150:β is defined as mass divided by drag force (mas per unit drag area). A higher mass per unit drag area causes aeroshell entry, descent, and landing to happen at low and dense points of the atmosphere and also reduces the elevation capability and the timeline margin for landing. This is because a higher mass/drag area means the spacecraft does not have sufficient drag to slow down early in its decent, relying on the thicker atmosphere found at lower altitudes for the majority of its deceleration. Furthermore, higher mass/drag ratios mean less mass can be allocated to the spacecraft's payload which will have secondary impacts on funding and mission's science goals. Factors that increase during EDL include heat load and rate, which causes the system to forcefully accommodate the increase in thermal loads. This situation reduces the useful landed mass capability of entry, descent, and landing because an increase in thermal load leads to a heavier support structure and thermal protection system (TPS) of the aeroshell. Static stability also needs to be taken into consideration as it is necessary to maintain a high-drag altitude. This is why a swept aeroshell forebody as opposed to a blunt one is required; the previous shape ensures this factor's existence but also reduces drag area. Thus, there is a resulting tradeoff between drag and stability that affects the design of an aeroshell's shape. Lift-to-drag ratio is also another factor that needs to be considered. The ideal level for a lift-to-drag ration is at non-zero. Maintaining a non-zero L/D ratio allows for a higher parachute deployment altitude and reduced loads during deceleration.
426:
121:, and other hardware needed for the specific mission's entry, descent, and landing sequence. The parachute is located at the apex of the back shell and slows the spacecraft during EDL. The pyrotechnic control system releases devices such as nuts, rockets, and the parachute mortar. The inertial measurement unit reports the orientation of the back shell while it is swaying underneath the parachute. Retrorockets, if equipped, can assist in the terminal descent and landing of the spacecraft vehicle; alternatively or additionally, a lander may have retrorockets mounted on its own body for terminal descent and landing use (after the backshell has been jettisoned). Other rockets may be equipped to provide horizontal force to the back shell, helping to orient it to a more vertical position during the main retrorocket burn.
141:. If its structure is well-designed enough and made from robust material (such as steel), then it can withstand a higher amount of g's. However, payload needs to be considered. Just because the spacecraft's structure can withstand high g's does not mean its payload can. For example, a payload of astronauts can only withstand approximately 9 g's, or 9 times their weight. Values that are more than this baseline increase risk of brain injury or death. It must also be able to withstand high temperature caused by the immense friction resulting from entering the atmosphere at hypersonic speed. Finally, it must be able to penetrate an atmosphere and land on a terrain accurately, without missing its target. A more constricted landing area calls for more strict accuracy. In such cases, a spacecraft will be more
450:
438:
391:
371:
301:
406:
20:
159:
109:, or forebody, which is located at the front of the aeroshell, and the back shell, which is located at the back of the aeroshell. The heat shield of the aeroshell faces the ram direction (forward) during a spacecraft's atmospheric entry, allowing it to absorb the high heat caused by compression of air in front of the craft. The backshell acts as a finalizer for the encapsulation of the payload. The backshell typically contains a
303:
307:
306:
302:
308:
324:, Hawaiʻi, at 18:45 UTC (08:45 local). A high-altitude helium balloon, which when fully inflated has a volume of 1,120,000 cubic meters (39,570,000 cu ft), lifted the vehicle to around 37,000 meters (120,000 ft). The vehicle detached at 21:05 UTC (11:05 local), and four small, solid-fuel rocket motors spun up the vehicle to provide stability.
305:
149:
The overall dynamics of aeroshells are influenced by inertial and drag forces, as defined it this equation: ß=m/CdA where m is defined as the mass of the aeroshell and its respective loads and CdA is defined as the amount of drag force an aeroshell can generate during a freestream condition. Overall,
145:
and possess a steeper re-entry trajectory angle. These factors combine to affect the re-entry corridor, the area in which a spacecraft must travel in order to avoid burning up or rebounding out of an atmosphere. All of these above requirements are met through the consideration, design, and adjustment
335:
4 and an altitude of approximately 55,000 meters (180,000 ft). Immediately after rocket burn-out, four more rocket motors despun the vehicle. Upon slowing to Mach 3.8, the 6-meter (20 ft) tube-shaped
Supersonic Inflatable Aerodynamic Decelerator (SIAD-R configuration) deployed. SIAD is
358:
Two more test flights of LDSD took place in mid-2015 at the
Pacific Missile Range Facility. They focused on the 8-meter (26 ft) SIAD-E and SSDS technologies, incorporating lessons learned during the 2014 test. Changes planned for the parachute include a rounder shape and structural
81:
slow descent. Airbags may also be inflated to cushion impact with the ground, in which case the spacecraft could bounce on the planet's surface after the first impact. In many cases, communication throughout the process is relayed or recorded for subsequent transfer.
339:
Upon slowing to Mach 2.5 (around 107 seconds after SIAD deployment), the
Supersonic Disk Sail (SSDS) parachute was deployed to slow the vehicle further. This parachute measures 33.5 meters (110 ft) in diameter, nearly twice as large as the one used for the
133:, heating, and impact and landing accuracy. A spacecraft must have a maximum value of deceleration low enough to keep the weakest points of its vehicle intact but high enough to penetrate the atmosphere without rebounding. Spacecraft structure and
265:
in order to decelerate during entry through a planet's atmosphere. It is essentially a disc-shaped vehicle containing an inflatable, doughnut-shaped balloon around the outside. The use of this type of system may allow an increase in the payload.
304:
50:(the forebody) and a back shell. The heat shield absorbs heat caused by air compression in front of the spacecraft during its atmospheric entry. The back shell carries the load being delivered, along with important components such as a
492:
146:
of a spacecraft's structure and trajectory. Future missions however are making use of atmospheric rebound, allowing re-entry capsules to travel further during their decent, and land in more convenient locations.
344:
mission. However, it began tearing apart after deployment, and the vehicle impacted the
Pacific Ocean at 21:35 UTC (11:35 local) travelling 32 to 48 kilometers per hour (20 to 30 mph). All hardware and
349:
were recovered. Despite the parachute incident, the mission was declared a success; the primary goal was proving the flight worthiness of the test vehicle, while SIAD and SSDS were secondary experiments.
425:
370:
507:
77:. During the latter stages of descent, a parachute is typically deployed and any heat shield is detached. Rockets may be located at the back shell to assist in control or to
97:
to
Jupiter. The size and geometry of an aeroshell is driven by the requirements of the EDL phase of its mission, as these parameters heavily influence its performance.
721:
405:
69:, process of a spacecraft's flight. First, the aeroshell decelerates the spacecraft as it penetrates the planet's atmosphere and must necessarily dissipate the
1091:
1109:
1086:
336:
intended to increase atmospheric drag on the vehicle by increasing the surface area of its leading side, thus increasing the rate of deceleration.
390:
73:
of the very high orbital speed. The heat shield absorbs some of this energy while much is also dissipated into the atmospheric gasses, mostly by
89:. They have been used on the majority of missions returning payloads to the Earth. They are also used for all landing missions to Mars, Venus,
129:
A spacecraft's mission objective determines what flight requirements are needed to ensure mission success. These flight requirements are
449:
437:
960:
663:
993:
1047:
899:
736:
868:
253:
503:
38:
shell that helps decelerate and protects a spacecraft vehicle from pressure, heat, and possible debris created by
925:
599:
317:
416:
316:
The test flight took place on June 28, 2014, with the test vehicle launching from the United States Navy's
762:
85:
Aeroshells are a key component of space probes that must land intact on the surface of any object with an
1098:
66:
285:
198:
181:
Mars landing program. To simulate the thin
Martian atmosphere, the parachute needed to be used at an
163:
118:
59:
930:
281:. After sufficient deceleration, a parachute on a long tether deploys to further slow the vehicle.
277:. This is done by inflating the balloon around the vehicle to increase the surface area and create
623:
396:
341:
74:
1066:
201:, where the vehicle was dropped and the engines beneath the vehicle boosted it to the required
178:
137:
mass affect how much maximum deceleration it can stand. This force is represented by "g's", or
533:
1133:
557:
173:'s Planetary Entry Parachute Program (PEPP) aeroshell, tested in 1966, was created to test
710:. Federal Aviation Administration - Advanced Aerospace Medicine On-line. pp. 310–311.
8:
190:
1021:
381:
1099:"Flight Dynamics of an Aeroshell Using an Attached Inflatable Aerodynamic Decelerator"
998:
270:
43:
19:
935:
796:
138:
39:
78:
377:
278:
262:
213:
70:
1127:
359:
reinforcement. Shortly after re-entry, however, the parachute was torn away.
346:
94:
55:
62:
that monitors the orientation of the shell during parachute-slowed descent.
834:"NASA's Low-Density Supersonic Decelerator Test Flight Hailed as a Success"
130:
90:
332:
142:
114:
106:
47:
35:
158:
833:
289:
86:
1067:"For Fuel Conservation in Space, NASA Engineers Prescribe Aerocapture"
900:"A Successful First Flight for of the Saucer Test Vehicle over Hawaii"
412:
232:
226:
212:
The
Voyager program was later canceled, replaced by the much smaller
206:
174:
110:
51:
162:
USAF Aeroshell "Flying Saucer" on public display in
Missile Park at
965:
664:"Orion Spacecraft to Test New Entry Technique on Artemis I Mission"
328:
202:
182:
23:
1097:
Axdahl, Erik; Cruz, Juan R.; Schoenenberger, Mark; Wilhite, Alan.
763:"NASA tests flying saucer craft for future manned mission to Mars"
767:
194:
186:
134:
649:
Roller
Coasters, G Forces, and Brain Trauma: On the Wrong Track?
869:"LDSD passes primary technology test but suffers chute failure"
236:
probes to the outer planets, which had nothing to do with the
694:
Multi-Objective
Hypersonic Entry Aeroshell Shape Optimization
583:
Multi-Objective Hypersonic Entry Aeroshell Shape Optimization
479:
Multi-Objective Hypersonic Entry Aeroshell Shape Optimization
321:
16:
Shell which protects a spacecraft during atmospheric reentry
1096:
1071:
732:
651:. Larchmont, NY: Mary Ann Liebert, Inc. pp. 1117–1118.
274:
237:
217:
170:
185:
more than 160,000 feet (49,000 m) above the Earth. A
1026:
961:"Flying Saucer Videos Reveal What Worked and What Didn't"
994:"NASA Mars test a success. Now to master the parachute"
117:
devices along with their electronics and batteries, an
1048:"Lockheed Martin To Design Mars Science Lab Aeroshell"
797:"Press Kit: Low-Density Supersonic Decelerator (LDSD)"
246:
696:. RESTON: AMER INST AERONAUT ASTRONAUT. p. 958.
585:. RESTON: AMER INST AERONAUT ASTRONAUT. p. 959.
284:
The vehicle is being developed and tested by NASA's
153:
761:Erdman, Shelby Lin; Botelho, Greg (June 29, 2014).
105:The aeroshell consists of two main components: the
1110:American Institute of Aeronautics and Astronautics
1092:Early Reentry Vehicles: Blunt Bodies and Ablatives
987:
985:
983:
827:
825:
823:
821:
481:. RESTON: AMER INST AERONAUT ASTRONAUT. p. 1.
331:solid-fuel motor ignited, powering the vehicle to
1022:"Parachute on Nasa 'flying saucer' fails in test"
791:
789:
787:
785:
1125:
980:
893:
891:
889:
818:
722:"Hypersonic Entry Aeroshell Shape Optimization"
954:
952:
862:
860:
858:
856:
854:
782:
193:was used to initially lift the aeroshell. The
760:
624:"Mars Exploration Rover Mission: The Mission"
926:"NASA to test giant Mars parachute on Earth"
917:
886:
949:
851:
754:
327:A half second after spin-up, the vehicle's
691:
580:
485:
476:
531:
431:33.5-meter Supersonic Ring Sail Parachute
897:
299:
295:
157:
18:
866:
65:Its purpose is used during the EDL, or
1126:
1019:
831:
261:is a space vehicle designed to create
58:, and monitoring electronics like an
991:
958:
923:
687:
685:
683:
661:
600:"Aeroshells: Keeping Spacecraft Safe"
380:releasing the aeroshell-clad lander (
594:
592:
472:
470:
353:
269:It is intended to be used to help a
558:"Pioneer Venus Project Information"
93:and (in the most extreme case) the
46:. Its main components consist of a
13:
867:Parslow, Matthew (June 28, 2014).
680:
254:Low-Density Supersonic Decelerator
247:Low-Density Supersonic Decelerator
139:Earth's gravitational acceleration
14:
1145:
646:
589:
504:U.S. Department of Transportation
467:
154:Planetary Entry Parachute Program
124:
898:McKinnon, Mika (June 29, 2014).
493:"Returning from Space: Re-Entry"
448:
436:
424:
404:
389:
369:
1013:
714:
700:
500:Federal Aviation Administration
992:Rosen, Julia (June 30, 2014).
959:Boyle, Alan (August 8, 2014).
924:Chang, Alicia (June 1, 2014).
832:Carney, Emily (July 1, 2014).
708:Returning from Space: Re-entry
655:
640:
616:
574:
550:
525:
415:heat shield on display at the
318:Pacific Missile Range Facility
1:
460:
417:Virginia Air and Space Museum
312:Video of the 2014 test flight
100:
1020:Allman, Tim (June 9, 2015).
662:Kraft, Rachel (2021-04-08).
7:
692:Theisinger, John.E (2009).
581:Theisinger, John.E (2009).
477:Theisinger, John.E (2009).
67:Entry, Descent, and Landing
10:
1150:
362:
376:Artist impression of the
286:Jet Propulsion Laboratory
199:White Sands Missile Range
197:then drifted west to the
164:White Sands Missile Range
119:inertial measurement unit
60:inertial measurement unit
931:Las Vegas Review-Journal
729:Solar System Exploration
292:is the project manager.
534:"Mars 2020's Aeroshell"
397:Mars Science Laboratory
342:Mars Science Laboratory
313:
167:
27:
538:NASA Mars Exploration
311:
296:June 2014 test flight
271:spacecraft decelerate
216:several years later.
161:
22:
562:nssdc.gsfc.nasa.gov
191:Roswell, New Mexico
1087:Space travel guide
647:Smith, Douglas.H.
399:giant heat shield.
314:
273:before landing on
168:
28:
999:Los Angeles Times
354:2015 test flights
309:
79:retropropulsively
44:atmospheric entry
1141:
1120:
1118:
1116:
1103:
1083:
1081:
1080:
1062:
1060:
1059:
1039:
1038:
1036:
1034:
1017:
1011:
1010:
1008:
1006:
989:
978:
977:
975:
973:
956:
947:
946:
944:
942:
936:Associated Press
921:
915:
914:
912:
910:
895:
884:
883:
881:
879:
873:NASA Spaceflight
864:
849:
848:
846:
844:
829:
816:
815:
813:
811:
801:
793:
780:
779:
777:
775:
758:
752:
751:
749:
747:
742:on 27 April 2015
741:
735:. Archived from
726:
718:
712:
711:
704:
698:
697:
689:
678:
677:
675:
674:
659:
653:
652:
644:
638:
637:
635:
634:
620:
614:
613:
611:
610:
596:
587:
586:
578:
572:
571:
569:
568:
554:
548:
547:
545:
544:
529:
523:
522:
520:
518:
513:on 19 March 2015
512:
506:. Archived from
497:
489:
483:
482:
474:
452:
440:
428:
408:
393:
373:
310:
279:atmospheric drag
263:atmospheric drag
1149:
1148:
1144:
1143:
1142:
1140:
1139:
1138:
1124:
1123:
1114:
1112:
1101:
1078:
1076:
1065:
1057:
1055:
1046:
1043:
1042:
1032:
1030:
1018:
1014:
1004:
1002:
990:
981:
971:
969:
957:
950:
940:
938:
922:
918:
908:
906:
896:
887:
877:
875:
865:
852:
842:
840:
830:
819:
809:
807:
799:
795:
794:
783:
773:
771:
759:
755:
745:
743:
739:
724:
720:
719:
715:
706:
705:
701:
690:
681:
672:
670:
660:
656:
645:
641:
632:
630:
622:
621:
617:
608:
606:
604:Lockheed Martin
598:
597:
590:
579:
575:
566:
564:
556:
555:
551:
542:
540:
532:mars.nasa.gov.
530:
526:
516:
514:
510:
495:
491:
490:
486:
475:
468:
463:
456:
453:
444:
441:
432:
429:
420:
409:
400:
394:
385:
374:
365:
356:
300:
298:
249:
156:
127:
103:
17:
12:
11:
5:
1147:
1137:
1136:
1122:
1121:
1094:
1089:
1084:
1063:
1041:
1040:
1012:
979:
948:
916:
885:
850:
817:
781:
753:
713:
699:
679:
654:
639:
615:
588:
573:
549:
524:
484:
465:
464:
462:
459:
458:
457:
455:8-meter SIAD-E
454:
447:
445:
443:6-meter SIAD-R
442:
435:
433:
430:
423:
421:
410:
403:
401:
395:
388:
386:
378:Viking Orbiter
375:
368:
364:
361:
355:
352:
347:data recorders
297:
294:
248:
245:
214:Viking program
209:was deployed.
189:launched from
155:
152:
126:
125:Design factors
123:
102:
99:
71:kinetic energy
56:rocket engines
15:
9:
6:
4:
3:
2:
1146:
1135:
1132:
1131:
1129:
1111:
1107:
1100:
1095:
1093:
1090:
1088:
1085:
1074:
1073:
1068:
1064:
1053:
1049:
1045:
1044:
1029:
1028:
1023:
1016:
1001:
1000:
995:
988:
986:
984:
968:
967:
962:
955:
953:
937:
933:
932:
927:
920:
905:
901:
894:
892:
890:
874:
870:
863:
861:
859:
857:
855:
839:
835:
828:
826:
824:
822:
805:
798:
792:
790:
788:
786:
770:
769:
764:
757:
738:
734:
730:
723:
717:
709:
703:
695:
688:
686:
684:
669:
665:
658:
650:
643:
629:
628:mars.nasa.gov
625:
619:
605:
601:
595:
593:
584:
577:
563:
559:
553:
539:
535:
528:
509:
505:
501:
494:
488:
480:
473:
471:
466:
451:
446:
439:
434:
427:
422:
418:
414:
407:
402:
398:
392:
387:
383:
379:
372:
367:
366:
360:
351:
348:
343:
337:
334:
330:
325:
323:
319:
293:
291:
287:
282:
280:
276:
272:
267:
264:
260:
256:
255:
244:
242:
239:
235:
234:
229:
228:
224:name for the
223:
219:
215:
210:
208:
204:
200:
196:
192:
188:
184:
180:
176:
172:
165:
160:
151:
147:
144:
140:
136:
132:
122:
120:
116:
112:
108:
98:
96:
95:Galileo probe
92:
88:
83:
80:
76:
72:
68:
63:
61:
57:
53:
49:
45:
41:
37:
36:heat-shielded
33:
25:
21:
1113:. Retrieved
1105:
1077:. Retrieved
1075:. 2006-08-17
1070:
1056:. Retrieved
1054:. 2006-03-30
1051:
1031:. Retrieved
1025:
1015:
1003:. Retrieved
997:
970:. Retrieved
964:
939:. Retrieved
929:
919:
907:. Retrieved
903:
876:. Retrieved
872:
841:. Retrieved
838:AmericaSpace
837:
808:. Retrieved
803:
772:. Retrieved
766:
756:
744:. Retrieved
737:the original
728:
716:
707:
702:
693:
671:. Retrieved
667:
657:
648:
642:
631:. Retrieved
627:
618:
607:. Retrieved
603:
582:
576:
565:. Retrieved
561:
552:
541:. Retrieved
537:
527:
515:. Retrieved
508:the original
499:
487:
478:
357:
338:
326:
315:
283:
268:
258:
252:
250:
240:
231:
225:
221:
211:
205:, where the
169:
148:
131:deceleration
128:
104:
84:
64:
31:
29:
1134:Spaceflight
220:reused the
143:streamlined
115:pyrotechnic
107:heat shield
48:heat shield
34:is a rigid
1079:2007-02-17
1058:2007-02-17
1052:Mars Daily
1005:August 12,
972:August 12,
941:August 12,
909:August 12,
878:August 12,
843:August 12,
810:August 12,
806:. May 2014
774:August 12,
673:2022-11-17
633:2019-12-02
609:2019-12-02
567:2022-11-16
543:2022-11-16
461:References
411:Detail of
290:Mark Adler
175:parachutes
101:Components
87:atmosphere
413:Apollo 12
382:Don Davis
243:program.
233:Voyager 2
227:Voyager 1
207:parachute
111:parachute
75:radiation
52:parachute
32:aeroshell
26:aeroshell
1128:Category
1115:12 April
1106:NASA.gov
966:NBC News
804:NASA.gov
746:12 April
517:12 April
329:Star 48B
203:altitude
183:altitude
177:for the
24:Viking 1
1033:June 9,
904:io9.com
768:CNN.com
363:Gallery
241:Voyager
222:Voyager
195:balloon
187:balloon
179:Voyager
135:payload
42:during
322:Kauaʻi
1102:(PDF)
800:(PDF)
740:(PDF)
725:(PDF)
511:(PDF)
496:(PDF)
91:Titan
1117:2015
1072:NASA
1035:2015
1007:2014
974:2014
943:2014
911:2014
880:2014
845:2014
812:2014
776:2014
748:2015
733:NASA
668:NASA
519:2015
333:Mach
275:Mars
259:LDSD
251:The
238:Mars
230:and
218:NASA
171:NASA
40:drag
1027:BBC
320:in
257:or
30:An
1130::
1108:.
1104:.
1069:.
1050:.
1024:.
996:.
982:^
963:.
951:^
934:.
928:.
902:.
888:^
871:.
853:^
836:.
820:^
802:.
784:^
765:.
731:.
727:.
682:^
666:.
626:.
602:.
591:^
560:.
536:.
502:.
498:.
469:^
384:).
288:.
113:,
54:,
1119:.
1082:.
1061:.
1037:.
1009:.
976:.
945:.
913:.
882:.
847:.
814:.
778:.
750:.
676:.
636:.
612:.
570:.
546:.
521:.
419:.
166:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
