14.
- ^ "Branson on Virgin Galactic crash: 'Space is hard – but worth it'". CNET. Retrieved August 1, 2015.
- ^ "ch2". history.nasa.gov. Archived from the original on 2015-11-29. Retrieved 2015-11-28.
- ^ "The Space Review: Point-to-point suborbital transportation: sounds good on paper, but…". www.thespacereview.com. Archived from the original on 1 August 2017. Retrieved 4 May 2018.
- .
- ^ Ralph, Eric (30 May 2019). "SpaceX CEO Elon Musk wants to use Starships as Earth-to-Earth transports". Teslarati. Retrieved 31 May 2019.
- ISBN 3-8118-4341-9.
- ^ "Bumper Project". White Sands Missile Range. Archived from the original on 2008-01-10.
- ^ Amos, Jonathan (3 June 2014). "Airbus drops model 'space jet'". BBC News. Archived from the original on 4 May 2018. Retrieved 4 May 2018.